1/*
  2 * TI SYSCON regmap reset driver
  3 *
  4 * Copyright (C) 2015-2016 Texas Instruments Incorporated - https://www.ti.com/
  5 *	Andrew F. Davis <afd@ti.com>
  6 *	Suman Anna <afd@ti.com>
  7 *
  8 * This program is free software; you can redistribute it and/or modify
  9 * it under the terms of the GNU General Public License version 2 as
 10 * published by the Free Software Foundation.
 11 *
 12 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 13 * kind, whether express or implied; without even the implied warranty
 14 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 15 * GNU General Public License for more details.
 16 */
 17
 18#include <linux/mfd/syscon.h>
 19#include <linux/module.h>
 20#include <linux/of.h>
 21#include <linux/platform_device.h>
 22#include <linux/regmap.h>
 23#include <linux/reset-controller.h>
 24
 25#include <dt-bindings/reset/ti-syscon.h>
 26
 27/**
 28 * struct ti_syscon_reset_control - reset control structure
 29 * @assert_offset: reset assert control register offset from syscon base
 30 * @assert_bit: reset assert bit in the reset assert control register
 31 * @deassert_offset: reset deassert control register offset from syscon base
 32 * @deassert_bit: reset deassert bit in the reset deassert control register
 33 * @status_offset: reset status register offset from syscon base
 34 * @status_bit: reset status bit in the reset status register
 35 * @flags: reset flag indicating how the (de)assert and status are handled
 36 */
 37struct ti_syscon_reset_control {
 38	unsigned int assert_offset;
 39	unsigned int assert_bit;
 40	unsigned int deassert_offset;
 41	unsigned int deassert_bit;
 42	unsigned int status_offset;
 43	unsigned int status_bit;
 44	u32 flags;
 45};
 46
 47/**
 48 * struct ti_syscon_reset_data - reset controller information structure
 49 * @rcdev: reset controller entity
 50 * @regmap: regmap handle containing the memory-mapped reset registers
 51 * @controls: array of reset controls
 52 * @nr_controls: number of controls in control array
 53 */
 54struct ti_syscon_reset_data {
 55	struct reset_controller_dev rcdev;
 56	struct regmap *regmap;
 57	struct ti_syscon_reset_control *controls;
 58	unsigned int nr_controls;
 59};
 60
 61#define to_ti_syscon_reset_data(rcdev)	\
 62	container_of(rcdev, struct ti_syscon_reset_data, rcdev)
 63
 64/**
 65 * ti_syscon_reset_assert() - assert device reset
 66 * @rcdev: reset controller entity
 67 * @id: ID of the reset to be asserted
 68 *
 69 * This function implements the reset driver op to assert a device's reset.
 70 * This asserts the reset in a manner prescribed by the reset flags.
 71 *
 72 * Return: 0 for successful request, else a corresponding error value
 73 */
 74static int ti_syscon_reset_assert(struct reset_controller_dev *rcdev,
 75				  unsigned long id)
 76{
 77	struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
 78	struct ti_syscon_reset_control *control;
 79	unsigned int mask, value;
 80
 81	if (id >= data->nr_controls)
 82		return -EINVAL;
 83
 84	control = &data->controls[id];
 85
 86	if (control->flags & ASSERT_NONE)
 87		return -ENOTSUPP; /* assert not supported for this reset */
 88
 89	mask = BIT(control->assert_bit);
 90	value = (control->flags & ASSERT_SET) ? mask : 0x0;
 91
 92	return regmap_update_bits(data->regmap, control->assert_offset, mask, value);
 93}
 94
 95/**
 96 * ti_syscon_reset_deassert() - deassert device reset
 97 * @rcdev: reset controller entity
 98 * @id: ID of reset to be deasserted
 99 *
100 * This function implements the reset driver op to deassert a device's reset.
101 * This deasserts the reset in a manner prescribed by the reset flags.
102 *
103 * Return: 0 for successful request, else a corresponding error value
104 */
105static int ti_syscon_reset_deassert(struct reset_controller_dev *rcdev,
106				    unsigned long id)
107{
108	struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
109	struct ti_syscon_reset_control *control;
110	unsigned int mask, value;
111
112	if (id >= data->nr_controls)
113		return -EINVAL;
114
115	control = &data->controls[id];
116
117	if (control->flags & DEASSERT_NONE)
118		return -ENOTSUPP; /* deassert not supported for this reset */
119
120	mask = BIT(control->deassert_bit);
121	value = (control->flags & DEASSERT_SET) ? mask : 0x0;
122
123	return regmap_update_bits(data->regmap, control->deassert_offset, mask, value);
124}
125
126/**
127 * ti_syscon_reset_status() - check device reset status
128 * @rcdev: reset controller entity
129 * @id: ID of the reset for which the status is being requested
130 *
131 * This function implements the reset driver op to return the status of a
132 * device's reset.
