1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) STMicroelectronics 2022 - All Rights Reserved
4 * Author: Gabriel Fernandez <gabriel.fernandez@foss.st.com> for STMicroelectronics.
5 */
6
7#include <linux/of.h>
8#include <linux/platform_device.h>
9#include <linux/regmap.h>
10#include <linux/reset-controller.h>
11#include <linux/slab.h>
12#include <linux/spinlock.h>
13
14#include "clk-stm32-core.h"
15
16#define STM32_RESET_ID_MASK GENMASK(15, 0)
17
18struct stm32_reset_data {
19	/* reset lock */
20	spinlock_t			lock;
21	struct reset_controller_dev	rcdev;
22	void __iomem			*membase;
23	u32				clear_offset;
24};
25
26static inline struct stm32_reset_data *
27to_stm32_reset_data(struct reset_controller_dev *rcdev)
28{
29	return container_of(rcdev, struct stm32_reset_data, rcdev);
30}
31
32static int stm32_reset_update(struct reset_controller_dev *rcdev,
33			      unsigned long id, bool assert)
34{
35	struct stm32_reset_data *data = to_stm32_reset_data(rcdev);
36	int reg_width = sizeof(u32);
37	int bank = id / (reg_width * BITS_PER_BYTE);
38	int offset = id % (reg_width * BITS_PER_BYTE);
39
40	if (data->clear_offset) {
41		void __iomem *addr;
42
43		addr = data->membase + (bank * reg_width);
44		if (!assert)
45			addr += data->clear_offset;
46
47		writel(BIT(offset), addr);
48
49	} else {
50		unsigned long flags;
51		u32 reg;
52
53		spin_lock_irqsave(&data->lock, flags);
54
55		reg = readl(data->membase + (bank * reg_width));
56
57		if (assert)
58			reg |= BIT(offset);
59		else
60			reg &= ~BIT(offset);
61
62		writel(reg, data->membase + (bank * reg_width));
63
64		spin_unlock_irqrestore(&data->lock, flags);
65	}
66
67	return 0;
68}
69
70static int stm32_reset_assert(struct reset_controller_dev *rcdev,
71			      unsigned long id)
72{
73	return stm32_reset_update(rcdev, id, true);
74}
75
76static int stm32_reset_deassert(struct reset_controller_dev *rcdev,
77				unsigned long id)
78{
79	return stm32_reset_update(rcdev, id, false);
80}
81
82static int stm32_reset_status(struct reset_controller_dev *rcdev,
83			      unsigned long id)
84{
85	struct stm32_reset_data *data = to_stm32_reset_data(rcdev);
86	int reg_width = sizeof(u32);
87	int bank = id / (reg_width * BITS_PER_BYTE);
88	int offset = id % (reg_width * BITS_PER_BYTE);
89	u32 reg;
90
91	reg = readl(data->membase + (bank * reg_width));
92
93	return !!(reg & BIT(offset));
94}
95
96static const struct reset_control_ops stm32_reset_ops = {
97	.assert		= stm32_reset_assert,
98	.deassert	= stm32_reset_deassert,
99	.status		= stm32_reset_status,
100};
101
102int stm32_rcc_reset_init(struct device *dev, const struct of_device_id *match,
103			 void __iomem *base)
104{
105	const struct stm32_rcc_match_data *data = match->data;
106	struct stm32_reset_data *reset_data = NULL;
107
108	data = match->data;
109
110	reset_data = kzalloc(sizeof(*reset_data), GFP_KERNEL);
111	if (!reset_data)
112		return -ENOMEM;
113
114	spin_lock_init(&reset_data->lock);
115	reset_data->membase = base;
116	reset_data->rcdev.owner = THIS_MODULE;
117	reset_data->rcdev.ops = &stm32_reset_ops;
118	reset_data->rcdev.of_node = dev_of_node(dev);
119	reset_data->rcdev.nr_resets = STM32_RESET_ID_MASK;
120	reset_data->clear_offset = data->clear_offset;
121
122	return reset_controller_register(&reset_data->rcdev);
123}
124