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 "reset-stm32.h"
15
16struct stm32_reset_data {
17 /* reset lock */
18 spinlock_t lock;
19 struct reset_controller_dev rcdev;
20 void __iomem *membase;
21 u32 clear_offset;
22};
23
24static inline struct stm32_reset_data *
25to_stm32_reset_data(struct reset_controller_dev *rcdev)
26{
27 return container_of(rcdev, struct stm32_reset_data, rcdev);
28}
29
30static int stm32_reset_update(struct reset_controller_dev *rcdev,
31 unsigned long id, bool assert)
32{
33 struct stm32_reset_data *data = to_stm32_reset_data(rcdev);
34 int reg_width = sizeof(u32);
35 int bank = id / (reg_width * BITS_PER_BYTE);
36 int offset = id % (reg_width * BITS_PER_BYTE);
37
38 if (data->clear_offset) {
39 void __iomem *addr;
40
41 addr = data->membase + (bank * reg_width);
42 if (!assert)
43 addr += data->clear_offset;
44
45 writel(BIT(offset), addr);
46
47 } else {
48 unsigned long flags;
49 u32 reg;
50
51 spin_lock_irqsave(&data->lock, flags);
52
53 reg = readl(addr: data->membase + (bank * reg_width));
54
55 if (assert)
56 reg |= BIT(offset);
57 else
58 reg &= ~BIT(offset);
59
60 writel(val: reg, addr: data->membase + (bank * reg_width));
61
62 spin_unlock_irqrestore(lock: &data->lock, flags);
63 }
64
65 return 0;
66}
67
68static int stm32_reset_assert(struct reset_controller_dev *rcdev,
69 unsigned long id)
70{
71 return stm32_reset_update(rcdev, id, assert: true);
72}
73
74static int stm32_reset_deassert(struct reset_controller_dev *rcdev,
75 unsigned long id)
76{
77 return stm32_reset_update(rcdev, id, assert: false);
78}
79
80static int stm32_reset_status(struct reset_controller_dev *rcdev,
81 unsigned long id)
82{
83 struct stm32_reset_data *data = to_stm32_reset_data(rcdev);
84 int reg_width = sizeof(u32);
85 int bank = id / (reg_width * BITS_PER_BYTE);
86 int offset = id % (reg_width * BITS_PER_BYTE);
87 u32 reg;
88
89 reg = readl(addr: data->membase + (bank * reg_width));
90
91 return !!(reg & BIT(offset));
92}
93
94static const struct reset_control_ops stm32_reset_ops = {
95 .assert = stm32_reset_assert,
96 .deassert = stm32_reset_deassert,
97 .status = stm32_reset_status,
98};
99
100int stm32_rcc_reset_init(struct device *dev, struct clk_stm32_reset_data *data,
101 void __iomem *base)
102{
103 struct stm32_reset_data *reset_data;
104
105 reset_data = kzalloc(size: sizeof(*reset_data), GFP_KERNEL);
106 if (!reset_data)
107 return -ENOMEM;
108
109 spin_lock_init(&reset_data->lock);
110
111 reset_data->membase = base;
112 reset_data->rcdev.owner = THIS_MODULE;
113 reset_data->rcdev.ops = &stm32_reset_ops;
114 reset_data->rcdev.of_node = dev_of_node(dev);
115 reset_data->rcdev.nr_resets = data->nr_lines;
116 reset_data->clear_offset = data->clear_offset;
117
118 return reset_controller_register(rcdev: &reset_data->rcdev);
119}
120

source code of linux/drivers/clk/stm32/reset-stm32.c