1 /* 2 * Reset Controller framework 3 * 4 * Copyright 2013 Philipp Zabel, Pengutronix 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 10 */ 11 #include <linux/device.h> 12 #include <linux/err.h> 13 #include <linux/export.h> 14 #include <linux/kernel.h> 15 #include <linux/module.h> 16 #include <linux/of.h> 17 #include <linux/reset.h> 18 #include <linux/reset-controller.h> 19 #include <linux/slab.h> 20 21 static DEFINE_MUTEX(reset_controller_list_mutex); 22 static LIST_HEAD(reset_controller_list); 23 24 /** 25 * struct reset_control - a reset control 26 * @rcdev: a pointer to the reset controller device 27 * this reset control belongs to 28 * @id: ID of the reset controller in the reset 29 * controller device 30 */ 31 struct reset_control { 32 struct reset_controller_dev *rcdev; 33 unsigned int id; 34 }; 35 36 /** 37 * of_reset_simple_xlate - translate reset_spec to the reset line number 38 * @rcdev: a pointer to the reset controller device 39 * @reset_spec: reset line specifier as found in the device tree 40 * @flags: a flags pointer to fill in (optional) 41 * 42 * This simple translation function should be used for reset controllers 43 * with 1:1 mapping, where reset lines can be indexed by number without gaps. 44 */ 45 static int of_reset_simple_xlate(struct reset_controller_dev *rcdev, 46 const struct of_phandle_args *reset_spec) 47 { 48 if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells)) 49 return -EINVAL; 50 51 if (reset_spec->args[0] >= rcdev->nr_resets) 52 return -EINVAL; 53 54 return reset_spec->args[0]; 55 } 56 57 /** 58 * reset_controller_register - register a reset controller device 59 * @rcdev: a pointer to the initialized reset controller device 60 */ 61 int reset_controller_register(struct reset_controller_dev *rcdev) 62 { 63 if (!rcdev->of_xlate) { 64 rcdev->of_reset_n_cells = 1; 65 rcdev->of_xlate = of_reset_simple_xlate; 66 } 67 68 mutex_lock(&reset_controller_list_mutex); 69 list_add(&rcdev->list, &reset_controller_list); 70 mutex_unlock(&reset_controller_list_mutex); 71 72 return 0; 73 } 74 EXPORT_SYMBOL_GPL(reset_controller_register); 75 76 /** 77 * reset_controller_unregister - unregister a reset controller device 78 * @rcdev: a pointer to the reset controller device 79 */ 80 void reset_controller_unregister(struct reset_controller_dev *rcdev) 81 { 82 mutex_lock(&reset_controller_list_mutex); 83 list_del(&rcdev->list); 84 mutex_unlock(&reset_controller_list_mutex); 85 } 86 EXPORT_SYMBOL_GPL(reset_controller_unregister); 87 88 /** 89 * reset_control_reset - reset the controlled device 90 * @rstc: reset controller 91 */ 92 int reset_control_reset(struct reset_control *rstc) 93 { 94 if (rstc->rcdev->ops->reset) 95 return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id); 96 97 return -ENOTSUPP; 98 } 99 EXPORT_SYMBOL_GPL(reset_control_reset); 100 101 /** 102 * reset_control_assert - asserts the reset line 103 * @rstc: reset controller 104 */ 105 int reset_control_assert(struct reset_control *rstc) 106 { 107 if (rstc->rcdev->ops->assert) 108 return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id); 109 110 return -ENOTSUPP; 111 } 112 EXPORT_SYMBOL_GPL(reset_control_assert); 113 114 /** 115 * reset_control_deassert - deasserts the reset line 116 * @rstc: reset controller 117 */ 118 int reset_control_deassert(struct reset_control *rstc) 119 { 120 if (rstc->rcdev->ops->deassert) 121 return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id); 122 123 return -ENOTSUPP; 124 } 125 EXPORT_SYMBOL_GPL(reset_control_deassert); 126 127 /** 128 * reset_control_status - returns a negative errno if not supported, a 129 * positive value if the reset line is asserted, or zero if the reset 130 * line is not asserted. 131 * @rstc: reset controller 132 */ 133 int reset_control_status(struct reset_control *rstc) 134 { 135 if (rstc->rcdev->ops->status) 136 return rstc->rcdev->ops->status(rstc->rcdev, rstc->id); 137 138 return -ENOTSUPP; 139 } 140 EXPORT_SYMBOL_GPL(reset_control_status); 141 142 /** 143 * of_reset_control_get_by_index - Lookup and obtain a reference to a reset 144 * controller by index. 145 * @node: device to be reset by the controller 146 * @index: index of the reset controller 147 * 148 * This is to be used to perform a list of resets for a device or power domain 149 * in whatever order. Returns a struct reset_control or IS_ERR() condition 150 * containing errno. 