linux-kernel - Re: [PATCH v2 1/3] gpio / ACPI: add ACPI support

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Date:	Fri, 16 Nov 2012 02:34:22 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:	linux-kernel@...r.kernel.org, lenb@...nel.org,
	rafael.j.wysocki@...el.com, broonie@...nsource.wolfsonmicro.com,
	grant.likely@...retlab.ca, linus.walleij@...aro.org,
	khali@...ux-fr.org, ben-linux@...ff.org, w.sang@...gutronix.de,
	bhelgaas@...gle.com, mathias.nyman@...ux.intel.com,
	linux-acpi@...r.kernel.org
Subject: Re: [PATCH v2 1/3] gpio / ACPI: add ACPI support

On Thursday, November 15, 2012 01:03:15 PM Mika Westerberg wrote:
> From: Mathias Nyman <mathias.nyman@...ux.intel.com>
> 
> Add support for translating ACPI GPIO pin numbers to Linux GPIO API pins.
> Needs a gpio controller driver with the acpi handler hook set.
> 
> Drivers can use acpi_get_gpio() to translate ACPI5 GpioIO and GpioInt
> resources to Linux GPIO's.
> 
> Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
> Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> ---
>  drivers/gpio/Kconfig        |    4 ++++
>  drivers/gpio/Makefile       |    1 +
>  drivers/gpio/gpiolib-acpi.c |   56 +++++++++++++++++++++++++++++++++++++++++++
>  include/linux/acpi_gpio.h   |   19 +++++++++++++++
>  4 files changed, 80 insertions(+)
>  create mode 100644 drivers/gpio/gpiolib-acpi.c
>  create mode 100644 include/linux/acpi_gpio.h
> 
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index f11d8e3..5c9b384 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -49,6 +49,10 @@ config OF_GPIO
>  	def_bool y
>  	depends on OF
>  
> +config GPIO_ACPI
> +	def_bool y
> +	depends on ACPI
> +
>  config DEBUG_GPIO
>  	bool "Debug GPIO calls"
>  	depends on DEBUG_KERNEL
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index 9aeed67..420dbac 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -4,6 +4,7 @@ ccflags-$(CONFIG_DEBUG_GPIO)	+= -DDEBUG
>  
>  obj-$(CONFIG_GPIOLIB)		+= gpiolib.o devres.o
>  obj-$(CONFIG_OF_GPIO)		+= gpiolib-of.o
> +obj-$(CONFIG_GPIO_ACPI)		+= gpiolib-acpi.o
>  
>  # Device drivers. Generally keep list sorted alphabetically
>  obj-$(CONFIG_GPIO_GENERIC)	+= gpio-generic.o
> diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
> new file mode 100644
> index 0000000..8ef9831
> --- /dev/null
> +++ b/drivers/gpio/gpiolib-acpi.c
> @@ -0,0 +1,56 @@
> +/*
> + * ACPI helpers for GPIO API
> + *
> + * Copyright (C) 2012, Intel Corporation
> + * Authors: Mathias Nyman <mathias.nyman@...ux.intel.com>
> + *          Mika Westerberg <mika.westerberg@...ux.intel.com>
> + *
> + * 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/errno.h>
> +#include <linux/gpio.h>
> +#include <linux/export.h>
> +#include <linux/acpi_gpio.h>
> +#include <linux/acpi.h>
> +
> +static int acpi_gpiochip_find(struct gpio_chip *gc, void *data)
> +{
> +	acpi_handle handle = data;
> +
> +	if (!gc->dev)
> +		return false;
> +
> +	return gc->dev->acpi_handle == handle;

I'd prefer DEVICE_ACPI_HANDLE() to be used in such places, we may want to
replace it with something else in the future or make it work differently.

> +}
> +
> +/**
> + * acpi_get_gpio() - Translate ACPI GPIO pin to GPIO number usable with GPIO API
> + * @path:	ACPI GPIO controller full path name, (e.g. "\\_SB.GPO1")
> + * @pin:	ACPI GPIO pin number (0-based, controller-relative)
> + *
> + * Returns GPIO number to use with Linux generic GPIO API, or errno error value
> + */
> +
> +int acpi_get_gpio(char *path, int pin)
> +{
> +	struct gpio_chip *chip;
> +	acpi_handle handle;
> +	acpi_status status;
> +
> +	status = acpi_get_handle(NULL, path, &handle);
> +	if (ACPI_FAILURE(status))
> +		return -ENODEV;
> +
> +	chip = gpiochip_find(handle, acpi_gpiochip_find);
> +	if (!chip)
> +		return -ENODEV;
> +
> +	if (!gpio_is_valid(chip->base + pin))
> +		return -EINVAL;
> +
> +	return chip->base + pin;
> +}
> +EXPORT_SYMBOL_GPL(acpi_get_gpio);
> diff --git a/include/linux/acpi_gpio.h b/include/linux/acpi_gpio.h
> new file mode 100644
> index 0000000..91615a3
> --- /dev/null
> +++ b/include/linux/acpi_gpio.h
> @@ -0,0 +1,19 @@
> +#ifndef _LINUX_ACPI_GPIO_H_
> +#define _LINUX_ACPI_GPIO_H_
> +
> +#include <linux/errno.h>
> +
> +#ifdef CONFIG_GPIO_ACPI
> +
> +int acpi_get_gpio(char *path, int pin);
> +
> +#else /* CONFIG_GPIO_ACPI */
> +
> +static inline int acpi_get_gpio(char *path, int pin)
> +{
> +	return -ENODEV;
> +}
> +
> +#endif /* CONFIG_GPIO_ACPI */
> +
> +#endif /* _LINUX_ACPI_GPIO_H_ */
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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