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/atomic.h>
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>
18 #include <linux/reset.h>
19 #include <linux/reset-controller.h>
20 #include <linux/slab.h>
22 static DEFINE_MUTEX(reset_list_mutex
);
23 static LIST_HEAD(reset_controller_list
);
26 * struct reset_control - a reset control
27 * @rcdev: a pointer to the reset controller device
28 * this reset control belongs to
29 * @list: list entry for the rcdev's reset controller list
30 * @id: ID of the reset controller in the reset
32 * @refcnt: Number of gets of this reset_control
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
36 struct reset_control
{
37 struct reset_controller_dev
*rcdev
;
38 struct list_head list
;
42 atomic_t deassert_count
;
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)
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.
54 static int of_reset_simple_xlate(struct reset_controller_dev
*rcdev
,
55 const struct of_phandle_args
*reset_spec
)
57 if (reset_spec
->args
[0] >= rcdev
->nr_resets
)
60 return reset_spec
->args
[0];
64 * reset_controller_register - register a reset controller device
65 * @rcdev: a pointer to the initialized reset controller device
67 int reset_controller_register(struct reset_controller_dev
*rcdev
)
69 if (!rcdev
->of_xlate
) {
70 rcdev
->of_reset_n_cells
= 1;
71 rcdev
->of_xlate
= of_reset_simple_xlate
;
74 INIT_LIST_HEAD(&rcdev
->reset_control_head
);
76 mutex_lock(&reset_list_mutex
);
77 list_add(&rcdev
->list
, &reset_controller_list
);
78 mutex_unlock(&reset_list_mutex
);
82 EXPORT_SYMBOL_GPL(reset_controller_register
);
85 * reset_controller_unregister - unregister a reset controller device
86 * @rcdev: a pointer to the reset controller device
88 void reset_controller_unregister(struct reset_controller_dev
*rcdev
)
90 mutex_lock(&reset_list_mutex
);
91 list_del(&rcdev
->list
);
92 mutex_unlock(&reset_list_mutex
);
94 EXPORT_SYMBOL_GPL(reset_controller_unregister
);
97 * reset_control_reset - reset the controlled device
98 * @rstc: reset controller
100 * Calling this on a shared reset controller is an error.
102 int reset_control_reset(struct reset_control
*rstc
)
104 if (WARN_ON(rstc
->shared
))
107 if (rstc
->rcdev
->ops
->reset
)
108 return rstc
->rcdev
->ops
->reset(rstc
->rcdev
, rstc
->id
);
112 EXPORT_SYMBOL_GPL(reset_control_reset
);
115 * reset_control_assert - asserts the reset line
116 * @rstc: reset controller
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.
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.
125 int reset_control_assert(struct reset_control
*rstc
)
127 if (!rstc
->rcdev
->ops
->assert)
131 if (WARN_ON(atomic_read(&rstc
->deassert_count
) == 0))
134 if (atomic_dec_return(&rstc
->deassert_count
) != 0)
138 return rstc
->rcdev
->ops
->assert(rstc
->rcdev
, rstc
->id
);
140 EXPORT_SYMBOL_GPL(reset_control_assert
);
143 * reset_control_deassert - deasserts the reset line
144 * @rstc: reset controller
146 * After calling this function, the reset is guaranteed to be deasserted.
