1/* 2 * OF helpers for the GPIO API 3 * 4 * Copyright (c) 2007-2008 MontaVista Software, Inc. 5 * 6 * Author: Anton Vorontsov <avorontsov@ru.mvista.com> 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License as published by 10 * the Free Software Foundation; either version 2 of the License, or 11 * (at your option) any later version. 12 */ 13 14#include <linux/device.h> 15#include <linux/errno.h> 16#include <linux/module.h> 17#include <linux/io.h> 18#include <linux/of.h> 19#include <linux/of_address.h> 20#include <linux/of_gpio.h> 21#include <linux/slab.h> 22 23/** 24 * of_get_gpio_flags - Get a GPIO number and flags to use with GPIO API 25 * @np: device node to get GPIO from 26 * @index: index of the GPIO 27 * @flags: a flags pointer to fill in 28 * 29 * Returns GPIO number to use with Linux generic GPIO API, or one of the errno 30 * value on the error condition. If @flags is not NULL the function also fills 31 * in flags for the GPIO. 32 */ 33int of_get_gpio_flags(struct device_node *np, int index, 34 enum of_gpio_flags *flags) 35{ 36 int ret; 37 struct device_node *gpio_np; 38 struct gpio_chip *gc; 39 int size; 40 const void *gpio_spec; 41 const __be32 *gpio_cells; 42 43 ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells", index, 44 &gpio_np, &gpio_spec); 45 if (ret) { 46 pr_debug("%s: can't parse gpios property\n", __func__); 47 goto err0; 48 } 49 50 gc = of_node_to_gpiochip(gpio_np); 51 if (!gc) { 52 pr_debug("%s: gpio controller %s isn't registered\n", 53 np->full_name, gpio_np->full_name); 54 ret = -ENODEV; 55 goto err1; 56 } 57 58 gpio_cells = of_get_property(gpio_np, "#gpio-cells", &size); 59 if (!gpio_cells || size != sizeof(*gpio_cells) || 60 be32_to_cpup(gpio_cells) != gc->of_gpio_n_cells) { 61 pr_debug("%s: wrong #gpio-cells for %s\n", 62 np->full_name, gpio_np->full_name); 63 ret = -EINVAL; 64 goto err1; 65 } 66 67 /* .xlate might decide to not fill in the flags, so clear it. */ 68 if (flags) 69 *flags = 0; 70 71 ret = gc->of_xlate(gc, np, gpio_spec, flags); 72 if (ret < 0) 73 goto err1; 74 75 ret += gc->base; 76err1: 77 of_node_put(gpio_np); 78err0: 79 pr_debug("%s exited with status %d\n", __func__, ret); 80 return ret; 81} 82EXPORT_SYMBOL(of_get_gpio_flags); 83 84/** 85 * of_gpio_count - Count GPIOs for a device 86 * @np: device node to count GPIOs for 87 * 88 * The function returns the count of GPIOs specified for a node. 89 * 90 * Note that the empty GPIO specifiers counts too. For example, 91 * 92 * gpios = <0 93 * &pio1 1 2 94 * 0 95 * &pio2 3 4>; 96 * 97 * defines four GPIOs (so this function will return 4), two of which 98 * are not specified. 99 */ 100unsigned int of_gpio_count(struct device_node *np) 101{ 102 unsigned int cnt = 0; 103 104 do { 105 int ret; 106 107 ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells", 108 cnt, NULL, NULL); 109 /* A hole in the gpios = <> counts anyway. */ 110 if (ret < 0 && ret != -EEXIST) 111 break; 112 } while (++cnt); 113 114 return cnt; 115} 116EXPORT_SYMBOL(of_gpio_count); 117 118/** 119 * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags 120 * @gc: pointer to the gpio_chip structure 121 * @np: device node of the GPIO chip 122 * @gpio_spec: gpio specifier as found in the device tree 123 * @flags: a flags pointer to fill in 124 * 125 * This is simple translation function, suitable for the most 1:1 mapped 126 * gpio chips. This function performs only one sanity check: whether gpio 127 * is less than ngpios (that is specified in the gpio_chip). 