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/property.h>
11#include <linux/module.h>
12#include <linux/err.h>
13#include <linux/types.h>
14#include <linux/of.h>
15#include <linux/regmap.h>
16#include <linux/mfd/syscon.h>
17
18#include "reset-syscfg.h"
19
20/**
21 * struct syscfg_reset_channel - Reset channel regmap configuration
22 *
23 * @reset: regmap field for the channel's reset bit.
24 * @ack: regmap field for the channel's ack bit (optional).
25 */
26struct syscfg_reset_channel {
27 struct regmap_field *reset;
28 struct regmap_field *ack;
29};
30
31/**
32 * struct syscfg_reset_controller - A reset controller which groups together
33 * a set of related reset bits, which may be located in different system
34 * configuration registers.
35 *
36 * @rst: base reset controller structure.
37 * @active_low: are the resets in this controller active low, i.e. clearing
38 * the reset bit puts the hardware into reset.
39 * @channels: An array of reset channels for this controller.
40 */
41struct syscfg_reset_controller {
42 struct reset_controller_dev rst;
43 bool active_low;
44 struct syscfg_reset_channel *channels;
45};
46
47#define to_syscfg_reset_controller(_rst) \
48 container_of(_rst, struct syscfg_reset_controller, rst)
49
50static int syscfg_reset_program_hw(struct reset_controller_dev *rcdev,
51 unsigned long idx, int assert)
52{
53 struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
54 const struct syscfg_reset_channel *ch;
55 u32 ctrl_val = rst->active_low ? !assert : !!assert;
56 int err;
57
58 if (idx >= rcdev->nr_resets)
59 return -EINVAL;
60
61 ch = &rst->channels[idx];
62
63 err = regmap_field_write(field: ch->reset, val: ctrl_val);
64 if (err)
65 return err;
66
67 if (ch->ack) {
68 u32 ack_val;
69
70 err = regmap_field_read_poll_timeout(ch->ack, ack_val, (ack_val == ctrl_val),
71 100, USEC_PER_SEC);
72 if (err)
73 return err;
74 }
75
76 return 0;
77}
78
79static int syscfg_reset_assert(struct reset_controller_dev *rcdev,
80 unsigned long idx)
81{
82 return syscfg_reset_program_hw(rcdev, idx, assert: true);
83}
84
85static int syscfg_reset_deassert(struct reset_controller_dev *rcdev,
86 unsigned long idx)
87{
88 return syscfg_reset_program_hw(rcdev, idx, assert: false);
89}
90
91static int syscfg_reset_dev(struct reset_controller_dev *rcdev,
92 unsigned long idx)
93{
94 int err;
95
96 err = syscfg_reset_assert(rcdev, idx);
97 if (err)
98 return err;
99
100 return syscfg_reset_deassert(rcdev, idx);
101}
102
103static int syscfg_reset_status(struct reset_controller_dev *rcdev,
104 unsigned long idx)
105{
106 struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
107 const struct syscfg_reset_channel *ch;
108 u32 ret_val = 0;
109 int err;
110
111 if (idx >= rcdev->nr_resets)
112 return -EINVAL;
113
114 ch = &rst->channels[idx];
115 if (ch->ack)
116 err = regmap_field_read(field: ch->ack, val: &ret_val);
117 else
118 err = regmap_field_read(field: ch->reset, val: &ret_val);
119 if (err)
120 return err;
121
122 return rst->active_low ? !ret_val : !!ret_val;
123}
124
125static const struct reset_control_ops syscfg_reset_ops = {
126 .reset = syscfg_reset_dev,
127 .assert = syscfg_reset_assert,
128 .deassert = syscfg_reset_deassert,
129 .status = syscfg_reset_status,
130};
131
132static int syscfg_reset_controller_register(struct device *dev,
133 const struct syscfg_reset_controller_data *data)
134{
135 struct syscfg_reset_controller *rc;
136 int i, err;
137
138 rc = devm_kzalloc(dev, size: sizeof(*rc), GFP_KERNEL);
139 if (!rc)
140 return -ENOMEM;
141
142 rc->channels = devm_kcalloc(dev, n: data->nr_channels,
143 size: sizeof(*rc->channels), GFP_KERNEL);
144 if (!rc->channels)
145 return -ENOMEM;
146
147 rc->rst.ops = &syscfg_reset_ops;
148 rc->rst.of_node = dev->of_node;
149 rc->rst.nr_resets = data->nr_channels;
150 rc->active_low = data->active_low;
151
152 for (i = 0; i < data->nr_channels; i++) {
153 struct regmap *map;
154 struct regmap_field *f;
155 const char *compatible = data->channels[i].compatible;
156
157 map = syscon_regmap_lookup_by_compatible(s: compatible);
158 if (IS_ERR(ptr: map))
159 return PTR_ERR(ptr: map);
160
161 f = devm_regmap_field_alloc(dev, regmap: map, reg_field: data->channels[i].reset);
162 if (IS_ERR(ptr: f))
163 return PTR_ERR(ptr: f);
164
165 rc->channels[i].reset = f;
166
167 if (!data->wait_for_ack)
168 continue;
169
170 f = devm_regmap_field_alloc(dev, regmap: map, reg_field: data->channels[i].ack);
171 if (IS_ERR(ptr: f))
172 return PTR_ERR(ptr: f);
173
174 rc->channels[i].ack = f;
175 }
176
177 err = reset_controller_register(rcdev: &rc->rst);
178 if (!err)
179 dev_info(dev, "registered\n");
180
181 return err;
182}
183
184int syscfg_reset_probe(struct platform_device *pdev)
185{
186 struct device *dev = pdev ? &pdev->dev : NULL;
187 const void *data;
188
189 if (!dev || !dev->driver)
190 return -ENODEV;
191
192 data = device_get_match_data(dev: &pdev->dev);
193 if (!data)
194 return -EINVAL;
195
196 return syscfg_reset_controller_register(dev, data);
197}
198

source code of linux/drivers/reset/sti/reset-syscfg.c