drivers/reset/core.c

   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 (reset_spec->args[0] >= rcdev->nr_resets)
  49                 return -EINVAL;
  50
  51         return reset_spec->args[0];
  52 }
  53
  54 /**
  55  * reset_controller_register - register a reset controller device
  56  * @rcdev: a pointer to the initialized reset controller device
  57  */
  58 int reset_controller_register(struct reset_controller_dev *rcdev)
  59 {
  60         if (!rcdev->of_xlate) {
  61                 rcdev->of_reset_n_cells = 1;
  62                 rcdev->of_xlate = of_reset_simple_xlate;
  63         }
  64
  65         mutex_lock(&reset_controller_list_mutex);
  66         list_add(&rcdev->list, &reset_controller_list);
  67         mutex_unlock(&reset_controller_list_mutex);
  68
  69         return 0;
  70 }
  71 EXPORT_SYMBOL_GPL(reset_controller_register);
  72
  73 /**
  74  * reset_controller_unregister - unregister a reset controller device
  75  * @rcdev: a pointer to the reset controller device
  76  */
  77 void reset_controller_unregister(struct reset_controller_dev *rcdev)
  78 {
  79         mutex_lock(&reset_controller_list_mutex);
  80         list_del(&rcdev->list);
  81         mutex_unlock(&reset_controller_list_mutex);
  82 }
  83 EXPORT_SYMBOL_GPL(reset_controller_unregister);
  84
  85 /**
  86  * reset_control_reset - reset the controlled device
  87  * @rstc: reset controller
  88  */
  89 int reset_control_reset(struct reset_control *rstc)
  90 {
  91         if (rstc->rcdev->ops->reset)
  92                 return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
  93
  94         return -ENOTSUPP;
  95 }
  96 EXPORT_SYMBOL_GPL(reset_control_reset);
  97
  98 /**
  99  * reset_control_assert - asserts the reset line
 100  * @rstc: reset controller
 101  */
 102 int reset_control_assert(struct reset_control *rstc)
 103 {
 104         if (rstc->rcdev->ops->assert)
 105                 return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
 106
 107         return -ENOTSUPP;
 108 }
 109 EXPORT_SYMBOL_GPL(reset_control_assert);
 110
 111 /**
 112  * reset_control_deassert - deasserts the reset line
 113  * @rstc: reset controller
 114  */
 115 int reset_control_deassert(struct reset_control *rstc)
 116 {
 117         if (rstc->rcdev->ops->deassert)
 118                 return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
 119
 120         return -ENOTSUPP;
 121 }
 122 EXPORT_SYMBOL_GPL(reset_control_deassert);
 123
 124 /**
 125  * reset_control_status - returns a negative errno if not supported, a
 126  * positive value if the reset line is asserted, or zero if the reset
 127  * line is not asserted.
 128  * @rstc: reset controller
 129  */
 130 int reset_control_status(struct reset_control *rstc)
 131 {
 132         if (rstc->rcdev->ops->status)
 133                 return rstc->rcdev->ops->status(rstc->rcdev, rstc->id);
 134
 135         return -ENOTSUPP;
 136 }
 137 EXPORT_SYMBOL_GPL(reset_control_status);
 138
 139 /**
 140  * of_reset_control_get_by_index - Lookup and obtain a reference to a reset
 141  * controller by index.
 142  * @node: device to be reset by the controller
 143  * @index: index of the reset controller
 144  *
 145  * This is to be used to perform a list of resets for a device or power domain
 146  * in whatever order. Returns a struct reset_control or IS_ERR() condition
 147  * containing errno.
 148  */
 149 struct reset_control *of_reset_control_get_by_index(struct device_node *node,
 150                                            int index)
 151 {
 152         struct reset_control *rstc;
 153         struct reset_controller_dev *r, *rcdev;
 154         struct of_phandle_args args;
 155         int rstc_id;
 156         int ret;
 157
 158         ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
 159                                          index, &args);
 160         if (ret)
 161                 return ERR_PTR(ret);
 162
 163         mutex_lock(&reset_controller_list_mutex);
 164         rcdev = NULL;
 165         list_for_each_entry(r, &reset_controller_list, list) {
 166                 if (args.np == r->of_node) {
 167                         rcdev = r;
 168                         break;
 169                 }
 170         }
 171         of_node_put(args.np);
 172
 173         if (!rcdev) {
 174                 mutex_unlock(&reset_controller_list_mutex);
 175                 return ERR_PTR(-EPROBE_DEFER);
 176         }
 177
 178         if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
 179                 mutex_unlock(&reset_controller_list_mutex);
 180                 return ERR_PTR(-EINVAL);
 181         }
 182
 183         rstc_id = rcdev->of_xlate(rcdev, &args);
 184         if (rstc_id < 0) {
 185                 mutex_unlock(&reset_controller_list_mutex);
 186                 return ERR_PTR(rstc_id);
 187         }
 188
 189         try_module_get(rcdev->owner);
 190         mutex_unlock(&reset_controller_list_mutex);
 191
 192         rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
 193         if (!rstc) {
 194                 module_put(rcdev->owner);
 195                 return ERR_PTR(-ENOMEM);
 196         }
 197
 198         rstc->rcdev = rcdev;
 199         rstc->id = rstc_id;
 200
 201         return rstc;
 202 }
 203 EXPORT_SYMBOL_GPL(of_reset_control_get_by_index);
 204
 205 /**
 206  * of_reset_control_get - Lookup and obtain a reference to a reset controller.
