linux/drivers/reset/core.c

797 lines
20 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/kref.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);
static DEFINE_MUTEX(reset_lookup_mutex);
static LIST_HEAD(reset_lookup_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
* @triggered_count: Number of times this reset line has been reset. Currently
* only used for shared resets, which means that the value
* will be either 0 or 1.
*/
struct reset_control {
struct reset_controller_dev *rcdev;
struct list_head list;
unsigned int id;
struct kref refcnt;
bool shared;
bool array;
atomic_t deassert_count;
atomic_t triggered_count;
};
/**
* struct reset_control_array - an array of reset controls
* @base: reset control for compatibility with reset control API functions
* @num_rstcs: number of reset controls
* @rstc: array of reset controls
*/
struct reset_control_array {
struct reset_control base;
unsigned int num_rstcs;
struct reset_control *rstc[];
};
/**
* 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_controller_add_lookup - register a set of lookup entries
* @lookup: array of reset lookup entries
* @num_entries: number of entries in the lookup array
*/
void reset_controller_add_lookup(struct reset_control_lookup *lookup,
unsigned int num_entries)
{
struct reset_control_lookup *entry;
unsigned int i;
mutex_lock(&reset_lookup_mutex);
for (i = 0; i < num_entries; i++) {
entry = &lookup[i];
if (!entry->dev_id || !entry->provider) {
pr_warn("%s(): reset lookup entry badly specified, skipping\n",
__func__);
continue;
}
list_add_tail(&entry->list, &reset_lookup_list);
}
mutex_unlock(&reset_lookup_mutex);
}
EXPORT_SYMBOL_GPL(reset_controller_add_lookup);
static inline struct reset_control_array *
rstc_to_array(struct reset_control *rstc) {
return container_of(rstc, struct reset_control_array, base);
}
static int reset_control_array_reset(struct reset_control_array *resets)
{
int ret, i;
for (i = 0; i < resets->num_rstcs; i++) {
ret = reset_control_reset(resets->rstc[i]);
if (ret)
return ret;
}
return 0;
}
static int reset_control_array_assert(struct reset_control_array *resets)
{
int ret, i;
for (i = 0; i < resets->num_rstcs; i++) {
ret = reset_control_assert(resets->rstc[i]);
if (ret)
goto err;
}
return 0;
err:
while (i--)
reset_control_deassert(resets->rstc[i]);
return ret;
}
static int reset_control_array_deassert(struct reset_control_array *resets)
{
int ret, i;
for (i = 0; i < resets->num_rstcs; i++) {
ret = reset_control_deassert(resets->rstc[i]);
if (ret)
goto err;
}
return 0;
err:
while (i--)
reset_control_assert(resets->rstc[i]);
return ret;
}
static inline bool reset_control_is_array(struct reset_control *rstc)
{
return rstc->array;
}
/**
* reset_control_reset - reset the controlled device
* @rstc: reset controller
*
* On a shared reset line the actual reset pulse is only triggered once for the
* lifetime of the reset_control instance: for all but the first caller this is
* a no-op.
* Consumers must not use reset_control_(de)assert on shared reset lines when
* reset_control_reset has been used.
*
* If rstc is NULL it is an optional reset and the function will just
* return 0.
*/
int reset_control_reset(struct reset_control *rstc)
{
int ret;
if (!rstc)
return 0;
if (WARN_ON(IS_ERR(rstc)))
return -EINVAL;
if (reset_control_is_array(rstc))
return reset_control_array_reset(rstc_to_array(rstc));
if (!rstc->rcdev->ops->reset)
return -ENOTSUPP;
if (rstc->shared) {
if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))
return -EINVAL;
if (atomic_inc_return(&rstc->triggered_count) != 1)
return 0;
}
ret = rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
if (rstc->shared && ret)
atomic_dec(&rstc->triggered_count);
return ret;
}
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.
* Consumers must not use reset_control_reset on shared reset lines when
* reset_control_(de)assert has been used.
* return 0.
*
* If rstc is NULL it is an optional reset and the function will just
* return 0.
*/
int reset_control_assert(struct reset_control *rstc)
{
if (!rstc)
return 0;
if (WARN_ON(IS_ERR(rstc)))
return -EINVAL;
if (reset_control_is_array(rstc))
return reset_control_array_assert(rstc_to_array(rstc));
if (rstc->shared) {
if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
return -EINVAL;
if (WARN_ON(atomic_read(&rstc->deassert_count) == 0))
return -EINVAL;
if (atomic_dec_return(&rstc->deassert_count) != 0)
return 0;
/*
* Shared reset controls allow the reset line to be in any state
* after this call, so doing nothing is a valid option.
