164 lines
4.0 KiB
C
164 lines
4.0 KiB
C
/*
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* OF helpers for the GPIO API
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*
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* Copyright (c) 2007-2008 MontaVista Software, Inc.
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*
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* Author: Anton Vorontsov <avorontsov@ru.mvista.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/io.h>
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#include <linux/of.h>
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#include <linux/of_gpio.h>
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#include <asm/prom.h>
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/**
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* of_get_gpio - Get a GPIO number from the device tree to use with GPIO API
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* @np: device node to get GPIO from
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* @index: index of the GPIO
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*
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* Returns GPIO number to use with Linux generic GPIO API, or one of the errno
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* value on the error condition.
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*/
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int of_get_gpio(struct device_node *np, int index)
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{
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int ret;
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struct device_node *gc;
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struct of_gpio_chip *of_gc = NULL;
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int size;
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const void *gpio_spec;
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const u32 *gpio_cells;
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ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells", index,
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&gc, &gpio_spec);
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if (ret) {
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pr_debug("%s: can't parse gpios property\n", __func__);
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goto err0;
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}
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of_gc = gc->data;
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if (!of_gc) {
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pr_debug("%s: gpio controller %s isn't registered\n",
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np->full_name, gc->full_name);
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ret = -ENODEV;
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goto err1;
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}
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gpio_cells = of_get_property(gc, "#gpio-cells", &size);
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if (!gpio_cells || size != sizeof(*gpio_cells) ||
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*gpio_cells != of_gc->gpio_cells) {
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pr_debug("%s: wrong #gpio-cells for %s\n",
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np->full_name, gc->full_name);
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ret = -EINVAL;
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goto err1;
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}
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ret = of_gc->xlate(of_gc, np, gpio_spec);
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if (ret < 0)
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goto err1;
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ret += of_gc->gc.base;
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err1:
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of_node_put(gc);
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err0:
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pr_debug("%s exited with status %d\n", __func__, ret);
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return ret;
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}
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EXPORT_SYMBOL(of_get_gpio);
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/**
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* of_gpio_simple_xlate - translate gpio_spec to the GPIO number
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* @of_gc: pointer to the of_gpio_chip structure
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* @np: device node of the GPIO chip
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* @gpio_spec: gpio specifier as found in the device tree
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*
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* This is simple translation function, suitable for the most 1:1 mapped
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* gpio chips. This function performs only one sanity check: whether gpio
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* is less than ngpios (that is specified in the gpio_chip).
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*/
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int of_gpio_simple_xlate(struct of_gpio_chip *of_gc, struct device_node *np,
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const void *gpio_spec)
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{
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const u32 *gpio = gpio_spec;
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if (*gpio > of_gc->gc.ngpio)
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return -EINVAL;
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return *gpio;
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}
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EXPORT_SYMBOL(of_gpio_simple_xlate);
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/**
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* of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
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* @np: device node of the GPIO chip
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* @mm_gc: pointer to the of_mm_gpio_chip allocated structure
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*
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* To use this function you should allocate and fill mm_gc with:
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*
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* 1) In the gpio_chip structure:
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* - all the callbacks
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*
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* 2) In the of_gpio_chip structure:
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* - gpio_cells
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* - xlate callback (optional)
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*
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* 3) In the of_mm_gpio_chip structure:
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* - save_regs callback (optional)
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*
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* If succeeded, this function will map bank's memory and will
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* do all necessary work for you. Then you'll able to use .regs
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* to manage GPIOs from the callbacks.
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*/
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int of_mm_gpiochip_add(struct device_node *np,
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struct of_mm_gpio_chip *mm_gc)
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{
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int ret = -ENOMEM;
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struct of_gpio_chip *of_gc = &mm_gc->of_gc;
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struct gpio_chip *gc = &of_gc->gc;
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gc->label = kstrdup(np->full_name, GFP_KERNEL);
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if (!gc->label)
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goto err0;
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mm_gc->regs = of_iomap(np, 0);
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if (!mm_gc->regs)
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goto err1;
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gc->base = -1;
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if (!of_gc->xlate)
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of_gc->xlate = of_gpio_simple_xlate;
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if (mm_gc->save_regs)
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mm_gc->save_regs(mm_gc);
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np->data = of_gc;
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ret = gpiochip_add(gc);
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if (ret)
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goto err2;
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/* We don't want to lose the node and its ->data */
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of_node_get(np);
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pr_debug("%s: registered as generic GPIO chip, base is %d\n",
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np->full_name, gc->base);
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return 0;
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err2:
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np->data = NULL;
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iounmap(mm_gc->regs);
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err1:
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kfree(gc->label);
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err0:
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pr_err("%s: GPIO chip registration failed with status %d\n",
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np->full_name, ret);
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return ret;
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}
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EXPORT_SYMBOL(of_mm_gpiochip_add);
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