148 int reset_control_deassert(struct reset_control
*rstc
)
150 if (!rstc
->rcdev
->ops
->deassert
)
154 if (atomic_inc_return(&rstc
->deassert_count
) != 1)
158 return rstc
->rcdev
->ops
->deassert(rstc
->rcdev
, rstc
->id
);
160 EXPORT_SYMBOL_GPL(reset_control_deassert
);
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
168 int reset_control_status(struct reset_control
*rstc
)
170 if (rstc
->rcdev
->ops
->status
)
171 return rstc
->rcdev
->ops
->status(rstc
->rcdev
, rstc
->id
);
175 EXPORT_SYMBOL_GPL(reset_control_status
);
177 static struct reset_control
*__reset_control_get(
178 struct reset_controller_dev
*rcdev
,
179 unsigned int index
, int shared
)
181 struct reset_control
*rstc
;
183 lockdep_assert_held(&reset_list_mutex
);
185 list_for_each_entry(rstc
, &rcdev
->reset_control_head
, list
) {
186 if (rstc
->id
== index
) {
187 if (WARN_ON(!rstc
->shared
|| !shared
))
188 return ERR_PTR(-EBUSY
);
195 rstc
= kzalloc(sizeof(*rstc
), GFP_KERNEL
);
197 return ERR_PTR(-ENOMEM
);
199 try_module_get(rcdev
->owner
);
202 list_add(&rstc
->list
, &rcdev
->reset_control_head
);
205 rstc
->shared
= shared
;
210 static void __reset_control_put(struct reset_control
*rstc
)
212 lockdep_assert_held(&reset_list_mutex
);
217 module_put(rstc
->rcdev
->owner
);
219 list_del(&rstc
->list
);
223 struct reset_control
*__of_reset_control_get(struct device_node
*node
,
224 const char *id
, int index
, int shared
)
226 struct reset_control
*rstc
;
227 struct reset_controller_dev
*r
, *rcdev
;
228 struct of_phandle_args args
;
233 return ERR_PTR(-EINVAL
);
236 index
= of_property_match_string(node
,
239 return ERR_PTR(-ENOENT
);
242 ret
= of_parse_phandle_with_args(node
, "resets", "#reset-cells",
247 mutex_lock(&reset_list_mutex
);
249 list_for_each_entry(r
, &reset_controller_list
, list
) {
250 if (args
.np
== r
->of_node
) {
255 of_node_put(args
.np
);
258 mutex_unlock(&reset_list_mutex
);
259 return ERR_PTR(-EPROBE_DEFER
);
262 if (WARN_ON(args
.args_count
!= rcdev
->of_reset_n_cells
)) {
263 mutex_unlock(&reset_list_mutex
);
264 return ERR_PTR(-EINVAL
);
267 rstc_id
= rcdev
->of_xlate(rcdev
, &args
);
269 mutex_unlock(&reset_list_mutex
);
270 return ERR_PTR(rstc_id
);
273 /* reset_list_mutex also protects the rcdev's reset_control list */
274 rstc
= __reset_control_get(rcdev
, rstc_id
, shared
);
276 mutex_unlock(&reset_list_mutex
);
280 EXPORT_SYMBOL_GPL(__of_reset_control_get
);
283 * reset_control_put - free the reset controller
284 * @rstc: reset controller
287 void reset_control_put(struct reset_control
*rstc
)
292 mutex_lock(&reset_list_mutex
);
293 __reset_control_put(rstc
);
294 mutex_unlock(&reset_list_mutex
);
296 EXPORT_SYMBOL_GPL(reset_control_put
);
298 static void devm_reset_control_release(struct device
*dev
, void *res
)
300 reset_control_put(*(struct reset_control
**)res
);
303 struct reset_control
*__devm_reset_control_get(struct device
*dev
,
304 const char *id
, int index
, int shared
)
306 struct reset_control
**ptr
, *rstc
;
308 ptr
= devres_alloc(devm_reset_control_release
, sizeof(*ptr
),
311 return ERR_PTR(-ENOMEM
);
313 rstc
= __of_reset_control_get(dev
? dev
->of_node
: NULL
,
317 devres_add(dev
, ptr
);
324 EXPORT_SYMBOL_GPL(__devm_reset_control_get
);
327 * device_reset - find reset controller associated with the device
329 * @dev: device to be reset by the controller
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
335 int device_reset(struct device
*dev
)
337 struct reset_control
*rstc
;
340 rstc
= reset_control_get(dev
, NULL
);
342 return PTR_ERR(rstc
);
344 ret
= reset_control_reset(rstc
);
346 reset_control_put(rstc
);
350 EXPORT_SYMBOL_GPL(device_reset
);