*/
if (!rstc->rcdev->ops->assert)
return 0;
} else {
/*
* If the reset controller does not implement .assert(), there
* is no way to guarantee that the reset line is asserted after
* this call.
*/
if (!rstc->rcdev->ops->assert)
return -ENOTSUPP;
}
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.
* Consumers must not use reset_control_reset on shared reset lines when
* reset_control_(de)assert has been used.
* return 0.
*
* If rstc is NULL it is an optional reset and the function will just
* return 0.
*/
int reset_control_deassert(struct reset_control *rstc)
{
if (!rstc)
return 0;
if (WARN_ON(IS_ERR(rstc)))
return -EINVAL;
if (reset_control_is_array(rstc))
return reset_control_array_deassert(rstc_to_array(rstc));
if (rstc->shared) {
if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
return -EINVAL;
if (atomic_inc_return(&rstc->deassert_count) != 1)
return 0;
}
/*
* If the reset controller does not implement .deassert(), we assume
* that it handles self-deasserting reset lines via .reset(). In that
* case, the reset lines are deasserted by default. If that is not the
* case, the reset controller driver should implement .deassert() and
* return -ENOTSUPP.
*/
if (!rstc->rcdev->ops->deassert)
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 or if the desc is NULL (optional reset).
* @rstc: reset controller
*/
int reset_control_status(struct reset_control *rstc)
{
if (!rstc)
return 0;
if (WARN_ON(IS_ERR(rstc)) || reset_control_is_array(rstc))
return -EINVAL;
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_internal(
struct reset_controller_dev *rcdev,
unsigned int index, bool 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);
kref_get(&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;
kref_init(&rstc->refcnt);
rstc->shared = shared;
return rstc;
}
static void __reset_control_release(struct kref *kref)
{
struct reset_control *rstc = container_of(kref, struct reset_control,
refcnt);
lockdep_assert_held(&reset_list_mutex);
module_put(rstc->rcdev->owner);
list_del(&rstc->list);
kfree(rstc);
}
static void __reset_control_put_internal(struct reset_control *rstc)
{
lockdep_assert_held(&reset_list_mutex);
kref_put(&rstc->refcnt, __reset_control_release);
}
struct reset_control *__of_reset_control_get(struct device_node *node,
const char *id, int index, bool shared,
bool optional)
{
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 == -EILSEQ)
return ERR_PTR(index);
if (index < 0)
return optional ? NULL : ERR_PTR(-ENOENT);
}
ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
index, &args);
if (ret == -EINVAL)
return ERR_PTR(ret);
if (ret)
return optional ? NULL : 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_internal(rcdev, rstc_id, shared);
mutex_unlock(&reset_list_mutex);
return rstc;
}
EXPORT_SYMBOL_GPL(__of_reset_control_get);
static struct reset_controller_dev *
__reset_controller_by_name(const char *name)
{
struct reset_controller_dev *rcdev;
lockdep_assert_held(&reset_list_mutex);
list_for_each_entry(rcdev, &reset_controller_list, list) {
if (!rcdev->dev)
continue;
if (!strcmp(name, dev_name(rcdev->dev)))
return rcdev;
}
return NULL;
}
static struct reset_control *
__reset_control_get_from_lookup(struct device *dev, const char *con_id,
bool shared, bool optional)
{
const struct reset_control_lookup *lookup;
struct reset_controller_dev *rcdev;
const char *dev_id = dev_name(dev);
struct reset_control *rstc = NULL;
if (!dev)
return ERR_PTR(-EINVAL);
mutex_lock(&reset_lookup_mutex);
list_for_each_entry(lookup, &reset_lookup_list, list) {
if (strcmp(lookup->dev_id, dev_id))
continue;
if ((!con_id && !lookup->con_id) ||
((con_id && lookup->con_id) &&
!strcmp(con_id, lookup->con_id))) {
mutex_lock(&reset_list_mutex);
rcdev = __reset_controller_by_name(lookup->provider);
if (!rcdev) {
mutex_unlock(&reset_list_mutex);
mutex_unlock(&reset_lookup_mutex);
/* Reset provider may not be ready yet. */
return ERR_PTR(-EPROBE_DEFER);
}
rstc = __reset_control_get_internal(rcdev,
lookup->index,
shared);
mutex_unlock(&reset_list_mutex);
break;
}
}
mutex_unlock(&reset_lookup_mutex);
if (!rstc)
return optional ? NULL : ERR_PTR(-ENOENT);
return rstc;
}
struct reset_control *__reset_control_get(struct device *dev, const char *id,
