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 struct device *dev; 34 unsigned int id; 35 }; 36 37 /** 38 * of_reset_simple_xlate - translate reset_spec to the reset line number 39 * @rcdev: a pointer to the reset controller device 40 * @reset_spec: reset line specifier as found in the device tree 41 * @flags: a flags pointer to fill in (optional) 42 * 43 * This simple translation function should be used for reset controllers 44 * with 1:1 mapping, where reset lines can be indexed by number without gaps. 45 */ 46 int of_reset_simple_xlate(struct reset_controller_dev *rcdev, 47 const struct of_phandle_args *reset_spec) 48 { 49 if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells)) 50 return -EINVAL; 51 52 if (reset_spec->args[0] >= rcdev->nr_resets) 53 return -EINVAL; 54 55 return reset_spec->args[0]; 56 } 57 EXPORT_SYMBOL_GPL(of_reset_simple_xlate); 58 59 /** 60 * reset_controller_register - register a reset controller device 61 * @rcdev: a pointer to the initialized reset controller device 62 */ 63 int reset_controller_register(struct reset_controller_dev *rcdev) 64 { 65 if (!rcdev->of_xlate) { 66 rcdev->of_reset_n_cells = 1; 67 rcdev->of_xlate = of_reset_simple_xlate; 68 } 69 70 mutex_lock(&reset_controller_list_mutex); 71 list_add(&rcdev->list, &reset_controller_list); 72 mutex_unlock(&reset_controller_list_mutex); 73 74 return 0; 75 } 76 EXPORT_SYMBOL_GPL(reset_controller_register); 77 78 /** 79 * reset_controller_unregister - unregister a reset controller device 80 * @rcdev: a pointer to the reset controller device 81 */ 82 void reset_controller_unregister(struct reset_controller_dev *rcdev) 83 { 84 mutex_lock(&reset_controller_list_mutex); 85 list_del(&rcdev->list); 86 mutex_unlock(&reset_controller_list_mutex); 87 } 88 EXPORT_SYMBOL_GPL(reset_controller_unregister); 89 90 /** 91 * reset_control_reset - reset the controlled device 92 * @rstc: reset controller 93 */ 94 int reset_control_reset(struct reset_control *rstc) 95 { 96 if (rstc->rcdev->ops->reset) 97 return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id); 98 99 return -ENOSYS; 100 } 101 EXPORT_SYMBOL_GPL(reset_control_reset); 102 103 /** 104 * reset_control_assert - asserts the reset line 105 * @rstc: reset controller 106 */ 107 int reset_control_assert(struct reset_control *rstc) 108 { 109 if (rstc->rcdev->ops->assert) 110 return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id); 111 112 return -ENOSYS; 113 } 114 EXPORT_SYMBOL_GPL(reset_control_assert); 115 116 /** 117 * reset_control_deassert - deasserts the reset line 118 * @rstc: reset controller 119 */ 120 int reset_control_deassert(struct reset_control *rstc) 121 { 122 if (rstc->rcdev->ops->deassert) 123 return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id); 124 125 return -ENOSYS; 126 } 127 EXPORT_SYMBOL_GPL(reset_control_deassert); 128 129 /** 130 * reset_control_get - Lookup and obtain a reference to a reset controller. 131 * @dev: device to be reset by the controller 132 * @id: reset line name 133 * 134 * Returns a struct reset_control or IS_ERR() condition containing errno. 135 * 136 * Use of id names is optional. 