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  * reset_control_status - returns a negative errno if not supported, a
 130  * positive value if the reset line is asserted, or zero if the reset
 131  * line is not asserted.
 132  * @rstc: reset controller
 133  */
 134 int reset_control_status(struct reset_control *rstc)
 135 {
 136         if (rstc->rcdev->ops->status)
 137                 return rstc->rcdev->ops->status(rstc->rcdev, rstc->id);
 138
 139         return -ENOSYS;
 140 }
 141 EXPORT_SYMBOL_GPL(reset_control_status);
 142
 143 /**
 144  * of_reset_control_get - Lookup and obtain a reference to a reset controller.
 145  * @node: device to be reset by the controller
 146  * @id: reset line name
 147  *
 148  * Returns a struct reset_control or IS_ERR() condition containing errno.
 149  *
 150  * Use of id names is optional.
 151  */
 152 struct reset_control *of_reset_control_get(struct device_node *node,
 153                                            const char *id)
 154 {
 155         struct reset_control *rstc = ERR_PTR(-EPROBE_DEFER);
 156         struct reset_controller_dev *r, *rcdev;
 157         struct of_phandle_args args;
 158         int index = 0;
 159         int rstc_id;
 160         int ret;
 161
 162         if (id)
 163                 index = of_property_match_string(node,
 164                                                  "reset-names", id);
 165         ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
 166                                          index, &args);
 167         if (ret)
 168                 return ERR_PTR(ret);
 169
 170         mutex_lock(&reset_controller_list_mutex);
 171         rcdev = NULL;
 172         list_for_each_entry(r, &reset_controller_list, list) {
 173                 if (args.np == r->of_node) {
 174                         rcdev = r;
 175                         break;
 176                 }
 177         }
 178         of_node_put(args.np);
 179
 180         if (!rcdev) {
 181                 mutex_unlock(&reset_controller_list_mutex);
 182                 return ERR_PTR(-EPROBE_DEFER);
 183         }
 184
 185         rstc_id = rcdev->of_xlate(rcdev, &args);
 186         if (rstc_id < 0) {
 187                 mutex_unlock(&reset_controller_list_mutex);
 188                 return ERR_PTR(rstc_id);
 189         }
 190
 191         try_module_get(rcdev->owner);
 192         mutex_unlock(&reset_controller_list_mutex);
 193
 194         rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
 195         if (!rstc) {
 196                 module_put(rcdev->owner);
 197                 return ERR_PTR(-ENOMEM);
 198         }
 199
 200         rstc->rcdev = rcdev;
 201         rstc->id = rstc_id;
 202
 203         return rstc;
 204 }
 205 EXPORT_SYMBOL_GPL(of_reset_control_get);
 206
 207 /**
 208  * reset_control_get - Lookup and obtain a reference to a reset controller.
 209  * @dev: device to be reset by the controller
 210  * @id: reset line name
 211  *
 212  * Returns a struct reset_control or IS_ERR() condition containing errno.
 213  *
 214  * Use of id names is optional.
 215  */
 216 struct reset_control *reset_control_get(struct device *dev, const char *id)
 217 {
 218         struct reset_control *rstc;
 219
 220         if (!dev)
 221                 return ERR_PTR(-EINVAL);
 222
 223         rstc = of_reset_control_get(dev->of_node, id);
 224         if (!IS_ERR(rstc))
 225                 rstc->dev = dev;
 226
 227         return rstc;
 228 }
 229 EXPORT_SYMBOL_GPL(reset_control_get);
 230
 231 /**
 232  * reset_control_put - free the reset controller
 233  * @rstc: reset controller
 234  */
 235
 236 void reset_control_put(struct reset_control *rstc)
 237 {
 238         if (IS_ERR(rstc))
 239                 return;
 240
 241         module_put(rstc->rcdev->owner);
 242         kfree(rstc);
 243 }
 244 EXPORT_SYMBOL_GPL(reset_control_put);
 245
 246 static void devm_reset_control_release(struct device *dev, void *res)
 247 {
 248         reset_control_put(*(struct reset_control **)res);
 249 }
 250
 251 /**
 252  * devm_reset_control_get - resource managed reset_control_get()
 253  * @dev: device to be reset by the controller
 254  * @id: reset line name
 255  *
 256  * Managed reset_control_get(). For reset controllers returned from this
 257  * function, reset_control_put() is called automatically on driver detach.
 258  * See reset_control_get() for more information.
 259  */
 260 struct reset_control *devm_reset_control_get(struct device *dev, const char *id)
 261 {
 262         struct reset_control **ptr, *rstc;
 263
 264         ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
 265                            GFP_KERNEL);
 266         if (!ptr)
 267                 return ERR_PTR(-ENOMEM);
 268
 269         rstc = reset_control_get(dev, id);
 270         if (!IS_ERR(rstc)) {
 271                 *ptr = rstc;
 272                 devres_add(dev, ptr);
 273         } else {
 274                 devres_free(ptr);
 275         }
 276
 277         return rstc;
 278 }
 279 EXPORT_SYMBOL_GPL(devm_reset_control_get);
 280
 281 /**
 282  * device_reset - find reset controller associated with the device
 283  *                and perform reset
 284  * @dev: device to be reset by the controller
 285  *
 286  * Convenience wrapper for reset_control_get() and reset_control_reset().
 287  * This is useful for the common case of devices with single, dedicated reset
 288  * lines.
 289  */
 290 int device_reset(struct device *dev)
 291 {
 292         struct reset_control *rstc;
 293         int ret;
 294
 295         rstc = reset_control_get(dev, NULL);
 296         if (IS_ERR(rstc))
 297                 return PTR_ERR(rstc);
 298
 299         ret = reset_control_reset(rstc);
 300
 301         reset_control_put(rstc);
 302
 303         return ret;
 304 }
 305 EXPORT_SYMBOL_GPL(device_reset);