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         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);