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/*
* OF helpers for the GPIO API
*
* Copyright (c) 2007-2008 MontaVista Software, Inc.
*
* Author: Anton Vorontsov <avorontsov@ru.mvista.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <linux/of_gpio.h>
#include <asm/prom.h>
/**
* 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. If @flags is not NULL the function also fills
* in flags for the GPIO.
*/
int of_get_gpio_flags(struct device_node *np, int index,
enum of_gpio_flags *flags)
{
int ret;
struct device_node *gc;
struct of_gpio_chip *of_gc = NULL;
int size;
const void *gpio_spec;
const __be32 *gpio_cells;
ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells", index,
&gc, &gpio_spec);
if (ret) {
pr_debug("%s: can't parse gpios property\n", __func__);
goto err0;
}
of_gc = gc->data;
if (!of_gc) {
pr_debug("%s: gpio controller %s isn't registered\n",
np->full_name, gc->full_name);
ret = -ENODEV;
goto err1;
}
gpio_cells = of_get_property(gc, "#gpio-cells", &size);
if (!gpio_cells || size != sizeof(*gpio_cells) ||
be32_to_cpup(gpio_cells) != of_gc->gpio_cells) {
pr_debug("%s: wrong #gpio-cells for %s\n",
np->full_name, gc->full_name);
ret = -EINVAL;
goto err1;
}
/* .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;
ret += of_gc->gc.base;
err1:
of_node_put(gc);
err0:
pr_debug("%s exited with status %d\n", __func__, ret);
return ret;
}
EXPORT_SYMBOL(of_get_gpio_flags);
/**
* of_gpio_count - Count GPIOs for a device
* @np: device node to count GPIOs for
*
* The function returns the count of GPIOs specified for a node.
*
* Note that the empty GPIO specifiers counts too. For example,
*
* gpios = <0
* &pio1 1 2
* 0
* &pio2 3 4>;
*
* defines four GPIOs (so this function will return 4), two of which
* are not specified.
*/
unsigned int of_gpio_count(struct device_node *np)
{
unsigned int cnt = 0;
do {
int ret;
ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells",
cnt, NULL, NULL);
/* A hole in the gpios = <> counts anyway. */
if (ret < 0 && ret != -EEXIST)
break;
} while (++cnt);
return cnt;
}
EXPORT_SYMBOL(of_gpio_count);
/**
* 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, enum of_gpio_flags *flags)
{
const __be32 *gpio = gpio_spec;
const u32 n = be32_to_cpup(gpio);
/*
* 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 (n > of_gc->gc.ngpio)
return -EINVAL;
if (flags)
*flags = be32_to_cpu(gpio[1]);
return n;
}
EXPORT_SYMBOL(of_gpio_simple_xlate);
/**
* of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
* @np: device node of the GPIO chip
* @mm_gc: pointer to the of_mm_gpio_chip allocated structure
*
* To use this function you should allocate and fill mm_gc with:
*
* 1) In the gpio_chip structure:
* - all the callbacks
*
* 2) In the of_gpio_chip structure:
* - gpio_cells
* - xlate callback (optional)
*
* 3) In the of_mm_gpio_chip structure:
* - save_regs callback (optional)
*
* If succeeded, this function will map bank's memory and will
* do all necessary work for you. Then you'll able to use .regs
* to manage GPIOs from the callbacks.
*/
int of_mm_gpiochip_add(struct device_node *np,
struct of_mm_gpio_chip *mm_gc)
{
int ret = -ENOMEM;
struct of_gpio_chip *of_gc = &mm_gc->of_gc;
struct gpio_chip *gc = &of_gc->gc;
gc->label = kstrdup(np->full_name, GFP_KERNEL);
if (!gc->label)
goto err0;
mm_gc->regs = of_iomap(np, 0);
if (!mm_gc->regs)
goto err1;
gc->base = -1;
if (!of_gc->xlate)
of_gc->xlate = of_gpio_simple_xlate;
if (mm_gc->save_regs)
mm_gc->save_regs(mm_gc);
np->data = of_gc;
ret = gpiochip_add(gc);
if (ret)
goto err2;
/* We don't want to lose the node and its ->data */
of_node_get(np);
pr_debug("%s: registered as generic GPIO chip, base is %d\n",
np->full_name, gc->base);
return 0;
err2:
np->data = NULL;
iounmap(mm_gc->regs);
err1:
kfree(gc->label);
err0:
pr_err("%s: GPIO chip registration failed with status %d\n",
np->full_name, ret);
return ret;
}
EXPORT_SYMBOL(of_mm_gpiochip_add);
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