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