1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) STMicroelectronics 2018 - All Rights Reserved
4 * Author: Gabriel Fernandez <gabriel.fernandez@st.com> for STMicroelectronics.
5 */
6
7#include <linux/device.h>
8#include <linux/err.h>
9#include <linux/io.h>
10#include <linux/of.h>
11#include <linux/platform_device.h>
12#include <linux/reset-controller.h>
13
14#define CLR_OFFSET 0x4
15
16struct stm32_reset_data {
17	struct reset_controller_dev	rcdev;
18	void __iomem			*membase;
19};
20
21static inline struct stm32_reset_data *
22to_stm32_reset_data(struct reset_controller_dev *rcdev)
23{
24	return container_of(rcdev, struct stm32_reset_data, rcdev);
25}
26
27static int stm32_reset_update(struct reset_controller_dev *rcdev,
28			      unsigned long id, bool assert)
29{
30	struct stm32_reset_data *data = to_stm32_reset_data(rcdev);
31	int reg_width = sizeof(u32);
32	int bank = id / (reg_width * BITS_PER_BYTE);
33	int offset = id % (reg_width * BITS_PER_BYTE);
34	void __iomem *addr;
35
36	addr = data->membase + (bank * reg_width);
37	if (!assert)
38		addr += CLR_OFFSET;
39
40	writel(BIT(offset), addr);
41
42	return 0;
43}
44
45static int stm32_reset_assert(struct reset_controller_dev *rcdev,
46			      unsigned long id)
47{
48	return stm32_reset_update(rcdev, id, true);
49}
50
51static int stm32_reset_deassert(struct reset_controller_dev *rcdev,
52				unsigned long id)
53{
54	return stm32_reset_update(rcdev, id, false);
55}
56
57static int stm32_reset_status(struct reset_controller_dev *rcdev,
58			      unsigned long id)
59{
60	struct stm32_reset_data *data = to_stm32_reset_data(rcdev);
61	int reg_width = sizeof(u32);
62	int bank = id / (reg_width * BITS_PER_BYTE);
63	int offset = id % (reg_width * BITS_PER_BYTE);
64	u32 reg;
65
66	reg = readl(data->membase + (bank * reg_width));
67
68	return !!(reg & BIT(offset));
69}
70
71static const struct reset_control_ops stm32_reset_ops = {
72	.assert		= stm32_reset_assert,
73	.deassert	= stm32_reset_deassert,
74	.status		= stm32_reset_status,
75};
76
77static const struct of_device_id stm32_reset_dt_ids[] = {
78	{ .compatible = "st,stm32mp1-rcc"},
79	{ /* sentinel */ },
80};
81
82static int stm32_reset_probe(struct platform_device *pdev)
83{
84	struct device *dev = &pdev->dev;
85	struct stm32_reset_data *data;
86	void __iomem *membase;
87	struct resource *res;
88
89	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
90	if (!data)
91		return -ENOMEM;
92
93	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
94	membase = devm_ioremap_resource(dev, res);
95	if (IS_ERR(membase))
96		return PTR_ERR(membase);
97
98	data->membase = membase;
99	data->rcdev.owner = THIS_MODULE;
100	data->rcdev.nr_resets = resource_size(res) * BITS_PER_BYTE;
101	data->rcdev.ops = &stm32_reset_ops;
102	data->rcdev.of_node = dev->of_node;
103
104	return devm_reset_controller_register(dev, &data->rcdev);
105}
106
107static struct platform_driver stm32_reset_driver = {
108	.probe	= stm32_reset_probe,
109	.driver = {
110		.name		= "stm32mp1-reset",
111		.of_match_table	= stm32_reset_dt_ids,
112	},
113};
114
115builtin_platform_driver(stm32_reset_driver);
116