Commit | Line | Data |
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61fc4131 PZ |
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 | */ | |
0b52297f | 11 | #include <linux/atomic.h> |
61fc4131 PZ |
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> | |
17 | #include <linux/of.h> | |
18 | #include <linux/reset.h> | |
19 | #include <linux/reset-controller.h> | |
20 | #include <linux/slab.h> | |
21 | ||
c15ddec2 | 22 | static DEFINE_MUTEX(reset_list_mutex); |
61fc4131 PZ |
23 | static LIST_HEAD(reset_controller_list); |
24 | ||
25 | /** | |
26 | * struct reset_control - a reset control | |
27 | * @rcdev: a pointer to the reset controller device | |
28 | * this reset control belongs to | |
c15ddec2 | 29 | * @list: list entry for the rcdev's reset controller list |
61fc4131 PZ |
30 | * @id: ID of the reset controller in the reset |
31 | * controller device | |
c15ddec2 | 32 | * @refcnt: Number of gets of this reset_control |
0b52297f HG |
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 | |
61fc4131 PZ |
35 | */ |
36 | struct reset_control { | |
37 | struct reset_controller_dev *rcdev; | |
c15ddec2 | 38 | struct list_head list; |
61fc4131 | 39 | unsigned int id; |
c15ddec2 | 40 | unsigned int refcnt; |
0b52297f HG |
41 | int shared; |
42 | atomic_t deassert_count; | |
61fc4131 PZ |
43 | }; |
44 | ||
45 | /** | |
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) | |
50 | * | |
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. | |
53 | */ | |
0c5b2b91 | 54 | static int of_reset_simple_xlate(struct reset_controller_dev *rcdev, |
61fc4131 PZ |
55 | const struct of_phandle_args *reset_spec) |
56 | { | |
61fc4131 PZ |
57 | if (reset_spec->args[0] >= rcdev->nr_resets) |
58 | return -EINVAL; | |
59 | ||
60 | return reset_spec->args[0]; | |
61 | } | |
61fc4131 PZ |
62 | |
63 | /** | |
64 | * reset_controller_register - register a reset controller device | |
65 | * @rcdev: a pointer to the initialized reset controller device | |
66 | */ | |
67 | int reset_controller_register(struct reset_controller_dev *rcdev) | |
68 | { | |
69 | if (!rcdev->of_xlate) { | |
70 | rcdev->of_reset_n_cells = 1; | |
71 | rcdev->of_xlate = of_reset_simple_xlate; | |
72 | } | |
73 | ||
c15ddec2 HG |
74 | INIT_LIST_HEAD(&rcdev->reset_control_head); |
75 | ||
76 | mutex_lock(&reset_list_mutex); | |
61fc4131 | 77 | list_add(&rcdev->list, &reset_controller_list); |
c15ddec2 | 78 | mutex_unlock(&reset_list_mutex); |
61fc4131 PZ |
79 | |
80 | return 0; | |
81 | } | |
82 | EXPORT_SYMBOL_GPL(reset_controller_register); | |
83 | ||
84 | /** | |
85 | * reset_controller_unregister - unregister a reset controller device | |
86 | * @rcdev: a pointer to the reset controller device | |
87 | */ | |
88 | void reset_controller_unregister(struct reset_controller_dev *rcdev) | |
89 | { | |
c15ddec2 | 90 | mutex_lock(&reset_list_mutex); |
61fc4131 | 91 | list_del(&rcdev->list); |
c15ddec2 | 92 | mutex_unlock(&reset_list_mutex); |
61fc4131 PZ |
93 | } |
94 | EXPORT_SYMBOL_GPL(reset_controller_unregister); | |
95 | ||
96 | /** | |
97 | * reset_control_reset - reset the controlled device | |
98 | * @rstc: reset controller | |
0b52297f HG |
99 | * |
100 | * Calling this on a shared reset controller is an error. | |
61fc4131 PZ |
101 | */ |
102 | int reset_control_reset(struct reset_control *rstc) | |
103 | { | |
0b52297f HG |
104 | if (WARN_ON(rstc->shared)) |
105 | return -EINVAL; | |
106 | ||
61fc4131 PZ |
107 | if (rstc->rcdev->ops->reset) |
108 | return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id); | |
109 | ||
39b4da71 | 110 | return -ENOTSUPP; |
61fc4131 PZ |
111 | } |
112 | EXPORT_SYMBOL_GPL(reset_control_reset); | |
113 | ||
114 | /** | |
115 | * reset_control_assert - asserts the reset line | |
116 | * @rstc: reset controller | |
0b52297f HG |
117 | * |
118 | * Calling this on an exclusive reset controller guarantees that the reset | |
