Patchwork [v2] ARM: realview: basic device tree implementation

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Submitter Linus Walleij
Date May 8, 2014, 10:08 p.m.
Message ID <1399586896-16906-1-git-send-email-linus.walleij@linaro.org>
Download mbox | patch
Permalink /patch/347261/
State New
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Comments

Linus Walleij - May 8, 2014, 10:08 p.m.
This implements basic device tree boot support for the RealView
platforms, with a basic device tree for ARM PB1176 as an example.

The implementation is done with a new DT-specific board file
using only pre-existing bindings for the basic IRQ, timer and
serial port drivers. A new compatible type is added to the GIC
for the ARM1176.

This implementation uses the MFD syscon handle from day one to
access the system controller registers, and register the devices
using the SoC bus.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
ChangeLog v1->v2:
- Adjust timer clock names to be the same as the example in the
  device tree binding.
- Remove all memory fixup code - this should be handled by the
  device tree specification of memory areas or by special MM hacks
  for the RealView PBX.
- Fix the documentation around syscon to specify that it can be in
  any node, need not be the root node.
- Switch device tree license to the BSD license, taken from
  arch/powerpc/boot/dts/p1024rdb_32b.dts
- Add a hunk for the new compatible string to
  Documentation/devicetree/bindings/arm/gic.txt
- Move the clocks out of the SoC node, certainly the xtal is not
  sitting on the SoC...
- Sort the selects in Kconfig alphabetically
- Use IS_ENABLED() for the l2x0 code snippet
- Instead of checking the board variant in the reset routine to
  figure out how to tweak the reset controller, have a compatible
  string for each syscon variant, map it to an enum that provides a
  unique type ID and that way figure out how to handle it in a maybe
  more elegant way.
- Open issue: what do to with the l2x0 stuff?
---
 Documentation/devicetree/bindings/arm/arm-boards |  57 ++++++
 Documentation/devicetree/bindings/arm/gic.txt    |   1 +
 arch/arm/boot/dts/Makefile                       |   1 +
 arch/arm/boot/dts/arm-realview-pb1176.dts        | 177 ++++++++++++++++++
 arch/arm/mach-realview/Kconfig                   |  10 +
 arch/arm/mach-realview/Makefile                  |   1 +
 arch/arm/mach-realview/realview-dt.c             | 225 +++++++++++++++++++++++
 arch/arm/mm/Kconfig                              |   2 +-
 drivers/irqchip/irq-gic.c                        |   1 +
 9 files changed, 474 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm/boot/dts/arm-realview-pb1176.dts
 create mode 100644 arch/arm/mach-realview/realview-dt.c
Arnd Bergmann - May 9, 2014, 10:44 a.m.
On Friday 09 May 2014, Linus Walleij wrote:

> diff --git a/arch/arm/boot/dts/arm-realview-pb1176.dts b/arch/arm/boot/dts/arm-realview-pb1176.dts
> new file mode 100644
> index 000000000000..0eea0f4a7b39
> --- /dev/null
> +++ b/arch/arm/boot/dts/arm-realview-pb1176.dts

Can you split this up into an arm-realview.dtsi file for the common parts and
a pb1176 specific file for the rest?

> +	soc {
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		compatible = "simple-bus";
> +		ranges;
> +
> +		syscon: syscon@10000000 {
> +			compatible = "arm,realview-pb1176-syscon", "syscon";
> +			reg = <0x10000000 0x1000>;
> +		};

Hmm, in order to have a proper reset driver, we probably want a separate
node for the reset controller. I believe the x-gene people have just
posted a generic reset driver based on syscon. Let's see if we can share
that.

> +		pb1176_serial0: uart@1010c000 {
> +			compatible = "arm,pl011", "arm,primecell";
> +			reg = <0x1010c000 0x1000>;
> +			interrupt-parent = <&intc_dc1176>;
> +			interrupts = <0 18 IRQ_TYPE_LEVEL_HIGH>;
> +			clocks = <&uartclk>, <&pclk>;
> +			clock-names = "uartclk", "apb_pclk";
> +		};

I believe the "official" name for a uart is serial@1010c000, not uart@1010c000.
I know we are inconsistent with that.

> +
> +/* Pointer to the system controller */
> +struct regmap *syscon_regmap;
> +u8 syscon_type;
> +
> +static struct map_desc realview_dt_io_desc[] __initdata = {
> +	{
> +		/* FIXME: static map needed for LED driver */
> +		.virtual	= IO_ADDRESS(REALVIEW_SYS_BASE),
> +		.pfn		= __phys_to_pfn(REALVIEW_SYS_BASE),
> +		.length		= SZ_4K,
> +		.type		= MT_DEVICE,
> +	},
> +};

I've looked at the driver and I don't see why this is required.
The driver does a devm_ioremap_resource(), which should work with
or without a static mapping.

> +/*
> + * We detect the different syscon types from the compatible strings.
> + */
> +enum realview_syscon {
> +	REALVIEW_SYSCON_EB,
> +	REALVIEW_SYSCON_PB1176,
> +	REALVIEW_SYSCON_PB11MP,
> +	REALVIEW_SYSCON_PBA8,
> +	REALVIEW_SYSCON_PBX,
> +};
> +
> +static const struct of_device_id realview_syscon_match[] = {
> +	{
> +		.compatible = "arm,realview-eb-syscon",
> +		.data = (void *)REALVIEW_SYSCON_EB,
> +	},
> +	{
> +		.compatible = "arm,realview-pb1176-syscon",
> +		.data = (void *)REALVIEW_SYSCON_PB1176,
> +	},
> +	{
> +		.compatible = "arm,realview-pb11mp-syscon",
> +		.data = (void *)REALVIEW_SYSCON_PB11MP,
> +	},
> +	{
> +		.compatible = "arm,realview-pba8-syscon",
> +		.data = (void *)REALVIEW_SYSCON_PBA8,
> +	},
> +	{
> +		.compatible = "arm,realview-pbx-syscon",
> +		.data = (void *)REALVIEW_SYSCON_PBX,
> +	},
> +};

If not the generic syscon reset driver, it should at least live in
drivers/power/reset/ rather than here.

> +#if IS_ENABLED(CONFIG_CACHE_L2X0)
> +	if (of_machine_is_compatible("arm,realview-eb"))
> +		/*
> +		 * 1MB (128KB/way), 8-way associativity,
> +		 * evmon/parity/share enabled
> +		 * Bits:  .... ...0 0111 1001 0000 .... .... ....
> +		 */
> +		l2x0_of_init(0x00790000, 0xfe000fff);
> +	else if (of_machine_is_compatible("arm,realview-pb1176"))
> +		/*
> +		 * 128Kb (16Kb/way) 8-way associativity.
> +		 * evmon/parity/share enabled.
> +		 */
> +		l2x0_of_init(0x00730000, 0xfe000fff);
> +	else if (of_machine_is_compatible("arm,realview-pb11mp"))
> +		/*
> +		 * 1MB (128KB/way), 8-way associativity,
> +		 * evmon/parity/share enabled
> +		 * Bits:  .... ...0 0111 1001 0000 .... .... ....
> +		 */
> +		l2x0_of_init(0x00730000, 0xfe000fff);
> +	else if (of_machine_is_compatible("arm,realview-pbx"))
> +		/*
> +		 * 16KB way size, 8-way associativity, parity disabled
> +		 * Bits:  .. 0 0 0 0 1 00 1 0 1 001 0 000 0 .... .... ....
> +		 */
> +		l2x0_of_init(0x02520000, 0xc0000fff);
> +#endif

You wrote that you added the #if IS_ENABLED() here. Why?

l2x0_of_init is already a nop if CONFIG_CACHE_L2X0 is not set. If you want to
skip a bit of dead code here, you could make it an inline function and do

	if (IS_ENABLED(CONFIG_CACHE_L2X0))
		realview_setup_l2x0();

Other than that, I still think we should avoid doing anything platform
specific here at all, and move it all into the l2x0_of_init function,
based on Russell's l2x0 patch series.

> +	soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
> +	if (!soc_dev_attr)
> +		return;
> +	ret = of_property_read_string(root, "compatible",
> +				      &soc_dev_attr->soc_id);
> +	if (ret)
> +		return;
> +	ret = of_property_read_string(root, "model", &soc_dev_attr->machine);
> +        if (ret)
> +		return;
> +	soc_dev_attr->family = "RealView";
> +	soc_dev = soc_device_register(soc_dev_attr);
> +	if (IS_ERR(soc_dev)) {
> +		kfree(soc_dev_attr);
> +		return;
> +	}
> +	parent = soc_device_to_device(soc_dev);
> +	ret = of_platform_populate(root, of_default_bus_match_table,
> +				   NULL, parent);
> +	if (ret) {
> +		pr_crit("could not populate device tree\n");
> +		return;
> +	}

I wonder if there is a way to do this without having code in the platform.
I would hate it if we get to the point where each platform is completely
empty but still requires a copy of this code.

We just faced the same discussion on the exynos chip id patches.

I also noticed that you pass the DT root here, which isn't actually
the intention of the soc device interface: you should pass the DT node
that has the on-chip devices but not the board-level (top-level) nodes
such as your fixed clocks.

> diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
> index 5bf7c3c3b301..5461c4401ed6 100644
> --- a/arch/arm/mm/Kconfig
> +++ b/arch/arm/mm/Kconfig
> @@ -928,7 +928,7 @@ config ARM_L1_CACHE_SHIFT
>  config ARM_DMA_MEM_BUFFERABLE
>  	bool "Use non-cacheable memory for DMA" if (CPU_V6 || CPU_V6K) && !CPU_V7
>  	depends on !(MACH_REALVIEW_PB1176 || REALVIEW_EB_ARM11MP || \
> -		     MACH_REALVIEW_PB11MP)
> +		     MACH_REALVIEW_PB11MP || REALVIEW_DT)
>  	default y if CPU_V6 || CPU_V6K || CPU_V7
>  	help
>  	  Historically, the kernel has used strongly ordered mappings to

Do you have an explanation for why this is needed? I don't remember seeing
this before, but I guess it gets in the way of multiplatform support.
Is this just a performance optimization on realview, or is it actually
required?


	Arnd
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Linus Walleij - May 22, 2014, 7:41 a.m.
On Fri, May 9, 2014 at 12:44 PM, Arnd Bergmann <arnd@arndb.de> wrote:

>> +++ b/arch/arm/boot/dts/arm-realview-pb1176.dts
>
> Can you split this up into an arm-realview.dtsi file for the common parts and
> a pb1176 specific file for the rest?

I wonder if that makes any kind of sense. The RealView platforms does not
really share much more than the name, sadly. For example: IP blocks
aren't even at the same address.

I could create a .dtsi file but it would be empty :-(

>> +     soc {
>> +             #address-cells = <1>;
>> +             #size-cells = <1>;
>> +             compatible = "simple-bus";
>> +             ranges;
>> +
>> +             syscon: syscon@10000000 {
>> +                     compatible = "arm,realview-pb1176-syscon", "syscon";
>> +                     reg = <0x10000000 0x1000>;
>> +             };
>
> Hmm, in order to have a proper reset driver, we probably want a separate
> node for the reset controller. I believe the x-gene people have just
> posted a generic reset driver based on syscon. Let's see if we can share
> that.

I have looked at it. Patch titled
"power: reset: Add generic SYSCON register mapped reset"

Sadly it does not work for our case. This is because it assumes that
reboot will be triggered by writing one value to one register. The RealViews
need you to *first* write to a special unlock register, then write a magic
value to a magic register.

So of course we could extend the syscon regmap reset driver by
starting to encode a jam table such as a sequence of register writes
to a sequence of registers, but we have refused such code in the past
because as I recall Grant said, it is the beginning of a byte code
interpreter and then we could as well bite the bullet and start
implementing open firmware.

This is exactly the type of thing that ACPI AML code usually does
by the way so what he says makes a *lot* of sense.

So for now I keep to our special driver.

>> +             pb1176_serial0: uart@1010c000 {
>> +                     compatible = "arm,pl011", "arm,primecell";
>> +                     reg = <0x1010c000 0x1000>;
>> +                     interrupt-parent = <&intc_dc1176>;
>> +                     interrupts = <0 18 IRQ_TYPE_LEVEL_HIGH>;
>> +                     clocks = <&uartclk>, <&pclk>;
>> +                     clock-names = "uartclk", "apb_pclk";
>> +             };
>
> I believe the "official" name for a uart is serial@1010c000, not uart@1010c000.
> I know we are inconsistent with that.

OK fixed.

