diff mbox

[v2,1/5] gpio: Cygnus: define Broadcom Cygnus GPIO binding

Message ID 1418006316-324-2-git-send-email-rjui@broadcom.com
State Superseded
Headers show

Commit Message

Ray Jui Dec. 8, 2014, 2:38 a.m. UTC 
Document the GPIO device tree binding for Broadcom Cygnus SoC

Signed-off-by: Ray Jui <rjui@broadcom.com>
Reviewed-by: Scott Branden <sbranden@broadcom.com>
---
 .../devicetree/bindings/gpio/brcm,cygnus-gpio.txt  |   85 ++++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/gpio/brcm,cygnus-gpio.txt

Comments

Arnd Bergmann Dec. 8, 2014, 11:22 a.m. UTC | #1 
On Sunday 07 December 2014 18:38:32 Ray Jui wrote:
> +Required properties:
> +
> +- compatible:
> +    Currently supported Cygnus GPIO controllers include:
> +    "brcm,cygnus-ccm-gpio": ChipcommonG GPIO controller
> +    "brcm,cygnus-asiu-gpio": ASIU GPIO controller
> +    "brcm,cygnus-crmu-gpio": CRMU GPIO controller

How different are these? If they are almost the same, would it
be better to use the same compatible string for all of them and
describe the differences in extra properties?

If they are rather different, maybe you should have a separate
binding and driver for each?

	Arnd
--
To unsubscribe from this list: send the line "unsubscribe linux-gpio" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Ray Jui Dec. 8, 2014, 4:55 p.m. UTC | #2 
On 12/8/2014 3:22 AM, Arnd Bergmann wrote:
> On Sunday 07 December 2014 18:38:32 Ray Jui wrote:
>> +Required properties:
>> +
>> +- compatible:
>> +    Currently supported Cygnus GPIO controllers include:
>> +    "brcm,cygnus-ccm-gpio": ChipcommonG GPIO controller
>> +    "brcm,cygnus-asiu-gpio": ASIU GPIO controller
>> +    "brcm,cygnus-crmu-gpio": CRMU GPIO controller
>
> How different are these? If they are almost the same, would it
> be better to use the same compatible string for all of them and
> describe the differences in extra properties?
>
> If they are rather different, maybe you should have a separate
> binding and driver for each?
>
> 	Arnd
>
They are quite similar with the following minor differences:
1) ChipcommonG GPIO controller uses a separate register block 
(0x0301d164) to control drive stregnth
2) Cannot control drive strength for the CMRU GPIO
3) CRMU GPIO controller's interrupt is not connected to GIC of A9. 
Currently that's taken care of by using a "no-interrupt" device tree 
property

I can change to use the common compatible string "brcm,cygnus-gpio". 
With an introduction of property "no-drv-stregnth" which should be set 
for CRMU GPIO controller. For ChipcommonG GPIO, it will have a second 
register block defined, so we'll know to use that second register block 
for drive strength configuration. For the rest, we assume normal drive 
strength configuration (i.e., ASIU in our case).

Looking at this again, it looks like the "no-interrupt" property is 
really redundant. For GPIO controller without interrupt connected to A9, 
we can simply leave its interrupt properties not defined. I'll get rid 
of it along with the above changes.
--
To unsubscribe from this list: send the line "unsubscribe linux-gpio" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Arnd Bergmann Dec. 8, 2014, 5:11 p.m. UTC | #3 
On Monday 08 December 2014 08:55:20 Ray Jui wrote:
> 
> On 12/8/2014 3:22 AM, Arnd Bergmann wrote:
> > On Sunday 07 December 2014 18:38:32 Ray Jui wrote:
> >> +Required properties:
> >> +
> >> +- compatible:
> >> +    Currently supported Cygnus GPIO controllers include:
> >> +    "brcm,cygnus-ccm-gpio": ChipcommonG GPIO controller
> >> +    "brcm,cygnus-asiu-gpio": ASIU GPIO controller
> >> +    "brcm,cygnus-crmu-gpio": CRMU GPIO controller
> >
> > How different are these? If they are almost the same, would it
> > be better to use the same compatible string for all of them and
> > describe the differences in extra properties?
> >
> > If they are rather different, maybe you should have a separate
> > binding and driver for each?
> >
> > 	Arnd
> >
> They are quite similar with the following minor differences:
> 1) ChipcommonG GPIO controller uses a separate register block 
> (0x0301d164) to control drive stregnth
> 2) Cannot control drive strength for the CMRU GPIO

This can be deducted from having one or two register blocks I
assume.

