tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
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 * 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 * A reset controller which groups together a set of related reset bits, which
32 * may be located in different system configuration registers.
33 *
34 * @rst: base reset controller structure.
35 * @active_low: are the resets in this controller active low, i.e. clearing
36 * the reset bit puts the hardware into reset.
37 * @channels: An array of reset channels for this controller.
38 */
39struct syscfg_reset_controller {
40 struct reset_controller_dev rst;
41 bool active_low;
42 struct syscfg_reset_channel *channels;
43};
44
45#define to_syscfg_reset_controller(_rst) \
46 container_of(_rst, struct syscfg_reset_controller, rst)
47
48static int syscfg_reset_program_hw(struct reset_controller_dev *rcdev,
49 unsigned long idx, int assert)
50{
51 struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
52 const struct syscfg_reset_channel *ch;
53 u32 ctrl_val = rst->active_low ? !assert : !!assert;
54 int err;
55
56 if (idx >= rcdev->nr_resets)
57 return -EINVAL;
58
59 ch = &rst->channels[idx];
60
61 err = regmap_field_write(ch->reset, ctrl_val);
62 if (err)
63 return err;
64
65 if (ch->ack) {
66 unsigned long timeout = jiffies + msecs_to_jiffies(1000);
67 u32 ack_val;
68
69 while (true) {
70 err = regmap_field_read(ch->ack, &ack_val);
71 if (err)
72 return err;
73
74 if (ack_val == ctrl_val)
75 break;
76
77 if (time_after(jiffies, timeout))
78 return -ETIME;
79
80 cpu_relax();
81 }
82 }
83
84 return 0;
85}
86
87static int syscfg_reset_assert(struct reset_controller_dev *rcdev,
88 unsigned long idx)
89{
90 return syscfg_reset_program_hw(rcdev, idx, true);
91}
92
93static int syscfg_reset_deassert(struct reset_controller_dev *rcdev,
94 unsigned long idx)
95{
96 return syscfg_reset_program_hw(rcdev, idx, false);
97}
98
99static int syscfg_reset_dev(struct reset_controller_dev *rcdev,
100 unsigned long idx)
101{
102 int err;
103
104 err = syscfg_reset_assert(rcdev, idx);
105 if (err)
106 return err;
107
108 return syscfg_reset_deassert(rcdev, idx);
109}
110
111static int syscfg_reset_status(struct reset_controller_dev *rcdev,
112 unsigned long idx)
113{
114 struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
115 const struct syscfg_reset_channel *ch;
116 u32 ret_val = 0;
117 int err;
118
119 if (idx >= rcdev->nr_resets)
120 return -EINVAL;
121
122 ch = &rst->channels[idx];
123 if (ch->ack)
124 err = regmap_field_read(ch->ack, &ret_val);
125 else
126 err = regmap_field_read(ch->reset, &ret_val);
127 if (err)
128 return err;
129
130 return rst->active_low ? !ret_val : !!ret_val;
131}
132
133static const struct reset_control_ops syscfg_reset_ops = {
134 .reset = syscfg_reset_dev,
135 .assert = syscfg_reset_assert,
136 .deassert = syscfg_reset_deassert,
137 .status = syscfg_reset_status,
138};
139
140static int syscfg_reset_controller_register(struct device *dev,
141 const struct syscfg_reset_controller_data *data)
142{
143 struct syscfg_reset_controller *rc;
144 int i, err;
145
146 rc = devm_kzalloc(dev, sizeof(*rc), GFP_KERNEL);
147 if (!rc)
148 return -ENOMEM;
149
150 rc->channels = devm_kcalloc(dev, data->nr_channels,
151 sizeof(*rc->channels), GFP_KERNEL);
152 if (!rc->channels)
153 return -ENOMEM;
154
155 rc->rst.ops = &syscfg_reset_ops,
156 rc->rst.of_node = dev->of_node;
157 rc->rst.nr_resets = data->nr_channels;
158 rc->active_low = data->active_low;
159
160 for (i = 0; i < data->nr_channels; i++) {
161 struct regmap *map;
162 struct regmap_field *f;
163 const char *compatible = data->channels[i].compatible;
164
165 map = syscon_regmap_lookup_by_compatible(compatible);
166 if (IS_ERR(map))
167 return PTR_ERR(map);
168
169 f = devm_regmap_field_alloc(dev, map, data->channels[i].reset);
170 if (IS_ERR(f))
171 return PTR_ERR(f);
172
173 rc->channels[i].reset = f;
174
175 if (!data->wait_for_ack)
176 continue;
177
178 f = devm_regmap_field_alloc(dev, map, data->channels[i].ack);
179 if (IS_ERR(f))
180 return PTR_ERR(f);
181
182 rc->channels[i].ack = f;
183 }
184
185 err = reset_controller_register(&rc->rst);
186 if (!err)
187 dev_info(dev, "registered\n");
188
189 return err;
190}
191
192int syscfg_reset_probe(struct platform_device *pdev)
193{
194 struct device *dev = pdev ? &pdev->dev : NULL;
195 const struct of_device_id *match;
196
197 if (!dev || !dev->driver)
198 return -ENODEV;
199
200 match = of_match_device(dev->driver->of_match_table, dev);
201 if (!match || !match->data)
202 return -EINVAL;
203
204 return syscfg_reset_controller_register(dev, match->data);
205}