>> +/* Pointer to the system controller */
>> +struct regmap *syscon_regmap;
>> +u8 syscon_type;
>> +
>> +static struct map_desc realview_dt_io_desc[] __initdata = {
>> +     {
>> +             /* FIXME: static map needed for LED driver */
>> +             .virtual        = IO_ADDRESS(REALVIEW_SYS_BASE),
>> +             .pfn            = __phys_to_pfn(REALVIEW_SYS_BASE),
>> +             .length         = SZ_4K,
>> +             .type           = MT_DEVICE,
>> +     },
>> +};
>
> I've looked at the driver and I don't see why this is required.
> The driver does a devm_ioremap_resource(), which should work with
> or without a static mapping.

Well yeah, the version of the driver that is in linux-next does this.
This was parallel work and I had no idea which would reach
mainline first :-)

Anyway, I just deleted because I realized it was better if I came
up with the concept of syscon-leds to handle this through the
syscon.

>> +/*
>> + * We detect the different syscon types from the compatible strings.
>> + */
>> +enum realview_syscon {
>> +     REALVIEW_SYSCON_EB,
>> +     REALVIEW_SYSCON_PB1176,
>> +     REALVIEW_SYSCON_PB11MP,
>> +     REALVIEW_SYSCON_PBA8,
>> +     REALVIEW_SYSCON_PBX,
>> +};
>> +
>> +static const struct of_device_id realview_syscon_match[] = {
>> +     {
>> +             .compatible = "arm,realview-eb-syscon",
>> +             .data = (void *)REALVIEW_SYSCON_EB,
>> +     },
>> +     {
>> +             .compatible = "arm,realview-pb1176-syscon",
>> +             .data = (void *)REALVIEW_SYSCON_PB1176,
>> +     },
>> +     {
>> +             .compatible = "arm,realview-pb11mp-syscon",
>> +             .data = (void *)REALVIEW_SYSCON_PB11MP,
>> +     },
>> +     {
>> +             .compatible = "arm,realview-pba8-syscon",
>> +             .data = (void *)REALVIEW_SYSCON_PBA8,
>> +     },
>> +     {
>> +             .compatible = "arm,realview-pbx-syscon",
>> +             .data = (void *)REALVIEW_SYSCON_PBX,
>> +     },
>> +};
>
> If not the generic syscon reset driver, it should at least live in
> drivers/power/reset/ rather than here.

This we can fix.

>> +#if IS_ENABLED(CONFIG_CACHE_L2X0)
>> +     if (of_machine_is_compatible("arm,realview-eb"))
>> +             /*
>> +              * 1MB (128KB/way), 8-way associativity,
>> +              * evmon/parity/share enabled
>> +              * Bits:  .... ...0 0111 1001 0000 .... .... ....
>> +              */
>> +             l2x0_of_init(0x00790000, 0xfe000fff);
>> +     else if (of_machine_is_compatible("arm,realview-pb1176"))
>> +             /*
>> +              * 128Kb (16Kb/way) 8-way associativity.
>> +              * evmon/parity/share enabled.
>> +              */
>> +             l2x0_of_init(0x00730000, 0xfe000fff);
>> +     else if (of_machine_is_compatible("arm,realview-pb11mp"))
>> +             /*
>> +              * 1MB (128KB/way), 8-way associativity,
>> +              * evmon/parity/share enabled
>> +              * Bits:  .... ...0 0111 1001 0000 .... .... ....
>> +              */
>> +             l2x0_of_init(0x00730000, 0xfe000fff);
>> +     else if (of_machine_is_compatible("arm,realview-pbx"))
>> +             /*
>> +              * 16KB way size, 8-way associativity, parity disabled
>> +              * Bits:  .. 0 0 0 0 1 00 1 0 1 001 0 000 0 .... .... ....
>> +              */
>> +             l2x0_of_init(0x02520000, 0xc0000fff);
>> +#endif
>
> You wrote that you added the #if IS_ENABLED() here. Why?

Mainly because I had this other review comment that I
should use IS_ENABLED() rather than #ifdef and it
seemed better but I don't know anymore...

> l2x0_of_init is already a nop if CONFIG_CACHE_L2X0 is not set. If you want to
> skip a bit of dead code here, you could make it an inline function and do
>
>         if (IS_ENABLED(CONFIG_CACHE_L2X0))
>                 realview_setup_l2x0();
>
> Other than that, I still think we should avoid doing anything platform
> specific here at all, and move it all into the l2x0_of_init function,
> based on Russell's l2x0 patch series.

I just need a base branch I guess, then I can build on
top of Russell's patches, it's just a matter of dependencies.

>> +     soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
>> +     if (!soc_dev_attr)
>> +             return;
>> +     ret = of_property_read_string(root, "compatible",
>> +                                   &soc_dev_attr->soc_id);
>> +     if (ret)
>> +             return;
>> +     ret = of_property_read_string(root, "model", &soc_dev_attr->machine);
>> +        if (ret)
>> +             return;
>> +     soc_dev_attr->family = "RealView";
>> +     soc_dev = soc_device_register(soc_dev_attr);
>> +     if (IS_ERR(soc_dev)) {
>> +             kfree(soc_dev_attr);
>> +             return;
>> +     }
>> +     parent = soc_device_to_device(soc_dev);
>> +     ret = of_platform_populate(root, of_default_bus_match_table,
>> +                                NULL, parent);
>> +     if (ret) {
>> +             pr_crit("could not populate device tree\n");
>> +             return;
>> +     }
>
> I wonder if there is a way to do this without having code in the platform.
> I would hate it if we get to the point where each platform is completely
> empty but still requires a copy of this code.

The question can be rephrased like this:
Should we create drivers/soc?

The structure of the SoC bus device is maybe a bit irritating but it
has been hammered into the device core so now we have to live with
it as it is.

> We just faced the same discussion on the exynos chip id patches.

Yes, same answer :-)

> I also noticed that you pass the DT root here, which isn't actually
> the intention of the soc device interface: you should pass the DT node
> that has the on-chip devices but not the board-level (top-level) nodes
> such as your fixed clocks.

Hm that's true. I introduced yet another set of compatible tuples
like this:
compatible = "simple-bus", "arm-realview-pb1176-soc"

It will, just like the reset driver generate a new batch of identical
compatible-strings and documenation sets, but it does have the
upside of clean separation.

>> diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
>> index 5bf7c3c3b301..5461c4401ed6 100644
>> --- a/arch/arm/mm/Kconfig
>> +++ b/arch/arm/mm/Kconfig
>> @@ -928,7 +928,7 @@ config ARM_L1_CACHE_SHIFT
>>  config ARM_DMA_MEM_BUFFERABLE
>>       bool "Use non-cacheable memory for DMA" if (CPU_V6 || CPU_V6K) && !CPU_V7
>>       depends on !(MACH_REALVIEW_PB1176 || REALVIEW_EB_ARM11MP || \
>> -                  MACH_REALVIEW_PB11MP)
>> +                  MACH_REALVIEW_PB11MP || REALVIEW_DT)
>>       default y if CPU_V6 || CPU_V6K || CPU_V7
>>       help
>>         Historically, the kernel has used strongly ordered mappings to
>
> Do you have an explanation for why this is needed? I don't remember seeing
> this before, but I guess it gets in the way of multiplatform support.
> Is this just a performance optimization on realview, or is it actually
> required?

I don't know that actually. And as DMA is likely only used
on PCI I have no way of testing it either without such hardware.
But I guess I can just leave it out for the time being.

Yours,
Linus Walleij
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Linus Walleij - May 22, 2014, 1:04 p.m.
On Thu, May 22, 2014 at 10:31 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Thursday 22 May 2014 09:41:39 Linus Walleij wrote:

>> The question can be rephrased like this:
>> Should we create drivers/soc?
>
> I think we just did, not sure if the patches have made it into linux-next
> already, but there were a couple of other platforms already that want this
> directory.

Awesomeness. Can you give me the title of a patch or branch
from ARM SoC I should pull in to build on top of this? Then I can
split off all the SoC bus business and have the machine file real
small, nice and clean.

Yours,
Linus Walleij
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Rob Herring - May 22, 2014, 1:17 p.m.
On Thu, May 8, 2014 at 5:08 PM, Linus Walleij <linus.walleij@linaro.org> wrote:
> This implements basic device tree boot support for the RealView
> platforms, with a basic device tree for ARM PB1176 as an example.
>
> The implementation is done with a new DT-specific board file
> using only pre-existing bindings for the basic IRQ, timer and
> serial port drivers. A new compatible type is added to the GIC
> for the ARM1176.
>
> This implementation uses the MFD syscon handle from day one to
> access the system controller registers, and register the devices
> using the SoC bus.
>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Rob Herring <robh@kernel.org>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
> ChangeLog v1->v2:
> - Adjust timer clock names to be the same as the example in the
>   device tree binding.
> - Remove all memory fixup code - this should be handled by the
>   device tree specification of memory areas or by special MM hacks
>   for the RealView PBX.
> - Fix the documentation around syscon to specify that it can be in
>   any node, need not be the root node.
> - Switch device tree license to the BSD license, taken from
>   arch/powerpc/boot/dts/p1024rdb_32b.dts
> - Add a hunk for the new compatible string to
>   Documentation/devicetree/bindings/arm/gic.txt
> - Move the clocks out of the SoC node, certainly the xtal is not
>   sitting on the SoC...
> - Sort the selects in Kconfig alphabetically
> - Use IS_ENABLED() for the l2x0 code snippet
> - Instead of checking the board variant in the reset routine to
>   figure out how to tweak the reset controller, have a compatible
>   string for each syscon variant, map it to an enum that provides a
>   unique type ID and that way figure out how to handle it in a maybe
>   more elegant way.
> - Open issue: what do to with the l2x0 stuff?
> ---
>  Documentation/devicetree/bindings/arm/arm-boards |  57 ++++++
>  Documentation/devicetree/bindings/arm/gic.txt    |   1 +
>  arch/arm/boot/dts/Makefile                       |   1 +
>  arch/arm/boot/dts/arm-realview-pb1176.dts        | 177 ++++++++++++++++++
>  arch/arm/mach-realview/Kconfig                   |  10 +
>  arch/arm/mach-realview/Makefile                  |   1 +
>  arch/arm/mach-realview/realview-dt.c             | 225 +++++++++++++++++++++++
>  arch/arm/mm/Kconfig                              |   2 +-
>  drivers/irqchip/irq-gic.c                        |   1 +
>  9 files changed, 474 insertions(+), 1 deletion(-)
>  create mode 100644 arch/arm/boot/dts/arm-realview-pb1176.dts
>  create mode 100644 arch/arm/mach-realview/realview-dt.c
>
> diff --git a/Documentation/devicetree/bindings/arm/arm-boards b/Documentation/devicetree/bindings/arm/arm-boards
> index 3509707f9320..86b36f399d1c 100644
> --- a/Documentation/devicetree/bindings/arm/arm-boards
> +++ b/Documentation/devicetree/bindings/arm/arm-boards
> @@ -86,3 +86,60 @@ Interrupt controllers:
>         compatible = "arm,versatile-sic";
>         interrupt-controller;
>         #interrupt-cells = <1>;
> +
> +
> +ARM RealView Boards
> +-------------------
> +The RealView boards cover tailored evaluation boards that are used to explore
> +the ARM11 and Cortex A-8 and Cortex A-9 processors.
> +
> +Required properties (in root node):
> +       /* RealView Emulation Baseboard */
> +       compatible = "arm,realview-eb";
> +        /* RealView Platform Baseboard for ARM1176JZF-S */
> +       compatible = "arm,realview-pb1176";
> +       /* RealView Platform Baseboard for ARM11 MPCore */
> +       compatible = "arm,realview-pb11mp";
> +       /* RealView Platform Baseboard for Cortex A-8 */
> +       compatible = "arm,realview-pba8";
> +       /* RealView Platform Baseboard Explore for Cortex A-9 */
> +       compatible = "arm,realview-pbx";
> +
> +Required nodes:
> +
> +- syscon: some node of the RealView platforms must have a
> +  system controller node pointing to the control registers,
> +  with the compatible string set to one of these tuples:
> +   "arm,realview-eb-syscon", "syscon"
> +   "arm,realview-pb1176-syscon", "syscon"
> +   "arm,realview-pb11mp-syscon", "syscon"
> +   "arm,realview-pba8-syscon", "syscon"
> +   "arm,realview-pbx-syscon", "syscon"
> +
> +  Required properties for the system controller:
> +  - regs: the location and size of the system controller registers,
> +    one range of 0x1000 bytes.
> +
> +Example:
> +
> +/dts-v1/;
> +#include <dt-bindings/interrupt-controller/irq.h>
> +#include "skeleton.dtsi"
> +
> +/ {
> +       model = "ARM RealView PB1176 with device tree";
> +       compatible = "arm,realview-pb1176";
> +
> +       soc {
> +               #address-cells = <1>;
> +               #size-cells = <1>;
> +               compatible = "simple-bus";
> +               ranges;
> +
> +               syscon: syscon@10000000 {
> +                       compatible = "arm,realview-syscon", "syscon";
> +                       reg = <0x10000000 0x1000>;
> +               };
> +
> +       };
> +};
> diff --git a/Documentation/devicetree/bindings/arm/gic.txt b/Documentation/devicetree/bindings/arm/gic.txt
> index 5573c08d3180..539420194efd 100644
> --- a/Documentation/devicetree/bindings/arm/gic.txt
> +++ b/Documentation/devicetree/bindings/arm/gic.txt
> @@ -16,6 +16,7 @@ Main node required properties:
>         "arm,cortex-a9-gic"
>         "arm,cortex-a7-gic"
>         "arm,arm11mp-gic"
> +       "arm,arm1176jzf-gic"
>  - interrupt-controller : Identifies the node as an interrupt controller
>  - #interrupt-cells : Specifies the number of cells needed to encode an
>    interrupt source.  The type shall be a <u32> and the value shall be 3.
> diff --git a/arch/arm/boot/dts/Makefile b/arch/arm/boot/dts/Makefile
> index 377b7c364033..1419a70026da 100644
> --- a/arch/arm/boot/dts/Makefile
> +++ b/arch/arm/boot/dts/Makefile
> @@ -294,6 +294,7 @@ dtb-$(CONFIG_ARCH_PRIMA2) += prima2-evb.dtb
>  dtb-$(CONFIG_ARCH_QCOM) += qcom-msm8660-surf.dtb \
>         qcom-msm8960-cdp.dtb \
>         qcom-apq8074-dragonboard.dtb
> +dtb-$(CONFIG_ARCH_REALVIEW) += arm-realview-pb1176.dtb
>  dtb-$(CONFIG_ARCH_S3C24XX) += s3c2416-smdk2416.dtb
>  dtb-$(CONFIG_ARCH_S3C64XX) += s3c6410-mini6410.dtb \
>         s3c6410-smdk6410.dtb
> diff --git a/arch/arm/boot/dts/arm-realview-pb1176.dts b/arch/arm/boot/dts/arm-realview-pb1176.dts
> new file mode 100644
> index 000000000000..0eea0f4a7b39
> --- /dev/null
> +++ b/arch/arm/boot/dts/arm-realview-pb1176.dts
> @@ -0,0 +1,177 @@
> +/*
> + * Copyright 2014 Linaro Ltd
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a copy
> + * of this software and associated documentation files (the "Software"), to deal
> + * in the Software without restriction, including without limitation the rights
> + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
> + * copies of the Software, and to permit persons to whom the Software is
> + * furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
> + * THE SOFTWARE.
> + */
> +
> +/dts-v1/;
> +#include <dt-bindings/interrupt-controller/irq.h>
> +#include "skeleton.dtsi"
> +
> +/ {
> +       model = "ARM RealView PB1176 with device tree";

