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: Philipp Zabel <p.zabel@pengutronix.de> Reviewed-by: Stephen Warren <swarren@nvidia.com> Reviewed-by: Shawn Guo <shawn.guo@linaro.org> Reviewed-by: Marek Vasut <marex@denx.de> Reviewed-by: Pavel Machek <pavel@ucw.cz>hifive-unleashed-5.1
Philipp Zabel
parent
4e11f848c6
commit
61fc413176
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@ -162,4 +162,6 @@ source "drivers/irqchip/Kconfig"
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source "drivers/ipack/Kconfig"
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source "drivers/reset/Kconfig"
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endmenu
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@ -37,6 +37,9 @@ obj-$(CONFIG_XEN) += xen/
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# regulators early, since some subsystems rely on them to initialize
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obj-$(CONFIG_REGULATOR) += regulator/
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# reset controllers early, since gpu drivers might rely on them to initialize
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obj-$(CONFIG_RESET_CONTROLLER) += reset/
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# tty/ comes before char/ so that the VT console is the boot-time
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# default.
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obj-y += tty/
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@ -0,0 +1,13 @@
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config ARCH_HAS_RESET_CONTROLLER
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bool
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menuconfig RESET_CONTROLLER
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bool "Reset Controller Support"
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default y if ARCH_HAS_RESET_CONTROLLER
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help
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Generic Reset Controller support.
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This framework is designed to abstract reset handling of devices
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via GPIOs or SoC-internal reset controller modules.
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If unsure, say no.
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@ -0,0 +1 @@
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obj-$(CONFIG_RESET_CONTROLLER) += core.o
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@ -0,0 +1,297 @@
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/*
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* Reset Controller framework
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*
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* Copyright 2013 Philipp Zabel, Pengutronix
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/export.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/reset.h>
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#include <linux/reset-controller.h>
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#include <linux/slab.h>
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static DEFINE_MUTEX(reset_controller_list_mutex);
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static LIST_HEAD(reset_controller_list);
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/**
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* struct reset_control - a reset control
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* @rcdev: a pointer to the reset controller device
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* this reset control belongs to
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* @id: ID of the reset controller in the reset
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* controller device
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*/
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struct reset_control {
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struct reset_controller_dev *rcdev;
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struct device *dev;
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unsigned int id;
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};
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/**
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* of_reset_simple_xlate - translate reset_spec to the reset line number
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* @rcdev: a pointer to the reset controller device
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* @reset_spec: reset line specifier as found in the device tree
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* @flags: a flags pointer to fill in (optional)
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*
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* This simple translation function should be used for reset controllers
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* with 1:1 mapping, where reset lines can be indexed by number without gaps.
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*/
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int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
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const struct of_phandle_args *reset_spec)
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{
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if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells))
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return -EINVAL;
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if (reset_spec->args[0] >= rcdev->nr_resets)
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return -EINVAL;
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return reset_spec->args[0];
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}
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EXPORT_SYMBOL_GPL(of_reset_simple_xlate);
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/**
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* reset_controller_register - register a reset controller device
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* @rcdev: a pointer to the initialized reset controller device
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*/
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int reset_controller_register(struct reset_controller_dev *rcdev)
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{
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if (!rcdev->of_xlate) {
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rcdev->of_reset_n_cells = 1;
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rcdev->of_xlate = of_reset_simple_xlate;
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}
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mutex_lock(&reset_controller_list_mutex);
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list_add(&rcdev->list, &reset_controller_list);
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mutex_unlock(&reset_controller_list_mutex);
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return 0;
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}
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EXPORT_SYMBOL_GPL(reset_controller_register);
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/**
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* reset_controller_unregister - unregister a reset controller device
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* @rcdev: a pointer to the reset controller device
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*/
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void reset_controller_unregister(struct reset_controller_dev *rcdev)
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{
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mutex_lock(&reset_controller_list_mutex);
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list_del(&rcdev->list);
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mutex_unlock(&reset_controller_list_mutex);
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}
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EXPORT_SYMBOL_GPL(reset_controller_unregister);
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/**
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* reset_control_reset - reset the controlled device
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* @rstc: reset controller
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*/
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int reset_control_reset(struct reset_control *rstc)
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{
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if (rstc->rcdev->ops->reset)
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return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
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return -ENOSYS;
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}
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EXPORT_SYMBOL_GPL(reset_control_reset);
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/**
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* reset_control_assert - asserts the reset line
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* @rstc: reset controller
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*/
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int reset_control_assert(struct reset_control *rstc)
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{
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if (rstc->rcdev->ops->assert)
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return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
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return -ENOSYS;
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}
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EXPORT_SYMBOL_GPL(reset_control_assert);
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/**
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* reset_control_deassert - deasserts the reset line
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* @rstc: reset controller
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*/
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int reset_control_deassert(struct reset_control *rstc)
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{
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if (rstc->rcdev->ops->deassert)
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return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
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return -ENOSYS;
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}
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EXPORT_SYMBOL_GPL(reset_control_deassert);
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/**
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* reset_control_get - Lookup and obtain a reference to a reset controller.
