linux/drivers/reset/core.c

388 lines
9.5 KiB
C

/*
* Reset Controller framework
*
* Copyright 2013 Philipp Zabel, Pengutronix
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#include <linux/atomic.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/reset.h>
#include <linux/reset-controller.h>
#include <linux/slab.h>
static DEFINE_MUTEX(reset_list_mutex);
static LIST_HEAD(reset_controller_list);
/**
* struct reset_control - a reset control
* @rcdev: a pointer to the reset controller device
* this reset control belongs to
* @list: list entry for the rcdev's reset controller list
* @id: ID of the reset controller in the reset
* controller device
* @refcnt: Number of gets of this reset_control
* @shared: Is this a shared (1), or an exclusive (0) reset_control?
* @deassert_cnt: Number of times this reset line has been deasserted
*/
struct reset_control {
struct reset_controller_dev *rcdev;
struct list_head list;
unsigned int id;
unsigned int refcnt;
int shared;
atomic_t deassert_count;
};
/**
* of_reset_simple_xlate - translate reset_spec to the reset line number
* @rcdev: a pointer to the reset controller device
* @reset_spec: reset line specifier as found in the device tree
* @flags: a flags pointer to fill in (optional)
*
* This simple translation function should be used for reset controllers
* with 1:1 mapping, where reset lines can be indexed by number without gaps.
*/
static int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
const struct of_phandle_args *reset_spec)
{
if (reset_spec->args[0] >= rcdev->nr_resets)
return -EINVAL;
return reset_spec->args[0];
}
/**
* reset_controller_register - register a reset controller device
* @rcdev: a pointer to the initialized reset controller device
*/
int reset_controller_register(struct reset_controller_dev *rcdev)
{
if (!rcdev->of_xlate) {
rcdev->of_reset_n_cells = 1;
rcdev->of_xlate = of_reset_simple_xlate;
}
INIT_LIST_HEAD(&rcdev->reset_control_head);
mutex_lock(&reset_list_mutex);
list_add(&rcdev->list, &reset_controller_list);
mutex_unlock(&reset_list_mutex);
return 0;
}
EXPORT_SYMBOL_GPL(reset_controller_register);
/**
* reset_controller_unregister - unregister a reset controller device
* @rcdev: a pointer to the reset controller device
*/
void reset_controller_unregister(struct reset_controller_dev *rcdev)
{
mutex_lock(&reset_list_mutex);
list_del(&rcdev->list);
mutex_unlock(&reset_list_mutex);
}
EXPORT_SYMBOL_GPL(reset_controller_unregister);
static void devm_reset_controller_release(struct device *dev, void *res)
{
reset_controller_unregister(*(struct reset_controller_dev **)res);
}
/**
* devm_reset_controller_register - resource managed reset_controller_register()
* @dev: device that is registering this reset controller
* @rcdev: a pointer to the initialized reset controller device
*
* Managed reset_controller_register(). For reset controllers registered by
* this function, reset_controller_unregister() is automatically called on
* driver detach. See reset_controller_register() for more information.
*/
int devm_reset_controller_register(struct device *dev,
struct reset_controller_dev *rcdev)
{
struct reset_controller_dev **rcdevp;
int ret;
rcdevp = devres_alloc(devm_reset_controller_release, sizeof(*rcdevp),
GFP_KERNEL);
if (!rcdevp)
return -ENOMEM;
ret = reset_controller_register(rcdev);
if (!ret) {
*rcdevp = rcdev;
devres_add(dev, rcdevp);
} else {
devres_free(rcdevp);
}
return ret;
}
EXPORT_SYMBOL_GPL(devm_reset_controller_register);
/**
* reset_control_reset - reset the controlled device
* @rstc: reset controller
*
* Calling this on a shared reset controller is an error.
*/
int reset_control_reset(struct reset_control *rstc)
{
if (WARN_ON(rstc->shared))
return -EINVAL;
if (rstc->rcdev->ops->reset)
return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
return -ENOTSUPP;
}
EXPORT_SYMBOL_GPL(reset_control_reset);
/**
* reset_control_assert - asserts the reset line
* @rstc: reset controller
*
* Calling this on an exclusive reset controller guarantees that the reset
* will be asserted. When called on a shared reset controller the line may
* still be deasserted, as long as other users keep it so.
*
* For shared reset controls a driver cannot expect the hw's registers and
* internal state to be reset, but must be prepared for this to happen.
*/
int reset_control_assert(struct reset_control *rstc)
{
if (!rstc->rcdev->ops->assert)
return -ENOTSUPP;
if (rstc->shared) {
if (WARN_ON(atomic_read(&rstc->deassert_count) == 0))
return -EINVAL;
if (atomic_dec_return(&rstc->deassert_count) != 0)
return 0;
}
return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
}
EXPORT_SYMBOL_GPL(reset_control_assert);
/**
* reset_control_deassert - deasserts the reset line
* @rstc: reset controller
*
* After calling this function, the reset is guaranteed to be deasserted.
