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 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);