429 lines
11 KiB
C
429 lines
11 KiB
C
/*
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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/atomic.h>
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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_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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* @list: list entry for the rcdev's reset controller list
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* @id: ID of the reset controller in the reset
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* controller device
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* @refcnt: Number of gets of this reset_control
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* @shared: Is this a shared (1), or an exclusive (0) reset_control?
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* @deassert_cnt: Number of times this reset line has been deasserted
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* @triggered_count: Number of times this reset line has been reset. Currently
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* only used for shared resets, which means that the value
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* will be either 0 or 1.
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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 list_head list;
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unsigned int id;
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unsigned int refcnt;
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int shared;
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atomic_t deassert_count;
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atomic_t triggered_count;
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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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static 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 (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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/**
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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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INIT_LIST_HEAD(&rcdev->reset_control_head);
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mutex_lock(&reset_list_mutex);
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list_add(&rcdev->list, &reset_controller_list);
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mutex_unlock(&reset_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_list_mutex);
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list_del(&rcdev->list);
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mutex_unlock(&reset_list_mutex);
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}
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EXPORT_SYMBOL_GPL(reset_controller_unregister);
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static void devm_reset_controller_release(struct device *dev, void *res)
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{
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reset_controller_unregister(*(struct reset_controller_dev **)res);
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}
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/**
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* devm_reset_controller_register - resource managed reset_controller_register()
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* @dev: device that is registering this reset controller
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* @rcdev: a pointer to the initialized reset controller device
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*
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* Managed reset_controller_register(). For reset controllers registered by
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* this function, reset_controller_unregister() is automatically called on
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* driver detach. See reset_controller_register() for more information.
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*/
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int devm_reset_controller_register(struct device *dev,
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struct reset_controller_dev *rcdev)
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{
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struct reset_controller_dev **rcdevp;
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int ret;
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rcdevp = devres_alloc(devm_reset_controller_release, sizeof(*rcdevp),
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GFP_KERNEL);
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if (!rcdevp)
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return -ENOMEM;
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ret = reset_controller_register(rcdev);
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if (!ret) {
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*rcdevp = rcdev;
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devres_add(dev, rcdevp);
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} else {
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devres_free(rcdevp);
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}
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return ret;
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}
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EXPORT_SYMBOL_GPL(devm_reset_controller_register);
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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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* On a shared reset line the actual reset pulse is only triggered once for the
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* lifetime of the reset_control instance: for all but the first caller this is
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* a no-op.
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* Consumers must not use reset_control_(de)assert on shared reset lines when
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* reset_control_reset has been used.
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*/
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int reset_control_reset(struct reset_control *rstc)
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{
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int ret;
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if (WARN_ON(IS_ERR_OR_NULL(rstc)))
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return -EINVAL;
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if (!rstc->rcdev->ops->reset)
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return -ENOTSUPP;
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if (rstc->shared) {
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if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))
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return -EINVAL;
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if (atomic_inc_return(&rstc->triggered_count) != 1)
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return 0;
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}
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ret = rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
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if (rstc->shared && !ret)
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atomic_dec(&rstc->triggered_count);
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return ret;
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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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* Calling this on an exclusive reset controller guarantees that the reset
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* will be asserted. When called on a shared reset controller the line may
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* still be deasserted, as long as other users keep it so.
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*
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* For shared reset controls a driver cannot expect the hw's registers and
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* internal state to be reset, but must be prepared for this to happen.
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* Consumers must not use reset_control_reset on shared reset lines when
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* reset_control_(de)assert has been used.
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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 (WARN_ON(IS_ERR_OR_NULL(rstc)))
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return -EINVAL;
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if (!rstc->rcdev->ops->assert)
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return -ENOTSUPP;
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if (rstc->shared) {
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if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
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return -EINVAL;
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if (WARN_ON(atomic_read(&rstc->deassert_count) == 0))
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return -EINVAL;
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if (atomic_dec_return(&rstc->deassert_count) != 0)
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return 0;
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}
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return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
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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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* After calling this function, the reset is guaranteed to be deasserted.
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* Consumers must not use reset_control_reset on shared reset lines when
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* reset_control_(de)assert has been used.
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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 (WARN_ON(IS_ERR_OR_NULL(rstc)))
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return -EINVAL;
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if (!rstc->rcdev->ops->deassert)
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return -ENOTSUPP;
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if (rstc->shared) {
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if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
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return -EINVAL;
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if (atomic_inc_return(&rstc->deassert_count) != 1)
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return 0;
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}
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return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
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}
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EXPORT_SYMBOL_GPL(reset_control_deassert);
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/**
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* reset_control_status - returns a negative errno if not supported, a
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* positive value if the reset line is asserted, or zero if the reset
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* line is not asserted.
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* @rstc: reset controller
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*/
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int reset_control_status(struct reset_control *rstc)
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{
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if (WARN_ON(IS_ERR_OR_NULL(rstc)))
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return -EINVAL;
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if (rstc->rcdev->ops->status)
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return rstc->rcdev->ops->status(rstc->rcdev, rstc->id);
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return -ENOTSUPP;
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}
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EXPORT_SYMBOL_GPL(reset_control_status);
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static struct reset_control *__reset_control_get(
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struct reset_controller_dev *rcdev,
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unsigned int index, int shared)
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{
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struct reset_control *rstc;
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lockdep_assert_held(&reset_list_mutex);
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list_for_each_entry(rstc, &rcdev->reset_control_head, list) {
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if (rstc->id == index) {
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if (WARN_ON(!rstc->shared || !shared))
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return ERR_PTR(-EBUSY);
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rstc->refcnt++;
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return rstc;
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}
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}
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rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
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if (!rstc)
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return ERR_PTR(-ENOMEM);
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try_module_get(rcdev->owner);
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rstc->rcdev = rcdev;
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list_add(&rstc->list, &rcdev->reset_control_head);
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rstc->id = index;
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rstc->refcnt = 1;
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rstc->shared = shared;
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return rstc;
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}
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static void __reset_control_put(struct reset_control *rstc)
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{
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lockdep_assert_held(&reset_list_mutex);
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if (--rstc->refcnt)
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return;
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module_put(rstc->rcdev->owner);
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list_del(&rstc->list);
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kfree(rstc);
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}
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struct reset_control *__of_reset_control_get(struct device_node *node,
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const char *id, int index, int shared)
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{
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struct reset_control *rstc;
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struct reset_controller_dev *r, *rcdev;
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struct of_phandle_args args;
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int rstc_id;
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int ret;
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if (!node)
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return ERR_PTR(-EINVAL);
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if (id) {
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index = of_property_match_string(node,
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"reset-names", id);
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if (index < 0)
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return ERR_PTR(-ENOENT);
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}
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ret = of_parse_phandle_with_args(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_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_list_mutex);
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return ERR_PTR(-EPROBE_DEFER);
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}
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if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
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mutex_unlock(&reset_list_mutex);
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return ERR_PTR(-EINVAL);
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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_list_mutex);
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return ERR_PTR(rstc_id);
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}
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/* reset_list_mutex also protects the rcdev's reset_control list */
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rstc = __reset_control_get(rcdev, rstc_id, shared);
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mutex_unlock(&reset_list_mutex);
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return rstc;
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}
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EXPORT_SYMBOL_GPL(__of_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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mutex_lock(&reset_list_mutex);
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__reset_control_put(rstc);
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mutex_unlock(&reset_list_mutex);
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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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struct reset_control *__devm_reset_control_get(struct device *dev,
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const char *id, int index, int shared)
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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 = __of_reset_control_get(dev ? dev->of_node : NULL,
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id, index, shared);
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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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/**
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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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