/*
* 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/of_gpio.h>
#include <asm/prom.h>
/**
* of_get_gpio - Get a GPIO number from the device tree 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.
*/
int of_get_gpio(struct device_node *np, int index)
{
int ret = -EINVAL;
struct device_node *gc;
struct of_gpio_chip *of_gc = NULL;
int size;
const u32 *gpios;
u32 nr_cells;
int i;
const void *gpio_spec;
const u32 *gpio_cells;
int gpio_index = 0;
gpios = of_get_property(np, "gpios", &size);
if (!gpios) {
ret = -ENOENT;
goto err0;
}
nr_cells = size / sizeof(u32);
for (i = 0; i < nr_cells; gpio_index++) {
const phandle *gpio_phandle;
gpio_phandle = gpios + i;
gpio_spec = gpio_phandle + 1;
/* one cell hole in the gpios = <>; */
if (!*gpio_phandle) {
if (gpio_index == index)
return -ENOENT;
i++;
continue;
}
gc = of_find_node_by_phandle(*gpio_phandle);
if (!gc) {
pr_debug("%s: could not find phandle for gpios\n",
np->full_name);
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);
goto err1;
}
gpio_cells = of_get_property(gc, "#gpio-cells", &size);
if (!gpio_cells || size != sizeof(*gpio_cells) ||
*gpio_cells != of_gc->gpio_cells) {
pr_debug("%s: wrong #gpio-cells for %s\n",
np->full_name, gc->full_name);
goto err1;
}
/* Next phandle is at phandle cells + #gpio-cells */
i += sizeof(*gpio_phandle) / sizeof(u32) + *gpio_cells;
if (i >= nr_cells + 1) {
pr_debug("%s: insufficient gpio-spec length\n",
np->full_name);
goto err1;
}
if (gpio_index == index)
break;
of_gc = NULL;
of_node_put(gc);
}
if (!of_gc) {
ret = -ENOENT;
goto err0;
}
ret = of_gc->xlate(of_gc, np, gpio_spec);
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);
/**
* of_gpio_simple_xlate - translate gpio_spec to the GPIO number
* @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
*
* 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 u32 *gpio = gpio_spec;
if (*gpio > of_gc->gc.ngpio)
return -EINVAL;
return *gpio;
}
EXPORT_SYMBOL(of_gpio_simple_xlate);
/* Should be sufficient for now, later we'll use dynamic bases. */
#if defined(CONFIG_PPC32) || defined(CONFIG_SPARC32)
#define GPIOS_PER_CHIP 32
#else
#define GPIOS_PER_CHIP 64
#endif
static int of_get_gpiochip_base(struct device_node *np)
{
struct device_node *gc = NULL;
int gpiochip_base = 0;
while ((gc = of_find_all_nodes(gc))) {
if (!of_get_property(gc, "gpio-controller", NULL))
continue;
if (gc != np) {
gpiochip_base += GPIOS_PER_CHIP;
continue;
}
of_node_put(gc);
if (gpiochip_base >= ARCH_NR_GPIOS)
return -ENOSPC;
return gpiochip_base;
}
return -ENOENT;
}
/**
* 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 = of_get_gpiochip_base(np);
if (gc->base < 0) {
ret = gc->base;
goto err1;
}
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);
