1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * TI SYSCON regmap reset driver
  4 *
  5 * Copyright (C) 2015-2016 Texas Instruments Incorporated - https://www.ti.com/
  6 *	Andrew F. Davis <afd@ti.com>
  7 *	Suman Anna <afd@ti.com>
  8 */
  9
 10#include <linux/mfd/syscon.h>
 11#include <linux/module.h>
 12#include <linux/of.h>
 13#include <linux/platform_device.h>
 14#include <linux/regmap.h>
 15#include <linux/reset-controller.h>
 16
 17#include <dt-bindings/reset/ti-syscon.h>
 18
 19/**
 20 * struct ti_syscon_reset_control - reset control structure
 21 * @assert_offset: reset assert control register offset from syscon base
 22 * @assert_bit: reset assert bit in the reset assert control register
 23 * @deassert_offset: reset deassert control register offset from syscon base
 24 * @deassert_bit: reset deassert bit in the reset deassert control register
 25 * @status_offset: reset status register offset from syscon base
 26 * @status_bit: reset status bit in the reset status register
 27 * @flags: reset flag indicating how the (de)assert and status are handled
 28 */
 29struct ti_syscon_reset_control {
 30	unsigned int assert_offset;
 31	unsigned int assert_bit;
 32	unsigned int deassert_offset;
 33	unsigned int deassert_bit;
 34	unsigned int status_offset;
 35	unsigned int status_bit;
 36	u32 flags;
 37};
 38
 39/**
 40 * struct ti_syscon_reset_data - reset controller information structure
 41 * @rcdev: reset controller entity
 42 * @regmap: regmap handle containing the memory-mapped reset registers
 43 * @controls: array of reset controls
 44 * @nr_controls: number of controls in control array
 45 */
 46struct ti_syscon_reset_data {
 47	struct reset_controller_dev rcdev;
 48	struct regmap *regmap;
 49	struct ti_syscon_reset_control *controls;
 50	unsigned int nr_controls;
 51};
 52
 53#define to_ti_syscon_reset_data(_rcdev)	\
 54	container_of(_rcdev, struct ti_syscon_reset_data, rcdev)
 55
 56/**
 57 * ti_syscon_reset_assert() - assert device reset
 58 * @rcdev: reset controller entity
 59 * @id: ID of the reset to be asserted
 60 *
 61 * This function implements the reset driver op to assert a device's reset.
 62 * This asserts the reset in a manner prescribed by the reset flags.
 63 *
 64 * Return: 0 for successful request, else a corresponding error value
 65 */
 66static int ti_syscon_reset_assert(struct reset_controller_dev *rcdev,
 67				  unsigned long id)
 68{
 69	struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
 70	struct ti_syscon_reset_control *control;
 71	unsigned int mask, value;
 72
 73	if (id >= data->nr_controls)
 74		return -EINVAL;
 75
 76	control = &data->controls[id];
 77
 78	if (control->flags & ASSERT_NONE)
 79		return -ENOTSUPP; /* assert not supported for this reset */
 80
 81	mask = BIT(control->assert_bit);
 82	value = (control->flags & ASSERT_SET) ? mask : 0x0;
 83
 84	return regmap_write_bits(data->regmap, control->assert_offset, mask, value);
 85}
 86
 87/**
 88 * ti_syscon_reset_deassert() - deassert device reset
 89 * @rcdev: reset controller entity
 90 * @id: ID of reset to be deasserted
 91 *
 92 * This function implements the reset driver op to deassert a device's reset.
 93 * This deasserts the reset in a manner prescribed by the reset flags.
 94 *
 95 * Return: 0 for successful request, else a corresponding error value
 96 */
 97static int ti_syscon_reset_deassert(struct reset_controller_dev *rcdev,
 98				    unsigned long id)
 99{
100	struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
101	struct ti_syscon_reset_control *control;
102	unsigned int mask, value;
103
104	if (id >= data->nr_controls)
105		return -EINVAL;
106
107	control = &data->controls[id];
108
109	if (control->flags & DEASSERT_NONE)
110		return -ENOTSUPP; /* deassert not supported for this reset */
111
112	mask = BIT(control->deassert_bit);
113	value = (control->flags & DEASSERT_SET) ? mask : 0x0;
114
115	return regmap_write_bits(data->regmap, control->deassert_offset, mask, value);
116}
117
118/**
119 * ti_syscon_reset_status() - check device reset status
120 * @rcdev: reset controller entity
121 * @id: ID of the reset for which the status is being requested
122 *
123 * This function implements the reset driver op to return the status of a
124 * device's reset.
