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