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of/gpio: Implement of_get_gpio_flags()

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This adds a new function, of_get_gpio_flags, which is like
of_get_gpio(), but accepts a new "flags" argument.  This new function
will be used by the drivers that need to retrieve additional GPIO
information, such as active-low flag.

Also, this changes the default ("simple") .xlate routine to warn about
bogus (< 2) #gpio-cells usage: the second cell should always be present
for GPIO flags.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Anton Vorontsov 2008-12-01 06:30:04 +00:00 committed by Paul Mackerras
parent 2fd091f3ee
commit b908b53d58
2 changed files with 63 additions and 11 deletions
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36
drivers/of/gpio.c
View file

@ -19,14 +19,17 @@
#include <asm/prom.h>
/**
* of_get_gpio - Get a GPIO number from the device tree to use with GPIO API
* of_get_gpio_flags - Get a GPIO number and flags to use with GPIO API
* @np: device node to get GPIO from
* @index: index of the GPIO
* @flags: a flags pointer to fill in
*
* Returns GPIO number to use with Linux generic GPIO API, or one of the errno
* value on the error condition.
* value on the error condition. If @flags is not NULL the function also fills
* in flags for the GPIO.
*/
int of_get_gpio(struct device_node *np, int index)
int of_get_gpio_flags(struct device_node *np, int index,
enum of_gpio_flags *flags)
{
int ret;
struct device_node *gc;
@ -59,7 +62,11 @@ int of_get_gpio(struct device_node *np, int index)
goto err1;
}
ret = of_gc->xlate(of_gc, np, gpio_spec);
/* .xlate might decide to not fill in the flags, so clear it. */
if (flags)
*flags = 0;
ret = of_gc->xlate(of_gc, np, gpio_spec, flags);
if (ret < 0)
goto err1;
@ -70,26 +77,41 @@ err0:
pr_debug("%s exited with status %d\n", __func__, ret);
return ret;
}
EXPORT_SYMBOL(of_get_gpio);
EXPORT_SYMBOL(of_get_gpio_flags);
/**
* of_gpio_simple_xlate - translate gpio_spec to the GPIO number
* of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
* @of_gc: pointer to the of_gpio_chip structure
* @np: device node of the GPIO chip
* @gpio_spec: gpio specifier as found in the device tree
* @flags: a flags pointer to fill in
*
* This is simple translation function, suitable for the most 1:1 mapped
* gpio chips. This function performs only one sanity check: whether gpio
* is less than ngpios (that is specified in the gpio_chip).
*/
int of_gpio_simple_xlate(struct of_gpio_chip *of_gc, struct device_node *np,
const void *gpio_spec)
const void *gpio_spec, enum of_gpio_flags *flags)
{
const u32 *gpio = gpio_spec;
/*
* We're discouraging gpio_cells < 2, since that way you'll have to
* write your own xlate function (that will have to retrive the GPIO
* number and the flags from a single gpio cell -- this is possible,
* but not recommended).
*/
if (of_gc->gpio_cells < 2) {
WARN_ON(1);
return -EINVAL;
}
if (*gpio > of_gc->gc.ngpio)
return -EINVAL;
if (flags)
*flags = gpio[1];
return *gpio;
}
EXPORT_SYMBOL(of_gpio_simple_xlate);

38
include/linux/of_gpio.h
View file

@ -14,9 +14,22 @@
#ifndef __LINUX_OF_GPIO_H
#define __LINUX_OF_GPIO_H
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/gpio.h>
struct device_node;
/*
* This is Linux-specific flags. By default controllers' and Linux' mapping
* match, but GPIO controllers are free to translate their own flags to
* Linux-specific in their .xlate callback. Though, 1:1 mapping is recommended.
*/
enum of_gpio_flags {
OF_GPIO_ACTIVE_LOW = 0x1,
};
#ifdef CONFIG_OF_GPIO
/*
@ -26,7 +39,7 @@ struct of_gpio_chip {
struct gpio_chip gc;
int gpio_cells;
int (*xlate)(struct of_gpio_chip *of_gc, struct device_node *np,
const void *gpio_spec);
const void *gpio_spec, enum of_gpio_flags *flags);
};
static inline struct of_gpio_chip *to_of_gpio_chip(struct gpio_chip *gc)
@ -50,20 +63,37 @@ static inline struct of_mm_gpio_chip *to_of_mm_gpio_chip(struct gpio_chip *gc)
return container_of(of_gc, struct of_mm_gpio_chip, of_gc);
}
extern int of_get_gpio(struct device_node *np, int index);
extern int of_get_gpio_flags(struct device_node *np, int index,
enum of_gpio_flags *flags);
extern int of_mm_gpiochip_add(struct device_node *np,
struct of_mm_gpio_chip *mm_gc);
extern int of_gpio_simple_xlate(struct of_gpio_chip *of_gc,
struct device_node *np,
const void *gpio_spec);
const void *gpio_spec,
enum of_gpio_flags *flags);
#else
/* Drivers may not strictly depend on the GPIO support, so let them link. */
static inline int of_get_gpio(struct device_node *np, int index)
static inline int of_get_gpio_flags(struct device_node *np, int index,
enum of_gpio_flags *flags)
{
return -ENOSYS;
}
#endif /* CONFIG_OF_GPIO */
/**
* of_get_gpio - Get a GPIO number to use with GPIO API
* @np: device node to get GPIO from
* @index: index of the GPIO
*
* Returns GPIO number to use with Linux generic GPIO API, or one of the errno
* value on the error condition.
*/
static inline int of_get_gpio(struct device_node *np, int index)
{
return of_get_gpio_flags(np, index, NULL);
}
#endif /* __LINUX_OF_GPIO_H */