int index, bool shared, bool optional)
{
if (dev->of_node)
return __of_reset_control_get(dev->of_node, id, index, shared,
optional);
return __reset_control_get_from_lookup(dev, id, shared, optional);
}
EXPORT_SYMBOL_GPL(__reset_control_get);
static void reset_control_array_put(struct reset_control_array *resets)
{
int i;
mutex_lock(&reset_list_mutex);
for (i = 0; i < resets->num_rstcs; i++)
__reset_control_put_internal(resets->rstc[i]);
mutex_unlock(&reset_list_mutex);
}
/**
* reset_control_put - free the reset controller
* @rstc: reset controller
*/
void reset_control_put(struct reset_control *rstc)
{
if (IS_ERR_OR_NULL(rstc))
return;
if (reset_control_is_array(rstc)) {
reset_control_array_put(rstc_to_array(rstc));
return;
}
mutex_lock(&reset_list_mutex);
__reset_control_put_internal(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, bool shared,
bool optional)
{
struct reset_control **ptr, *rstc;
ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
GFP_KERNEL);
if (!ptr)
return ERR_PTR(-ENOMEM);
rstc = __reset_control_get(dev, id, index, shared, optional);
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
* @optional: whether it is optional to reset the device
*
* 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, bool optional)
{
struct reset_control *rstc;
int ret;
rstc = __reset_control_get(dev, NULL, 0, 0, optional);
if (IS_ERR(rstc))
return PTR_ERR(rstc);
ret = reset_control_reset(rstc);
reset_control_put(rstc);
return ret;
}
EXPORT_SYMBOL_GPL(__device_reset);
/**
* APIs to manage an array of reset controls.
*/
/**
* of_reset_control_get_count - Count number of resets available with a device
*
* @node: device node that contains 'resets'.
*
* Returns positive reset count on success, or error number on failure and
* on count being zero.
*/
static int of_reset_control_get_count(struct device_node *node)
{
int count;
if (!node)
return -EINVAL;
count = of_count_phandle_with_args(node, "resets", "#reset-cells");
if (count == 0)
count = -ENOENT;
return count;
}
/**
* of_reset_control_array_get - Get a list of reset controls using
* device node.
*
* @np: device node for the device that requests the reset controls array
* @shared: whether reset controls are shared or not
* @optional: whether it is optional to get the reset controls
*
* Returns pointer to allocated reset_control_array on success or
* error on failure
*/
struct reset_control *
of_reset_control_array_get(struct device_node *np, bool shared, bool optional)
{
struct reset_control_array *resets;
struct reset_control *rstc;
int num, i;
num = of_reset_control_get_count(np);
if (num < 0)
return optional ? NULL : ERR_PTR(num);
resets = kzalloc(struct_size(resets, rstc, num), GFP_KERNEL);
if (!resets)
return ERR_PTR(-ENOMEM);
for (i = 0; i < num; i++) {
rstc = __of_reset_control_get(np, NULL, i, shared, optional);
if (IS_ERR(rstc))
goto err_rst;
resets->rstc[i] = rstc;
}
resets->num_rstcs = num;
resets->base.array = true;
return &resets->base;
err_rst:
mutex_lock(&reset_list_mutex);
while (--i >= 0)
__reset_control_put_internal(resets->rstc[i]);
mutex_unlock(&reset_list_mutex);
kfree(resets);
return rstc;
}
EXPORT_SYMBOL_GPL(of_reset_control_array_get);
/**
* devm_reset_control_array_get - Resource managed reset control array get
*
* @dev: device that requests the list of reset controls
* @shared: whether reset controls are shared or not
* @optional: whether it is optional to get the reset controls
*
* The reset control array APIs are intended for a list of resets
* that just have to be asserted or deasserted, without any
* requirements on the order.
*
* Returns pointer to allocated reset_control_array on success or
* error on failure
*/
struct reset_control *
devm_reset_control_array_get(struct device *dev, bool shared, bool optional)
{
struct reset_control **devres;
struct reset_control *rstc;
devres = devres_alloc(devm_reset_control_release, sizeof(*devres),
GFP_KERNEL);
if (!devres)
return ERR_PTR(-ENOMEM);
rstc = of_reset_control_array_get(dev->of_node, shared, optional);
if (IS_ERR(rstc)) {
devres_free(devres);
return rstc;
}
*devres = rstc;
devres_add(dev, devres);
return rstc;
}
EXPORT_SYMBOL_GPL(devm_reset_control_array_get);