Isn't "with device tree" redundant?

> +       compatible = "arm,realview-pb1176";
> +
> +       chosen { };
> +
> +       aliases {
> +               serial0 = &pb1176_serial0;
> +               serial1 = &pb1176_serial1;
> +               serial2 = &pb1176_serial2;
> +               serial3 = &pb1176_serial3;
> +       };
> +
> +       memory {
> +               /* 128 MiB memory @ 0x0 */
> +               reg = <0x00000000 0x08000000>;
> +       };
> +
> +       xtal24mhz: xtal24mhz@24M {
> +               #clock-cells = <0>;
> +               compatible = "fixed-clock";
> +               clock-frequency = <24000000>;
> +       };
> +
> +       timclk: timclk@1M {
> +               #clock-cells = <0>;
> +               compatible = "fixed-factor-clock";
> +               clock-div = <24>;
> +               clock-mult = <1>;
> +               clocks = <&xtal24mhz>;
> +       };
> +
> +       uartclk: uartclk@24M {
> +               #clock-cells = <0>;
> +               compatible = "fixed-factor-clock";
> +               clock-div = <1>;
> +               clock-mult = <1>;
> +               clocks = <&xtal24mhz>;
> +       };
> +
> +       /* FIXME: this actually hangs off the PLL clocks */
> +       pclk: pclk@0 {
> +               #clock-cells = <0>;
> +               compatible = "fixed-clock";
> +               clock-frequency = <0>;
> +       };
> +
> +       soc {
> +               #address-cells = <1>;
> +               #size-cells = <1>;
> +               compatible = "simple-bus";
> +               ranges;
> +
> +               syscon: syscon@10000000 {
> +                       compatible = "arm,realview-pb1176-syscon", "syscon";
> +                       reg = <0x10000000 0x1000>;
> +               };
> +
> +               /* Primary DevChip GIC synthesized with the CPU */
> +               intc_dc1176: interrupt-controller@10120000 {
> +                       compatible = "arm,arm1176jzf-gic";
> +                       #interrupt-cells = <3>;
> +                       #address-cells = <1>;
> +                       interrupt-controller;
> +                       reg = <0x10121000 0x1000>,
> +                             <0x10120000 0x100>;
> +               };
> +
> +               /* This GIC on the board is cascaded off the DevChip GIC */
> +               intc_pb1176: interrupt-controller@10040000 {
> +                       compatible = "arm,arm1176jzf-gic";
> +                       #interrupt-cells = <3>;
> +                       #address-cells = <1>;
> +                       interrupt-controller;
> +                       reg = <0x10041000 0x1000>,
> +                             <0x10040000 0x100>;
> +                       interrupt-parent = <&intc_dc1176>;
> +                       interrupts = <0 31 IRQ_TYPE_LEVEL_HIGH>;
> +               };
> +
> +               L2: l2-cache {
> +                       compatible = "arm,l220-cache";
> +                       reg = <0x10110000 0x1000>;
> +                       interrupt-parent = <&intc_dc1176>;
> +                       interrupts = <0 13 IRQ_TYPE_LEVEL_HIGH>;
> +                       cache-unified;
> +                       cache-level = <2>;
> +               };
> +
> +               pmu {
> +                       compatible = "arm,arm1176-pmu";
> +                       interrupt-parent = <&intc_dc1176>;
> +                       interrupts = <0 7 IRQ_TYPE_LEVEL_HIGH>;
> +               };
> +
> +               timer01: timer@10104000 {
> +                       compatible = "arm,sp804", "arm,primecell";
> +                       reg = <0x10104000 0x1000>;
> +                       interrupt-parent = <&intc_dc1176>;
> +                       interrupts = <0 8 IRQ_TYPE_LEVEL_HIGH>, <0 9 IRQ_TYPE_LEVEL_HIGH>;
> +                       clocks = <&timclk>, <&timclk>, <&pclk>;
> +                       clock-names = "timer1", "timer2", "apb_pclk";
> +               };
> +
> +               timer23: timer@10105000 {
> +                       compatible = "arm,sp804", "arm,primecell";
> +                       reg = <0x10105000 0x1000>;
> +                       interrupt-parent = <&intc_dc1176>;
> +                       interrupts = <0 10 IRQ_TYPE_LEVEL_HIGH>;
> +                       arm,sp804-has-irq = <1>;
> +                       clocks = <&timclk>, <&timclk>, <&pclk>;
> +                       clock-names = "timer1", "timer2", "apb_pclk";
> +               };
> +
> +               pb1176_serial0: uart@1010c000 {
> +                       compatible = "arm,pl011", "arm,primecell";
> +                       reg = <0x1010c000 0x1000>;
> +                       interrupt-parent = <&intc_dc1176>;
> +                       interrupts = <0 18 IRQ_TYPE_LEVEL_HIGH>;
> +                       clocks = <&uartclk>, <&pclk>;
> +                       clock-names = "uartclk", "apb_pclk";
> +               };
> +
> +               pb1176_serial1: uart@1010d000 {
> +                       compatible = "arm,pl011", "arm,primecell";
> +                       reg = <0x1010d000 0x1000>;
> +                       interrupt-parent = <&intc_dc1176>;
> +                       interrupts = <0 19 IRQ_TYPE_LEVEL_HIGH>;
> +                       clocks = <&uartclk>, <&pclk>;
> +                       clock-names = "uartclk", "apb_pclk";
> +               };
> +
> +               pb1176_serial2: uart@1010e000 {
> +                       compatible = "arm,pl011", "arm,primecell";
> +                       reg = <0x1010e000 0x1000>;
> +                       interrupt-parent = <&intc_dc1176>;
> +                       interrupts = <0 20 IRQ_TYPE_LEVEL_HIGH>;
> +                       clocks = <&uartclk>, <&pclk>;
> +                       clock-names = "uartclk", "apb_pclk";
> +               };
> +
> +               pb1176_serial3: uart@1010f000 {
> +                       compatible = "arm,pl011", "arm,primecell";
> +                       reg = <0x1010f000 0x1000>;
> +                       interrupt-parent = <&intc_dc1176>;
> +                       interrupts = <0 21 IRQ_TYPE_LEVEL_HIGH>;
> +                       clocks = <&uartclk>, <&pclk>;
> +                       clock-names = "uartclk", "apb_pclk";
> +               };
> +       };
> +};
> diff --git a/arch/arm/mach-realview/Kconfig b/arch/arm/mach-realview/Kconfig
> index 9db2029aa632..65a07f5b5225 100644
> --- a/arch/arm/mach-realview/Kconfig
> +++ b/arch/arm/mach-realview/Kconfig
> @@ -1,6 +1,16 @@
>  menu "RealView platform type"
>         depends on ARCH_REALVIEW
>
> +config REALVIEW_DT
> +       bool "Support RealView(R) Device Tree based boot"
> +       select ARM_GIC
> +       select MFD_SYSCON
> +       select SOC_BUS
> +       select USE_OF
> +       help
> +         Include support for booting the ARM(R) RealView(R) evaluation
> +         boards using a device tree machine description.
> +
>  config MACH_REALVIEW_EB
>         bool "Support RealView(R) Emulation Baseboard"
>         select ARM_GIC
> diff --git a/arch/arm/mach-realview/Makefile b/arch/arm/mach-realview/Makefile
> index 541fa4c109ef..e07fdf7ae8a7 100644
> --- a/arch/arm/mach-realview/Makefile
> +++ b/arch/arm/mach-realview/Makefile
> @@ -3,6 +3,7 @@
>  #
>
>  obj-y                                  := core.o
> +obj-$(CONFIG_REALVIEW_DT)              += realview-dt.o
>  obj-$(CONFIG_MACH_REALVIEW_EB)         += realview_eb.o
>  obj-$(CONFIG_MACH_REALVIEW_PB11MP)     += realview_pb11mp.o
>  obj-$(CONFIG_MACH_REALVIEW_PB1176)     += realview_pb1176.o
> diff --git a/arch/arm/mach-realview/realview-dt.c b/arch/arm/mach-realview/realview-dt.c
> new file mode 100644
> index 000000000000..4ba7c5303d09
> --- /dev/null
> +++ b/arch/arm/mach-realview/realview-dt.c
> @@ -0,0 +1,225 @@
> +/*
> + * Copyright (C) 2014 Linaro Ltd.
> + *
> + * Author: Linus Walleij <linus.walleij@linaro.org>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2, as
> + * published by the Free Software Foundation.
> + *
> + */
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/irqchip.h>
> +#include <linux/irqchip/arm-gic.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/regmap.h>
> +#include <linux/sys_soc.h>
> +#include <linux/slab.h>
> +#include <asm/mach/map.h>
> +#include <asm/mach/arch.h>
> +#include <asm/hardware/cache-l2x0.h>
> +#include <mach/hardware.h>
> +#include <mach/platform.h>
> +#include <mach/board-eb.h>
> +#include <mach/board-pb1176.h>
> +#include <mach/board-pb11mp.h>
> +#include <mach/board-pbx.h>
> +#include "core.h"
> +
> +/* Pointer to the system controller */
> +struct regmap *syscon_regmap;
> +u8 syscon_type;
> +
> +static struct map_desc realview_dt_io_desc[] __initdata = {
> +       {
> +               /* FIXME: static map needed for LED driver */

Don't you have patches to fix this? I need them for Versatile
conversion as well.