137 */ 138 struct reset_control *reset_control_get(struct device *dev, const char *id) 139 { 140 struct reset_control *rstc = ERR_PTR(-EPROBE_DEFER); 141 struct reset_controller_dev *r, *rcdev; 142 struct of_phandle_args args; 143 int index = 0; 144 int rstc_id; 145 int ret; 146 147 if (!dev) 148 return ERR_PTR(-EINVAL); 149 150 if (id) 151 index = of_property_match_string(dev->of_node, 152 "reset-names", id); 153 ret = of_parse_phandle_with_args(dev->of_node, "resets", "#reset-cells", 154 index, &args); 155 if (ret) 156 return ERR_PTR(ret); 157 158 mutex_lock(&reset_controller_list_mutex); 159 rcdev = NULL; 160 list_for_each_entry(r, &reset_controller_list, list) { 161 if (args.np == r->of_node) { 162 rcdev = r; 163 break; 164 } 165 } 166 of_node_put(args.np); 167 168 if (!rcdev) { 169 mutex_unlock(&reset_controller_list_mutex); 170 return ERR_PTR(-ENODEV); 171 } 172 173 rstc_id = rcdev->of_xlate(rcdev, &args); 174 if (rstc_id < 0) { 175 mutex_unlock(&reset_controller_list_mutex); 176 return ERR_PTR(rstc_id); 177 } 178 179 try_module_get(rcdev->owner); 180 mutex_unlock(&reset_controller_list_mutex); 181 182 rstc = kzalloc(sizeof(*rstc), GFP_KERNEL); 183 if (!rstc) { 184 module_put(rcdev->owner); 185 return ERR_PTR(-ENOMEM); 186 } 187 188 rstc->dev = dev; 189 rstc->rcdev = rcdev; 190 rstc->id = rstc_id; 191 192 return rstc; 193 } 194 EXPORT_SYMBOL_GPL(reset_control_get); 195 196 /** 197 * reset_control_put - free the reset controller 198 * @rstc: reset controller 199 */ 200 201 void reset_control_put(struct reset_control *rstc) 202 { 203 if (IS_ERR(rstc)) 204 return; 205 206 module_put(rstc->rcdev->owner); 207 kfree(rstc); 208 } 209 EXPORT_SYMBOL_GPL(reset_control_put); 210 211 static void devm_reset_control_release(struct device *dev, void *res) 212 { 213 reset_control_put(*(struct reset_control **)res); 214 } 215 216 /** 217 * devm_reset_control_get - resource managed reset_control_get() 218 * @dev: device to be reset by the controller 219 * @id: reset line name 220 * 221 * Managed reset_control_get(). For reset controllers returned from this 222 * function, reset_control_put() is called automatically on driver detach. 223 * See reset_control_get() for more information. 224 */ 225 struct reset_control *devm_reset_control_get(struct device *dev, const char *id) 226 { 227 struct reset_control **ptr, *rstc; 228 229 ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr), 230 GFP_KERNEL); 231 if (!ptr) 232 return ERR_PTR(-ENOMEM); 233 234 rstc = reset_control_get(dev, id); 235 if (!IS_ERR(rstc)) { 236 *ptr = rstc; 237 devres_add(dev, ptr); 238 } else { 239 devres_free(ptr); 240 } 241 242 return rstc; 243 } 244 EXPORT_SYMBOL_GPL(devm_reset_control_get); 245 246 static int devm_reset_control_match(struct device *dev, void *res, void *data) 247 { 248 struct reset_control **rstc = res; 249 if (WARN_ON(!rstc || !*rstc)) 250 return 0; 251 return *rstc == data; 252 } 253 254 /** 255 * devm_reset_control_put - resource managed reset_control_put() 256 * @rstc: reset controller to free 257 * 258 * Deallocate a reset control allocated withd devm_reset_control_get(). 259 * This function will not need to be called normally, as devres will take 260 * care of freeing the resource. 261 */ 262 void devm_reset_control_put(struct reset_control *rstc) 263 { 264 int ret; 265 266 ret = devres_release(rstc->dev, devm_reset_control_release, 267 devm_reset_control_match, rstc); 268 if (ret) 269 WARN_ON(ret); 270 } 271 EXPORT_SYMBOL_GPL(devm_reset_control_put); 272 273 /** 274 * device_reset - find reset controller associated with the device 275 * and perform reset 276 * @dev: device to be reset by the controller 277 * 278 * Convenience wrapper for reset_control_get() and reset_control_reset(). 279 * This is useful for the common case of devices with single, dedicated reset 280 * lines. 281 */ 282 int device_reset(struct device *dev) 283 { 284 struct reset_control *rstc; 285 int ret; 286 287 rstc = reset_control_get(dev, NULL); 288 if (IS_ERR(rstc)) 289 return PTR_ERR(rstc); 290 291 ret = reset_control_reset(rstc); 292 293 reset_control_put(rstc); 294 295 return ret; 296 } 297 EXPORT_SYMBOL_GPL(device_reset); 298