Commit 61fc4131 authored by Philipp Zabel's avatar Philipp Zabel

reset: Add reset controller API

This adds a simple API for devices to request being reset
by separate reset controller hardware and implements the
reset signal device tree binding.
Signed-off-by: default avatarPhilipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: default avatarStephen Warren <swarren@nvidia.com>
Reviewed-by: default avatarShawn Guo <shawn.guo@linaro.org>
Reviewed-by: default avatarMarek Vasut <marex@denx.de>
Reviewed-by: default avatarPavel Machek <pavel@ucw.cz>
parent 4e11f848
......@@ -162,4 +162,6 @@ source "drivers/irqchip/Kconfig"
source "drivers/ipack/Kconfig"
source "drivers/reset/Kconfig"
endmenu
......@@ -37,6 +37,9 @@ obj-$(CONFIG_XEN) += xen/
# regulators early, since some subsystems rely on them to initialize
obj-$(CONFIG_REGULATOR) += regulator/
# reset controllers early, since gpu drivers might rely on them to initialize
obj-$(CONFIG_RESET_CONTROLLER) += reset/
# tty/ comes before char/ so that the VT console is the boot-time
# default.
obj-y += tty/
......
config ARCH_HAS_RESET_CONTROLLER
bool
menuconfig RESET_CONTROLLER
bool "Reset Controller Support"
default y if ARCH_HAS_RESET_CONTROLLER
help
Generic Reset Controller support.
This framework is designed to abstract reset handling of devices
via GPIOs or SoC-internal reset controller modules.
If unsure, say no.
obj-$(CONFIG_RESET_CONTROLLER) += core.o
/*
* 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/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_controller_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
* @id: ID of the reset controller in the reset
* controller device
*/
struct reset_control {
struct reset_controller_dev *rcdev;
struct device *dev;
unsigned int id;
};
/**
* 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.
*/
int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
const struct of_phandle_args *reset_spec)
{
if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells))
return -EINVAL;
if (reset_spec->args[0] >= rcdev->nr_resets)
return -EINVAL;
return reset_spec->args[0];
}
EXPORT_SYMBOL_GPL(of_reset_simple_xlate);
/**
* 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;
}
mutex_lock(&reset_controller_list_mutex);
list_add(&rcdev->list, &reset_controller_list);
mutex_unlock(&reset_controller_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_controller_list_mutex);
list_del(&rcdev->list);
mutex_unlock(&reset_controller_list_mutex);
}
EXPORT_SYMBOL_GPL(reset_controller_unregister);
/**
* reset_control_reset - reset the controlled device
* @rstc: reset controller
*/
int reset_control_reset(struct reset_control *rstc)
{
if (rstc->rcdev->ops->reset)
return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
return -ENOSYS;
}
EXPORT_SYMBOL_GPL(reset_control_reset);
/**
* reset_control_assert - asserts the reset line
* @rstc: reset controller
*/
int reset_control_assert(struct reset_control *rstc)
{
if (rstc->rcdev->ops->assert)
return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
return -ENOSYS;
}
EXPORT_SYMBOL_GPL(reset_control_assert);
/**
* reset_control_deassert - deasserts the reset line
* @rstc: reset controller
*/
int reset_control_deassert(struct reset_control *rstc)
{
if (rstc->rcdev->ops->deassert)
return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
return -ENOSYS;
}
EXPORT_SYMBOL_GPL(reset_control_deassert);
/**
* reset_control_get - Lookup and obtain a reference to a reset controller.
* @dev: device to be reset by the controller
* @id: reset line name
*
* Returns a struct reset_control or IS_ERR() condition containing errno.
*
* Use of id names is optional.