133 *
134 * Return: 0 if reset is deasserted, true if reset is asserted, else a
135 * corresponding error value
136 */
137static int ti_syscon_reset_status(struct reset_controller_dev *rcdev,
138				  unsigned long id)
139{
140	struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
141	struct ti_syscon_reset_control *control;
142	unsigned int reset_state;
143	int ret;
144
145	if (id >= data->nr_controls)
146		return -EINVAL;
147
148	control = &data->controls[id];
149
150	if (control->flags & STATUS_NONE)
151		return -ENOTSUPP; /* status not supported for this reset */
152
153	ret = regmap_read(data->regmap, control->status_offset, &reset_state);
154	if (ret)
155		return ret;
156
157	return !(reset_state & BIT(control->status_bit)) ==
158		!(control->flags & STATUS_SET);
159}
160
161static const struct reset_control_ops ti_syscon_reset_ops = {
162	.assert		= ti_syscon_reset_assert,
163	.deassert	= ti_syscon_reset_deassert,
164	.status		= ti_syscon_reset_status,
165};
166
167static int ti_syscon_reset_probe(struct platform_device *pdev)
168{
169	struct device *dev = &pdev->dev;
170	struct device_node *np = dev->of_node;
171	struct ti_syscon_reset_data *data;
172	struct regmap *regmap;
173	const __be32 *list;
174	struct ti_syscon_reset_control *controls;
175	int size, nr_controls, i;
176
177	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
178	if (!data)
179		return -ENOMEM;
180
181	regmap = syscon_node_to_regmap(np->parent);
182	if (IS_ERR(regmap))
183		return PTR_ERR(regmap);
184
185	list = of_get_property(np, "ti,reset-bits", &size);
186	if (!list || (size / sizeof(*list)) % 7 != 0) {
187		dev_err(dev, "invalid DT reset description\n");
188		return -EINVAL;
189	}
190
191	nr_controls = (size / sizeof(*list)) / 7;
192	controls = devm_kcalloc(dev, nr_controls, sizeof(*controls),
193				GFP_KERNEL);
194	if (!controls)
195		return -ENOMEM;
196
197	for (i = 0; i < nr_controls; i++) {
198		controls[i].assert_offset = be32_to_cpup(list++);
199		controls[i].assert_bit = be32_to_cpup(list++);
200		controls[i].deassert_offset = be32_to_cpup(list++);
201		controls[i].deassert_bit = be32_to_cpup(list++);
202		controls[i].status_offset = be32_to_cpup(list++);
203		controls[i].status_bit = be32_to_cpup(list++);
204		controls[i].flags = be32_to_cpup(list++);
205	}
206
207	data->rcdev.ops = &ti_syscon_reset_ops;
208	data->rcdev.owner = THIS_MODULE;
209	data->rcdev.of_node = np;
210	data->rcdev.nr_resets = nr_controls;
211	data->regmap = regmap;
212	data->controls = controls;
213	data->nr_controls = nr_controls;
214
215	platform_set_drvdata(pdev, data);
216
217	return devm_reset_controller_register(dev, &data->rcdev);
218}
219
220static const struct of_device_id ti_syscon_reset_of_match[] = {
221	{ .compatible = "ti,syscon-reset", },
222	{ /* sentinel */ },
223};
224MODULE_DEVICE_TABLE(of, ti_syscon_reset_of_match);
225
226static struct platform_driver ti_syscon_reset_driver = {
227	.probe = ti_syscon_reset_probe,
228	.driver = {
229		.name = "ti-syscon-reset",
230		.of_match_table = ti_syscon_reset_of_match,
231	},
232};
233module_platform_driver(ti_syscon_reset_driver);
234
235MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
236MODULE_AUTHOR("Suman Anna <s-anna@ti.com>");
237MODULE_DESCRIPTION("TI SYSCON Regmap Reset Driver");
238MODULE_LICENSE("GPL v2");