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* @dev: device to be reset by the controller
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* @id: reset line name
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*
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* Returns a struct reset_control or IS_ERR() condition containing errno.
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*
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* Use of id names is optional.
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*/
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struct reset_control *reset_control_get(struct device *dev, const char *id)
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{
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struct reset_control *rstc = ERR_PTR(-EPROBE_DEFER);
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struct reset_controller_dev *r, *rcdev;
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struct of_phandle_args args;
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int index = 0;
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int rstc_id;
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int ret;
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if (!dev)
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return ERR_PTR(-EINVAL);
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if (id)
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index = of_property_match_string(dev->of_node,
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"reset-names", id);
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ret = of_parse_phandle_with_args(dev->of_node, "resets", "#reset-cells",
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index, &args);
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if (ret)
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return ERR_PTR(ret);
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mutex_lock(&reset_controller_list_mutex);
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rcdev = NULL;
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list_for_each_entry(r, &reset_controller_list, list) {
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if (args.np == r->of_node) {
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rcdev = r;
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break;
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}
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}
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of_node_put(args.np);
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if (!rcdev) {
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mutex_unlock(&reset_controller_list_mutex);
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return ERR_PTR(-ENODEV);
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}
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rstc_id = rcdev->of_xlate(rcdev, &args);
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if (rstc_id < 0) {
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mutex_unlock(&reset_controller_list_mutex);
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return ERR_PTR(rstc_id);
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}
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try_module_get(rcdev->owner);
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mutex_unlock(&reset_controller_list_mutex);
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rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
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if (!rstc) {
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module_put(rstc->rcdev->owner);
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return ERR_PTR(-ENOMEM);
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}
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rstc->dev = dev;
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rstc->rcdev = rcdev;
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rstc->id = rstc_id;
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return rstc;
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}
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EXPORT_SYMBOL_GPL(reset_control_get);
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/**
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* reset_control_put - free the reset controller
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* @rstc: reset controller
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*/
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void reset_control_put(struct reset_control *rstc)
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{
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if (IS_ERR(rstc))
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return;
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module_put(rstc->rcdev->owner);
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kfree(rstc);
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}
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EXPORT_SYMBOL_GPL(reset_control_put);
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static void devm_reset_control_release(struct device *dev, void *res)
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{
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reset_control_put(*(struct reset_control **)res);
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}
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/**
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* devm_reset_control_get - resource managed reset_control_get()
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* @dev: device to be reset by the controller
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* @id: reset line name
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*
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* Managed reset_control_get(). For reset controllers returned from this
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* function, reset_control_put() is called automatically on driver detach.
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* See reset_control_get() for more information.