> +               .virtual        = IO_ADDRESS(REALVIEW_SYS_BASE),
> +               .pfn            = __phys_to_pfn(REALVIEW_SYS_BASE),
> +               .length         = SZ_4K,
> +               .type           = MT_DEVICE,
> +       },
> +};
> +
> +static void __init realview_dt_map_io(void)
> +{
> +       iotable_init(realview_dt_io_desc, ARRAY_SIZE(realview_dt_io_desc));
> +}
> +
> +/*
> + * We detect the different syscon types from the compatible strings.
> + */
> +enum realview_syscon {
> +       REALVIEW_SYSCON_EB,
> +       REALVIEW_SYSCON_PB1176,
> +       REALVIEW_SYSCON_PB11MP,
> +       REALVIEW_SYSCON_PBA8,
> +       REALVIEW_SYSCON_PBX,
> +};
> +
> +static const struct of_device_id realview_syscon_match[] = {
> +       {
> +               .compatible = "arm,realview-eb-syscon",
> +               .data = (void *)REALVIEW_SYSCON_EB,
> +       },
> +       {
> +               .compatible = "arm,realview-pb1176-syscon",
> +               .data = (void *)REALVIEW_SYSCON_PB1176,
> +       },
> +       {
> +               .compatible = "arm,realview-pb11mp-syscon",
> +               .data = (void *)REALVIEW_SYSCON_PB11MP,
> +       },
> +       {
> +               .compatible = "arm,realview-pba8-syscon",
> +               .data = (void *)REALVIEW_SYSCON_PBA8,
> +       },
> +       {
> +               .compatible = "arm,realview-pbx-syscon",
> +               .data = (void *)REALVIEW_SYSCON_PBX,
> +       },
> +};
> +
> +static void __init realview_dt_init_machine(void)
> +{
> +       struct device_node *root;
> +       struct device_node *syscon;
> +       const struct of_device_id *syscon_id;
> +       struct soc_device *soc_dev;
> +       struct soc_device_attribute *soc_dev_attr;
> +       struct device *parent;
> +       u32 coreid;
> +       int ret;
> +
> +#if IS_ENABLED(CONFIG_CACHE_L2X0)
> +       if (of_machine_is_compatible("arm,realview-eb"))
> +               /*
> +                * 1MB (128KB/way), 8-way associativity,

These should go into DT properties. Cache attributes are already
defined in ePAPR.

> +                * evmon/parity/share enabled

These can probably be unconditionally enabled except for parity which
could be a DT property.

> +                * Bits:  .... ...0 0111 1001 0000 .... .... ....
> +                */
> +               l2x0_of_init(0x00790000, 0xfe000fff);
> +       else if (of_machine_is_compatible("arm,realview-pb1176"))
> +               /*
> +                * 128Kb (16Kb/way) 8-way associativity.
> +                * evmon/parity/share enabled.
> +                */
> +               l2x0_of_init(0x00730000, 0xfe000fff);
> +       else if (of_machine_is_compatible("arm,realview-pb11mp"))
> +               /*
> +                * 1MB (128KB/way), 8-way associativity,
> +                * evmon/parity/share enabled
> +                * Bits:  .... ...0 0111 1001 0000 .... .... ....
> +                */
> +               l2x0_of_init(0x00730000, 0xfe000fff);
> +       else if (of_machine_is_compatible("arm,realview-pbx"))
> +               /*
> +                * 16KB way size, 8-way associativity, parity disabled
> +                * Bits:  .. 0 0 0 0 1 00 1 0 1 001 0 000 0 .... .... ....
> +                */
> +               l2x0_of_init(0x02520000, 0xc0000fff);
> +#endif
> +
> +        /* Here we create an SoC device for the root node */
> +       root = of_find_node_by_path("/");
> +       if (!root)
> +               return;
> +       syscon = of_find_matching_node_and_match(root, realview_syscon_match,
> +                                                &syscon_id);
> +       if (!syscon)
> +               return;
> +       syscon_type = (enum realview_syscon)syscon_id->data;
> +
> +       soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
> +       if (!soc_dev_attr)
> +               return;
> +       ret = of_property_read_string(root, "compatible",
> +                                     &soc_dev_attr->soc_id);
> +       if (ret)
> +               return;
> +       ret = of_property_read_string(root, "model", &soc_dev_attr->machine);
> +        if (ret)
> +               return;
> +       soc_dev_attr->family = "RealView";
> +       soc_dev = soc_device_register(soc_dev_attr);
> +       if (IS_ERR(soc_dev)) {
> +               kfree(soc_dev_attr);
> +               return;
> +       }
> +       parent = soc_device_to_device(soc_dev);

We really need to standardize this soc device stuff so that platforms
always have a parent soc device or not.

> +       ret = of_platform_populate(root, of_default_bus_match_table,
> +                                  NULL, parent);
> +       if (ret) {
> +               pr_crit("could not populate device tree\n");
> +               return;
> +       }
> +
> +       syscon_regmap = syscon_node_to_regmap(syscon);
> +       if (IS_ERR(syscon_regmap)) {
> +               pr_crit("could not locate syscon regmap\n");
> +               return;
> +       }
> +       ret = regmap_read(syscon_regmap, REALVIEW_SYS_ID_OFFSET, &coreid);
> +       if (ret)
> +               return;
> +       pr_info("RealView Syscon type %02x, Core ID: 0x%08x\n",
> +               syscon_type, coreid);
> +       /* FIXME: add attributes for SoC to sysfs */
> +}
> +
> +static void realview_dt_restart(enum reboot_mode mode, const char *cmd)
> +{
> +       if (IS_ERR(syscon_regmap))
> +               return;
> +
> +       /* Unlock the reset register */
> +       regmap_write(syscon_regmap, REALVIEW_SYS_LOCK_OFFSET,
> +                    REALVIEW_SYS_LOCK_VAL);
> +       /* Then hit reset on the different machines */
> +       switch (syscon_type) {
> +       case REALVIEW_SYSCON_EB:
> +               regmap_write(syscon_regmap,
> +                            REALVIEW_SYS_RESETCTL_OFFSET, 0x0008);
> +               break;
> +       case REALVIEW_SYSCON_PB1176:
> +               regmap_write(syscon_regmap,
> +                            REALVIEW_SYS_RESETCTL_OFFSET, 0x0100);
> +               break;
> +       case REALVIEW_SYSCON_PB11MP:
> +       case REALVIEW_SYSCON_PBA8:
> +               regmap_write(syscon_regmap, REALVIEW_SYS_RESETCTL_OFFSET,
> +                            0x0000);
> +               regmap_write(syscon_regmap, REALVIEW_SYS_RESETCTL_OFFSET,
> +                            0x0004);
> +               break;
> +       case REALVIEW_SYSCON_PBX:
> +               regmap_write(syscon_regmap, REALVIEW_SYS_RESETCTL_OFFSET,
> +                            0x00f0);
> +               regmap_write(syscon_regmap, REALVIEW_SYS_RESETCTL_OFFSET,
> +                            0x00f4);
> +               break;
> +       }
> +       dsb();

Barriers need comments as to why they are needed.

Rob
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Linus Walleij - May 22, 2014, 1:30 p.m.
On Thu, May 22, 2014 at 3:17 PM, Rob Herring <robh@kernel.org> wrote:
> On Thu, May 8, 2014 at 5:08 PM, Linus Walleij <linus.walleij@linaro.org> wrote:

>> +       model = "ARM RealView PB1176 with device tree";
>
> Isn't "with device tree" redundant?

Nuked it.

>> +static struct map_desc realview_dt_io_desc[] __initdata = {
>> +       {
>> +               /* FIXME: static map needed for LED driver */
>
> Don't you have patches to fix this? I need them for Versatile
> conversion as well.

Done away with. The legacy driver was moved to drivers/leds/leds-versatile.c
and I then contemplated adding DT support to it but it was a *bad*
idea.

Instead I have created drivers/leds/leds-syscon.c that can handle
any LEDs in a syscon. Will post in next iteration as soon as
I get the drivers/soc dependency in place.

>> +#if IS_ENABLED(CONFIG_CACHE_L2X0)
>> +       if (of_machine_is_compatible("arm,realview-eb"))
>> +               /*
>> +                * 1MB (128KB/way), 8-way associativity,
>
> These should go into DT properties. Cache attributes are already
> defined in ePAPR.

Yes, the dependencies to do this with DT is floating around somewhere
in the ARM tree or Russells tree I think, maybe I cannot do this until
the next kernel cycle.

>> +                * evmon/parity/share enabled
>
> These can probably be unconditionally enabled except for parity which
> could be a DT property.

I'll wait and see what I need to add really.

>> +       parent = soc_device_to_device(soc_dev);
>
> We really need to standardize this soc device stuff so that platforms
> always have a parent soc device or not.

Arnds position is that the entire platform/board should not be
a "soc device" and that seems correct since the board is no SoC.

So I will spin this off into a SoC driver and push under
drivers/soc and bind to the SoC node in the device tree.

Yours,
Linus Walleij
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Arnd Bergmann - May 22, 2014, 1:36 p.m.
On Thursday 22 May 2014 15:30:39 Linus Walleij wrote:
> >> +       parent = soc_device_to_device(soc_dev);
> >
> > We really need to standardize this soc device stuff so that platforms
> > always have a parent soc device or not.
> 
> Arnds position is that the entire platform/board should not be
> a "soc device" and that seems correct since the board is no SoC.
> 
> So I will spin this off into a SoC driver and push under
> drivers/soc and bind to the SoC node in the device tree.

To be clear, this has nothing to do with whether this is strictly a SoC
or not. I would still want to see all the internal components of the
main chip under the soc node, and probably anything that is attached
to one of its interfaces under those nodes. The parts that should not
be under /soc are the ones that are not in the device hierarchy, such
as external clock generators.

	Arnd
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Arnd Bergmann - May 22, 2014, 1:38 p.m.
On Thursday 22 May 2014 15:04:07 Linus Walleij wrote:
> On Thu, May 22, 2014 at 10:31 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> > On Thursday 22 May 2014 09:41:39 Linus Walleij wrote:
> 
> >> The question can be rephrased like this:
> >> Should we create drivers/soc?
> >
> > I think we just did, not sure if the patches have made it into linux-next
> > already, but there were a couple of other platforms already that want this
> > directory.
> 
> Awesomeness. Can you give me the title of a patch or branch
> from ARM SoC I should pull in to build on top of this? Then I can
> split off all the SoC bus business and have the machine file real
> small, nice and clean.

I'd have to check again, it seems that as of today, there is no drivers/soc
on arm-soc yet. I do remember that there were at least two platforms besides
yours that want it though, so we have to coordinate it a bit.

Then again, as I expect all of them to go through arm-soc, we can probably
resolve the conflicts in our tree.

	Arnd
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Jason - May 22, 2014, 1:41 p.m.
On Fri, May 09, 2014 at 12:08:16AM +0200, Linus Walleij wrote:
> This implements basic device tree boot support for the RealView
> platforms, with a basic device tree for ARM PB1176 as an example.
> 
> The implementation is done with a new DT-specific board file
> using only pre-existing bindings for the basic IRQ, timer and
> serial port drivers. A new compatible type is added to the GIC
> for the ARM1176.
> 
> This implementation uses the MFD syscon handle from day one to
> access the system controller registers, and register the devices
> using the SoC bus.
> 
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Rob Herring <robh@kernel.org>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
> ChangeLog v1->v2:
> - Adjust timer clock names to be the same as the example in the
>   device tree binding.
> - Remove all memory fixup code - this should be handled by the
>   device tree specification of memory areas or by special MM hacks
>   for the RealView PBX.
> - Fix the documentation around syscon to specify that it can be in
>   any node, need not be the root node.
> - Switch device tree license to the BSD license, taken from
>   arch/powerpc/boot/dts/p1024rdb_32b.dts
> - Add a hunk for the new compatible string to
>   Documentation/devicetree/bindings/arm/gic.txt
> - Move the clocks out of the SoC node, certainly the xtal is not
>   sitting on the SoC...
> - Sort the selects in Kconfig alphabetically
> - Use IS_ENABLED() for the l2x0 code snippet
> - Instead of checking the board variant in the reset routine to
>   figure out how to tweak the reset controller, have a compatible
>   string for each syscon variant, map it to an enum that provides a
>   unique type ID and that way figure out how to handle it in a maybe
>   more elegant way.
> - Open issue: what do to with the l2x0 stuff?
> ---
>  Documentation/devicetree/bindings/arm/arm-boards |  57 ++++++
>  Documentation/devicetree/bindings/arm/gic.txt    |   1 +
>  arch/arm/boot/dts/Makefile                       |   1 +
>  arch/arm/boot/dts/arm-realview-pb1176.dts        | 177 ++++++++++++++++++
>  arch/arm/mach-realview/Kconfig                   |  10 +
>  arch/arm/mach-realview/Makefile                  |   1 +
>  arch/arm/mach-realview/realview-dt.c             | 225 +++++++++++++++++++++++
>  arch/arm/mm/Kconfig                              |   2 +-
>  drivers/irqchip/irq-gic.c                        |   1 +
>  9 files changed, 474 insertions(+), 1 deletion(-)
>  create mode 100644 arch/arm/boot/dts/arm-realview-pb1176.dts
>  create mode 100644 arch/arm/mach-realview/realview-dt.c
> 
...
> diff --git a/Documentation/devicetree/bindings/arm/gic.txt b/Documentation/devicetree/bindings/arm/gic.txt
> index 5573c08d3180..539420194efd 100644
> --- a/Documentation/devicetree/bindings/arm/gic.txt
> +++ b/Documentation/devicetree/bindings/arm/gic.txt
> @@ -16,6 +16,7 @@ Main node required properties:
>  	"arm,cortex-a9-gic"
>  	"arm,cortex-a7-gic"
>  	"arm,arm11mp-gic"
> +	"arm,arm1176jzf-gic"
>  - interrupt-controller : Identifies the node as an interrupt controller
>  - #interrupt-cells : Specifies the number of cells needed to encode an
>    interrupt source.  The type shall be a <u32> and the value shall be 3.
...
> diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
> index 57d165e026f4..70281b38c73b 100644
> --- a/drivers/irqchip/irq-gic.c
> +++ b/drivers/irqchip/irq-gic.c
> @@ -1073,6 +1073,7 @@ gic_of_init(struct device_node *node, struct device_node *parent)
>  }
>  IRQCHIP_DECLARE(cortex_a15_gic, "arm,cortex-a15-gic", gic_of_init);
>  IRQCHIP_DECLARE(cortex_a9_gic, "arm,cortex-a9-gic", gic_of_init);
> +IRQCHIP_DECLARE(arm1176jzf_gic, "arm,arm1176jzf-gic", gic_of_init);
>  IRQCHIP_DECLARE(msm_8660_qgic, "qcom,msm-8660-qgic", gic_of_init);
>  IRQCHIP_DECLARE(msm_qgic2, "qcom,msm-qgic2", gic_of_init);

Please place in alphabetical order.  We're starting to collect
compatible strings for this driver...

