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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Texas Instrument's System Control Interface (TI-SCI) reset driver4 *5 * Copyright (C) 2015-2017 Texas Instruments Incorporated - https://www.ti.com/6 * Andrew F. Davis <afd@ti.com>7 */8 9#include <linux/idr.h>10#include <linux/module.h>11#include <linux/mutex.h>12#include <linux/of.h>13#include <linux/platform_device.h>14#include <linux/reset-controller.h>15#include <linux/soc/ti/ti_sci_protocol.h>16 17/**18 * struct ti_sci_reset_control - reset control structure19 * @dev_id: SoC-specific device identifier20 * @reset_mask: reset mask to use for toggling reset21 * @lock: synchronize reset_mask read-modify-writes22 */23struct ti_sci_reset_control {24 u32 dev_id;25 u32 reset_mask;26 struct mutex lock;27};28 29/**30 * struct ti_sci_reset_data - reset controller information structure31 * @rcdev: reset controller entity32 * @dev: reset controller device pointer33 * @sci: TI SCI handle used for communication with system controller34 * @idr: idr structure for mapping ids to reset control structures35 */36struct ti_sci_reset_data {37 struct reset_controller_dev rcdev;38 struct device *dev;39 const struct ti_sci_handle *sci;40 struct idr idr;41};42 43#define to_ti_sci_reset_data(p) \44 container_of((p), struct ti_sci_reset_data, rcdev)45 46/**47 * ti_sci_reset_set() - program a device's reset48 * @rcdev: reset controller entity49 * @id: ID of the reset to toggle50 * @assert: boolean flag to indicate assert or deassert51 *52 * This is a common internal function used to assert or deassert a device's53 * reset using the TI SCI protocol. The device's reset is asserted if the54 * @assert argument is true, or deasserted if @assert argument is false.55 * The mechanism itself is a read-modify-write procedure, the current device56 * reset register is read using a TI SCI device operation, the new value is57 * set or un-set using the reset's mask, and the new reset value written by58 * using another TI SCI device operation.59 *60 * Return: 0 for successful request, else a corresponding error value61 */62static int ti_sci_reset_set(struct reset_controller_dev *rcdev,63 unsigned long id, bool assert)64{65 struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);66 const struct ti_sci_handle *sci = data->sci;67 const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops;68 struct ti_sci_reset_control *control;69 u32 reset_state;70 int ret;71 72 control = idr_find(&data->idr, id);73 if (!control)74 return -EINVAL;75 76 mutex_lock(&control->lock);77 78 ret = dev_ops->get_device_resets(sci, control->dev_id, &reset_state);79 if (ret)80 goto out;81 82 if (assert)83 reset_state |= control->reset_mask;84 else85 reset_state &= ~control->reset_mask;86 87 ret = dev_ops->set_device_resets(sci, control->dev_id, reset_state);88out:89 mutex_unlock(&control->lock);90 91 return ret;92}93 94/**95 * ti_sci_reset_assert() - assert device reset96 * @rcdev: reset controller entity97 * @id: ID of the reset to be asserted98 *99 * This function implements the reset driver op to assert a device's reset100 * using the TI SCI protocol. This invokes the function ti_sci_reset_set()101 * with the corresponding parameters as passed in, but with the @assert102 * argument set to true for asserting the reset.103 *104 * Return: 0 for successful request, else a corresponding error value105 */106static int ti_sci_reset_assert(struct reset_controller_dev *rcdev,107 unsigned long id)108{109 return ti_sci_reset_set(rcdev, id, true);110}111 112/**113 * ti_sci_reset_deassert() - deassert device reset114 * @rcdev: reset controller entity115 * @id: ID of the reset to be deasserted116 *117 * This function implements the reset driver op to deassert a device's reset118 * using the TI SCI protocol. This invokes the function ti_sci_reset_set()119 * with the corresponding parameters as passed in, but with the @assert120 * argument set to false for deasserting the reset.121 *122 * Return: 0 for successful request, else a corresponding error value123 */124static int ti_sci_reset_deassert(struct reset_controller_dev *rcdev,125 unsigned long id)126{127 return ti_sci_reset_set(rcdev, id, false);128}129 