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*/
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struct reset_control *devm_reset_control_get(struct device *dev, const char *id)
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{
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struct reset_control **ptr, *rstc;
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ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
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GFP_KERNEL);
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if (!ptr)
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return ERR_PTR(-ENOMEM);
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rstc = reset_control_get(dev, id);
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if (!IS_ERR(rstc)) {
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*ptr = rstc;
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devres_add(dev, ptr);
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} else {
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devres_free(ptr);
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}
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return rstc;
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}
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EXPORT_SYMBOL_GPL(devm_reset_control_get);
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static int devm_reset_control_match(struct device *dev, void *res, void *data)
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{
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struct reset_control **rstc = res;
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if (WARN_ON(!rstc || !*rstc))
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return 0;
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return *rstc == data;
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}
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/**
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* devm_reset_control_put - resource managed reset_control_put()
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* @rstc: reset controller to free
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*
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* Deallocate a reset control allocated withd devm_reset_control_get().
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* This function will not need to be called normally, as devres will take
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* care of freeing the resource.
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*/
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void devm_reset_control_put(struct reset_control *rstc)
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{
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int ret;
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ret = devres_release(rstc->dev, devm_reset_control_release,
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devm_reset_control_match, rstc);
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if (ret)
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WARN_ON(ret);
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}
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EXPORT_SYMBOL_GPL(devm_reset_control_put);
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/**
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* device_reset - find reset controller associated with the device
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* and perform reset
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* @dev: device to be reset by the controller
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*
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* Convenience wrapper for reset_control_get() and reset_control_reset().
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* This is useful for the common case of devices with single, dedicated reset
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* lines.
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*/
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int device_reset(struct device *dev)
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{
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struct reset_control *rstc;
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int ret;
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rstc = reset_control_get(dev, NULL);
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if (IS_ERR(rstc))
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return PTR_ERR(rstc);
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ret = reset_control_reset(rstc);
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reset_control_put(rstc);
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return ret;
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}
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EXPORT_SYMBOL_GPL(device_reset);
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@ -0,0 +1,51 @@
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#ifndef _LINUX_RESET_CONTROLLER_H_
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#define _LINUX_RESET_CONTROLLER_H_
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#include <linux/list.h>
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struct reset_controller_dev;
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/**
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* struct reset_control_ops
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*
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* @reset: for self-deasserting resets, does all necessary
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* things to reset the device
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* @assert: manually assert the reset line, if supported
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* @deassert: manually deassert the reset line, if supported
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*/
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struct reset_control_ops {
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int (*reset)(struct reset_controller_dev *rcdev, unsigned long id);
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int (*assert)(struct reset_controller_dev *rcdev, unsigned long id);
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int (*deassert)(struct reset_controller_dev *rcdev, unsigned long id);
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};
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struct module;
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struct device_node;
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/**
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* struct reset_controller_dev - reset controller entity that might
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* provide multiple reset controls
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* @ops: a pointer to device specific struct reset_control_ops
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* @owner: kernel module of the reset controller driver
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* @list: internal list of reset controller devices
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* @of_node: corresponding device tree node as phandle target
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* @of_reset_n_cells: number of cells in reset line specifiers
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* @of_xlate: translation function to translate from specifier as found in the
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* device tree to id as given to the reset control ops
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* @nr_resets: number of reset controls in this reset controller device
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*/
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struct reset_controller_dev {
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struct reset_control_ops *ops;
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struct module *owner;
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struct list_head list;
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struct device_node *of_node;
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int of_reset_n_cells;
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int (*of_xlate)(struct reset_controller_dev *rcdev,
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const struct of_phandle_args *reset_spec);
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unsigned int nr_resets;
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};
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int reset_controller_register(struct reset_controller_dev *rcdev);
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void reset_controller_unregister(struct reset_controller_dev *rcdev);
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#endif
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@ -0,0 +1,17 @@
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#ifndef _LINUX_RESET_H_
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#define _LINUX_RESET_H_
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struct device;
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struct reset_control;
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int reset_control_reset(struct reset_control *rstc);
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int reset_control_assert(struct reset_control *rstc);
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int reset_control_deassert(struct reset_control *rstc);
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struct reset_control *reset_control_get(struct device *dev, const char *id);
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void reset_control_put(struct reset_control *rstc);
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struct reset_control *devm_reset_control_get(struct device *dev, const char *id);
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int device_reset(struct device *dev);
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#endif
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