Acked-by: Jason Cooper <jason@lakedaemon.net>

thx,

Jason.
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Catalin Marinas - May 22, 2014, 2:45 p.m.
On Thu, May 22, 2014 at 09:31:37AM +0100, Arnd Bergmann wrote:
> commit 42c4dafe803dcad82980fd8b0831a89032156f93
> Author: Catalin Marinas <catalin.marinas@arm.com>
> Date:   Thu Jul 1 13:22:48 2010 +0100
> 
>     ARM: 6202/1: Do not ARM_DMA_MEM_BUFFERABLE on RealView boards with L210/L220
>     
>     RealView boards with certain revisions of the L210/L220 cache controller
>     may have issues (hardware deadlock) with the mandatory barriers (DSB
>     followed by an L2 cache sync) when ARM_DMA_MEM_BUFFERABLE is enabled.
>     The patch disables ARM_DMA_MEM_BUFFERABLE for these boards.
>     
>     Tested-by: Linus Walleij <linus.walleij@stericsson.com>
>     Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
>     Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Looking through the L220 errata document, I think this relates to 425331
which says that a cache sync can deadlock the system if the write buffer
is not empty. By making the DMA memory Strongly Ordered, we avoid the
L220 write buffer. In addition to the above commit, we also had
2503a5ecd86c (ARM: 6201/1: RealView: Do not use outer_sync() on
ARM11MPCore boards with L220).

The above only solves the issue for coherent DMA allocations. Streaming
DMA requires additional changes to cache-l2x0.c but they are all weird
and depend on how the L2x0 is wired (for example, using SWP to access
the L2x0 registers works on one RealView board but not on another).
Anyway, I don't think we have any streaming DMA used on these RealView
boards.

If we only use the DMA coherent buffers for CLCD on these boards, we
don't really need the outer_sync() either so we could go back to
bufferable DMA memory (strangely enough, this L2 cache workaround looks
similar to Marvell's PCI+PL310 problem where we want to avoid
outer_sync()).
Arnd Bergmann - May 22, 2014, 3:49 p.m.
On Thursday 22 May 2014 15:45:03 Catalin Marinas wrote:
> On Thu, May 22, 2014 at 09:31:37AM +0100, Arnd Bergmann wrote:
> > commit 42c4dafe803dcad82980fd8b0831a89032156f93
> > Author: Catalin Marinas <catalin.marinas@arm.com>
> > Date:   Thu Jul 1 13:22:48 2010 +0100
> > 
> >     ARM: 6202/1: Do not ARM_DMA_MEM_BUFFERABLE on RealView boards with L210/L220
> >     
> >     RealView boards with certain revisions of the L210/L220 cache controller
> >     may have issues (hardware deadlock) with the mandatory barriers (DSB
> >     followed by an L2 cache sync) when ARM_DMA_MEM_BUFFERABLE is enabled.
> >     The patch disables ARM_DMA_MEM_BUFFERABLE for these boards.
> >     
> >     Tested-by: Linus Walleij <linus.walleij@stericsson.com>
> >     Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
> >     Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
> 
> Looking through the L220 errata document, I think this relates to 425331
> which says that a cache sync can deadlock the system if the write buffer
> is not empty.

Hmm, but isn't the write buffer empty here because we have just issued
a dsb()?

> By making the DMA memory Strongly Ordered, we avoid the
> L220 write buffer. In addition to the above commit, we also had
> 2503a5ecd86c (ARM: 6201/1: RealView: Do not use outer_sync() on
> ARM11MPCore boards with L220).

Ah, so this also stands in the way of multiplatform realview :(

> The above only solves the issue for coherent DMA allocations. Streaming
> DMA requires additional changes to cache-l2x0.c but they are all weird
> and depend on how the L2x0 is wired (for example, using SWP to access
> the L2x0 registers works on one RealView board but not on another).
> Anyway, I don't think we have any streaming DMA used on these RealView
> boards.

Yes, I think that is correct. MMCI, SSP and serial could all use
DMA but are not configured to do it.

> If we only use the DMA coherent buffers for CLCD on these boards, we
> don't really need the outer_sync() either so we could go back to
> bufferable DMA memory (strangely enough, this L2 cache workaround looks
> similar to Marvell's PCI+PL310 problem where we want to avoid
> outer_sync()).

Ah, so you think we can add another hook to NULL out outer_cache.sync
per platform?

	Arnd
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Catalin Marinas - May 22, 2014, 4:09 p.m.
On Thu, May 22, 2014 at 04:49:16PM +0100, Arnd Bergmann wrote:
> On Thursday 22 May 2014 15:45:03 Catalin Marinas wrote:
> > On Thu, May 22, 2014 at 09:31:37AM +0100, Arnd Bergmann wrote:
> > > commit 42c4dafe803dcad82980fd8b0831a89032156f93
> > > Author: Catalin Marinas <catalin.marinas@arm.com>
> > > Date:   Thu Jul 1 13:22:48 2010 +0100
> > > 
> > >     ARM: 6202/1: Do not ARM_DMA_MEM_BUFFERABLE on RealView boards with L210/L220
> > >     
> > >     RealView boards with certain revisions of the L210/L220 cache controller
> > >     may have issues (hardware deadlock) with the mandatory barriers (DSB
> > >     followed by an L2 cache sync) when ARM_DMA_MEM_BUFFERABLE is enabled.
> > >     The patch disables ARM_DMA_MEM_BUFFERABLE for these boards.
> > >     
> > >     Tested-by: Linus Walleij <linus.walleij@stericsson.com>
> > >     Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
> > >     Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
> > 
> > Looking through the L220 errata document, I think this relates to 425331
> > which says that a cache sync can deadlock the system if the write buffer
> > is not empty.
> 
> Hmm, but isn't the write buffer empty here because we have just issued
> a dsb()?

The problem with these outer caches is that DSB doesn't propagate to
them (and I hope to never see such caches again ;)). So an mb() on such
systems needs to be dsb()+outer_sync(). The dsb() pushes data from the
CPU write buffer into the L2x0 write buffer and outer_sync() does the
flushing out of the outer cache write buffer (which strangely enough
buffers even if the memory access is Normal NonCacheable).

> > If we only use the DMA coherent buffers for CLCD on these boards, we
> > don't really need the outer_sync() either so we could go back to
> > bufferable DMA memory (strangely enough, this L2 cache workaround looks
> > similar to Marvell's PCI+PL310 problem where we want to avoid
> > outer_sync()).
> 
> Ah, so you think we can add another hook to NULL out outer_cache.sync
> per platform?

Yes, with the note that mb() no longer guarantees the write being
flushed to RAM but just to the L2 write buffer. If CLCD framebuffer is
the only DMA device, we don't need to worry about such barriers since we
map it as writecombine anyway (hence bufferable).

Unless Linus or Pawel think there are other DMA capable devices in use
here, I'm happy to enable ARM_DMA_MEM_BUFFERABLE for these boards.
Nicolas Pitre - May 22, 2014, 6:09 p.m.
On Thu, 22 May 2014, Arnd Bergmann wrote:

> On Thursday 22 May 2014 15:45:03 Catalin Marinas wrote:
> > By making the DMA memory Strongly Ordered, we avoid the
> > L220 write buffer. In addition to the above commit, we also had
> > 2503a5ecd86c (ARM: 6201/1: RealView: Do not use outer_sync() on
> > ARM11MPCore boards with L220).
> 
> Ah, so this also stands in the way of multiplatform realview :(

Isn't the real value of a multiplatform realview in the ability to use 
it with Qemu?  Did Qemu go to the extreme of emulating all those cache 
issues?


Nicolas
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Arnd Bergmann - May 22, 2014, 6:26 p.m.
On Thursday 22 May 2014 14:09:52 Nicolas Pitre wrote:
> On Thu, 22 May 2014, Arnd Bergmann wrote:
> 
> > On Thursday 22 May 2014 15:45:03 Catalin Marinas wrote:
> > > By making the DMA memory Strongly Ordered, we avoid the
> > > L220 write buffer. In addition to the above commit, we also had
> > > 2503a5ecd86c (ARM: 6201/1: RealView: Do not use outer_sync() on
> > > ARM11MPCore boards with L220).
> > 
> > Ah, so this also stands in the way of multiplatform realview 
> 
> Isn't the real value of a multiplatform realview in the ability to use 
> it with Qemu?  Did Qemu go to the extreme of emulating all those cache 
> issues?

The qemu developers have in the past always argued strongly that they
want to run the same kernel that runs on real hardware. Having a kernel
that runs only on the emulated version but not on actual hardware is
clearly against that goal, and  we should use CONFIG_ARCH_VIRT for
that purpose.

	Arnd
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Nicolas Pitre - May 22, 2014, 6:39 p.m.
On Thu, 22 May 2014, Arnd Bergmann wrote:

> On Thursday 22 May 2014 14:09:52 Nicolas Pitre wrote:
> > On Thu, 22 May 2014, Arnd Bergmann wrote:
> > 
> > > On Thursday 22 May 2014 15:45:03 Catalin Marinas wrote:
> > > > By making the DMA memory Strongly Ordered, we avoid the
> > > > L220 write buffer. In addition to the above commit, we also had
> > > > 2503a5ecd86c (ARM: 6201/1: RealView: Do not use outer_sync() on
> > > > ARM11MPCore boards with L220).
> > > 
> > > Ah, so this also stands in the way of multiplatform realview 
> > 
> > Isn't the real value of a multiplatform realview in the ability to use 
> > it with Qemu?  Did Qemu go to the extreme of emulating all those cache 
> > issues?
> 
> The qemu developers have in the past always argued strongly that they
> want to run the same kernel that runs on real hardware. Having a kernel
> that runs only on the emulated version but not on actual hardware is
> clearly against that goal, and  we should use CONFIG_ARCH_VIRT for
> that purpose.

But the kernel that actually runs on the real hardware also runs on Qemu 
already.  It is just that, by some coincidence, a multi-platform kernel 
that pretends to have the same peripherals as a Realview board could 
also be used on Qemu.

Otherwise I really don't see the point in making the code more complex 
just to make a multi-platform kernel run on actual Realview hardware 
that is quite obsolete now and that very few people have access to.


Nicolas
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Linus Walleij - May 22, 2014, 6:52 p.m.
On Thu, May 22, 2014 at 5:49 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Thursday 22 May 2014 15:45:03 Catalin Marinas wrote:

>> Anyway, I don't think we have any streaming DMA used on these RealView
>> boards.
>
> Yes, I think that is correct. MMCI, SSP and serial could all use
> DMA but are not configured to do it.

PB1176 has no working DMA (borked DMA hardware), the PB11MPCore
actually has working DMA but only on UART TX and maybe AACI
(haven't tested) no clue about the Cortex boards PBA8 and PBX though.

