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/device.h>
12 #include <linux/err.h>
13 #include <linux/export.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
17 #include <linux/reset.h>
18 #include <linux/reset-controller.h>
19 #include <linux/slab.h>
21 static DEFINE_MUTEX(reset_controller_list_mutex);
22 static LIST_HEAD(reset_controller_list);
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
31 struct reset_control {
32 struct reset_controller_dev *rcdev;
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)
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.
45 static int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
46 const struct of_phandle_args *reset_spec)
48 if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells))
51 if (reset_spec->args[0] >= rcdev->nr_resets)
54 return reset_spec->args[0];
58 * reset_controller_register - register a reset controller device
59 * @rcdev: a pointer to the initialized reset controller device
61 int reset_controller_register(struct reset_controller_dev *rcdev)
63 if (!rcdev->of_xlate) {
64 rcdev->of_reset_n_cells = 1;
65 rcdev->of_xlate = of_reset_simple_xlate;
68 mutex_lock(&reset_controller_list_mutex);
69 list_add(&rcdev->list, &reset_controller_list);
70 mutex_unlock(&reset_controller_list_mutex);
74 EXPORT_SYMBOL_GPL(reset_controller_register);
77 * reset_controller_unregister - unregister a reset controller device
78 * @rcdev: a pointer to the reset controller device
80 void reset_controller_unregister(struct reset_controller_dev *rcdev)
82 mutex_lock(&reset_controller_list_mutex);
83 list_del(&rcdev->list);
84 mutex_unlock(&reset_controller_list_mutex);
86 EXPORT_SYMBOL_GPL(reset_controller_unregister);
89 * reset_control_reset - reset the controlled device
90 * @rstc: reset controller
92 int reset_control_reset(struct reset_control *rstc)
94 if (rstc->rcdev->ops->reset)
95 return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
99 EXPORT_SYMBOL_GPL(reset_control_reset);
102 * reset_control_assert - asserts the reset line
103 * @rstc: reset controller
105 int reset_control_assert(struct reset_control *rstc)
107 if (rstc->rcdev->ops->assert)
108 return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
112 EXPORT_SYMBOL_GPL(reset_control_assert);
115 * reset_control_deassert - deasserts the reset line
116 * @rstc: reset controller
118 int reset_control_deassert(struct reset_control *rstc)
120 if (rstc->rcdev->ops->deassert)
121 return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
125 EXPORT_SYMBOL_GPL(reset_control_deassert);
128 * reset_control_status - returns a negative errno if not supported, a
129 * positive value if the reset line is asserted, or zero if the reset
130 * line is not asserted.
131 * @rstc: reset controller
133 int reset_control_status(struct reset_control *rstc)
135 if (rstc->rcdev->ops->status)
136 return rstc->rcdev->ops->status(rstc->rcdev, rstc->id);
140 EXPORT_SYMBOL_GPL(reset_control_status);
143 * of_reset_control_get_by_index - Lookup and obtain a reference to a reset
144 * controller by index.
145 * @node: device to be reset by the controller
146 * @index: index of the reset controller
148 * This is to be used to perform a list of resets for a device or power domain
149 * in whatever order. Returns a struct reset_control or IS_ERR() condition
152 struct reset_control *of_reset_control_get_by_index(struct device_node *node,
155 struct reset_control *rstc = ERR_PTR(-EPROBE_DEFER);
156 struct reset_controller_dev *r, *rcdev;
157 struct of_phandle_args args;
161 ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
166 mutex_lock(&reset_controller_list_mutex);
168 list_for_each_entry(r, &reset_controller_list, list) {
169 if (args.np == r->of_node) {
174 of_node_put(args.np);
177 mutex_unlock(&reset_controller_list_mutex);
178 return ERR_PTR(-EPROBE_DEFER);
181 rstc_id = rcdev->of_xlate(rcdev, &args);
183 mutex_unlock(&reset_controller_list_mutex);
184 return ERR_PTR(rstc_id);
187 try_module_get(rcdev->owner);
188 mutex_unlock(&reset_controller_list_mutex);
190 rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
192 module_put(rcdev->owner);
193 return ERR_PTR(-ENOMEM);
201 EXPORT_SYMBOL_GPL(of_reset_control_get_by_index);
204 * of_reset_control_get - Lookup and obtain a reference to a reset controller.
205 * @node: device to be reset by the controller
206 * @id: reset line name
208 * Returns a struct reset_control or IS_ERR() condition containing errno.
210 * Use of id names is optional.
212 struct reset_control *of_reset_control_get(struct device_node *node,
218 index = of_property_match_string(node,
221 return ERR_PTR(-ENOENT);
223 return of_reset_control_get_by_index(node, index);
225 EXPORT_SYMBOL_GPL(of_reset_control_get);
228 * reset_control_get - Lookup and obtain a reference to a reset controller.
229 * @dev: device to be reset by the controller
230 * @id: reset line name
232 * Returns a struct reset_control or IS_ERR() condition containing errno.
234 * Use of id names is optional.
236 struct reset_control *reset_control_get(struct device *dev, const char *id)
239 return ERR_PTR(-EINVAL);
241 return of_reset_control_get(dev->of_node, id);
243 EXPORT_SYMBOL_GPL(reset_control_get);
246 * reset_control_put - free the reset controller
247 * @rstc: reset controller
250 void reset_control_put(struct reset_control *rstc)
255 module_put(rstc->rcdev->owner);
258 EXPORT_SYMBOL_GPL(reset_control_put);
260 static void devm_reset_control_release(struct device *dev, void *res)
262 reset_control_put(*(struct reset_control **)res);
266 * devm_reset_control_get - resource managed reset_control_get()
267 * @dev: device to be reset by the controller
268 * @id: reset line name
270 * Managed reset_control_get(). For reset controllers returned from this
271 * function, reset_control_put() is called automatically on driver detach.
272 * See reset_control_get() for more information.
274 struct reset_control *devm_reset_control_get(struct device *dev, const char *id)
276 struct reset_control **ptr, *rstc;
278 ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
281 return ERR_PTR(-ENOMEM);
283 rstc = reset_control_get(dev, id);
286 devres_add(dev, ptr);
293 EXPORT_SYMBOL_GPL(devm_reset_control_get);
296 * device_reset - find reset controller associated with the device
298 * @dev: device to be reset by the controller
300 * Convenience wrapper for reset_control_get() and reset_control_reset().
301 * This is useful for the common case of devices with single, dedicated reset
304 int device_reset(struct device *dev)
306 struct reset_control *rstc;
309 rstc = reset_control_get(dev, NULL);
311 return PTR_ERR(rstc);
313 ret = reset_control_reset(rstc);
315 reset_control_put(rstc);
319 EXPORT_SYMBOL_GPL(device_reset);