130/**131 * ti_sci_reset_status() - check device reset status132 * @rcdev: reset controller entity133 * @id: ID of reset to be checked134 *135 * This function implements the reset driver op to return the status of a136 * device's reset using the TI SCI protocol. The reset register value is read137 * by invoking the TI SCI device operation .get_device_resets(), and the138 * status of the specific reset is extracted and returned using this reset's139 * reset mask.140 *141 * Return: 0 if reset is deasserted, or a non-zero value if reset is asserted142 */143static int ti_sci_reset_status(struct reset_controller_dev *rcdev,144 unsigned long id)145{146 struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);147 const struct ti_sci_handle *sci = data->sci;148 const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops;149 struct ti_sci_reset_control *control;150 u32 reset_state;151 int ret;152 153 control = idr_find(&data->idr, id);154 if (!control)155 return -EINVAL;156 157 ret = dev_ops->get_device_resets(sci, control->dev_id, &reset_state);158 if (ret)159 return ret;160 161 return reset_state & control->reset_mask;162}163 164static const struct reset_control_ops ti_sci_reset_ops = {165 .assert = ti_sci_reset_assert,166 .deassert = ti_sci_reset_deassert,167 .status = ti_sci_reset_status,168};169 170/**171 * ti_sci_reset_of_xlate() - translate a set of OF arguments to a reset ID172 * @rcdev: reset controller entity173 * @reset_spec: OF reset argument specifier174 *175 * This function performs the translation of the reset argument specifier176 * values defined in a reset consumer device node. The function allocates a177 * reset control structure for that device reset, and will be used by the178 * driver for performing any reset functions on that reset. An idr structure179 * is allocated and used to map to the reset control structure. This idr180 * is used by the driver to do reset lookups.181 *182 * Return: 0 for successful request, else a corresponding error value183 */184static int ti_sci_reset_of_xlate(struct reset_controller_dev *rcdev,185 const struct of_phandle_args *reset_spec)186{187 struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);188 struct ti_sci_reset_control *control;189 190 if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells))191 return -EINVAL;192 193 control = devm_kzalloc(data->dev, sizeof(*control), GFP_KERNEL);194 if (!control)195 return -ENOMEM;196 197 control->dev_id = reset_spec->args[0];198 control->reset_mask = reset_spec->args[1];199 mutex_init(&control->lock);200 201 return idr_alloc(&data->idr, control, 0, 0, GFP_KERNEL);202}203 204static const struct of_device_id ti_sci_reset_of_match[] = {205 { .compatible = "ti,sci-reset", },206 { /* sentinel */ },207};208MODULE_DEVICE_TABLE(of, ti_sci_reset_of_match);209 210static int ti_sci_reset_probe(struct platform_device *pdev)211{212 struct ti_sci_reset_data *data;213 214 if (!pdev->dev.of_node)215 return -ENODEV;216 217 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);218 if (!data)219 return -ENOMEM;220 221 data->sci = devm_ti_sci_get_handle(&pdev->dev);222 if (IS_ERR(data->sci))223 return PTR_ERR(data->sci);224 225 data->rcdev.ops = &ti_sci_reset_ops;226 data->rcdev.owner = THIS_MODULE;227 data->rcdev.of_node = pdev->dev.of_node;228 data->rcdev.of_reset_n_cells = 2;229 data->rcdev.of_xlate = ti_sci_reset_of_xlate;230 data->dev = &pdev->dev;231 idr_init(&data->idr);232 233 platform_set_drvdata(pdev, data);234 235 return reset_controller_register(&data->rcdev);236}237 238static void ti_sci_reset_remove(struct platform_device *pdev)239{240 struct ti_sci_reset_data *data = platform_get_drvdata(pdev);241 242 reset_controller_unregister(&data->rcdev);243 244 idr_destroy(&data->idr);245}246 247static struct platform_driver ti_sci_reset_driver = {248 .probe = ti_sci_reset_probe,249 .remove_new = ti_sci_reset_remove,250 .driver = {251 .name = "ti-sci-reset",252 .of_match_table = ti_sci_reset_of_match,253 },254};255module_platform_driver(ti_sci_reset_driver);256 257MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");258MODULE_DESCRIPTION("TI System Control Interface (TI SCI) Reset driver");259MODULE_LICENSE("GPL v2");260