128 */ 129static int of_gpio_simple_xlate(struct gpio_chip *gc, struct device_node *np, 130 const void *gpio_spec, u32 *flags) 131{ 132 const __be32 *gpio = gpio_spec; 133 const u32 n = be32_to_cpup(gpio); 134 135 /* 136 * We're discouraging gpio_cells < 2, since that way you'll have to 137 * write your own xlate function (that will have to retrive the GPIO 138 * number and the flags from a single gpio cell -- this is possible, 139 * but not recommended). 140 */ 141 if (gc->of_gpio_n_cells < 2) { 142 WARN_ON(1); 143 return -EINVAL; 144 } 145 146 if (n > gc->ngpio) 147 return -EINVAL; 148 149 if (flags) 150 *flags = be32_to_cpu(gpio[1]); 151 152 return n; 153} 154 155/** 156 * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank) 157 * @np: device node of the GPIO chip 158 * @mm_gc: pointer to the of_mm_gpio_chip allocated structure 159 * 160 * To use this function you should allocate and fill mm_gc with: 161 * 162 * 1) In the gpio_chip structure: 163 * - all the callbacks 164 * - of_gpio_n_cells 165 * - of_xlate callback (optional) 166 * 167 * 3) In the of_mm_gpio_chip structure: 168 * - save_regs callback (optional) 169 * 170 * If succeeded, this function will map bank's memory and will 171 * do all necessary work for you. Then you'll able to use .regs 172 * to manage GPIOs from the callbacks. 173 */ 174int of_mm_gpiochip_add(struct device_node *np, 175 struct of_mm_gpio_chip *mm_gc) 176{ 177 int ret = -ENOMEM; 178 struct gpio_chip *gc = &mm_gc->gc; 179 180 gc->label = kstrdup(np->full_name, GFP_KERNEL); 181 if (!gc->label) 182 goto err0; 183 184 mm_gc->regs = of_iomap(np, 0); 185 if (!mm_gc->regs) 186 goto err1; 187 188 gc->base = -1; 189 190 if (mm_gc->save_regs) 191 mm_gc->save_regs(mm_gc); 192 193 mm_gc->gc.of_node = np; 194 195 ret = gpiochip_add(gc); 196 if (ret) 197 goto err2; 198 199 pr_debug("%s: registered as generic GPIO chip, base is %d\n", 200 np->full_name, gc->base); 201 return 0; 202err2: 203 iounmap(mm_gc->regs); 204err1: 205 kfree(gc->label); 206err0: 207 pr_err("%s: GPIO chip registration failed with status %d\n", 208 np->full_name, ret); 209 return ret; 210} 211EXPORT_SYMBOL(of_mm_gpiochip_add); 212 213void of_gpiochip_add(struct gpio_chip *chip) 214{ 215 if ((!chip->of_node) && (chip->dev)) 216 chip->of_node = chip->dev->of_node; 217 218 if (!chip->of_node) 219 return; 220 221 if (!chip->of_xlate) { 222 chip->of_gpio_n_cells = 2; 223 chip->of_xlate = of_gpio_simple_xlate; 224 } 225 226 of_node_get(chip->of_node); 227} 228 229void of_gpiochip_remove(struct gpio_chip *chip) 230{ 231 if (chip->of_node) 232 of_node_put(chip->of_node); 233} 234 235/* Private function for resolving node pointer to gpio_chip */ 236static int of_gpiochip_is_match(struct gpio_chip *chip, void *data) 237{ 238 return chip->of_node == data; 239} 240 241struct gpio_chip *of_node_to_gpiochip(struct device_node *np) 242{ 243 return gpiochip_find(np, of_gpiochip_is_match); 244} 245