125 *
126 * Return: 0 if reset is deasserted, true if reset is asserted, else a
127 * corresponding error value
128 */
129static int ti_syscon_reset_status(struct reset_controller_dev *rcdev,
130				  unsigned long id)
131{
132	struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
133	struct ti_syscon_reset_control *control;
134	unsigned int reset_state;
135	int ret;
136
137	if (id >= data->nr_controls)
138		return -EINVAL;
139
140	control = &data->controls[id];
141
142	if (control->flags & STATUS_NONE)
143		return -ENOTSUPP; /* status not supported for this reset */
144
145	ret = regmap_read(data->regmap, control->status_offset, &reset_state);
146	if (ret)
147		return ret;
148
149	return !(reset_state & BIT(control->status_bit)) ==
150		!(control->flags & STATUS_SET);
151}
152
153static const struct reset_control_ops ti_syscon_reset_ops = {
154	.assert		= ti_syscon_reset_assert,
155	.deassert	= ti_syscon_reset_deassert,
156	.status		= ti_syscon_reset_status,
157};
158
159static int ti_syscon_reset_probe(struct platform_device *pdev)
160{
161	struct device *dev = &pdev->dev;
162	struct device_node *np = dev->of_node;
163	struct ti_syscon_reset_data *data;
164	struct regmap *regmap;
165	const __be32 *list;
166	struct ti_syscon_reset_control *controls;
167	int size, nr_controls, i;
168
169	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
170	if (!data)
171		return -ENOMEM;
172
173	regmap = syscon_node_to_regmap(np->parent);
174	if (IS_ERR(regmap))
175		return PTR_ERR(regmap);
176
177	list = of_get_property(np, "ti,reset-bits", &size);
178	if (!list || (size / sizeof(*list)) % 7 != 0) {
179		dev_err(dev, "invalid DT reset description\n");
180		return -EINVAL;
181	}
182
183	nr_controls = (size / sizeof(*list)) / 7;
184	controls = devm_kcalloc(dev, nr_controls, sizeof(*controls),
185				GFP_KERNEL);
186	if (!controls)
187		return -ENOMEM;
188
189	for (i = 0; i < nr_controls; i++) {
190		controls[i].assert_offset = be32_to_cpup(list++);
191		controls[i].assert_bit = be32_to_cpup(list++);
192		controls[i].deassert_offset = be32_to_cpup(list++);
193		controls[i].deassert_bit = be32_to_cpup(list++);
194		controls[i].status_offset = be32_to_cpup(list++);
195		controls[i].status_bit = be32_to_cpup(list++);
196		controls[i].flags = be32_to_cpup(list++);
197	}
198
199	data->rcdev.ops = &ti_syscon_reset_ops;
200	data->rcdev.owner = THIS_MODULE;
201	data->rcdev.of_node = np;
202	data->rcdev.nr_resets = nr_controls;
203	data->regmap = regmap;
204	data->controls = controls;
205	data->nr_controls = nr_controls;
206
207	return devm_reset_controller_register(dev, &data->rcdev);
208}
209
210static const struct of_device_id ti_syscon_reset_of_match[] = {
211	{ .compatible = "ti,syscon-reset", },
212	{ /* sentinel */ },
213};
214MODULE_DEVICE_TABLE(of, ti_syscon_reset_of_match);
215
216static struct platform_driver ti_syscon_reset_driver = {
217	.probe = ti_syscon_reset_probe,
218	.driver = {
219		.name = "ti-syscon-reset",
220		.of_match_table = ti_syscon_reset_of_match,
221	},
222};
223module_platform_driver(ti_syscon_reset_driver);
224
225MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
226MODULE_AUTHOR("Suman Anna <s-anna@ti.com>");
227MODULE_DESCRIPTION("TI SYSCON Regmap Reset Driver");
228MODULE_LICENSE("GPL v2");