Commit 863fbf49 authored by Anton Vorontsov's avatar Anton Vorontsov Committed by Paul Mackerras

[POWERPC] OF helpers for the GPIO API

This implements various helpers to support OF bindings for the GPIO
LIB API.

Previously this was PowerPC specific, but it seems this code isn't
arch-dependent anyhow, so let's place it into of/.

SPARC will not see this addition yet, real hardware seem to not use
GPIOs at all. But this might change:

   http://www.leox.org/docs/faq_MLleon.html

"16-bit I/O port" sounds promising. :-)
Signed-off-by: default avatarAnton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: default avatarGrant Likely <grant.likely@secretlab.ca>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent a2879fef
config OF_DEVICE
def_bool y
depends on OF && (SPARC || PPC_OF)
config OF_GPIO
def_bool y
depends on OF && PPC_OF && HAVE_GPIO_LIB
help
OpenFirmware GPIO accessors
obj-y = base.o
obj-$(CONFIG_OF_DEVICE) += device.o platform.o
obj-$(CONFIG_OF_GPIO) += gpio.o
/*
* 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);
/*
* 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.
*/
#ifndef __LINUX_OF_GPIO_H
#define __LINUX_OF_GPIO_H
#include <linux/errno.h>
#include <asm/gpio.h>
#ifdef CONFIG_OF_GPIO
/*
* Generic OF GPIO chip
*/
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);
};
static inline struct of_gpio_chip *to_of_gpio_chip(struct gpio_chip *gc)
{
return container_of(gc, struct of_gpio_chip, gc);
}
/*
* OF GPIO chip for memory mapped banks
*/
struct of_mm_gpio_chip {
struct of_gpio_chip of_gc;
void (*save_regs)(struct of_mm_gpio_chip *mm_gc);
void __iomem *regs;
};
static inline struct of_mm_gpio_chip *to_of_mm_gpio_chip(struct gpio_chip *gc)
{
struct of_gpio_chip *of_gc = to_of_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_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);
#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)
{
return -ENOSYS;
}
#endif /* CONFIG_OF_GPIO */
#endif /* __LINUX_OF_GPIO_H */
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