/*
* Texas Instrument's System Control Interface (TI-SCI) reset driver
*
* Copyright (C) 2015-2017 Texas Instruments Incorporated - http://www.ti.com/
* Andrew F. Davis <afd@ti.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed "as is" WITHOUT ANY WARRANTY of any
* kind, whether express or implied; without even the implied warranty
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/idr.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/reset-controller.h>
#include <linux/soc/ti/ti_sci_protocol.h>
/**
* struct ti_sci_reset_control - reset control structure
* @dev_id: SoC-specific device identifier
* @reset_mask: reset mask to use for toggling reset
* @lock: synchronize reset_mask read-modify-writes
*/
struct ti_sci_reset_control {
u32 dev_id;
u32 reset_mask;
struct mutex lock;
};
/**
* struct ti_sci_reset_data - reset controller information structure
* @rcdev: reset controller entity
* @dev: reset controller device pointer
* @sci: TI SCI handle used for communication with system controller
* @idr: idr structure for mapping ids to reset control structures
*/
struct ti_sci_reset_data {
struct reset_controller_dev rcdev;
struct device *dev;
const struct ti_sci_handle *sci;
struct idr idr;
};
#define to_ti_sci_reset_data(p) \
container_of((p), struct ti_sci_reset_data, rcdev)
/**
* ti_sci_reset_set() - program a device's reset
* @rcdev: reset controller entity
* @id: ID of the reset to toggle
* @assert: boolean flag to indicate assert or deassert
*
* This is a common internal function used to assert or deassert a device's
* reset using the TI SCI protocol. The device's reset is asserted if the
* @assert argument is true, or deasserted if @assert argument is false.
* The mechanism itself is a read-modify-write procedure, the current device
* reset register is read using a TI SCI device operation, the new value is
* set or un-set using the reset's mask, and the new reset value written by
* using another TI SCI device operation.
*
* Return: 0 for successful request, else a corresponding error value
*/
static int ti_sci_reset_set(struct reset_controller_dev *rcdev,
unsigned long id, bool assert)
{
struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);
const struct ti_sci_handle *sci = data->sci;
const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops;
struct ti_sci_reset_control *control;
u32 reset_state;
int ret;
control = idr_find(&data->idr, id);
if (!control)
return -EINVAL;
mutex_lock(&control->lock);
ret = dev_ops->get_device_resets(sci, control->dev_id, &reset_state);
if (ret)
goto out;
if (assert)
reset_state |= control->reset_mask;
else
reset_state &= ~control->reset_mask;
ret = dev_ops->set_device_resets(sci, control->dev_id, reset_state);
out:
mutex_unlock(&control->lock);
return ret;
}
/**
* ti_sci_reset_assert() - assert device reset
* @rcdev: reset controller entity
* @id: ID of the reset to be asserted
*
* This function implements the reset driver op to assert a device's reset
* using the TI SCI protocol. This invokes the function ti_sci_reset_set()
* with the corresponding parameters as passed in, but with the @assert
* argument set to true for asserting the reset.
*
* Return: 0 for successful request, else a corresponding error value
*/
static int ti_sci_reset_assert(struct reset_controller_dev *rcdev,
unsigned long id)
{
return ti_sci_reset_set(rcdev, id, true);
}
/**
* ti_sci_reset_deassert() - deassert device reset
* @rcdev: reset controller entity
* @id: ID of the reset to be deasserted
*
* This function implements the reset driver op to deassert a device's reset
* using the TI SCI protocol. This invokes the function ti_sci_reset_set()
* with the corresponding parameters as passed in, but with the @assert
* argument set to false for deasserting the reset.
*
* Return: 0 for successful request, else a corresponding error value
*/
static int ti_sci_reset_deassert(struct reset_controller_dev *rcdev,
unsigned long id)
{
return ti_sci_reset_set(rcdev, id, false);
}
/**
* ti_sci_reset_status() - check device reset status
* @rcdev: reset controller entity
* @id: ID of reset to be checked
*
* This function implements the reset driver op to return the status of a
* device's reset using the TI SCI protocol. The reset register value is read
* by invoking the TI SCI device operation .get_device_resets(), and the
* status of the specific reset is extracted and returned using this reset's
* reset mask.
*
* Return: 0 if reset is deasserted, or a non-zero value if reset is asserted
*/
static int ti_sci_reset_status(struct reset_controller_dev *rcdev,
unsigned long id)
{
struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);
const struct ti_sci_handle *sci = data->sci;
const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops;
struct ti_sci_reset_control *control;
u32 reset_state;
int ret;
control = idr_find(&data->idr, id);
if (!control)
return -EINVAL;
ret = dev_ops->get_device_resets(sci, control->dev_id, &reset_state);
if (ret)
return ret;
return reset_state & control->reset_mask;
}
static const struct reset_control_ops ti_sci_reset_ops = {
.assert = ti_sci_reset_assert,
.deassert = ti_sci_reset_deassert,
.status = ti_sci_reset_status,
};
/**
* ti_sci_reset_of_xlate() - translate a set of OF arguments to a reset ID
* @rcdev: reset controller entity
* @reset_spec: OF reset argument specifier
*
* This function performs the translation of the reset argument specifier
* values defined in a reset consumer device node. The function allocates a
* reset control structure for that device reset, and will be used by the
* driver for performing any reset functions on that reset. An idr structure
* is allocated and used to map to the reset control structure. This idr
* is used by the driver to do reset lookups.
*
* Return: 0 for successful request, else a corresponding error value
*/
static int ti_sci_reset_of_xlate(struct reset_controller_dev *rcdev,
const struct of_phandle_args *reset_spec)
{
struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);
struct ti_sci_reset_control *control;
if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells))
return -EINVAL;
control = devm_kzalloc(data->dev, sizeof(*control), GFP_KERNEL);
if (!control)
return -ENOMEM;
control->dev_id = reset_spec->args[0];
control->reset_mask = reset_spec->args[1];
mutex_init(&control->lock);
return idr_alloc(&data->idr, control, 0, 0, GFP_KERNEL);
}
static const struct of_device_id ti_sci_reset_of_match[] = {
{ .compatible = "ti,sci-reset", },
{ /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, ti_sci_reset_of_match);
static int ti_sci_reset_probe(struct platform_device *pdev)
{
struct ti_sci_reset_data *data;
if (!pdev->dev.of_node)
return -ENODEV;
data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
data->sci = devm_ti_sci_get_handle(&pdev->dev);
if (IS_ERR(data->sci))
return PTR_ERR(data->sci);
data->rcdev.ops = &ti_sci_reset_ops;
data->rcdev.owner = THIS_MODULE;
data->rcdev.of_node = pdev->dev.of_node;
data->rcdev.of_reset_n_cells = 2;
data->rcdev.of_xlate = ti_sci_reset_of_xlate;
data->dev = &pdev->dev;
idr_init(&data->idr);
platform_set_drvdata(pdev, data);
return reset_controller_register(&data->rcdev);
}
static int ti_sci_reset_remove(struct platform_device *pdev)
{
struct ti_sci_reset_data *data = platform_get_drvdata(pdev);
reset_controller_unregister(&data->rcdev);
idr_destroy(&data->idr);
return 0;
}
static struct platform_driver ti_sci_reset_driver = {
.probe = ti_sci_reset_probe,
.remove = ti_sci_reset_remove,
.driver = {
.name = "ti-sci-reset",
.of_match_table = ti_sci_reset_of_match,
},
};
module_platform_driver(ti_sci_reset_driver);
MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
MODULE_DESCRIPTION("TI System Control Interface (TI SCI) Reset driver");
MODULE_LICENSE("GPL v2");