Yours,
Linus Walleij
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Arnd Bergmann - May 22, 2014, 8:25 p.m.
On Thursday 22 May 2014 14:39:20 Nicolas Pitre wrote:
> On Thu, 22 May 2014, Arnd Bergmann wrote:
> 
> > On Thursday 22 May 2014 14:09:52 Nicolas Pitre wrote:
> > > On Thu, 22 May 2014, Arnd Bergmann wrote:
> > > 
> > > > On Thursday 22 May 2014 15:45:03 Catalin Marinas wrote:
> > > > > By making the DMA memory Strongly Ordered, we avoid the
> > > > > L220 write buffer. In addition to the above commit, we also had
> > > > > 2503a5ecd86c (ARM: 6201/1: RealView: Do not use outer_sync() on
> > > > > ARM11MPCore boards with L220).
> > > > 
> > > > Ah, so this also stands in the way of multiplatform realview 
> > > 
> > > Isn't the real value of a multiplatform realview in the ability to use 
> > > it with Qemu?  Did Qemu go to the extreme of emulating all those cache 
> > > issues?
> > 
> > The qemu developers have in the past always argued strongly that they
> > want to run the same kernel that runs on real hardware. Having a kernel
> > that runs only on the emulated version but not on actual hardware is
> > clearly against that goal, and  we should use CONFIG_ARCH_VIRT for
> > that purpose.
> 
> But the kernel that actually runs on the real hardware also runs on Qemu 
> already.  It is just that, by some coincidence, a multi-platform kernel 
> that pretends to have the same peripherals as a Realview board could 
> also be used on Qemu.
> 
> Otherwise I really don't see the point in making the code more complex 
> just to make a multi-platform kernel run on actual Realview hardware 
> that is quite obsolete now and that very few people have access to.

The main reason is that out of principle I want to get to the point where
every ARMv6 and ARMv7 machine is part of CONFIG_ARCH_MULTIPLATFORM.

Then again, once we introduce CONFIG_BROKEN_MULTIPLATFORM, we could
have an option that depends on that, and turns on both
ARM_DMA_MEM_BUFFERABLE as well as the hack to remove the outer_sync
from mb() and wmb() for CONFIG_SMP.

	Arnd
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Arnd Bergmann - May 22, 2014, 8:35 p.m.
On Thursday 22 May 2014 20:52:38 Linus Walleij wrote:
> On Thu, May 22, 2014 at 5:49 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> > On Thursday 22 May 2014 15:45:03 Catalin Marinas wrote:
> 
> >> Anyway, I don't think we have any streaming DMA used on these RealView
> >> boards.
> >
> > Yes, I think that is correct. MMCI, SSP and serial could all use
> > DMA but are not configured to do it.
> 
> PB1176 has no working DMA (borked DMA hardware), the PB11MPCore
> actually has working DMA but only on UART TX and maybe AACI
> (haven't tested) no clue about the Cortex boards PBA8 and PBX though.

I don't see any DMA data passed to the pl011 driver for PB11MPCore
or any other realview board, so even if it works, we don't use it.

The AACI driver doesn't seem to support DMA.

PBA8 and PBX don't need the hack because they don't have a broken
l2x0.

	Arnd
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Sebastian Hesselbarth - May 22, 2014, 10:34 p.m.
On 05/22/2014 09:41 AM, Linus Walleij wrote:
> On Fri, May 9, 2014 at 12:44 PM, Arnd Bergmann <arnd@arndb.de> wrote:
>>> +++ b/arch/arm/boot/dts/arm-realview-pb1176.dts
>>
>> Can you split this up into an arm-realview.dtsi file for the common parts and
>> a pb1176 specific file for the rest?
> 
> I wonder if that makes any kind of sense. The RealView platforms does not
> really share much more than the name, sadly. For example: IP blocks
> aren't even at the same address.
> 
> I could create a .dtsi file but it would be empty :-(
> 
>>> +     soc {
>>> +             #address-cells = <1>;
>>> +             #size-cells = <1>;
>>> +             compatible = "simple-bus";
>>> +             ranges;
>>> +
>>> +             syscon: syscon@10000000 {
>>> +                     compatible = "arm,realview-pb1176-syscon", "syscon";
>>> +                     reg = <0x10000000 0x1000>;
>>> +             };
>>
>> Hmm, in order to have a proper reset driver, we probably want a separate
>> node for the reset controller. I believe the x-gene people have just
>> posted a generic reset driver based on syscon. Let's see if we can share
>> that.
> 
> I have looked at it. Patch titled
> "power: reset: Add generic SYSCON register mapped reset"
> 
> Sadly it does not work for our case. This is because it assumes that
> reboot will be triggered by writing one value to one register. The RealViews
> need you to *first* write to a special unlock register, then write a magic
> value to a magic register.
> 
> So of course we could extend the syscon regmap reset driver by
> starting to encode a jam table such as a sequence of register writes
> to a sequence of registers, but we have refused such code in the past
> because as I recall Grant said, it is the beginning of a byte code
> interpreter and then we could as well bite the bullet and start
> implementing open firmware.
> 
> This is exactly the type of thing that ACPI AML code usually does
> by the way so what he says makes a *lot* of sense.
> 
> So for now I keep to our special driver.

+1 for drivers/soc _and_ of_xlate for regmap instead of syscon.

driven by Mike Turquette's request to join mach-berlin clock node into a
single node, we currently use pinctrl driver (that must be somewhere in
Linus inbox) as a crutch to register a regmap for other drivers.

I also saw that Arnd requested to not chop chip registers into tiny
pieces for Linux subsystems but rather have a single DT node and make
the drivers use it.

Mike also mentioned he is fine with different subsystem drivers reusing
the same node property-wise, i.e. reset and clock in a single node.

With Berlin (and other SoCs for sure) ultimately there will be a bunch
of drivers that require the io resource and the node early and
non-early. Now, using syscon would still require dummy nodes for each
subsystem, as there will be only one driver registered to a single DT
node.

With a drivers/soc we'd have a good place for those messy, SoC-specific
registers to put a driver that hooks up to a single node and takes care
of registering e.g. pinctrl and reset the plain-old platform_device
way. It will be a little bit like arm/mach-foo before, but maybe we
have to admit that on SoCs there will always be some amount of
very specific, non-probable, non-describable registers that simply need
special treatment.

Sebastian

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Linus Walleij - May 29, 2014, 9:38 a.m.
On Thu, May 22, 2014 at 10:35 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Thursday 22 May 2014 20:52:38 Linus Walleij wrote:
>> On Thu, May 22, 2014 at 5:49 PM, Arnd Bergmann <arnd@arndb.de> wrote:
>> > On Thursday 22 May 2014 15:45:03 Catalin Marinas wrote:
>>
>> >> Anyway, I don't think we have any streaming DMA used on these RealView
>> >> boards.
>> >
>> > Yes, I think that is correct. MMCI, SSP and serial could all use
>> > DMA but are not configured to do it.
>>
>> PB1176 has no working DMA (borked DMA hardware), the PB11MPCore
>> actually has working DMA but only on UART TX and maybe AACI
>> (haven't tested) no clue about the Cortex boards PBA8 and PBX though.
>
> I don't see any DMA data passed to the pl011 driver for PB11MPCore
> or any other realview board, so even if it works, we don't use it.

No I was more saying it works in theory... and we actually have
patches to enable it for e.g. memcpy on Versatile and PB11MP
that I floated at times, Russell also experimented around with it.

> The AACI driver doesn't seem to support DMA.

Nope, but the hardware does.

> PBA8 and PBX don't need the hack because they don't have a broken
> l2x0.

True!

Yours,
Linus Walleij
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Linus Walleij - May 29, 2014, 9:44 a.m.
On Fri, May 23, 2014 at 12:34 AM, Sebastian Hesselbarth
<sebastian.hesselbarth@gmail.com> wrote:
> On 05/22/2014 09:41 AM, Linus Walleij wrote:

>> So for now I keep to our special driver.
>
> +1 for drivers/soc _and_ of_xlate for regmap instead of syscon.
>
> driven by Mike Turquette's request to join mach-berlin clock node into a
> single node, we currently use pinctrl driver (that must be somewhere in
> Linus inbox) as a crutch to register a regmap for other drivers.

I've merged it actually, I think. Else hit me on any missed patches.

> With a drivers/soc we'd have a good place for those messy, SoC-specific
> registers to put a driver that hooks up to a single node and takes care
> of registering e.g. pinctrl and reset the plain-old platform_device
> way. It will be a little bit like arm/mach-foo before, but maybe we
> have to admit that on SoCs there will always be some amount of
> very specific, non-probable, non-describable registers that simply need
> special treatment.

Hmmmm well I want to see that code before I believe it ... but
I get what you mean.

Yours,
Linus Walleij
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Sebastian Hesselbarth - May 29, 2014, 10:10 a.m.
On 05/29/2014 11:44 AM, Linus Walleij wrote:
> On Fri, May 23, 2014 at 12:34 AM, Sebastian Hesselbarth
> <sebastian.hesselbarth@gmail.com> wrote:
>> On 05/22/2014 09:41 AM, Linus Walleij wrote:
>>> So for now I keep to our special driver.
>>
>> +1 for drivers/soc _and_ of_xlate for regmap instead of syscon.
>>
>> driven by Mike Turquette's request to join mach-berlin clock node into a
>> single node, we currently use pinctrl driver (that must be somewhere in
>> Linus inbox) as a crutch to register a regmap for other drivers.
> 
> I've merged it actually, I think. Else hit me on any missed patches.

Yeah, you did. Thanks, no more patches on this one.

>> With a drivers/soc we'd have a good place for those messy, SoC-specific
>> registers to put a driver that hooks up to a single node and takes care
>> of registering e.g. pinctrl and reset the plain-old platform_device
>> way. It will be a little bit like arm/mach-foo before, but maybe we
>> have to admit that on SoCs there will always be some amount of
>> very specific, non-probable, non-describable registers that simply need
>> special treatment.
> 
> Hmmmm well I want to see that code before I believe it ... but
> I get what you mean.

Well, the register set on Berlin I was thinking about tackles pinctrl,
padmux, clock, reset and some other freaky stuff I cannot recall. The
mess in it is that there is no order you can apply to split it up into
separate nodes. Moreover, the next SoC has some registers just shoved
into it, moving some other registers.

It is already painful to deal with in code, and I have been through
several iterations of the clk driver with both choppy-DT and one-DT node
approaches.

At some point, Linux subsystem driven DT node tailoring isn't the
answer. Sometimes it fits very well, sometimes you will either end up
with gazillions of "clocks"/"clock-names" properties (just think of
a pll with 2x8 outputs) or the same amount of "reg" properties to
collect e.g. all registers dealing with reset.

The way we will go for it on Berlin is now:

(a) have a single node for the whole chip-ctrl register set
(b) register clk driver on it (early, as it provides timer clk)
(c) register one chip-ctrl driver on it that will
    (d) reserve the iomap,
    (e) register a regmap-mmio,
    (f) register platform_devices for {pinctrl,reset,...} that will
        use regmap-mmio and read their properties from the single
        node

The individual drivers should stay in their respective drivers/ folder,
but (c) needs a good home. It would have been mach-foo in the past, and
could be drivers/soc now. In (f), I tend to just lookup regmap by name,
no DT involved at all.

BTW, syscon is of no use here at all, once it registers itself as a
driver for the node, there will be no other drivers registered. That
would at least require (again subsystem driven) dummy-nodes for
pinctrl, clk, reset.

Also, using some of_xlate as we already have for clk, gpio, pinctrl ...
would put an end to syscon's syscon_get_regmap_from_{foo,bar,baz,...}
that gets a new helper every cycle.

Sebastian
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Linus Walleij - May 29, 2014, 2:13 p.m.
On Thu, May 29, 2014 at 12:10 PM, Sebastian Hesselbarth
<sebastian.hesselbarth@gmail.com> wrote:
> On 05/29/2014 11:44 AM, Linus Walleij wrote:

>> Hmmmm well I want to see that code before I believe it ... but
>> I get what you mean.
>
> Well, the register set on Berlin I was thinking about tackles pinctrl,
> padmux, clock, reset and some other freaky stuff I cannot recall. The
> mess in it is that there is no order you can apply to split it up into
> separate nodes. Moreover, the next SoC has some registers just shoved
> into it, moving some other registers.

Berlin hardware engineers seem to be hellbent on complicating
your life.

> The way we will go for it on Berlin is now:
>
> (a) have a single node for the whole chip-ctrl register set
> (b) register clk driver on it (early, as it provides timer clk)
> (c) register one chip-ctrl driver on it that will
>     (d) reserve the iomap,
>     (e) register a regmap-mmio,
>     (f) register platform_devices for {pinctrl,reset,...} that will
>         use regmap-mmio and read their properties from the single
>         node

OK makes perfect sense actually.

> The individual drivers should stay in their respective drivers/ folder,
> but (c) needs a good home. It would have been mach-foo in the past, and
> could be drivers/soc now. In (f), I tend to just lookup regmap by name,
> no DT involved at all.

OK

> BTW, syscon is of no use here at all, once it registers itself as a
> driver for the node, there will be no other drivers registered. That
> would at least require (again subsystem driven) dummy-nodes for
> pinctrl, clk, reset.

Yeah that sucks, we need something more flexible no question
about that.

