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 * of_reset_control_get - Lookup and obtain a reference to a reset controller.
130 * @node: device to be reset by the controller
131 * @id: reset line name
132 *
133 * Returns a struct reset_control or IS_ERR() condition containing errno.
134 *
135 * Use of id names is optional.
136 */
137struct reset_control *of_reset_control_get(struct device_node *node,
138					   const char *id)
139{
140	struct reset_control *rstc = ERR_PTR(-EPROBE_DEFER);
141	struct reset_controller_dev *r, *rcdev;
142	struct of_phandle_args args;
143	int index = 0;
144	int rstc_id;
145	int ret;
146
147	if (id)
148		index = of_property_match_string(node,
149						 "reset-names", id);
150	ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
151					 index, &args);
152	if (ret)
153		return ERR_PTR(ret);
154
155	mutex_lock(&reset_controller_list_mutex);
156	rcdev = NULL;
157	list_for_each_entry(r, &reset_controller_list, list) {
158		if (args.np == r->of_node) {
159			rcdev = r;
160			break;
161		}
162	}
163	of_node_put(args.np);
164
165	if (!rcdev) {
166		mutex_unlock(&reset_controller_list_mutex);
167		return ERR_PTR(-EPROBE_DEFER);
168	}
169
170	rstc_id = rcdev->of_xlate(rcdev, &args);
171	if (rstc_id < 0) {
172		mutex_unlock(&reset_controller_list_mutex);
173		return ERR_PTR(rstc_id);
174	}
175
176	try_module_get(rcdev->owner);
177	mutex_unlock(&reset_controller_list_mutex);
178
179	rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
180	if (!rstc) {
181		module_put(rcdev->owner);
182		return ERR_PTR(-ENOMEM);
183	}
184
185	rstc->rcdev = rcdev;
186	rstc->id = rstc_id;
187
188	return rstc;
189}
190EXPORT_SYMBOL_GPL(of_reset_control_get);
191
192/**
193 * reset_control_get - Lookup and obtain a reference to a reset controller.
194 * @dev: device to be reset by the controller
195 * @id: reset line name
196 *
197 * Returns a struct reset_control or IS_ERR() condition containing errno.
198 *
199 * Use of id names is optional.
200 */
201struct reset_control *reset_control_get(struct device *dev, const char *id)
202{
203	struct reset_control *rstc;
204
205	if (!dev)
206		return ERR_PTR(-EINVAL);
207
208	rstc = of_reset_control_get(dev->of_node, id);
209	if (!IS_ERR(rstc))
210		rstc->dev = dev;
211
212	return rstc;
213}
214EXPORT_SYMBOL_GPL(reset_control_get);
215
216/**
217 * reset_control_put - free the reset controller
218 * @rstc: reset controller
219 */
220
221void reset_control_put(struct reset_control *rstc)
222{
223	if (IS_ERR(rstc))
224		return;
225
226	module_put(rstc->rcdev->owner);
227	kfree(rstc);
228}
229EXPORT_SYMBOL_GPL(reset_control_put);
230
231static void devm_reset_control_release(struct device *dev, void *res)
232{
233	reset_control_put(*(struct reset_control **)res);
234}
235
236/**
237 * devm_reset_control_get - resource managed reset_control_get()
238 * @dev: device to be reset by the controller
239 * @id: reset line name
240 *
241 * Managed reset_control_get(). For reset controllers returned from this
242 * function, reset_control_put() is called automatically on driver detach.
243 * See reset_control_get() for more information.
244 */
245struct reset_control *devm_reset_control_get(struct device *dev, const char *id)
246{
247	struct reset_control **ptr, *rstc;
248
249	ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
250			   GFP_KERNEL);
251	if (!ptr)
252		return ERR_PTR(-ENOMEM);
253
254	rstc = reset_control_get(dev, id);
255	if (!IS_ERR(rstc)) {
256		*ptr = rstc;
257		devres_add(dev, ptr);
258	} else {
259		devres_free(ptr);
260	}
261
262	return rstc;
263}
264EXPORT_SYMBOL_GPL(devm_reset_control_get);
265
266/**
267 * device_reset - find reset controller associated with the device
268 *                and perform reset
269 * @dev: device to be reset by the controller
270 *
271 * Convenience wrapper for reset_control_get() and reset_control_reset().
272 * This is useful for the common case of devices with single, dedicated reset
273 * lines.
274 */
275int device_reset(struct device *dev)
276{
277	struct reset_control *rstc;
278	int ret;
279
280	rstc = reset_control_get(dev, NULL);
281	if (IS_ERR(rstc))
282		return PTR_ERR(rstc);
283
284	ret = reset_control_reset(rstc);
285
286	reset_control_put(rstc);
287
288	return ret;
289}
290EXPORT_SYMBOL_GPL(device_reset);