 207  * @node: device to be reset by the controller
 208  * @id: reset line name
 209  *
 210  * Returns a struct reset_control or IS_ERR() condition containing errno.
 211  *
 212  * Use of id names is optional.
 213  */
 214 struct reset_control *of_reset_control_get(struct device_node *node,
 215                                            const char *id)
 216 {
 217         int index = 0;
 218
 219         if (id) {
 220                 index = of_property_match_string(node,
 221                                                  "reset-names", id);
 222                 if (index < 0)
 223                         return ERR_PTR(-ENOENT);
 224         }
 225         return of_reset_control_get_by_index(node, index);
 226 }
 227 EXPORT_SYMBOL_GPL(of_reset_control_get);
 228
 229 /**
 230  * reset_control_get - Lookup and obtain a reference to a reset controller.
 231  * @dev: device to be reset by the controller
 232  * @id: reset line name
 233  *
 234  * Returns a struct reset_control or IS_ERR() condition containing errno.
 235  *
 236  * Use of id names is optional.
 237  */
 238 struct reset_control *reset_control_get(struct device *dev, const char *id)
 239 {
 240         if (!dev)
 241                 return ERR_PTR(-EINVAL);
 242
 243         return of_reset_control_get(dev->of_node, id);
 244 }
 245 EXPORT_SYMBOL_GPL(reset_control_get);
 246
 247 /**
 248  * reset_control_put - free the reset controller
 249  * @rstc: reset controller
 250  */
 251
 252 void reset_control_put(struct reset_control *rstc)
 253 {
 254         if (IS_ERR(rstc))
 255                 return;
 256
 257         module_put(rstc->rcdev->owner);
 258         kfree(rstc);
 259 }
 260 EXPORT_SYMBOL_GPL(reset_control_put);
 261
 262 static void devm_reset_control_release(struct device *dev, void *res)
 263 {
 264         reset_control_put(*(struct reset_control **)res);
 265 }
 266
 267 /**
 268  * devm_reset_control_get - resource managed reset_control_get()
 269  * @dev: device to be reset by the controller
 270  * @id: reset line name
 271  *
 272  * Managed reset_control_get(). For reset controllers returned from this
 273  * function, reset_control_put() is called automatically on driver detach.
 274  * See reset_control_get() for more information.
 275  */
 276 struct reset_control *devm_reset_control_get(struct device *dev, const char *id)
 277 {
 278         struct reset_control **ptr, *rstc;
 279
 280         ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
 281                            GFP_KERNEL);
 282         if (!ptr)
 283                 return ERR_PTR(-ENOMEM);
 284
 285         rstc = reset_control_get(dev, id);
 286         if (!IS_ERR(rstc)) {
 287                 *ptr = rstc;
 288                 devres_add(dev, ptr);
 289         } else {
 290                 devres_free(ptr);
 291         }
 292
 293         return rstc;
 294 }
 295 EXPORT_SYMBOL_GPL(devm_reset_control_get);
 296
 297 /**
 298  * device_reset - find reset controller associated with the device
 299  *                and perform reset
 300  * @dev: device to be reset by the controller
 301  *
 302  * Convenience wrapper for reset_control_get() and reset_control_reset().
 303  * This is useful for the common case of devices with single, dedicated reset
 304  * lines.
 305  */
 306 int device_reset(struct device *dev)
 307 {
 308         struct reset_control *rstc;
 309         int ret;
 310
 311         rstc = reset_control_get(dev, NULL);
 312         if (IS_ERR(rstc))
 313                 return PTR_ERR(rstc);
 314
 315         ret = reset_control_reset(rstc);
 316
 317         reset_control_put(rstc);
 318
 319         return ret;
 320 }
 321 EXPORT_SYMBOL_GPL(device_reset);