diff options
Diffstat (limited to 'drivers/of/gpio.c')
| -rw-r--r-- | drivers/of/gpio.c | 242 |
1 files changed, 242 insertions, 0 deletions
diff --git a/drivers/of/gpio.c b/drivers/of/gpio.c new file mode 100644 index 00000000000..000681e98f2 --- /dev/null +++ b/drivers/of/gpio.c @@ -0,0 +1,242 @@ +/* + * 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); |