1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Texas Instrument's System Control Interface (TI-SCI) reset driver
  4 *
  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 structure
 19 * @dev_id: SoC-specific device identifier
 20 * @reset_mask: reset mask to use for toggling reset
 21 * @lock: synchronize reset_mask read-modify-writes
 22 */
 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 structure
 31 * @rcdev: reset controller entity
 32 * @dev: reset controller device pointer
 33 * @sci: TI SCI handle used for communication with system controller
 34 * @idr: idr structure for mapping ids to reset control structures
 35 */
 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 reset
 48 * @rcdev: reset controller entity
 49 * @id: ID of the reset to toggle
 50 * @assert: boolean flag to indicate assert or deassert
 51 *
 52 * This is a common internal function used to assert or deassert a device's
 53 * reset using the TI SCI protocol. The device's reset is asserted if the
 54 * @assert argument is true, or deasserted if @assert argument is false.
 55 * The mechanism itself is a read-modify-write procedure, the current device
 56 * reset register is read using a TI SCI device operation, the new value is
 57 * set or un-set using the reset's mask, and the new reset value written by
 58 * using another TI SCI device operation.
 59 *
 60 * Return: 0 for successful request, else a corresponding error value
 61 */
 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	else
 85		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 reset
 96 * @rcdev: reset controller entity
 97 * @id: ID of the reset to be asserted
 98 *
 99 * This function implements the reset driver op to assert a device's reset
100 * using the TI SCI protocol. This invokes the function ti_sci_reset_set()
101 * with the corresponding parameters as passed in, but with the @assert
102 * argument set to true for asserting the reset.
103 *
104 * Return: 0 for successful request, else a corresponding error value
105 */
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 reset
114 * @rcdev: reset controller entity
115 * @id: ID of the reset to be deasserted
116 *
117 * This function implements the reset driver op to deassert a device's reset
118 * using the TI SCI protocol. This invokes the function ti_sci_reset_set()
119 * with the corresponding parameters as passed in, but with the @assert
120 * argument set to false for deasserting the reset.
121 *
122 * Return: 0 for successful request, else a corresponding error value
123 */
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 status
132 * @rcdev: reset controller entity
133 * @id: ID of reset to be checked
134 *
135 * This function implements the reset driver op to return the status of a
136 * device's reset using the TI SCI protocol. The reset register value is read
137 * by invoking the TI SCI device operation .get_device_resets(), and the
138 * status of the specific reset is extracted and returned using this reset's
139 * reset mask.
140 *
141 * Return: 0 if reset is deasserted, or a non-zero value if reset is asserted
142 */
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 ID
172 * @rcdev: reset controller entity
173 * @reset_spec: OF reset argument specifier
174 *
175 * This function performs the translation of the reset argument specifier
176 * values defined in a reset consumer device node. The function allocates a
177 * reset control structure for that device reset, and will be used by the
178 * driver for performing any reset functions on that reset. An idr structure
179 * is allocated and used to map to the reset control structure. This idr
180 * is used by the driver to do reset lookups.
181 *
182 * Return: 0 for successful request, else a corresponding error value
183 */
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 int 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	return 0;
247}
248
249static struct platform_driver ti_sci_reset_driver = {
250	.probe = ti_sci_reset_probe,
251	.remove = ti_sci_reset_remove,
252	.driver = {
253		.name = "ti-sci-reset",
254		.of_match_table = ti_sci_reset_of_match,
255	},
256};
257module_platform_driver(ti_sci_reset_driver);
258
259MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
260MODULE_DESCRIPTION("TI System Control Interface (TI SCI) Reset driver");
261MODULE_LICENSE("GPL v2");