> 3) CRMU GPIO controller's interrupt is not connected to GIC of A9. 
> Currently that's taken care of by using a "no-interrupt" device tree 
> property

No need for this property even, just see if there is an "interrupts"
property or not.
 
> I can change to use the common compatible string "brcm,cygnus-gpio". 
> With an introduction of property "no-drv-stregnth" which should be set 
> for CRMU GPIO controller. 

Ok.

> For ChipcommonG GPIO, it will have a second 
> register block defined, so we'll know to use that second register block 
> for drive strength configuration. For the rest, we assume normal drive 
> strength configuration (i.e., ASIU in our case).

Maybe see if something older than cygnus was already using a compatible
gpio controller and then use the name of that.

> Looking at this again, it looks like the "no-interrupt" property is 
> really redundant. For GPIO controller without interrupt connected to A9, 
> we can simply leave its interrupt properties not defined. I'll get rid 
> of it along with the above changes.

Right.

	Arnd
--
To unsubscribe from this list: send the line "unsubscribe linux-gpio" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
diff mbox

Patch

diff --git a/Documentation/devicetree/bindings/gpio/brcm,cygnus-gpio.txt b/Documentation/devicetree/bindings/gpio/brcm,cygnus-gpio.txt
new file mode 100644
index 0000000..24a1513
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/brcm,cygnus-gpio.txt
@@ -0,0 +1,85 @@ 
+Broadcom Cygnus GPIO Controller
+
+Required properties:
+
+- compatible:
+    Currently supported Cygnus GPIO controllers include:
+    "brcm,cygnus-ccm-gpio": ChipcommonG GPIO controller
+    "brcm,cygnus-asiu-gpio": ASIU GPIO controller
+    "brcm,cygnus-crmu-gpio": CRMU GPIO controller
+
+- reg:
+    Define the base and range of the I/O address space that contain the Cygnus
+GPIO controller registers
+
+- ngpios:
+    Total number of GPIOs the controller provides
+
+- #gpio-cells:
+    Must be two. The first cell is the GPIO pin number (within the
+controller's domain) and the second cell is used for the following:
+    bit[0]: polarity (0 for normal and 1 for inverted)
+    bit[18:16]: internal pull up/down: 0 - pull up/down disabled
+                                       1 - pull up enabled
+                                       2 - pull down enabled
+    bit[22:20]: drive strength: 0 - 2 mA
+                                1 - 4 mA
+                                2 - 6 mA
+                                3 - 8 mA
+                                4 - 10 mA
+                                5 - 12 mA
+                                6 - 14 mA
+                                7 - 16 mA
+
+- gpio-controller:
+    Specifies that the node is a GPIO controller
+
+Optional properties:
+
+- interrupt-controller:
+    Specifies that the node is an interrupt controller. Not all Cygnus GPIO
+interfaces support interrupt, e.g., the CRMU GPIO controller does not have its
+interrupt routed to the main processor's GIC
+
+- interrupts:
+    The interrupt outputs from the GPIO controller.
+
+- no-interrupt:
+    Specifies that the GPIO interface does not support interrupt
+
+Example:
+	gpio_asiu: gpio@180a5000 {
+		compatible = "brcm,cygnus-asiu-gpio";
+		reg = <0x180a5000 0x668>;
+		ngpios = <122>;
+		#gpio-cells = <2>;
+		gpio-controller;
+		interrupt-controller;
+		interrupts = <GIC_SPI 174 IRQ_TYPE_LEVEL_HIGH>;
+	};
+
+	gpio_crmu: gpio@03024800 {
+		compatible = "brcm,cygnus-crmu-gpio";
+		reg = <0x03024800 0x50>;
+		ngpios = <6>;
+		#gpio-cells = <2>;
+		gpio-controller;
+		no-interrupt;
+	};
+
+	/*
+	 * Touchscreen that uses the ASIU GPIO 100, with internal pull-up
+	 * enabled
+	 */
+	tsc {
+		...
+		...
+		gpio-event = <&gpio_asiu 100 0x10000>;
+	};
+
+	/* Bluetooth that uses the CRMU GPIO 2, with polarity inverted */
+	bluetooth {
+		...
+		...
+		bcm,rfkill-bank-sel = <&gpio_crmu 2 1>
+	}