diff options
Diffstat (limited to 'drivers/gpio/gpiolib-of.c')
| -rw-r--r-- | drivers/gpio/gpiolib-of.c | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c new file mode 100644 index 00000000000..d18068a9f3e --- /dev/null +++ b/drivers/gpio/gpiolib-of.c @@ -0,0 +1,236 @@ +/* + * 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/device.h> +#include <linux/errno.h> +#include <linux/module.h> +#include <linux/io.h> +#include <linux/gpio.h> +#include <linux/of.h> +#include <linux/of_address.h> +#include <linux/of_gpio.h> +#include <linux/slab.h> + +/* Private data structure for of_gpiochip_is_match */ +struct gg_data { + enum of_gpio_flags *flags; + struct of_phandle_args gpiospec; + + int out_gpio; +}; + +/* Private function for resolving node pointer to gpio_chip */ +static int of_gpiochip_find_and_xlate(struct gpio_chip *gc, void *data) +{ + struct gg_data *gg_data = data; + int ret; + + if ((gc->of_node != gg_data->gpiospec.np) || + (gc->of_gpio_n_cells != gg_data->gpiospec.args_count) || + (!gc->of_xlate)) + return false; + + ret = gc->of_xlate(gc, &gg_data->gpiospec, gg_data->flags); + if (ret < 0) + return false; + + gg_data->out_gpio = ret + gc->base; + return true; +} + +/** + * of_get_named_gpio_flags() - Get a GPIO number and flags to use with GPIO API + * @np: device node to get GPIO from + * @propname: property name containing gpio specifier(s) + * @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_named_gpio_flags(struct device_node *np, const char *propname, + int index, enum of_gpio_flags *flags) +{ + struct gg_data gg_data = { .flags = flags, .out_gpio = -ENODEV }; + int ret; + + /* .of_xlate might decide to not fill in the flags, so clear it. */ + if (flags) + *flags = 0; + + ret = of_parse_phandle_with_args(np, propname, "#gpio-cells", index, + &gg_data.gpiospec); + if (ret) { + pr_debug("%s: can't parse gpios property\n", __func__); + return -EINVAL; + } + + gpiochip_find(&gg_data, of_gpiochip_find_and_xlate); + + of_node_put(gg_data.gpiospec.np); + pr_debug("%s exited with status %d\n", __func__, ret); + return gg_data.out_gpio; +} +EXPORT_SYMBOL(of_get_named_gpio_flags); + +/** + * of_gpio_named_count - Count GPIOs for a device + * @np: device node to count GPIOs for + * @propname: property name containing gpio specifier(s) + * + * 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_named_count(struct device_node *np, const char* propname) +{ + unsigned int cnt = 0; + + do { + int ret; + + ret = of_parse_phandle_with_args(np, propname, "#gpio-cells", + cnt, NULL); + /* A hole in the gpios = <> counts anyway. */ + if (ret < 0 && ret != -EEXIST) + break; + } while (++cnt); + + return cnt; +} +EXPORT_SYMBOL(of_gpio_named_count); + +/** + * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags + * @gc: pointer to the 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 gpio_chip *gc, + const struct of_phandle_args *gpiospec, u32 *flags) +{ + /* + * 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 (gc->of_gpio_n_cells < 2) { + WARN_ON(1); + return -EINVAL; + } + + if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells)) + return -EINVAL; + + if (gpiospec->args[0] >= gc->ngpio) + return -EINVAL; + + if (flags) + *flags = gpiospec->args[1]; + + return gpiospec->args[0]; +} +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 + * - of_gpio_n_cells + * - of_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 gpio_chip *gc = &mm_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 (mm_gc->save_regs) + mm_gc->save_regs(mm_gc); + + mm_gc->gc.of_node = np; + + ret = gpiochip_add(gc); + if (ret) + goto err2; + + return 0; +err2: + 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); + +void of_gpiochip_add(struct gpio_chip *chip) +{ + if ((!chip->of_node) && (chip->dev)) + chip->of_node = chip->dev->of_node; + + if (!chip->of_node) + return; + + if (!chip->of_xlate) { + chip->of_gpio_n_cells = 2; + chip->of_xlate = of_gpio_simple_xlate; + } + + of_node_get(chip->of_node); +} + +void of_gpiochip_remove(struct gpio_chip *chip) +{ + if (chip->of_node) + of_node_put(chip->of_node); +} |