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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
21static DEFINE_MUTEX(reset_controller_list_mutex);
22static 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 */
31struct reset_control {
32 struct reset_controller_dev *rcdev;
33 unsigned int id;
34};
35
36/**
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)
41 *
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.
44 */
45static int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
46 const struct of_phandle_args *reset_spec)
47{
48 if (reset_spec->args[0] >= rcdev->nr_resets)
49 return -EINVAL;
50
51 return reset_spec->args[0];
52}
53
54/**
55 * reset_controller_register - register a reset controller device
56 * @rcdev: a pointer to the initialized reset controller device
57 */
58int reset_controller_register(struct reset_controller_dev *rcdev)
59{
60 if (!rcdev->of_xlate) {
61 rcdev->of_reset_n_cells = 1;
62 rcdev->of_xlate = of_reset_simple_xlate;
63 }
64
65 mutex_lock(&reset_controller_list_mutex);
66 list_add(&rcdev->list, &reset_controller_list);
67 mutex_unlock(&reset_controller_list_mutex);
68
69 return 0;
70}
71EXPORT_SYMBOL_GPL(reset_controller_register);
72
73/**
74 * reset_controller_unregister - unregister a reset controller device
75 * @rcdev: a pointer to the reset controller device
76 */
77void reset_controller_unregister(struct reset_controller_dev *rcdev)
78{
79 mutex_lock(&reset_controller_list_mutex);
80 list_del(&rcdev->list);
81 mutex_unlock(&reset_controller_list_mutex);
82}
83EXPORT_SYMBOL_GPL(reset_controller_unregister);
84
85/**
86 * reset_control_reset - reset the controlled device
87 * @rstc: reset controller
88 */
89int reset_control_reset(struct reset_control *rstc)
90{
91 if (rstc->rcdev->ops->reset)
92 return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
93
94 return -ENOTSUPP;
95}
96EXPORT_SYMBOL_GPL(reset_control_reset);
97
98/**
99 * reset_control_assert - asserts the reset line
100 * @rstc: reset controller
101 */
102int reset_control_assert(struct reset_control *rstc)
103{
104 if (rstc->rcdev->ops->assert)
105 return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
106
107 return -ENOTSUPP;
108}
109EXPORT_SYMBOL_GPL(reset_control_assert);
110
111/**
112 * reset_control_deassert - deasserts the reset line
113 * @rstc: reset controller
114 */
115int reset_control_deassert(struct reset_control *rstc)
116{
117 if (rstc->rcdev->ops->deassert)
118 return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
119
120 return -ENOTSUPP;
121}
122EXPORT_SYMBOL_GPL(reset_control_deassert);
123
124/**
125 * reset_control_status - returns a negative errno if not supported, a
126 * positive value if the reset line is asserted, or zero if the reset
127 * line is not asserted.
128 * @rstc: reset controller
129 */
130int reset_control_status(struct reset_control *rstc)
131{
132 if (rstc->rcdev->ops->status)
133 return rstc->rcdev->ops->status(rstc->rcdev, rstc->id);
134
135 return -ENOTSUPP;
136}
137EXPORT_SYMBOL_GPL(reset_control_status);
138
139/**
140 * of_reset_control_get_by_index - Lookup and obtain a reference to a reset
141 * controller by index.
142 * @node: device to be reset by the controller
143 * @index: index of the reset controller
144 *
145 * This is to be used to perform a list of resets for a device or power domain
146 * in whatever order. Returns a struct reset_control or IS_ERR() condition
147 * containing errno.
