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_find_and_xlate */ 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 /* Return -EPROBE_DEFER to support probe() functions to be called 66 * later when the GPIO actually becomes available 67 */ 68 struct gg_data gg_data = { .flags = flags, .out_gpio = -EPROBE_DEFER }; 69 int ret; 70 71 /* .of_xlate might decide to not fill in the flags, so clear it. */ 72 if (flags) 73 *flags = 0; 74 75 ret = of_parse_phandle_with_args(np, propname, "#gpio-cells", index, 76 &gg_data.gpiospec); 77 if (ret) { 78 pr_debug("%s: can't parse gpios property\n", __func__); 79 return ret; 80 } 81 82 gpiochip_find(&gg_data, of_gpiochip_find_and_xlate); 83 84 of_node_put(gg_data.gpiospec.np); 85 pr_debug("%s exited with status %d\n", __func__, gg_data.out_gpio); 86 return gg_data.out_gpio; 87 } 88 EXPORT_SYMBOL(of_get_named_gpio_flags); 89 90 /** 91 * of_gpio_named_count - Count GPIOs for a device 92 * @np: device node to count GPIOs for 93 * @propname: property name containing gpio specifier(s) 94 * 95 * The function returns the count of GPIOs specified for a node. 96 * 97 * Note that the empty GPIO specifiers counts too. For example, 98 * 99 * gpios = <0 100 * &pio1 1 2 101 * 0 102 * &pio2 3 4>; 103 * 104 * defines four GPIOs (so this function will return 4), two of which 105 * are not specified. 106 */ 107 unsigned int of_gpio_named_count(struct device_node *np, const char* propname) 108 { 109 unsigned int cnt = 0; 110 111 do { 112 int ret; 113 114 ret = of_parse_phandle_with_args(np, propname, "#gpio-cells", 115 cnt, NULL); 116 /* A hole in the gpios = <> counts anyway. */ 117 if (ret < 0 && ret != -EEXIST) 118 break; 119 } while (++cnt); 120 121 return cnt; 122 } 123 EXPORT_SYMBOL(of_gpio_named_count); 124 125 /** 126 * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags 127 * @gc: pointer to the gpio_chip structure 128 * @np: device node of the GPIO chip 129 * @gpio_spec: gpio specifier as found in the device tree 130 * @flags: a flags pointer to fill in 131 * 132 * This is simple translation function, suitable for the most 1:1 mapped 133 * gpio chips. This function performs only one sanity check: whether gpio 134 * is less than ngpios (that is specified in the gpio_chip). 135 */ 136 int of_gpio_simple_xlate(struct gpio_chip *gc, 137 const struct of_phandle_args *gpiospec, u32 *flags) 138 { 139 /* 140 * We're discouraging gpio_cells < 2, since that way you'll have to 141 * write your own xlate function (that will have to retrive the GPIO 142 * number and the flags from a single gpio cell -- this is possible, 143 * but not recommended). 144 */ 145 if (gc->of_gpio_n_cells < 2) { 146 WARN_ON(1); 147 return -EINVAL; 148 } 149 150 if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells)) 151 return -EINVAL; 152 153 if (gpiospec->args[0] >= gc->ngpio) 154 return -EINVAL; 155 156 if (flags) 157 *flags = gpiospec->args[1]; 158 159 return gpiospec->args[0]; 160 } 161 EXPORT_SYMBOL(of_gpio_simple_xlate); 162 163 /** 164 * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank) 165 * @np: device node of the GPIO chip 166 * @mm_gc: pointer to the of_mm_gpio_chip allocated structure 167 * 168 * To use this function you should allocate and fill mm_gc with: 169 * 170 * 1) In the gpio_chip structure: 171 * - all the callbacks 172 * - of_gpio_n_cells 173 * - of_xlate callback (optional) 174 * 175 * 3) In the of_mm_gpio_chip structure: 176 * - save_regs callback (optional) 177 * 178 * If succeeded, this function will map bank's memory and will 179 * do all necessary work for you. Then you'll able to use .regs 180 * to manage GPIOs from the callbacks. 181 */ 182 int of_mm_gpiochip_add(struct device_node *np, 183 struct of_mm_gpio_chip *mm_gc) 184 { 185 int ret = -ENOMEM; 186 struct gpio_chip *gc = &mm_gc->gc; 187 188 gc->label = kstrdup(np->full_name, GFP_KERNEL); 189 if (!gc->label) 190 goto err0; 191 192 mm_gc->regs = of_iomap(np, 0); 193 if (!mm_gc->regs) 194 goto err1; 195 196 gc->base = -1; 197 198 if (mm_gc->save_regs) 199 mm_gc->save_regs(mm_gc); 200 201 mm_gc->gc.of_node = np; 202 203 ret = gpiochip_add(gc); 204 if (ret) 205 goto err2; 206 207 return 0; 208 err2: 209 iounmap(mm_gc->regs); 210 err1: 211 kfree(gc->label); 212 err0: 213 pr_err("%s: GPIO chip registration failed with status %d\n", 214 np->full_name, ret); 215 return ret; 216 } 217 EXPORT_SYMBOL(of_mm_gpiochip_add); 218 219 void of_gpiochip_add(struct gpio_chip *chip) 220 { 221 if ((!chip->of_node) && (chip->dev)) 222 chip->of_node = chip->dev->of_node; 223 224 if (!chip->of_node) 225 return; 226 227 if (!chip->of_xlate) { 228 chip->of_gpio_n_cells = 2; 229 chip->of_xlate = of_gpio_simple_xlate; 230 } 231 232 of_node_get(chip->of_node); 233 } 234 235 void of_gpiochip_remove(struct gpio_chip *chip) 236 { 237 if (chip->of_node) 238 of_node_put(chip->of_node); 239 } 240