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 static 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 58 /** 59 * reset_controller_register - register a reset controller device 60 * @rcdev: a pointer to the initialized reset controller device 61 */ 62 int reset_controller_register(struct reset_controller_dev *rcdev) 63 { 64 if (!rcdev->of_xlate) { 65 rcdev->of_reset_n_cells = 1; 66 rcdev->of_xlate = of_reset_simple_xlate; 67 } 68 69 mutex_lock(&reset_controller_list_mutex); 70 list_add(&rcdev->list, &reset_controller_list); 71 mutex_unlock(&reset_controller_list_mutex); 72 73 return 0; 74 } 75 EXPORT_SYMBOL_GPL(reset_controller_register); 76 77 /** 78 * reset_controller_unregister - unregister a reset controller device 79 * @rcdev: a pointer to the reset controller device 80 */ 81 void reset_controller_unregister(struct reset_controller_dev *rcdev) 82 { 83 mutex_lock(&reset_controller_list_mutex); 84 list_del(&rcdev->list); 85 mutex_unlock(&reset_controller_list_mutex); 86 } 87 EXPORT_SYMBOL_GPL(reset_controller_unregister); 88 89 /** 90 * reset_control_reset - reset the controlled device 91 * @rstc: reset controller 92 */ 93 int reset_control_reset(struct reset_control *rstc) 94 { 95 if (rstc->rcdev->ops->reset) 96 return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id); 97 98 return -ENOSYS; 99 } 100 EXPORT_SYMBOL_GPL(reset_control_reset); 101 102 /** 103 * reset_control_assert - asserts the reset line 104 * @rstc: reset controller 105 */ 106 int reset_control_assert(struct reset_control *rstc) 107 { 108 if (rstc->rcdev->ops->assert) 109 return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id); 110 111 return -ENOSYS; 112 } 113 EXPORT_SYMBOL_GPL(reset_control_assert); 114 115 /** 116 * reset_control_deassert - deasserts the reset line 117 * @rstc: reset controller 118 */ 119 int reset_control_deassert(struct reset_control *rstc) 120 { 121 if (rstc->rcdev->ops->deassert) 122 return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id); 123 124 return -ENOSYS; 125 } 126 EXPORT_SYMBOL_GPL(reset_control_deassert); 127 128 /** 129 * of_reset_control_get - Lookup and obtain a reference to a reset controller. 130 * @node: device to be reset by the controller 131 * @id: reset line name 132 * 133 * Returns a struct reset_control or IS_ERR() condition containing errno. 134 * 135 * Use of id names is optional. 136 */ 137 struct reset_control *of_reset_control_get(struct device_node *node, 138 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 (id) 148 index = of_property_match_string(node, 149 "reset-names", id); 150 ret = of_parse_phandle_with_args(node, "resets", "#reset-cells", 151 index, &args); 152 if (ret) 153 return ERR_PTR(ret); 154 155 mutex_lock(&reset_controller_list_mutex); 156 rcdev = NULL; 157 list_for_each_entry(r, &reset_controller_list, list) { 158 if (args.np == r->of_node) { 159 rcdev = r; 160 break; 161 } 162 } 163 of_node_put(args.np); 164 165 if (!rcdev) { 166 mutex_unlock(&reset_controller_list_mutex); 167 return ERR_PTR(-EPROBE_DEFER); 168 } 169 170 rstc_id = rcdev->of_xlate(rcdev, &args); 171 if (rstc_id < 0) { 172 mutex_unlock(&reset_controller_list_mutex); 173 return ERR_PTR(rstc_id); 174 } 175 176 try_module_get(rcdev->owner); 177 mutex_unlock(&reset_controller_list_mutex); 178 179 rstc = kzalloc(sizeof(*rstc), GFP_KERNEL); 180 if (!rstc) { 181 module_put(rcdev->owner); 182 return ERR_PTR(-ENOMEM); 183 } 184 185 rstc->rcdev = rcdev; 186 rstc->id = rstc_id; 187 188 return rstc; 189 } 190 EXPORT_SYMBOL_GPL(of_reset_control_get); 191 192 /** 193 * reset_control_get - Lookup and obtain a reference to a reset controller. 194 * @dev: device to be reset by the controller 195 * @id: reset line name 196 * 197 * Returns a struct reset_control or IS_ERR() condition containing errno. 198 * 199 * Use of id names is optional. 200 */ 201 struct reset_control *reset_control_get(struct device *dev, const char *id) 202 { 203 struct reset_control *rstc; 204 205 if (!dev) 206 return ERR_PTR(-EINVAL); 207 208 rstc = of_reset_control_get(dev->of_node, id); 209 if (!IS_ERR(rstc)) 210 rstc->dev = dev; 211 212 return rstc; 213 } 214 EXPORT_SYMBOL_GPL(reset_control_get); 215 216 /** 217 * reset_control_put - free the reset controller 218 * @rstc: reset controller 219 */ 220 221 void reset_control_put(struct reset_control *rstc) 222 { 223 if (IS_ERR(rstc)) 224 return; 225 226 module_put(rstc->rcdev->owner); 227 kfree(rstc); 228 } 229 EXPORT_SYMBOL_GPL(reset_control_put); 230 231 static void devm_reset_control_release(struct device *dev, void *res) 232 { 233 reset_control_put(*(struct reset_control **)res); 234 } 235 236 /** 237 * devm_reset_control_get - resource managed reset_control_get() 238 * @dev: device to be reset by the controller 239 * @id: reset line name 240 * 241 * Managed reset_control_get(). For reset controllers returned from this 242 * function, reset_control_put() is called automatically on driver detach. 243 * See reset_control_get() for more information. 244 */ 245 struct reset_control *devm_reset_control_get(struct device *dev, const char *id) 246 { 247 struct reset_control **ptr, *rstc; 248 249 ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr), 250 GFP_KERNEL); 251 if (!ptr) 252 return ERR_PTR(-ENOMEM); 253 254 rstc = reset_control_get(dev, id); 255 if (!IS_ERR(rstc)) { 256 *ptr = rstc; 257 devres_add(dev, ptr); 258 } else { 259 devres_free(ptr); 260 } 261 262 return rstc; 263 } 264 EXPORT_SYMBOL_GPL(devm_reset_control_get); 265 266 /** 267 * device_reset - find reset controller associated with the device 268 * and perform reset 269 * @dev: device to be reset by the controller 270 * 271 * Convenience wrapper for reset_control_get() and reset_control_reset(). 272 * This is useful for the common case of devices with single, dedicated reset 273 * lines. 274 */ 275 int device_reset(struct device *dev) 276 { 277 struct reset_control *rstc; 278 int ret; 279 280 rstc = reset_control_get(dev, NULL); 281 if (IS_ERR(rstc)) 282 return PTR_ERR(rstc); 283 284 ret = reset_control_reset(rstc); 285 286 reset_control_put(rstc); 287 288 return ret; 289 } 290 EXPORT_SYMBOL_GPL(device_reset); 291