Will the chipctrl driver be as generic as syscon or a
Berlin-specific thing?

> Also, using some of_xlate as we already have for clk, gpio, pinctrl ...
> would put an end to syscon's syscon_get_regmap_from_{foo,bar,baz,...}
> that gets a new helper every cycle.

This part I don't understand but I guess I will understand it
when I see the code.

Yours,
Linus Walleij
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Sebastian Hesselbarth - May 29, 2014, 2:47 p.m.
On 05/29/2014 04:13 PM, Linus Walleij wrote:
> On Thu, May 29, 2014 at 12:10 PM, Sebastian Hesselbarth
> <sebastian.hesselbarth@gmail.com> wrote:
>> On 05/29/2014 11:44 AM, Linus Walleij wrote:
>>> Hmmmm well I want to see that code before I believe it ... but
>>> I get what you mean.
>>
>> Well, the register set on Berlin I was thinking about tackles pinctrl,
>> padmux, clock, reset and some other freaky stuff I cannot recall. The
>> mess in it is that there is no order you can apply to split it up into
>> separate nodes. Moreover, the next SoC has some registers just shoved
>> into it, moving some other registers.
> 
> Berlin hardware engineers seem to be hellbent on complicating
> your life.

Tell me about it! ;)

Although, I don't think it is exclusive to Berlin but other vendors,
too.

>> The way we will go for it on Berlin is now:
>>
>> (a) have a single node for the whole chip-ctrl register set
>> (b) register clk driver on it (early, as it provides timer clk)
>> (c) register one chip-ctrl driver on it that will
>>     (d) reserve the iomap,
>>     (e) register a regmap-mmio,
>>     (f) register platform_devices for {pinctrl,reset,...} that will
>>         use regmap-mmio and read their properties from the single
>>         node
> 
> OK makes perfect sense actually.
> 
>> The individual drivers should stay in their respective drivers/ folder,
>> but (c) needs a good home. It would have been mach-foo in the past, and
>> could be drivers/soc now. In (f), I tend to just lookup regmap by name,
>> no DT involved at all.
> 
> OK
> 
>> BTW, syscon is of no use here at all, once it registers itself as a
>> driver for the node, there will be no other drivers registered. That
>> would at least require (again subsystem driven) dummy-nodes for
>> pinctrl, clk, reset.
> 
> Yeah that sucks, we need something more flexible no question
> about that.
> 
> Will the chipctrl driver be as generic as syscon or a
> Berlin-specific thing?

There is nothing berlin-specific about it except what regmap(s) and
platform_devices are registered. I can think of some generic helpers
to ease looping over regmap structs to be registered, IIRC driver core
already provides the same for platform_devices.

Actually, syscon is already a good starting point, it just lacks to
register platform_devices using the DT-registered regmap.

>> Also, using some of_xlate as we already have for clk, gpio, pinctrl ...
>> would put an end to syscon's syscon_get_regmap_from_{foo,bar,baz,...}
>> that gets a new helper every cycle.
> 
> This part I don't understand but I guess I will understand it
> when I see the code.

git grep 'struct regmap \*syscon' drivers/mfd/syscon.c
drivers/mfd/syscon.c:struct regmap *syscon_node_to_regmap(struct
device_node *np)
drivers/mfd/syscon.c:struct regmap
*syscon_regmap_lookup_by_compatible(const char *s)
drivers/mfd/syscon.c:struct regmap
*syscon_regmap_lookup_by_pdevname(const char *s)
drivers/mfd/syscon.c:struct regmap
*syscon_regmap_lookup_by_phandle(struct device_node *np,

and IIRC I have seen pending patches adding more syscon_regmap_by_foo
helpers.

My point is that we should have some regmap-provider to allow
us to use phandle+specifier, just like of_clk_get and friends work.

With some more time after v3.16-rc1 drops, I plan to provide a
chip-ctrl driver for Berlin. Most likely not too generic or based
on extending syscon but definitely something to talk about.

Sebastian
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Patch

diff --git a/Documentation/devicetree/bindings/arm/arm-boards b/Documentation/devicetree/bindings/arm/arm-boards
index 3509707f9320..86b36f399d1c 100644
--- a/Documentation/devicetree/bindings/arm/arm-boards
+++ b/Documentation/devicetree/bindings/arm/arm-boards
@@ -86,3 +86,60 @@  Interrupt controllers:
 	compatible = "arm,versatile-sic";
 	interrupt-controller;
 	#interrupt-cells = <1>;
+
+
+ARM RealView Boards
+-------------------
+The RealView boards cover tailored evaluation boards that are used to explore
+the ARM11 and Cortex A-8 and Cortex A-9 processors.
+
+Required properties (in root node):
+	/* RealView Emulation Baseboard */
+	compatible = "arm,realview-eb";
+	 /* RealView Platform Baseboard for ARM1176JZF-S */
+	compatible = "arm,realview-pb1176";
+	/* RealView Platform Baseboard for ARM11 MPCore */
+	compatible = "arm,realview-pb11mp";
+	/* RealView Platform Baseboard for Cortex A-8 */
+	compatible = "arm,realview-pba8";
+	/* RealView Platform Baseboard Explore for Cortex A-9 */
+	compatible = "arm,realview-pbx";
+
+Required nodes:
+
+- syscon: some node of the RealView platforms must have a
+  system controller node pointing to the control registers,
+  with the compatible string set to one of these tuples:
+   "arm,realview-eb-syscon", "syscon"
+   "arm,realview-pb1176-syscon", "syscon"
+   "arm,realview-pb11mp-syscon", "syscon"
+   "arm,realview-pba8-syscon", "syscon"
+   "arm,realview-pbx-syscon", "syscon"
+
+  Required properties for the system controller:
+  - regs: the location and size of the system controller registers,
+    one range of 0x1000 bytes.
+
+Example:
+
+/dts-v1/;
+#include <dt-bindings/interrupt-controller/irq.h>
+#include "skeleton.dtsi"
+
+/ {
+	model = "ARM RealView PB1176 with device tree";
+	compatible = "arm,realview-pb1176";
+
+	soc {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		compatible = "simple-bus";
+		ranges;
+
+		syscon: syscon@10000000 {
+			compatible = "arm,realview-syscon", "syscon";
+			reg = <0x10000000 0x1000>;
+		};
+
+	};
+};
diff --git a/Documentation/devicetree/bindings/arm/gic.txt b/Documentation/devicetree/bindings/arm/gic.txt
index 5573c08d3180..539420194efd 100644
--- a/Documentation/devicetree/bindings/arm/gic.txt
+++ b/Documentation/devicetree/bindings/arm/gic.txt
@@ -16,6 +16,7 @@  Main node required properties:
 	"arm,cortex-a9-gic"
 	"arm,cortex-a7-gic"
 	"arm,arm11mp-gic"
+	"arm,arm1176jzf-gic"
 - interrupt-controller : Identifies the node as an interrupt controller
 - #interrupt-cells : Specifies the number of cells needed to encode an
   interrupt source.  The type shall be a <u32> and the value shall be 3.
diff --git a/arch/arm/boot/dts/Makefile b/arch/arm/boot/dts/Makefile
index 377b7c364033..1419a70026da 100644
--- a/arch/arm/boot/dts/Makefile
+++ b/arch/arm/boot/dts/Makefile
@@ -294,6 +294,7 @@  dtb-$(CONFIG_ARCH_PRIMA2) += prima2-evb.dtb
 dtb-$(CONFIG_ARCH_QCOM) += qcom-msm8660-surf.dtb \
 	qcom-msm8960-cdp.dtb \
 	qcom-apq8074-dragonboard.dtb
+dtb-$(CONFIG_ARCH_REALVIEW) += arm-realview-pb1176.dtb
 dtb-$(CONFIG_ARCH_S3C24XX) += s3c2416-smdk2416.dtb
 dtb-$(CONFIG_ARCH_S3C64XX) += s3c6410-mini6410.dtb \
 	s3c6410-smdk6410.dtb
diff --git a/arch/arm/boot/dts/arm-realview-pb1176.dts b/arch/arm/boot/dts/arm-realview-pb1176.dts
new file mode 100644
index 000000000000..0eea0f4a7b39
--- /dev/null
+++ b/arch/arm/boot/dts/arm-realview-pb1176.dts
@@ -0,0 +1,177 @@ 
+/*
+ * Copyright 2014 Linaro Ltd
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+/dts-v1/;
+#include <dt-bindings/interrupt-controller/irq.h>
+#include "skeleton.dtsi"
+
+/ {
+	model = "ARM RealView PB1176 with device tree";
+	compatible = "arm,realview-pb1176";
+
+	chosen { };
+
+	aliases {
+		serial0 = &pb1176_serial0;
+		serial1 = &pb1176_serial1;
+		serial2 = &pb1176_serial2;
+		serial3 = &pb1176_serial3;
+	};
+
+	memory {
+		/* 128 MiB memory @ 0x0 */
+		reg = <0x00000000 0x08000000>;
+	};
+
+	xtal24mhz: xtal24mhz@24M {
+		#clock-cells = <0>;
+		compatible = "fixed-clock";
+		clock-frequency = <24000000>;
+	};
+
+	timclk: timclk@1M {
+		#clock-cells = <0>;
+		compatible = "fixed-factor-clock";
+		clock-div = <24>;
+		clock-mult = <1>;
+		clocks = <&xtal24mhz>;
+	};
+
+	uartclk: uartclk@24M {
+		#clock-cells = <0>;
+		compatible = "fixed-factor-clock";
+		clock-div = <1>;
+		clock-mult = <1>;
+		clocks = <&xtal24mhz>;
+	};
+
+	/* FIXME: this actually hangs off the PLL clocks */
+	pclk: pclk@0 {
+		#clock-cells = <0>;
+		compatible = "fixed-clock";
+		clock-frequency = <0>;
+	};
+
+	soc {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		compatible = "simple-bus";
+		ranges;
+
+		syscon: syscon@10000000 {
+			compatible = "arm,realview-pb1176-syscon", "syscon";
+			reg = <0x10000000 0x1000>;
+		};
+
+		/* Primary DevChip GIC synthesized with the CPU */
+		intc_dc1176: interrupt-controller@10120000 {
+			compatible = "arm,arm1176jzf-gic";
+			#interrupt-cells = <3>;
+			#address-cells = <1>;
+			interrupt-controller;
+			reg = <0x10121000 0x1000>,
+			      <0x10120000 0x100>;
+		};
+
+		/* This GIC on the board is cascaded off the DevChip GIC */
+		intc_pb1176: interrupt-controller@10040000 {
+			compatible = "arm,arm1176jzf-gic";
+			#interrupt-cells = <3>;
+			#address-cells = <1>;
+			interrupt-controller;
+			reg = <0x10041000 0x1000>,
+			      <0x10040000 0x100>;
+			interrupt-parent = <&intc_dc1176>;
+			interrupts = <0 31 IRQ_TYPE_LEVEL_HIGH>;
+		};
+
+		L2: l2-cache {
+			compatible = "arm,l220-cache";
+			reg = <0x10110000 0x1000>;
+			interrupt-parent = <&intc_dc1176>;
+			interrupts = <0 13 IRQ_TYPE_LEVEL_HIGH>;
+			cache-unified;
+			cache-level = <2>;
+		};
+
+		pmu {
+			compatible = "arm,arm1176-pmu";
+			interrupt-parent = <&intc_dc1176>;
+			interrupts = <0 7 IRQ_TYPE_LEVEL_HIGH>;
+		};
+
+		timer01: timer@10104000 {
+			compatible = "arm,sp804", "arm,primecell";
+			reg = <0x10104000 0x1000>;
+			interrupt-parent = <&intc_dc1176>;
+			interrupts = <0 8 IRQ_TYPE_LEVEL_HIGH>, <0 9 IRQ_TYPE_LEVEL_HIGH>;
+			clocks = <&timclk>, <&timclk>, <&pclk>;
+			clock-names = "timer1", "timer2", "apb_pclk";
+		};
+
+		timer23: timer@10105000 {
+			compatible = "arm,sp804", "arm,primecell";
+			reg = <0x10105000 0x1000>;
+			interrupt-parent = <&intc_dc1176>;
+			interrupts = <0 10 IRQ_TYPE_LEVEL_HIGH>;
+			arm,sp804-has-irq = <1>;
+			clocks = <&timclk>, <&timclk>, <&pclk>;
+			clock-names = "timer1", "timer2", "apb_pclk";
+		};
+
+		pb1176_serial0: uart@1010c000 {
+			compatible = "arm,pl011", "arm,primecell";
+			reg = <0x1010c000 0x1000>;
+			interrupt-parent = <&intc_dc1176>;
+			interrupts = <0 18 IRQ_TYPE_LEVEL_HIGH>;
+			clocks = <&uartclk>, <&pclk>;
+			clock-names = "uartclk", "apb_pclk";
+		};
+
+		pb1176_serial1: uart@1010d000 {
+			compatible = "arm,pl011", "arm,primecell";
+			reg = <0x1010d000 0x1000>;
+			interrupt-parent = <&intc_dc1176>;
+			interrupts = <0 19 IRQ_TYPE_LEVEL_HIGH>;
+			clocks = <&uartclk>, <&pclk>;
+			clock-names = "uartclk", "apb_pclk";
+		};
+
+		pb1176_serial2: uart@1010e000 {
+			compatible = "arm,pl011", "arm,primecell";
+			reg = <0x1010e000 0x1000>;
+			interrupt-parent = <&intc_dc1176>;
+			interrupts = <0 20 IRQ_TYPE_LEVEL_HIGH>;
+			clocks = <&uartclk>, <&pclk>;
+			clock-names = "uartclk", "apb_pclk";
+		};
+
+		pb1176_serial3: uart@1010f000 {
+			compatible = "arm,pl011", "arm,primecell";
+			reg = <0x1010f000 0x1000>;
+			interrupt-parent = <&intc_dc1176>;
+			interrupts = <0 21 IRQ_TYPE_LEVEL_HIGH>;
+			clocks = <&uartclk>, <&pclk>;
+			clock-names = "uartclk", "apb_pclk";
+		};
+	};
+};
diff --git a/arch/arm/mach-realview/Kconfig b/arch/arm/mach-realview/Kconfig
index 9db2029aa632..65a07f5b5225 100644
--- a/arch/arm/mach-realview/Kconfig
+++ b/arch/arm/mach-realview/Kconfig
@@ -1,6 +1,16 @@ 
 menu "RealView platform type"
 	depends on ARCH_REALVIEW
 