*/
struct reset_control *reset_control_get(struct device *dev, const char *id)
{
struct reset_control *rstc = ERR_PTR(-EPROBE_DEFER);
struct reset_controller_dev *r, *rcdev;
struct of_phandle_args args;
int index = 0;
int rstc_id;
int ret;
if (!dev)
return ERR_PTR(-EINVAL);
if (id)
index = of_property_match_string(dev->of_node,
"reset-names", id);
ret = of_parse_phandle_with_args(dev->of_node, "resets", "#reset-cells",
index, &args);
if (ret)
return ERR_PTR(ret);
mutex_lock(&reset_controller_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_controller_list_mutex);
return ERR_PTR(-ENODEV);
}
rstc_id = rcdev->of_xlate(rcdev, &args);
if (rstc_id < 0) {
mutex_unlock(&reset_controller_list_mutex);
return ERR_PTR(rstc_id);
}
try_module_get(rcdev->owner);
mutex_unlock(&reset_controller_list_mutex);
rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
if (!rstc) {
module_put(rstc->rcdev->owner);
return ERR_PTR(-ENOMEM);
}
rstc->dev = dev;
rstc->rcdev = rcdev;
rstc->id = rstc_id;
return rstc;
}
EXPORT_SYMBOL_GPL(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;
module_put(rstc->rcdev->owner);
kfree(rstc);
}
EXPORT_SYMBOL_GPL(reset_control_put);
static void devm_reset_control_release(struct device *dev, void *res)
{
reset_control_put(*(struct reset_control **)res);
}
/**
* devm_reset_control_get - resource managed reset_control_get()
* @dev: device to be reset by the controller
* @id: reset line name
*
* Managed reset_control_get(). For reset controllers returned from this
* function, reset_control_put() is called automatically on driver detach.
* See reset_control_get() for more information.
*/
struct reset_control *devm_reset_control_get(struct device *dev, const char *id)
{
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);
if (!IS_ERR(rstc)) {
*ptr = rstc;
devres_add(dev, ptr);
} else {
devres_free(ptr);
}
return rstc;
}
EXPORT_SYMBOL_GPL(devm_reset_control_get);
static int devm_reset_control_match(struct device *dev, void *res, void *data)
{
struct reset_control **rstc = res;
if (WARN_ON(!rstc || !*rstc))
return 0;
return *rstc == data;
}
/**
* devm_reset_control_put - resource managed reset_control_put()
* @rstc: reset controller to free
*
* Deallocate a reset control allocated withd devm_reset_control_get().
* This function will not need to be called normally, as devres will take
* care of freeing the resource.
*/
void devm_reset_control_put(struct reset_control *rstc)
{
int ret;
ret = devres_release(rstc->dev, devm_reset_control_release,
devm_reset_control_match, rstc);
if (ret)
WARN_ON(ret);
}
EXPORT_SYMBOL_GPL(devm_reset_control_put);
/**
* 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);
#ifndef _LINUX_RESET_CONTROLLER_H_
#define _LINUX_RESET_CONTROLLER_H_
#include <linux/list.h>
struct reset_controller_dev;
/**
* struct reset_control_ops
*
* @reset: for self-deasserting resets, does all necessary
* things to reset the device
* @assert: manually assert the reset line, if supported
* @deassert: manually deassert the reset line, if supported
*/
struct reset_control_ops {
int (*reset)(struct reset_controller_dev *rcdev, unsigned long id);
int (*assert)(struct reset_controller_dev *rcdev, unsigned long id);
int (*deassert)(struct reset_controller_dev *rcdev, unsigned long id);
};
struct module;
struct device_node;
/**
* struct reset_controller_dev - reset controller entity that might
* provide multiple reset controls
* @ops: a pointer to device specific struct reset_control_ops
* @owner: kernel module of the reset controller driver
* @list: internal list of reset controller devices
* @of_node: corresponding device tree node as phandle target
* @of_reset_n_cells: number of cells in reset line specifiers
* @of_xlate: translation function to translate from specifier as found in the
* device tree to id as given to the reset control ops
* @nr_resets: number of reset controls in this reset controller device
*/
struct reset_controller_dev {
struct reset_control_ops *ops;
struct module *owner;
struct list_head list;
struct device_node *of_node;
int of_reset_n_cells;
int (*of_xlate)(struct reset_controller_dev *rcdev,
const struct of_phandle_args *reset_spec);
unsigned int nr_resets;
};
int reset_controller_register(struct reset_controller_dev *rcdev);
void reset_controller_unregister(struct reset_controller_dev *rcdev);
#endif
#ifndef _LINUX_RESET_H_
#define _LINUX_RESET_H_
struct device;
struct reset_control;
int reset_control_reset(struct reset_control *rstc);
int reset_control_assert(struct reset_control *rstc);
int reset_control_deassert(struct reset_control *rstc);
struct reset_control *reset_control_get(struct device *dev, const char *id);
void reset_control_put(struct reset_control *rstc);
struct reset_control *devm_reset_control_get(struct device *dev, const char *id);
int device_reset(struct device *dev);
#endif
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