[v4,06/18] arm: pci: add a align_resource hook

The PCI specifications says that an I/O region must be aligned on a 4
KB boundary, and a memory region aligned on a 1 MB boundary.

However, the Marvell PCIe interfaces rely on address decoding windows
(which allow to associate a range of physical addresses with a given
device). For PCIe memory windows, those windows are defined with a 1
MB granularity (which matches the PCI specs), but PCIe I/O windows can
only be defined with a 64 KB granularity, so they have to be 64 KB
aligned. We therefore need to tell the PCI core about this special
alignement requirement.

The PCI core already calls pcibios_align_resource() in the ARM PCI
core, specifically for such purposes. So this patch extends the ARM
PCI core so that it calls a ->align_resource() hook registered by the
PCI driver, exactly like the existing ->map_irq() and ->swizzle()
hooks.

A particular PCI driver can register a align_resource() hook, and do
its own specific alignement, depending on the specific constraints of
the underlying hardware.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Russell King <linux@arm.linux.org.uk>
---
 arch/arm/include/asm/mach/pci.h |   11 +++++++++++
 arch/arm/kernel/bios32.c        |    6 ++++++
 2 files changed, 17 insertions(+)

Russell,

Shall I submit the following patch to the ARM patch system? It is
an important dependency of the Marvell PCIe driver.

Note that this patch had already been submitted, and you suggested
using numerical values instead of a function hook, but in fact a
function hook is really needed as the PCIe alignment constraints of the
Marvell HW cannot be simply expressed through numerical values: the
alignment constraints depend on the size of the PCIe region being
considered.

See mvebu_pcie_align_resource() in
http://lists.infradead.org/pipermail/linux-arm-kernel/2013-March/153659.html
if you want to see how we use this hook.

Thanks,

Thomas

On Fri,  8 Mar 2013 16:19:08 +0100, Thomas Petazzoni wrote:
> The PCI specifications says that an I/O region must be aligned on a 4
> KB boundary, and a memory region aligned on a 1 MB boundary.
> 
> However, the Marvell PCIe interfaces rely on address decoding windows
> (which allow to associate a range of physical addresses with a given
> device). For PCIe memory windows, those windows are defined with a 1
> MB granularity (which matches the PCI specs), but PCIe I/O windows can
> only be defined with a 64 KB granularity, so they have to be 64 KB
> aligned. We therefore need to tell the PCI core about this special
> alignement requirement.
> 
> The PCI core already calls pcibios_align_resource() in the ARM PCI
> core, specifically for such purposes. So this patch extends the ARM
> PCI core so that it calls a ->align_resource() hook registered by the
> PCI driver, exactly like the existing ->map_irq() and ->swizzle()
> hooks.
> 
> A particular PCI driver can register a align_resource() hook, and do
> its own specific alignement, depending on the specific constraints of
> the underlying hardware.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> Cc: Russell King <linux@arm.linux.org.uk>
> ---
>  arch/arm/include/asm/mach/pci.h |   11 +++++++++++
>  arch/arm/kernel/bios32.c        |    6 ++++++
>  2 files changed, 17 insertions(+)
> 
> diff --git a/arch/arm/include/asm/mach/pci.h b/arch/arm/include/asm/mach/pci.h
> index 5cf2e97..7d2c3c8 100644
> --- a/arch/arm/include/asm/mach/pci.h
> +++ b/arch/arm/include/asm/mach/pci.h
> @@ -30,6 +30,11 @@ struct hw_pci {
>  	void		(*postinit)(void);
>  	u8		(*swizzle)(struct pci_dev *dev, u8 *pin);
>  	int		(*map_irq)(const struct pci_dev *dev, u8 slot, u8 pin);
> +	resource_size_t (*align_resource)(struct pci_dev *dev,
> +					  const struct resource *res,
> +					  resource_size_t start,
> +					  resource_size_t size,
> +					  resource_size_t align);
>  };
>  
>  /*
> @@ -51,6 +56,12 @@ struct pci_sys_data {
>  	u8		(*swizzle)(struct pci_dev *, u8 *);
>  					/* IRQ mapping				*/
>  	int		(*map_irq)(const struct pci_dev *, u8, u8);
> +					/* Resource alignement requirements	*/
> +	resource_size_t (*align_resource)(struct pci_dev *dev,
> +					  const struct resource *res,
> +					  resource_size_t start,
> +					  resource_size_t size,
> +					  resource_size_t align);
>  	void		*private_data;	/* platform controller private data	*/
>  };
>  
> diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
> index a1f73b5..b2ed73c 100644
> --- a/arch/arm/kernel/bios32.c
> +++ b/arch/arm/kernel/bios32.c
> @@ -462,6 +462,7 @@ static void pcibios_init_hw(struct hw_pci *hw, struct list_head *head)
>  		sys->busnr   = busnr;
>  		sys->swizzle = hw->swizzle;
>  		sys->map_irq = hw->map_irq;
> +		sys->align_resource = hw->align_resource;
>  		INIT_LIST_HEAD(&sys->resources);
>  
>  		if (hw->private_data)
> @@ -574,6 +575,8 @@ char * __init pcibios_setup(char *str)
>  resource_size_t pcibios_align_resource(void *data, const struct resource *res,
>  				resource_size_t size, resource_size_t align)
>  {
> +	struct pci_dev *dev = data;
> +	struct pci_sys_data *sys = dev->sysdata;
>  	resource_size_t start = res->start;
>  
>  	if (res->flags & IORESOURCE_IO && start & 0x300)
> @@ -581,6 +584,9 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
>  
>  	start = (start + align - 1) & ~(align - 1);
>  
> +	if (sys->align_resource)
> +		return sys->align_resource(dev, res, start, size, align);
> +
>  	return start;
>  }
>