+config REALVIEW_DT
+	bool "Support RealView(R) Device Tree based boot"
+	select ARM_GIC
+	select MFD_SYSCON
+	select SOC_BUS
+	select USE_OF
+	help
+	  Include support for booting the ARM(R) RealView(R) evaluation
+	  boards using a device tree machine description.
+
 config MACH_REALVIEW_EB
 	bool "Support RealView(R) Emulation Baseboard"
 	select ARM_GIC
diff --git a/arch/arm/mach-realview/Makefile b/arch/arm/mach-realview/Makefile
index 541fa4c109ef..e07fdf7ae8a7 100644
--- a/arch/arm/mach-realview/Makefile
+++ b/arch/arm/mach-realview/Makefile
@@ -3,6 +3,7 @@ 
 #
 
 obj-y					:= core.o
+obj-$(CONFIG_REALVIEW_DT)		+= realview-dt.o
 obj-$(CONFIG_MACH_REALVIEW_EB)		+= realview_eb.o
 obj-$(CONFIG_MACH_REALVIEW_PB11MP)	+= realview_pb11mp.o
 obj-$(CONFIG_MACH_REALVIEW_PB1176)	+= realview_pb1176.o
diff --git a/arch/arm/mach-realview/realview-dt.c b/arch/arm/mach-realview/realview-dt.c
new file mode 100644
index 000000000000..4ba7c5303d09
--- /dev/null
+++ b/arch/arm/mach-realview/realview-dt.c
@@ -0,0 +1,225 @@ 
+/*
+ * Copyright (C) 2014 Linaro Ltd.
+ *
+ * Author: Linus Walleij <linus.walleij@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ */
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/irqchip.h>
+#include <linux/irqchip/arm-gic.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+#include <linux/sys_soc.h>
+#include <linux/slab.h>
+#include <asm/mach/map.h>
+#include <asm/mach/arch.h>
+#include <asm/hardware/cache-l2x0.h>
+#include <mach/hardware.h>
+#include <mach/platform.h>
+#include <mach/board-eb.h>
+#include <mach/board-pb1176.h>
+#include <mach/board-pb11mp.h>
+#include <mach/board-pbx.h>
+#include "core.h"
+
+/* Pointer to the system controller */
+struct regmap *syscon_regmap;
+u8 syscon_type;
+
+static struct map_desc realview_dt_io_desc[] __initdata = {
+	{
+		/* FIXME: static map needed for LED driver */
+		.virtual	= IO_ADDRESS(REALVIEW_SYS_BASE),
+		.pfn		= __phys_to_pfn(REALVIEW_SYS_BASE),
+		.length		= SZ_4K,
+		.type		= MT_DEVICE,
+	},
+};
+
+static void __init realview_dt_map_io(void)
+{
+	iotable_init(realview_dt_io_desc, ARRAY_SIZE(realview_dt_io_desc));
+}
+
+/*
+ * We detect the different syscon types from the compatible strings.
+ */
+enum realview_syscon {
+	REALVIEW_SYSCON_EB,
+	REALVIEW_SYSCON_PB1176,
+	REALVIEW_SYSCON_PB11MP,
+	REALVIEW_SYSCON_PBA8,
+	REALVIEW_SYSCON_PBX,
+};
+
+static const struct of_device_id realview_syscon_match[] = {
+	{
+		.compatible = "arm,realview-eb-syscon",
+		.data = (void *)REALVIEW_SYSCON_EB,
+	},
+	{
+		.compatible = "arm,realview-pb1176-syscon",
+		.data = (void *)REALVIEW_SYSCON_PB1176,
+	},
+	{
+		.compatible = "arm,realview-pb11mp-syscon",
+		.data = (void *)REALVIEW_SYSCON_PB11MP,
+	},
+	{
+		.compatible = "arm,realview-pba8-syscon",
+		.data = (void *)REALVIEW_SYSCON_PBA8,
+	},
+	{
+		.compatible = "arm,realview-pbx-syscon",
+		.data = (void *)REALVIEW_SYSCON_PBX,
+	},
+};
+
+static void __init realview_dt_init_machine(void)
+{
+	struct device_node *root;
+	struct device_node *syscon;
+	const struct of_device_id *syscon_id;
+	struct soc_device *soc_dev;
+	struct soc_device_attribute *soc_dev_attr;
+	struct device *parent;
+	u32 coreid;
+	int ret;
+
+#if IS_ENABLED(CONFIG_CACHE_L2X0)
+	if (of_machine_is_compatible("arm,realview-eb"))
+		/*
+		 * 1MB (128KB/way), 8-way associativity,
+		 * evmon/parity/share enabled
+		 * Bits:  .... ...0 0111 1001 0000 .... .... ....
+		 */
+		l2x0_of_init(0x00790000, 0xfe000fff);
+	else if (of_machine_is_compatible("arm,realview-pb1176"))
+		/*
+		 * 128Kb (16Kb/way) 8-way associativity.
+		 * evmon/parity/share enabled.
+		 */
+		l2x0_of_init(0x00730000, 0xfe000fff);
+	else if (of_machine_is_compatible("arm,realview-pb11mp"))
+		/*
+		 * 1MB (128KB/way), 8-way associativity,
+		 * evmon/parity/share enabled
+		 * Bits:  .... ...0 0111 1001 0000 .... .... ....
+		 */
+		l2x0_of_init(0x00730000, 0xfe000fff);
+	else if (of_machine_is_compatible("arm,realview-pbx"))
+		/*
+		 * 16KB way size, 8-way associativity, parity disabled
+		 * Bits:  .. 0 0 0 0 1 00 1 0 1 001 0 000 0 .... .... ....
+		 */
+		l2x0_of_init(0x02520000, 0xc0000fff);
+#endif
+
+        /* Here we create an SoC device for the root node */
+	root = of_find_node_by_path("/");
+	if (!root)
+		return;
+	syscon = of_find_matching_node_and_match(root, realview_syscon_match,
+						 &syscon_id);
+	if (!syscon)
+		return;
+	syscon_type = (enum realview_syscon)syscon_id->data;
+
+	soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
+	if (!soc_dev_attr)
+		return;
+	ret = of_property_read_string(root, "compatible",
+				      &soc_dev_attr->soc_id);
+	if (ret)
+		return;
+	ret = of_property_read_string(root, "model", &soc_dev_attr->machine);
+        if (ret)
+		return;
+	soc_dev_attr->family = "RealView";
+	soc_dev = soc_device_register(soc_dev_attr);
+	if (IS_ERR(soc_dev)) {
+		kfree(soc_dev_attr);
+		return;
+	}
+	parent = soc_device_to_device(soc_dev);
+	ret = of_platform_populate(root, of_default_bus_match_table,
+				   NULL, parent);
+	if (ret) {
+		pr_crit("could not populate device tree\n");
+		return;
+	}
+
+	syscon_regmap = syscon_node_to_regmap(syscon);
+	if (IS_ERR(syscon_regmap)) {
+		pr_crit("could not locate syscon regmap\n");
+		return;
+	}
+	ret = regmap_read(syscon_regmap, REALVIEW_SYS_ID_OFFSET, &coreid);
+	if (ret)
+		return;
+	pr_info("RealView Syscon type %02x, Core ID: 0x%08x\n",
+		syscon_type, coreid);
+	/* FIXME: add attributes for SoC to sysfs */
+}
+
+static void realview_dt_restart(enum reboot_mode mode, const char *cmd)
+{
+	if (IS_ERR(syscon_regmap))
+		return;
+
+	/* Unlock the reset register */
+	regmap_write(syscon_regmap, REALVIEW_SYS_LOCK_OFFSET,
+		     REALVIEW_SYS_LOCK_VAL);
+	/* Then hit reset on the different machines */
+	switch (syscon_type) {
+	case REALVIEW_SYSCON_EB:
+		regmap_write(syscon_regmap,
+			     REALVIEW_SYS_RESETCTL_OFFSET, 0x0008);
+		break;
+	case REALVIEW_SYSCON_PB1176:
+		regmap_write(syscon_regmap,
+			     REALVIEW_SYS_RESETCTL_OFFSET, 0x0100);
+		break;
+	case REALVIEW_SYSCON_PB11MP:
+	case REALVIEW_SYSCON_PBA8:
+		regmap_write(syscon_regmap, REALVIEW_SYS_RESETCTL_OFFSET,
+			     0x0000);
+		regmap_write(syscon_regmap, REALVIEW_SYS_RESETCTL_OFFSET,
+			     0x0004);
+		break;
+	case REALVIEW_SYSCON_PBX:
+		regmap_write(syscon_regmap, REALVIEW_SYS_RESETCTL_OFFSET,
+			     0x00f0);
+		regmap_write(syscon_regmap, REALVIEW_SYS_RESETCTL_OFFSET,
+			     0x00f4);
+		break;
+	}
+	dsb();
+}
+
+static const char *realview_dt_platform_compat[] __initconst = {
+	"arm,realview-eb",
+	"arm,realview-pb1176",
+	"arm,realview-pb11mp",
+	"arm,realview-pba8",
+	"arm,realview-pbx",
+	NULL,
+};
+
+DT_MACHINE_START(REALVIEW_DT, "ARM RealView Machine (Device Tree Support)")
+	.map_io		= realview_dt_map_io,
+	.init_machine	= realview_dt_init_machine,
+#ifdef CONFIG_ZONE_DMA
+	.dma_zone_size	= SZ_256M,
+#endif
+	.dt_compat	= realview_dt_platform_compat,
+	.restart	= realview_dt_restart,
+MACHINE_END
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index 5bf7c3c3b301..5461c4401ed6 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -928,7 +928,7 @@  config ARM_L1_CACHE_SHIFT
 config ARM_DMA_MEM_BUFFERABLE
 	bool "Use non-cacheable memory for DMA" if (CPU_V6 || CPU_V6K) && !CPU_V7
 	depends on !(MACH_REALVIEW_PB1176 || REALVIEW_EB_ARM11MP || \
-		     MACH_REALVIEW_PB11MP)
+		     MACH_REALVIEW_PB11MP || REALVIEW_DT)
 	default y if CPU_V6 || CPU_V6K || CPU_V7
 	help
 	  Historically, the kernel has used strongly ordered mappings to
diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
index 57d165e026f4..70281b38c73b 100644
--- a/drivers/irqchip/irq-gic.c
+++ b/drivers/irqchip/irq-gic.c
@@ -1073,6 +1073,7 @@  gic_of_init(struct device_node *node, struct device_node *parent)
 }
 IRQCHIP_DECLARE(cortex_a15_gic, "arm,cortex-a15-gic", gic_of_init);
 IRQCHIP_DECLARE(cortex_a9_gic, "arm,cortex-a9-gic", gic_of_init);
+IRQCHIP_DECLARE(arm1176jzf_gic, "arm,arm1176jzf-gic", gic_of_init);
 IRQCHIP_DECLARE(msm_8660_qgic, "qcom,msm-8660-qgic", gic_of_init);
 IRQCHIP_DECLARE(msm_qgic2, "qcom,msm-qgic2", gic_of_init);