2 * Reset Controller framework
4 * Copyright 2013 Philipp Zabel, Pengutronix
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.
11 #include <linux/atomic.h>
12 #include <linux/device.h>
13 #include <linux/err.h>
14 #include <linux/export.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
18 #include <linux/reset.h>
19 #include <linux/reset-controller.h>
20 #include <linux/slab.h>
22 static DEFINE_MUTEX(reset_list_mutex);
23 static LIST_HEAD(reset_controller_list);
26 * struct reset_control - a reset control
27 * @rcdev: a pointer to the reset controller device
28 * this reset control belongs to
29 * @list: list entry for the rcdev's reset controller list
30 * @id: ID of the reset controller in the reset
32 * @refcnt: Number of gets of this reset_control
33 * @shared: Is this a shared (1), or an exclusive (0) reset_control?
34 * @deassert_cnt: Number of times this reset line has been deasserted
36 struct reset_control {
37 struct reset_controller_dev *rcdev;
38 struct list_head list;
42 atomic_t deassert_count;
46 * of_reset_simple_xlate - translate reset_spec to the reset line number
47 * @rcdev: a pointer to the reset controller device
48 * @reset_spec: reset line specifier as found in the device tree
49 * @flags: a flags pointer to fill in (optional)
51 * This simple translation function should be used for reset controllers
52 * with 1:1 mapping, where reset lines can be indexed by number without gaps.
54 static int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
55 const struct of_phandle_args *reset_spec)
57 if (reset_spec->args[0] >= rcdev->nr_resets)
60 return reset_spec->args[0];
64 * reset_controller_register - register a reset controller device
65 * @rcdev: a pointer to the initialized reset controller device
67 int reset_controller_register(struct reset_controller_dev *rcdev)
69 if (!rcdev->of_xlate) {
70 rcdev->of_reset_n_cells = 1;
71 rcdev->of_xlate = of_reset_simple_xlate;
74 INIT_LIST_HEAD(&rcdev->reset_control_head);
76 mutex_lock(&reset_list_mutex);
77 list_add(&rcdev->list, &reset_controller_list);
78 mutex_unlock(&reset_list_mutex);
82 EXPORT_SYMBOL_GPL(reset_controller_register);
85 * reset_controller_unregister - unregister a reset controller device
86 * @rcdev: a pointer to the reset controller device
88 void reset_controller_unregister(struct reset_controller_dev *rcdev)
90 mutex_lock(&reset_list_mutex);
91 list_del(&rcdev->list);
92 mutex_unlock(&reset_list_mutex);
94 EXPORT_SYMBOL_GPL(reset_controller_unregister);
96 static void devm_reset_controller_release(struct device *dev, void *res)
98 reset_controller_unregister(*(struct reset_controller_dev **)res);
102 * devm_reset_controller_register - resource managed reset_controller_register()
103 * @dev: device that is registering this reset controller
104 * @rcdev: a pointer to the initialized reset controller device
106 * Managed reset_controller_register(). For reset controllers registered by
107 * this function, reset_controller_unregister() is automatically called on
108 * driver detach. See reset_controller_register() for more information.
110 int devm_reset_controller_register(struct device *dev,
111 struct reset_controller_dev *rcdev)
113 struct reset_controller_dev **rcdevp;
116 rcdevp = devres_alloc(devm_reset_controller_release, sizeof(*rcdevp),
121 ret = reset_controller_register(rcdev);
124 devres_add(dev, rcdevp);
131 EXPORT_SYMBOL_GPL(devm_reset_controller_register);
134 * reset_control_reset - reset the controlled device
135 * @rstc: reset controller
137 * Calling this on a shared reset controller is an error.
139 int reset_control_reset(struct reset_control *rstc)
141 if (WARN_ON(IS_ERR_OR_NULL(rstc)) ||
142 WARN_ON(rstc->shared))
145 if (rstc->rcdev->ops->reset)
146 return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
150 EXPORT_SYMBOL_GPL(reset_control_reset);
153 * reset_control_assert - asserts the reset line
154 * @rstc: reset controller
156 * Calling this on an exclusive reset controller guarantees that the reset
157 * will be asserted. When called on a shared reset controller the line may
158 * still be deasserted, as long as other users keep it so.
160 * For shared reset controls a driver cannot expect the hw's registers and
161 * internal state to be reset, but must be prepared for this to happen.
163 int reset_control_assert(struct reset_control *rstc)
165 if (WARN_ON(IS_ERR_OR_NULL(rstc)))
168 if (!rstc->rcdev->ops->assert)
172 if (WARN_ON(atomic_read(&rstc->deassert_count) == 0))
175 if (atomic_dec_return(&rstc->deassert_count) != 0)
179 return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
181 EXPORT_SYMBOL_GPL(reset_control_assert);
184 * reset_control_deassert - deasserts the reset line
185 * @rstc: reset controller
187 * After calling this function, the reset is guaranteed to be deasserted.