119 | * will be asserted. When called on a shared reset controller the line may | |
120 | * still be deasserted, as long as other users keep it so. | |
121 | * | |
122 | * For shared reset controls a driver cannot expect the hw's registers and | |
123 | * internal state to be reset, but must be prepared for this to happen. | |
61fc4131 PZ |
124 | */ |
125 | int reset_control_assert(struct reset_control *rstc) | |
126 | { | |
0b52297f HG |
127 | if (!rstc->rcdev->ops->assert) |
128 | return -ENOTSUPP; | |
61fc4131 | 129 | |
0b52297f HG |
130 | if (rstc->shared) { |
131 | if (WARN_ON(atomic_read(&rstc->deassert_count) == 0)) | |
132 | return -EINVAL; | |
133 | ||
134 | if (atomic_dec_return(&rstc->deassert_count) != 0) | |
135 | return 0; | |
136 | } | |
137 | ||
138 | return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id); | |
61fc4131 PZ |
139 | } |
140 | EXPORT_SYMBOL_GPL(reset_control_assert); | |
141 | ||
142 | /** | |
143 | * reset_control_deassert - deasserts the reset line | |
144 | * @rstc: reset controller | |
0b52297f HG |
145 | * |
146 | * After calling this function, the reset is guaranteed to be deasserted. | |
61fc4131 PZ |
147 | */ |
148 | int reset_control_deassert(struct reset_control *rstc) | |
149 | { | |
0b52297f HG |
150 | if (!rstc->rcdev->ops->deassert) |
151 | return -ENOTSUPP; | |
61fc4131 | 152 | |
0b52297f HG |
153 | if (rstc->shared) { |
154 | if (atomic_inc_return(&rstc->deassert_count) != 1) | |
155 | return 0; | |
156 | } | |
157 | ||
158 | return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id); | |
61fc4131 PZ |
159 | } |
160 | EXPORT_SYMBOL_GPL(reset_control_deassert); | |
161 | ||
729de41b DN |
162 | /** |
163 | * reset_control_status - returns a negative errno if not supported, a | |
164 | * positive value if the reset line is asserted, or zero if the reset | |
165 | * line is not asserted. | |
166 | * @rstc: reset controller | |
167 | */ | |
168 | int reset_control_status(struct reset_control *rstc) | |
169 | { | |
170 | if (rstc->rcdev->ops->status) | |
171 | return rstc->rcdev->ops->status(rstc->rcdev, rstc->id); | |
172 | ||
39b4da71 | 173 | return -ENOTSUPP; |
729de41b DN |
174 | } |
175 | EXPORT_SYMBOL_GPL(reset_control_status); | |
176 | ||
c15ddec2 HG |
177 | static struct reset_control *__reset_control_get( |
178 | struct reset_controller_dev *rcdev, | |
0b52297f | 179 | unsigned int index, int shared) |
c15ddec2 HG |
180 | { |
181 | struct reset_control *rstc; | |
182 | ||
183 | lockdep_assert_held(&reset_list_mutex); | |
184 | ||
185 | list_for_each_entry(rstc, &rcdev->reset_control_head, list) { | |
186 | if (rstc->id == index) { | |
0b52297f HG |
187 | if (WARN_ON(!rstc->shared || !shared)) |
188 | return ERR_PTR(-EBUSY); | |
189 | ||
c15ddec2 HG |
190 | rstc->refcnt++; |
191 | return rstc; | |
192 | } | |
193 | } | |
194 | ||
195 | rstc = kzalloc(sizeof(*rstc), GFP_KERNEL); | |
196 | if (!rstc) | |
197 | return ERR_PTR(-ENOMEM); | |
198 | ||
199 | try_module_get(rcdev->owner); | |
200 | ||
201 | rstc->rcdev = rcdev; | |
202 | list_add(&rstc->list, &rcdev->reset_control_head); | |
203 | rstc->id = index; | |
204 | rstc->refcnt = 1; | |
0b52297f | 205 | rstc->shared = shared; |
c15ddec2 HG |
206 | |
207 | return rstc; | |
208 | } | |
209 | ||
210 | static void __reset_control_put(struct reset_control *rstc) | |
211 | { | |
212 | lockdep_assert_held(&reset_list_mutex); | |
213 | ||
214 | if (--rstc->refcnt) | |
215 | return; | |
216 | ||
217 | module_put(rstc->rcdev->owner); | |
218 | ||
219 | list_del(&rstc->list); | |
220 | kfree(rstc); | |
221 | } | |
222 | ||
6c96f05c | 223 | struct reset_control *__of_reset_control_get(struct device_node *node, |
0b52297f | 224 | const char *id, int index, int shared) |
61fc4131 | 225 | { |
d056c9b8 | 226 | struct reset_control *rstc; |
61fc4131 PZ |
227 | struct reset_controller_dev *r, *rcdev; |
228 | struct of_phandle_args args; | |
61fc4131 PZ |
229 | int rstc_id; |