148 */
149struct reset_control *of_reset_control_get_by_index(struct device_node *node,
150 int index)
151{
152 struct reset_control *rstc;
153 struct reset_controller_dev *r, *rcdev;
154 struct of_phandle_args args;
155 int rstc_id;
156 int ret;
157
158 ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
159 index, &args);
160 if (ret)
161 return ERR_PTR(ret);
162
163 mutex_lock(&reset_controller_list_mutex);
164 rcdev = NULL;
165 list_for_each_entry(r, &reset_controller_list, list) {
166 if (args.np == r->of_node) {
167 rcdev = r;
168 break;
169 }
170 }
171 of_node_put(args.np);
172
173 if (!rcdev) {
174 mutex_unlock(&reset_controller_list_mutex);
175 return ERR_PTR(-EPROBE_DEFER);
176 }
177
178 if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
179 mutex_unlock(&reset_controller_list_mutex);
180 return ERR_PTR(-EINVAL);
181 }
182
183 rstc_id = rcdev->of_xlate(rcdev, &args);
184 if (rstc_id < 0) {
185 mutex_unlock(&reset_controller_list_mutex);
186 return ERR_PTR(rstc_id);
187 }
188
189 try_module_get(rcdev->owner);
190 mutex_unlock(&reset_controller_list_mutex);
191
192 rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
193 if (!rstc) {
194 module_put(rcdev->owner);
195 return ERR_PTR(-ENOMEM);
196 }
197
198 rstc->rcdev = rcdev;
199 rstc->id = rstc_id;
200
201 return rstc;
202}
203EXPORT_SYMBOL_GPL(of_reset_control_get_by_index);
204
205/**
206 * of_reset_control_get - Lookup and obtain a reference to a reset controller.
207 * @node: device to be reset by the controller
208 * @id: reset line name
209 *
210 * Returns a struct reset_control or IS_ERR() condition containing errno.
211 *
212 * Use of id names is optional.
213 */
214struct reset_control *of_reset_control_get(struct device_node *node,
215 const char *id)
216{
217 int index = 0;
218
219 if (id) {
220 index = of_property_match_string(node,
221 "reset-names", id);
222 if (index < 0)
223 return ERR_PTR(-ENOENT);
224 }
225 return of_reset_control_get_by_index(node, index);
226}
227EXPORT_SYMBOL_GPL(of_reset_control_get);
228
229/**
230 * reset_control_get - Lookup and obtain a reference to a reset controller.
231 * @dev: device to be reset by the controller
232 * @id: reset line name
233 *
234 * Returns a struct reset_control or IS_ERR() condition containing errno.
235 *
236 * Use of id names is optional.
237 */
238struct reset_control *reset_control_get(struct device *dev, const char *id)
239{
240 if (!dev)
241 return ERR_PTR(-EINVAL);
242
243 return of_reset_control_get(dev->of_node, id);
244}
245EXPORT_SYMBOL_GPL(reset_control_get);
246
247/**
248 * reset_control_put - free the reset controller
249 * @rstc: reset controller
250 */
251
252void reset_control_put(struct reset_control *rstc)
253{
254 if (IS_ERR(rstc))
255 return;
256
257 module_put(rstc->rcdev->owner);
258 kfree(rstc);
259}
260EXPORT_SYMBOL_GPL(reset_control_put);
261
262static void devm_reset_control_release(struct device *dev, void *res)
263{
264 reset_control_put(*(struct reset_control **)res);
265}
266
267/**
268 * devm_reset_control_get - resource managed reset_control_get()
269 * @dev: device to be reset by the controller
270 * @id: reset line name
271 *
272 * Managed reset_control_get(). For reset controllers returned from this
273 * function, reset_control_put() is called automatically on driver detach.
274 * See reset_control_get() for more information.
275 */
276struct reset_control *devm_reset_control_get(struct device *dev, const char *id)
277{
278 struct reset_control **ptr, *rstc;
279
280 ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
281 GFP_KERNEL);
282 if (!ptr)
283 return ERR_PTR(-ENOMEM);
284
285 rstc = reset_control_get(dev, id);
286 if (!IS_ERR(rstc)) {
287 *ptr = rstc;
288 devres_add(dev, ptr);
289 } else {
290 devres_free(ptr);
291 }
292
293 return rstc;
294}
295EXPORT_SYMBOL_GPL(devm_reset_control_get);
296
297/**
298 * device_reset - find reset controller associated with the device
299 * and perform reset
300 * @dev: device to be reset by the controller
301 *
302 * Convenience wrapper for reset_control_get() and reset_control_reset().
303 * This is useful for the common case of devices with single, dedicated reset
304 * lines.
305 */
306int device_reset(struct device *dev)
307{
308 struct reset_control *rstc;
309 int ret;
310
311 rstc = reset_control_get(dev, NULL);
312 if (IS_ERR(rstc))
313 return PTR_ERR(rstc);
314
315 ret = reset_control_reset(rstc);
316
317 reset_control_put(rstc);
318
319 return ret;
320}
321EXPORT_SYMBOL_GPL(device_reset);