189 int reset_control_deassert(struct reset_control *rstc)
191 if (WARN_ON(IS_ERR_OR_NULL(rstc)))
194 if (!rstc->rcdev->ops->deassert)
198 if (atomic_inc_return(&rstc->deassert_count) != 1)
202 return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
204 EXPORT_SYMBOL_GPL(reset_control_deassert);
207 * reset_control_status - returns a negative errno if not supported, a
208 * positive value if the reset line is asserted, or zero if the reset
209 * line is not asserted.
210 * @rstc: reset controller
212 int reset_control_status(struct reset_control *rstc)
214 if (WARN_ON(IS_ERR_OR_NULL(rstc)))
217 if (rstc->rcdev->ops->status)
218 return rstc->rcdev->ops->status(rstc->rcdev, rstc->id);
222 EXPORT_SYMBOL_GPL(reset_control_status);
224 static struct reset_control *__reset_control_get(
225 struct reset_controller_dev *rcdev,
226 unsigned int index, int shared)
228 struct reset_control *rstc;
230 lockdep_assert_held(&reset_list_mutex);
232 list_for_each_entry(rstc, &rcdev->reset_control_head, list) {
233 if (rstc->id == index) {
234 if (WARN_ON(!rstc->shared || !shared))
235 return ERR_PTR(-EBUSY);
242 rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
244 return ERR_PTR(-ENOMEM);
246 try_module_get(rcdev->owner);
249 list_add(&rstc->list, &rcdev->reset_control_head);
252 rstc->shared = shared;
257 static void __reset_control_put(struct reset_control *rstc)
259 lockdep_assert_held(&reset_list_mutex);
264 module_put(rstc->rcdev->owner);
266 list_del(&rstc->list);
270 struct reset_control *__of_reset_control_get(struct device_node *node,
271 const char *id, int index, int shared)
273 struct reset_control *rstc;
274 struct reset_controller_dev *r, *rcdev;
275 struct of_phandle_args args;
280 return ERR_PTR(-EINVAL);
283 index = of_property_match_string(node,
286 return ERR_PTR(-ENOENT);
289 ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
294 mutex_lock(&reset_list_mutex);
296 list_for_each_entry(r, &reset_controller_list, list) {
297 if (args.np == r->of_node) {
302 of_node_put(args.np);
305 mutex_unlock(&reset_list_mutex);
306 return ERR_PTR(-EPROBE_DEFER);
309 if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
310 mutex_unlock(&reset_list_mutex);
311 return ERR_PTR(-EINVAL);
314 rstc_id = rcdev->of_xlate(rcdev, &args);
316 mutex_unlock(&reset_list_mutex);
317 return ERR_PTR(rstc_id);
320 /* reset_list_mutex also protects the rcdev's reset_control list */
321 rstc = __reset_control_get(rcdev, rstc_id, shared);
323 mutex_unlock(&reset_list_mutex);
327 EXPORT_SYMBOL_GPL(__of_reset_control_get);
330 * reset_control_put - free the reset controller
331 * @rstc: reset controller
334 void reset_control_put(struct reset_control *rstc)
339 mutex_lock(&reset_list_mutex);
340 __reset_control_put(rstc);
341 mutex_unlock(&reset_list_mutex);
343 EXPORT_SYMBOL_GPL(reset_control_put);
345 static void devm_reset_control_release(struct device *dev, void *res)
347 reset_control_put(*(struct reset_control **)res);
350 struct reset_control *__devm_reset_control_get(struct device *dev,
351 const char *id, int index, int shared)
353 struct reset_control **ptr, *rstc;
355 ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
358 return ERR_PTR(-ENOMEM);
360 rstc = __of_reset_control_get(dev ? dev->of_node : NULL,
364 devres_add(dev, ptr);
371 EXPORT_SYMBOL_GPL(__devm_reset_control_get);
374 * device_reset - find reset controller associated with the device
376 * @dev: device to be reset by the controller
378 * Convenience wrapper for reset_control_get() and reset_control_reset().
379 * This is useful for the common case of devices with single, dedicated reset
382 int device_reset(struct device *dev)
384 struct reset_control *rstc;
387 rstc = reset_control_get(dev, NULL);
389 return PTR_ERR(rstc);
391 ret = reset_control_reset(rstc);
393 reset_control_put(rstc);
397 EXPORT_SYMBOL_GPL(device_reset);