*/
int reset_control_deassert(struct reset_control *rstc)
{
if (!rstc->rcdev->ops->deassert)
return -ENOTSUPP;
if (rstc->shared) {
if (atomic_inc_return(&rstc->deassert_count) != 1)
return 0;
}
return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
}
EXPORT_SYMBOL_GPL(reset_control_deassert);
/**
* reset_control_status - returns a negative errno if not supported, a
* positive value if the reset line is asserted, or zero if the reset
* line is not asserted.
* @rstc: reset controller
*/
int reset_control_status(struct reset_control *rstc)
{
if (rstc->rcdev->ops->status)
return rstc->rcdev->ops->status(rstc->rcdev, rstc->id);
return -ENOTSUPP;
}
EXPORT_SYMBOL_GPL(reset_control_status);
static struct reset_control *__reset_control_get(
struct reset_controller_dev *rcdev,
unsigned int index, int shared)
{
struct reset_control *rstc;
lockdep_assert_held(&reset_list_mutex);
list_for_each_entry(rstc, &rcdev->reset_control_head, list) {
if (rstc->id == index) {
if (WARN_ON(!rstc->shared || !shared))
return ERR_PTR(-EBUSY);
rstc->refcnt++;
return rstc;
}
}
rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
if (!rstc)
return ERR_PTR(-ENOMEM);
try_module_get(rcdev->owner);
rstc->rcdev = rcdev;
list_add(&rstc->list, &rcdev->reset_control_head);
rstc->id = index;
rstc->refcnt = 1;
rstc->shared = shared;
return rstc;
}
static void __reset_control_put(struct reset_control *rstc)
{
lockdep_assert_held(&reset_list_mutex);
if (--rstc->refcnt)
return;
module_put(rstc->rcdev->owner);
list_del(&rstc->list);
kfree(rstc);
}
struct reset_control *__of_reset_control_get(struct device_node *node,
const char *id, int index, int shared)
{
struct reset_control *rstc;
struct reset_controller_dev *r, *rcdev;
struct of_phandle_args args;
int rstc_id;
int ret;
if (!node)
return ERR_PTR(-EINVAL);
if (id) {
index = of_property_match_string(node,
"reset-names", id);
if (index < 0)
return ERR_PTR(-ENOENT);
}
ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
index, &args);
if (ret)
return ERR_PTR(ret);
mutex_lock(&reset_list_mutex);
rcdev = NULL;
list_for_each_entry(r, &reset_controller_list, list) {
if (args.np == r->of_node) {
rcdev = r;
break;
}
}
of_node_put(args.np);
if (!rcdev) {
mutex_unlock(&reset_list_mutex);
return ERR_PTR(-EPROBE_DEFER);
}
if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
mutex_unlock(&reset_list_mutex);
return ERR_PTR(-EINVAL);
}
rstc_id = rcdev->of_xlate(rcdev, &args);
if (rstc_id < 0) {
mutex_unlock(&reset_list_mutex);
return ERR_PTR(rstc_id);
}
/* reset_list_mutex also protects the rcdev's reset_control list */
rstc = __reset_control_get(rcdev, rstc_id, shared);
mutex_unlock(&reset_list_mutex);
return rstc;
}
EXPORT_SYMBOL_GPL(__of_reset_control_get);
/**
* reset_control_put - free the reset controller
* @rstc: reset controller
*/
void reset_control_put(struct reset_control *rstc)
{
if (IS_ERR(rstc))
return;
mutex_lock(&reset_list_mutex);
__reset_control_put(rstc);
mutex_unlock(&reset_list_mutex);
}
EXPORT_SYMBOL_GPL(reset_control_put);
static void devm_reset_control_release(struct device *dev, void *res)
{
reset_control_put(*(struct reset_control **)res);
}
struct reset_control *__devm_reset_control_get(struct device *dev,
const char *id, int index, int shared)
{
struct reset_control **ptr, *rstc;
ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
GFP_KERNEL);
if (!ptr)
return ERR_PTR(-ENOMEM);
rstc = __of_reset_control_get(dev ? dev->of_node : NULL,
id, index, shared);
if (!IS_ERR(rstc)) {
*ptr = rstc;
devres_add(dev, ptr);
} else {
devres_free(ptr);
}
return rstc;
}
EXPORT_SYMBOL_GPL(__devm_reset_control_get);
/**
* device_reset - find reset controller associated with the device
* and perform reset
* @dev: device to be reset by the controller
*
* Convenience wrapper for reset_control_get() and reset_control_reset().
* This is useful for the common case of devices with single, dedicated reset
* lines.
*/
int device_reset(struct device *dev)
{
struct reset_control *rstc;
int ret;
rstc = reset_control_get(dev, NULL);
if (IS_ERR(rstc))
return PTR_ERR(rstc);
ret = reset_control_reset(rstc);
reset_control_put(rstc);
return ret;
}
EXPORT_SYMBOL_GPL(device_reset);