151 */ 152 struct reset_control *of_reset_control_get_by_index(struct device_node *node, 153 int index) 154 { 155 struct reset_control *rstc = ERR_PTR(-EPROBE_DEFER); 156 struct reset_controller_dev *r, *rcdev; 157 struct of_phandle_args args; 158 int rstc_id; 159 int ret; 160 161 ret = of_parse_phandle_with_args(node, "resets", "#reset-cells", 162 index, &args); 163 if (ret) 164 return ERR_PTR(ret); 165 166 mutex_lock(&reset_controller_list_mutex); 167 rcdev = NULL; 168 list_for_each_entry(r, &reset_controller_list, list) { 169 if (args.np == r->of_node) { 170 rcdev = r; 171 break; 172 } 173 } 174 of_node_put(args.np); 175 176 if (!rcdev) { 177 mutex_unlock(&reset_controller_list_mutex); 178 return ERR_PTR(-EPROBE_DEFER); 179 } 180 181 rstc_id = rcdev->of_xlate(rcdev, &args); 182 if (rstc_id < 0) { 183 mutex_unlock(&reset_controller_list_mutex); 184 return ERR_PTR(rstc_id); 185 } 186 187 try_module_get(rcdev->owner); 188 mutex_unlock(&reset_controller_list_mutex); 189 190 rstc = kzalloc(sizeof(*rstc), GFP_KERNEL); 191 if (!rstc) { 192 module_put(rcdev->owner); 193 return ERR_PTR(-ENOMEM); 194 } 195 196 rstc->rcdev = rcdev; 197 rstc->id = rstc_id; 198 199 return rstc; 200 } 201 EXPORT_SYMBOL_GPL(of_reset_control_get_by_index); 202 203 /** 204 * of_reset_control_get - Lookup and obtain a reference to a reset controller. 205 * @node: device to be reset by the controller 206 * @id: reset line name 207 * 208 * Returns a struct reset_control or IS_ERR() condition containing errno. 209 * 210 * Use of id names is optional. 211 */ 212 struct reset_control *of_reset_control_get(struct device_node *node, 213 const char *id) 214 { 215 int index = 0; 216 217 if (id) { 218 index = of_property_match_string(node, 219 "reset-names", id); 220 if (index < 0) 221 return ERR_PTR(-ENOENT); 222 } 223 return of_reset_control_get_by_index(node, index); 224 } 225 EXPORT_SYMBOL_GPL(of_reset_control_get); 226 227 /** 228 * reset_control_get - Lookup and obtain a reference to a reset controller. 229 * @dev: device to be reset by the controller 230 * @id: reset line name 231 * 232 * Returns a struct reset_control or IS_ERR() condition containing errno. 233 * 234 * Use of id names is optional. 235 */ 236 struct reset_control *reset_control_get(struct device *dev, const char *id) 237 { 238 if (!dev) 239 return ERR_PTR(-EINVAL); 240 241 return of_reset_control_get(dev->of_node, id); 242 } 243 EXPORT_SYMBOL_GPL(reset_control_get); 244 245 /** 246 * reset_control_put - free the reset controller 247 * @rstc: reset controller 248 */ 249 250 void reset_control_put(struct reset_control *rstc) 251 { 252 if (IS_ERR(rstc)) 253 return; 254 255 module_put(rstc->rcdev->owner); 256 kfree(rstc); 257 } 258 EXPORT_SYMBOL_GPL(reset_control_put); 259 260 static void devm_reset_control_release(struct device *dev, void *res) 261 { 262 reset_control_put(*(struct reset_control **)res); 263 } 264 265 /** 266 * devm_reset_control_get - resource managed reset_control_get() 267 * @dev: device to be reset by the controller 268 * @id: reset line name 269 * 270 * Managed reset_control_get(). For reset controllers returned from this 271 * function, reset_control_put() is called automatically on driver detach. 272 * See reset_control_get() for more information. 273 */ 274 struct reset_control *devm_reset_control_get(struct device *dev, const char *id) 275 { 276 struct reset_control **ptr, *rstc; 277 278 ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr), 279 GFP_KERNEL); 280 if (!ptr) 281 return ERR_PTR(-ENOMEM); 282 283 rstc = reset_control_get(dev, id); 284 if (!IS_ERR(rstc)) { 285 *ptr = rstc; 286 devres_add(dev, ptr); 287 } else { 288 devres_free(ptr); 289 } 290 291 return rstc; 292 } 293 EXPORT_SYMBOL_GPL(devm_reset_control_get); 294 295 /** 296 * device_reset - find reset controller associated with the device 297 * and perform reset 298 * @dev: device to be reset by the controller 299 * 300 * Convenience wrapper for reset_control_get() and reset_control_reset(). 301 * This is useful for the common case of devices with single, dedicated reset 302 * lines. 303 */ 304 int device_reset(struct device *dev) 305 { 306 struct reset_control *rstc; 307 int ret; 308 309 rstc = reset_control_get(dev, NULL); 310 if (IS_ERR(rstc)) 311 return PTR_ERR(rstc); 312 313 ret = reset_control_reset(rstc); 314 315 reset_control_put(rstc); 316 317 return ret; 318 } 319 EXPORT_SYMBOL_GPL(device_reset); 320