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(data->membase + (bank * reg_width));
 54
 55		if (assert)
 56			reg |= BIT(offset);
 57		else
 58			reg &= ~BIT(offset);
 59
 60		writel(reg, data->membase + (bank * reg_width));
 61
 62		spin_unlock_irqrestore(&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, 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, 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(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(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(&reset_data->rcdev);
119}