1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2013 STMicroelectronics Limited
4 * Author: Stephen Gallimore <stephen.gallimore@st.com>
5 *
6 * Inspired by mach-imx/src.c
7 */
8#include <linux/kernel.h>
9#include <linux/platform_device.h>
10#include <linux/module.h>
11#include <linux/err.h>
12#include <linux/types.h>
13#include <linux/of_device.h>
14#include <linux/regmap.h>
15#include <linux/mfd/syscon.h>
16
17#include "reset-syscfg.h"
18
19/**
20 * struct syscfg_reset_channel - Reset channel regmap configuration
21 *
22 * @reset: regmap field for the channel's reset bit.
23 * @ack: regmap field for the channel's ack bit (optional).
24 */
25struct syscfg_reset_channel {
26	struct regmap_field *reset;
27	struct regmap_field *ack;
28};
29
30/**
31 * struct syscfg_reset_controller - A reset controller which groups together
32 * a set of related reset bits, which may be located in different system
33 * configuration registers.
34 *
35 * @rst: base reset controller structure.
36 * @active_low: are the resets in this controller active low, i.e. clearing
37 *              the reset bit puts the hardware into reset.
38 * @channels: An array of reset channels for this controller.
39 */
40struct syscfg_reset_controller {
41	struct reset_controller_dev rst;
42	bool active_low;
43	struct syscfg_reset_channel *channels;
44};
45
46#define to_syscfg_reset_controller(_rst) \
47	container_of(_rst, struct syscfg_reset_controller, rst)
48
49static int syscfg_reset_program_hw(struct reset_controller_dev *rcdev,
50				   unsigned long idx, int assert)
51{
52	struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
53	const struct syscfg_reset_channel *ch;
54	u32 ctrl_val = rst->active_low ? !assert : !!assert;
55	int err;
56
57	if (idx >= rcdev->nr_resets)
58		return -EINVAL;
59
60	ch = &rst->channels[idx];
61
62	err = regmap_field_write(ch->reset, ctrl_val);
63	if (err)
64		return err;
65
66	if (ch->ack) {
67		u32 ack_val;
68
69		err = regmap_field_read_poll_timeout(ch->ack, ack_val, (ack_val == ctrl_val),
70						     100, USEC_PER_SEC);
71		if (err)
72			return err;
73	}
74
75	return 0;
76}
77
78static int syscfg_reset_assert(struct reset_controller_dev *rcdev,
79			       unsigned long idx)
80{
81	return syscfg_reset_program_hw(rcdev, idx, true);
82}
83
84static int syscfg_reset_deassert(struct reset_controller_dev *rcdev,
85				 unsigned long idx)
86{
87	return syscfg_reset_program_hw(rcdev, idx, false);
88}
89
90static int syscfg_reset_dev(struct reset_controller_dev *rcdev,
91			    unsigned long idx)
92{
93	int err;
94
95	err = syscfg_reset_assert(rcdev, idx);
96	if (err)
97		return err;
98
99	return syscfg_reset_deassert(rcdev, idx);
100}
101
102static int syscfg_reset_status(struct reset_controller_dev *rcdev,
103			       unsigned long idx)
104{
105	struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
106	const struct syscfg_reset_channel *ch;
107	u32 ret_val = 0;
108	int err;
109
110	if (idx >= rcdev->nr_resets)
111		return -EINVAL;
112
113	ch = &rst->channels[idx];
114	if (ch->ack)
115		err = regmap_field_read(ch->ack, &ret_val);
116	else
117		err = regmap_field_read(ch->reset, &ret_val);
118	if (err)
119		return err;
120
121	return rst->active_low ? !ret_val : !!ret_val;
122}
123
124static const struct reset_control_ops syscfg_reset_ops = {
125	.reset    = syscfg_reset_dev,
126	.assert   = syscfg_reset_assert,
127	.deassert = syscfg_reset_deassert,
128	.status   = syscfg_reset_status,
129};
130
131static int syscfg_reset_controller_register(struct device *dev,
132				const struct syscfg_reset_controller_data *data)
133{
134	struct syscfg_reset_controller *rc;
135	int i, err;
136
137	rc = devm_kzalloc(dev, sizeof(*rc), GFP_KERNEL);
138	if (!rc)
139		return -ENOMEM;
140
141	rc->channels = devm_kcalloc(dev, data->nr_channels,
142				    sizeof(*rc->channels), GFP_KERNEL);
143	if (!rc->channels)
144		return -ENOMEM;
145
146	rc->rst.ops = &syscfg_reset_ops;
147	rc->rst.of_node = dev->of_node;
148	rc->rst.nr_resets = data->nr_channels;
149	rc->active_low = data->active_low;
150
151	for (i = 0; i < data->nr_channels; i++) {
152		struct regmap *map;
153		struct regmap_field *f;
154		const char *compatible = data->channels[i].compatible;
155
156		map = syscon_regmap_lookup_by_compatible(compatible);
157		if (IS_ERR(map))
158			return PTR_ERR(map);
159
160		f = devm_regmap_field_alloc(dev, map, data->channels[i].reset);
161		if (IS_ERR(f))
162			return PTR_ERR(f);
163
164		rc->channels[i].reset = f;
165
166		if (!data->wait_for_ack)
167			continue;
168
169		f = devm_regmap_field_alloc(dev, map, data->channels[i].ack);
170		if (IS_ERR(f))
171			return PTR_ERR(f);
172
173		rc->channels[i].ack = f;
174	}
175
176	err = reset_controller_register(&rc->rst);
177	if (!err)
178		dev_info(dev, "registered\n");
179
180	return err;
181}
182
183int syscfg_reset_probe(struct platform_device *pdev)
184{
185	struct device *dev = pdev ? &pdev->dev : NULL;
186	const struct of_device_id *match;
187
188	if (!dev || !dev->driver)
189		return -ENODEV;
190
191	match = of_match_device(dev->driver->of_match_table, dev);
192	if (!match || !match->data)
193		return -EINVAL;
194
195	return syscfg_reset_controller_register(dev, match->data);
196}
197