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	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 */
46static 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 */
62int 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}
75EXPORT_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 */
81void 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}
87EXPORT_SYMBOL_GPL(reset_controller_unregister);
88
89/**
90 * reset_control_reset - reset the controlled device
91 * @rstc: reset controller
92 */
93int 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}
100EXPORT_SYMBOL_GPL(reset_control_reset);
101
102/**
103 * reset_control_assert - asserts the reset line
104 * @rstc: reset controller
105 */
106int 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}
113EXPORT_SYMBOL_GPL(reset_control_assert);
114
115/**
116 * reset_control_deassert - deasserts the reset line
117 * @rstc: reset controller
118 */
119int 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}
126EXPORT_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 */
134int 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}
141EXPORT_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 */
152struct 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}
205EXPORT_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 */
216struct 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}
229EXPORT_SYMBOL_GPL(reset_control_get);
230
231/**
232 * reset_control_put - free the reset controller
233 * @rstc: reset controller
234 */
235
236void 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}
244EXPORT_SYMBOL_GPL(reset_control_put);
245
246static 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 */
260struct 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}
279EXPORT_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 */
290int 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}
305EXPORT_SYMBOL_GPL(device_reset);
306