1// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
2/*
3 * Amlogic Meson Reset Controller driver
4 *
5 * Copyright (c) 2016 BayLibre, SAS.
6 * Author: Neil Armstrong <narmstrong@baylibre.com>
7 */
8#include <linux/err.h>
9#include <linux/init.h>
10#include <linux/io.h>
11#include <linux/of.h>
12#include <linux/module.h>
13#include <linux/platform_device.h>
14#include <linux/reset-controller.h>
15#include <linux/slab.h>
16#include <linux/types.h>
17
18#define BITS_PER_REG 32
19
20struct meson_reset_param {
21 int reg_count;
22 int level_offset;
23};
24
25struct meson_reset {
26 void __iomem *reg_base;
27 const struct meson_reset_param *param;
28 struct reset_controller_dev rcdev;
29 spinlock_t lock;
30};
31
32static int meson_reset_reset(struct reset_controller_dev *rcdev,
33 unsigned long id)
34{
35 struct meson_reset *data =
36 container_of(rcdev, struct meson_reset, rcdev);
37 unsigned int bank = id / BITS_PER_REG;
38 unsigned int offset = id % BITS_PER_REG;
39 void __iomem *reg_addr = data->reg_base + (bank << 2);
40
41 writel(BIT(offset), addr: reg_addr);
42
43 return 0;
44}
45
46static int meson_reset_level(struct reset_controller_dev *rcdev,
47 unsigned long id, bool assert)
48{
49 struct meson_reset *data =
50 container_of(rcdev, struct meson_reset, rcdev);
51 unsigned int bank = id / BITS_PER_REG;
52 unsigned int offset = id % BITS_PER_REG;
53 void __iomem *reg_addr;
54 unsigned long flags;
55 u32 reg;
56
57 reg_addr = data->reg_base + data->param->level_offset + (bank << 2);
58
59 spin_lock_irqsave(&data->lock, flags);
60
61 reg = readl(addr: reg_addr);
62 if (assert)
63 writel(val: reg & ~BIT(offset), addr: reg_addr);
64 else
65 writel(val: reg | BIT(offset), addr: reg_addr);
66
67 spin_unlock_irqrestore(lock: &data->lock, flags);
68
69 return 0;
70}
71
72static int meson_reset_assert(struct reset_controller_dev *rcdev,
73 unsigned long id)
74{
75 return meson_reset_level(rcdev, id, assert: true);
76}
77
78static int meson_reset_deassert(struct reset_controller_dev *rcdev,
79 unsigned long id)
80{
81 return meson_reset_level(rcdev, id, assert: false);
82}
83
84static const struct reset_control_ops meson_reset_ops = {
85 .reset = meson_reset_reset,
86 .assert = meson_reset_assert,
87 .deassert = meson_reset_deassert,
88};
89
90static const struct meson_reset_param meson8b_param = {
91 .reg_count = 8,
92 .level_offset = 0x7c,
93};
94
95static const struct meson_reset_param meson_a1_param = {
96 .reg_count = 3,
97 .level_offset = 0x40,
98};
99
100static const struct meson_reset_param meson_s4_param = {
101 .reg_count = 6,
102 .level_offset = 0x40,
103};
104
105static const struct of_device_id meson_reset_dt_ids[] = {
106 { .compatible = "amlogic,meson8b-reset", .data = &meson8b_param},
107 { .compatible = "amlogic,meson-gxbb-reset", .data = &meson8b_param},
108 { .compatible = "amlogic,meson-axg-reset", .data = &meson8b_param},
109 { .compatible = "amlogic,meson-a1-reset", .data = &meson_a1_param},
110 { .compatible = "amlogic,meson-s4-reset", .data = &meson_s4_param},
111 { /* sentinel */ },
112};
113MODULE_DEVICE_TABLE(of, meson_reset_dt_ids);
114
115static int meson_reset_probe(struct platform_device *pdev)
116{
117 struct meson_reset *data;
118
119 data = devm_kzalloc(dev: &pdev->dev, size: sizeof(*data), GFP_KERNEL);
120 if (!data)
121 return -ENOMEM;
122
123 data->reg_base = devm_platform_ioremap_resource(pdev, index: 0);
124 if (IS_ERR(ptr: data->reg_base))
125 return PTR_ERR(ptr: data->reg_base);
126
127 data->param = of_device_get_match_data(dev: &pdev->dev);
128 if (!data->param)
129 return -ENODEV;
130
131 spin_lock_init(&data->lock);
132
133 data->rcdev.owner = THIS_MODULE;
134 data->rcdev.nr_resets = data->param->reg_count * BITS_PER_REG;
135 data->rcdev.ops = &meson_reset_ops;
136 data->rcdev.of_node = pdev->dev.of_node;
137
138 return devm_reset_controller_register(dev: &pdev->dev, rcdev: &data->rcdev);
139}
140
141static struct platform_driver meson_reset_driver = {
142 .probe = meson_reset_probe,
143 .driver = {
144 .name = "meson_reset",
145 .of_match_table = meson_reset_dt_ids,
146 },
147};
148module_platform_driver(meson_reset_driver);
149
150MODULE_DESCRIPTION("Amlogic Meson Reset Controller driver");
151MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
152MODULE_LICENSE("Dual BSD/GPL");
153

source code of linux/drivers/reset/reset-meson.c