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	const struct stm32_reset_cfg	**reset_lines;
 23};
 24
 25static inline struct stm32_reset_data *
 26to_stm32_reset_data(struct reset_controller_dev *rcdev)
 27{
 28	return container_of(rcdev, struct stm32_reset_data, rcdev);
 29}
 30
 31static const struct stm32_reset_cfg *stm32_get_reset_line(struct reset_controller_dev *rcdev,
 32							  unsigned long id,
 33							  struct stm32_reset_cfg *line)
 34{
 35	struct stm32_reset_data *data = to_stm32_reset_data(rcdev);
 36
 37	if (!data->reset_lines) {
 38		int reg_width = sizeof(u32);
 39		int bank = id / (reg_width * BITS_PER_BYTE);
 40		int offset = id % (reg_width * BITS_PER_BYTE);
 41
 42		line->offset = bank * reg_width;
 43		line->bit_idx = offset;
 44		line->set_clr = (data->clear_offset ? true : false);
 45
 46		return line;
 47	}
 48
 49	return data->reset_lines[id];
 50}
 51
 52static int stm32_reset_update(struct reset_controller_dev *rcdev,
 53			      unsigned long id, bool assert)
 54{
 55	struct stm32_reset_data *data = to_stm32_reset_data(rcdev);
 56	struct stm32_reset_cfg line_reset;
 57	const struct stm32_reset_cfg *ptr_line;
 58
 59	ptr_line = stm32_get_reset_line(rcdev, id, &line_reset);
 60	if (!ptr_line)
 61		return -EPERM;
 62
 63	if (ptr_line->set_clr) {
 64		void __iomem *addr;
 65
 66		addr = data->membase + ptr_line->offset;
 67		if (!assert)
 68			addr += data->clear_offset;
 69
 70		writel(BIT(ptr_line->bit_idx), addr);
 71
 72	} else {
 73		unsigned long flags;
 74		u32 reg;
 75
 76		spin_lock_irqsave(&data->lock, flags);
 77
 78		reg = readl(data->membase + ptr_line->offset);
 79
 80		if (assert)
 81			reg |= BIT(ptr_line->bit_idx);
 82		else
 83			reg &= ~BIT(ptr_line->bit_idx);
 84
 85		writel(reg, data->membase + ptr_line->offset);
 86
 87		spin_unlock_irqrestore(&data->lock, flags);
 88	}
 89
 90	return 0;
 91}
 92
 93static int stm32_reset_assert(struct reset_controller_dev *rcdev,
 94			      unsigned long id)
 95{
 96	return stm32_reset_update(rcdev, id, true);
 97}
 98
 99static int stm32_reset_deassert(struct reset_controller_dev *rcdev,
100				unsigned long id)
101{
102	return stm32_reset_update(rcdev, id, false);
103}
104
105static int stm32_reset_status(struct reset_controller_dev *rcdev,
106			      unsigned long id)
107{
108	struct stm32_reset_data *data = to_stm32_reset_data(rcdev);
109	struct stm32_reset_cfg line_reset;
110	const struct stm32_reset_cfg *ptr_line;
111	u32 reg;
112
113	ptr_line = stm32_get_reset_line(rcdev, id, &line_reset);
114	if (!ptr_line)
115		return -EPERM;
116
117	reg = readl(data->membase + ptr_line->offset);
118
119	return !!(reg & BIT(ptr_line->bit_idx));
120}
121
122static const struct reset_control_ops stm32_reset_ops = {
123	.assert		= stm32_reset_assert,
124	.deassert	= stm32_reset_deassert,
125	.status		= stm32_reset_status,
126};
127
128int stm32_rcc_reset_init(struct device *dev, struct clk_stm32_reset_data *data,
129			 void __iomem *base)
130{
131	struct stm32_reset_data *reset_data;
132
133	reset_data = kzalloc(sizeof(*reset_data), GFP_KERNEL);
134	if (!reset_data)
135		return -ENOMEM;
136
137	spin_lock_init(&reset_data->lock);
138
139	reset_data->membase = base;
140	reset_data->rcdev.owner = THIS_MODULE;
141	reset_data->rcdev.ops = &stm32_reset_ops;
142	reset_data->rcdev.of_node = dev_of_node(dev);
143	reset_data->rcdev.nr_resets = data->nr_lines;
144	reset_data->reset_lines = data->reset_lines;
145	reset_data->clear_offset = data->clear_offset;
146
147	return reset_controller_register(&reset_data->rcdev);
148}