230 | int ret; | |
231 | ||
6c96f05c HG |
232 | if (!node) |
233 | return ERR_PTR(-EINVAL); | |
234 | ||
235 | if (id) { | |
236 | index = of_property_match_string(node, | |
237 | "reset-names", id); | |
238 | if (index < 0) | |
239 | return ERR_PTR(-ENOENT); | |
240 | } | |
241 | ||
fc0a5921 | 242 | ret = of_parse_phandle_with_args(node, "resets", "#reset-cells", |
61fc4131 PZ |
243 | index, &args); |
244 | if (ret) | |
245 | return ERR_PTR(ret); | |
246 | ||
c15ddec2 | 247 | mutex_lock(&reset_list_mutex); |
61fc4131 PZ |
248 | rcdev = NULL; |
249 | list_for_each_entry(r, &reset_controller_list, list) { | |
250 | if (args.np == r->of_node) { | |
251 | rcdev = r; | |
252 | break; | |
253 | } | |
254 | } | |
255 | of_node_put(args.np); | |
256 | ||
257 | if (!rcdev) { | |
c15ddec2 | 258 | mutex_unlock(&reset_list_mutex); |
3d103020 | 259 | return ERR_PTR(-EPROBE_DEFER); |
61fc4131 PZ |
260 | } |
261 | ||
e677774f | 262 | if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) { |
c15ddec2 | 263 | mutex_unlock(&reset_list_mutex); |
e677774f MR |
264 | return ERR_PTR(-EINVAL); |
265 | } | |
266 | ||
61fc4131 PZ |
267 | rstc_id = rcdev->of_xlate(rcdev, &args); |
268 | if (rstc_id < 0) { | |
c15ddec2 | 269 | mutex_unlock(&reset_list_mutex); |
61fc4131 PZ |
270 | return ERR_PTR(rstc_id); |
271 | } | |
272 | ||
c15ddec2 | 273 | /* reset_list_mutex also protects the rcdev's reset_control list */ |
0b52297f | 274 | rstc = __reset_control_get(rcdev, rstc_id, shared); |
61fc4131 | 275 | |
c15ddec2 | 276 | mutex_unlock(&reset_list_mutex); |
61fc4131 PZ |
277 | |
278 | return rstc; | |
279 | } | |
6c96f05c | 280 | EXPORT_SYMBOL_GPL(__of_reset_control_get); |
61fc4131 PZ |
281 | |
282 | /** | |
283 | * reset_control_put - free the reset controller | |
284 | * @rstc: reset controller | |
285 | */ | |
286 | ||
287 | void reset_control_put(struct reset_control *rstc) | |
288 | { | |
289 | if (IS_ERR(rstc)) | |
290 | return; | |
291 | ||
c15ddec2 HG |
292 | mutex_lock(&reset_list_mutex); |
293 | __reset_control_put(rstc); | |
294 | mutex_unlock(&reset_list_mutex); | |
61fc4131 PZ |
295 | } |
296 | EXPORT_SYMBOL_GPL(reset_control_put); | |
297 | ||
298 | static void devm_reset_control_release(struct device *dev, void *res) | |
299 | { | |
300 | reset_control_put(*(struct reset_control **)res); | |
301 | } | |
302 | ||
6c96f05c | 303 | struct reset_control *__devm_reset_control_get(struct device *dev, |
0b52297f | 304 | const char *id, int index, int shared) |
61fc4131 PZ |
305 | { |
306 | struct reset_control **ptr, *rstc; | |
307 | ||
308 | ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr), | |
309 | GFP_KERNEL); | |
310 | if (!ptr) | |
311 | return ERR_PTR(-ENOMEM); | |
312 | ||
0b52297f HG |
313 | rstc = __of_reset_control_get(dev ? dev->of_node : NULL, |
314 | id, index, shared); | |
61fc4131 PZ |
315 | if (!IS_ERR(rstc)) { |
316 | *ptr = rstc; | |
317 | devres_add(dev, ptr); | |
318 | } else { | |
319 | devres_free(ptr); | |
320 | } | |
321 | ||
322 | return rstc; | |
323 | } | |
6c96f05c | 324 | EXPORT_SYMBOL_GPL(__devm_reset_control_get); |
61fc4131 | 325 | |
61fc4131 PZ |
326 | /** |
327 | * device_reset - find reset controller associated with the device | |
328 | * and perform reset | |
329 | * @dev: device to be reset by the controller | |
330 | * | |
331 | * Convenience wrapper for reset_control_get() and reset_control_reset(). | |
332 | * This is useful for the common case of devices with single, dedicated reset | |
333 | * lines. | |
334 | */ | |
335 | int device_reset(struct device *dev) | |
336 | { | |
337 | struct reset_control *rstc; | |
338 | int ret; | |
339 | ||
340 | rstc = reset_control_get(dev, NULL); | |
341 | if (IS_ERR(rstc)) | |
342 | return PTR_ERR(rstc); | |
343 | ||
344 | ret = reset_control_reset(rstc); | |
345 | ||
346 | reset_control_put(rstc); | |
347 | ||
348 | return ret; | |
349 | } | |
350 | EXPORT_SYMBOL_GPL(device_reset); |