Subject: [PATCH] gpio: Device tree support for LPC32xx

From: [email-masked] (Grant Likely)
Date: Tue, 03 Apr 2012 09:04:30 -0600

On Tue,  3 Apr 2012 00:58:33 +0200, Roland Stigge <[email-masked]> wrote:
> This patch adds device tree support for gpio-lpc32xx.c
> 
> Signed-off-by: Roland Stigge <[email-masked]>
> 
> ---
> 
>  Applies to v3.4-rc1
> 
>  Can add this patch to the LPC32xx series for an update, if necessary.
> 
>  Thanks to Arnd Bergmann for the help with registering GPIO via OF!

Hi Roland,

Comments below.

> 
>  Documentation/devicetree/bindings/gpio/gpio_lpc32xx.txt |   71 ++++++++++++++++
>  arch/arm/mach-lpc32xx/include/mach/gpio.h               |    9 +-
>  drivers/gpio/gpio-lpc32xx.c                             |   45 +++++++++-
>  3 files changed, 120 insertions(+), 5 deletions(-)
> 
> --- /dev/null
> +++ linux-2.6/Documentation/devicetree/bindings/gpio/gpio_lpc32xx.txt
> @@ -0,0 +1,71 @@
> +NXP LPC32xx SoC GPIO controller
> +
> +Required properties:
> +- compatible: "nxp,lpc32xx-gpio"
> +- reg: Physical base address and length of the controller's registers.
> +- #address-cells: For indexing of the subnodes (GPIO groups of the SoC)
> +- #size-cells: Always 0
> +- #gpio-cells: Should be two. The first cell is the pin number and the
> +  second cell is used to specify optional parameters:
> +  - bit 0 specifies polarity (0 for normal, 1 for inverted)

Having #gpio-cells in the parent node doesn't make much sense when it
looks like the users reference the child node banks directly and which
have their own #gpio-cells properties.

> +
> +Required properties of sub-nodes which describe the GPIO groups of LPC32xx:
> +- gpio-controller: Marks the device node as a GPIO controller.
> +- #gpio-cells: Should be two. The first cell is the pin number and the
> +  second cell is used to specify optional parameters:
> +  - bit 0 specifies polarity (0 for normal, 1 for inverted)
> +- reg: Index of the GPIO group
> +- gpio-lines: Number of GPIOs in that subnode/GPIO group

The driver doesn't appear to be using the gpio-lines property.  Is it
really necessary?

> +
> +Example:
> +
> +	gpio: gpio at 40028000 {
> +		compatible = "nxp,lpc32xx-gpio";
> +		reg = <0x40028000 0x1000>;
> +		/* create a private address space for enumeration */
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +		#gpio-cells = <2>;
> +
> +		gpio_p0: gpio-bank at 0 {
> +			gpio-controller;
> +			#gpio-cells = <2>;
> +			gpio-lines = <8>;
> +			reg = <0>;
> +		};
> +
> +		gpio_p1: gpio-bank at 1 {
> +			gpio-controller;
> +			#gpio-cells = <2>;
> +			gpio-lines = <24>;
> +			reg = <1>;
> +		};
> +
> +		gpio_p2: gpio-bank at 2 {
> +			gpio-controller;
> +			#gpio-cells = <2>;
> +			gpio-lines = <13>;
> +			reg = <2>;
> +		};
> +
> +		gpio_p3: gpio-bank at 3 {
> +			gpio-controller;
> +			#gpio-cells = <2>;
> +			gpio-lines = <6>;
> +			reg = <3>;
> +		};
> +
> +		gpi_p3: gpio-bank at 4 {
> +			gpio-controller;
> +			#gpio-cells = <2>;
> +			gpio-lines = <28>;
> +			reg = <4>;
> +		};
> +
> +		gpo_p3: gpio-bank at 5 {
> +			gpio-controller;
> +			#gpio-cells = <2>;
> +			gpio-lines = <24>;
> +			reg = <5>;
> +		};
> +	};
> --- linux-2.6.orig/arch/arm/mach-lpc32xx/include/mach/gpio.h
> +++ linux-2.6/arch/arm/mach-lpc32xx/include/mach/gpio.h
> @@ -1 +1,8 @@
> -/* empty */
> +#ifndef __MACH_GPIO_H
> +#define __MACH_GPIO_H
> +
> +#include "gpio-lpc32xx.h"
> +
> +#define ARCH_NR_GPIOS (LPC32XX_GPO_P3_GRP + LPC32XX_GPO_P3_MAX)
> +
> +#endif /* __MACH_GPIO_H */
> --- linux-2.6.orig/drivers/gpio/gpio-lpc32xx.c
> +++ linux-2.6/drivers/gpio/gpio-lpc32xx.c
> @@ -21,6 +21,9 @@
>  #include <linux/io.h>
>  #include <linux/errno.h>
>  #include <linux/gpio.h>
> +#include <linux/of_gpio.h>
> +#include <linux/platform_device.h>
> +#include <linux/module.h>
>  
>  #include <mach/hardware.h>
>  #include <mach/platform.h>
> @@ -454,10 +457,44 @@ static struct lpc32xx_gpio_chip lpc32xx_
>  	},
>  };
>  
> -void __init lpc32xx_gpio_init(void)
> +static int __devinit lpc32xx_gpio_probe(struct platform_device *pdev)
>  {
> -	int i;
> +	struct device_node *node;
>  
> -	for (i = 0; i < ARRAY_SIZE(lpc32xx_gpiochip); i++)
> -		gpiochip_add(&lpc32xx_gpiochip[i].chip);
> +	for_each_child_of_node(pdev->dev.of_node, node) {
> +		if (of_device_is_available(node)) {
> +			u32 index;
> +			struct gpio_chip *chip;
> +			if (of_property_read_u32(node, "reg", &index) < 0)
> +				continue;
> +			if (index >= ARRAY_SIZE(lpc32xx_gpiochip))
> +				continue;
> +			chip = &lpc32xx_gpiochip[index].chip;
> +			chip->of_node = of_node_get(node);
> +			gpiochip_add(chip);
> +		}
> +	}
> +
> +	return 0;
>  }
> +
> +static struct of_device_id lpc32xx_gpio_of_match[] __devinitdata = {
> +	{ .compatible = "nxp,lpc32xx-gpio", },
> +	{ },
> +};
> +
> +static struct platform_driver lpc32xx_gpio_driver = {
> +	.driver		= {
> +		.name	= "lpc32xx-gpio",
> +		.owner	= THIS_MODULE,
> +		.of_match_table = lpc32xx_gpio_of_match,
> +	},
> +	.probe		= lpc32xx_gpio_probe,
> +};
> +
> +static int __init lpc32xx_gpio_init(void)
> +{
> +	return platform_driver_register(&lpc32xx_gpio_driver);
> +}
> +postcore_initcall(lpc32xx_gpio_init);

module_platform_driver() please.  Also, now that deferred probe is
merged, there should no longer be any need to mess around with
initcall levels to get gpio drivers probed early.

g.