1/*
  2 * Copyright (C) Maxime Coquelin 2015
  3 * Author:  Maxime Coquelin <mcoquelin.stm32@gmail.com>
  4 * License terms:  GNU General Public License (GPL), version 2
  5 *
  6 * Heavily based on sunxi driver from Maxime Ripard.
  7 */
  8
  9#include <linux/err.h>
 10#include <linux/io.h>
 11#include <linux/of.h>
 12#include <linux/of_address.h>
 13#include <linux/platform_device.h>
 14#include <linux/reset-controller.h>
 15#include <linux/slab.h>
 16#include <linux/spinlock.h>
 17#include <linux/types.h>
 18
 19struct stm32_reset_data {
 20	spinlock_t			lock;
 21	void __iomem			*membase;
 22	struct reset_controller_dev	rcdev;
 23};
 24
 25static int stm32_reset_assert(struct reset_controller_dev *rcdev,
 26			      unsigned long id)
 27{
 28	struct stm32_reset_data *data = container_of(rcdev,
 29						     struct stm32_reset_data,
 30						     rcdev);
 31	int bank = id / BITS_PER_LONG;
 32	int offset = id % BITS_PER_LONG;
 33	unsigned long flags;
 34	u32 reg;
 35
 36	spin_lock_irqsave(&data->lock, flags);
 37
 38	reg = readl(data->membase + (bank * 4));
 39	writel(reg | BIT(offset), data->membase + (bank * 4));
 40
 41	spin_unlock_irqrestore(&data->lock, flags);
 42
 43	return 0;
 44}
 45
 46static int stm32_reset_deassert(struct reset_controller_dev *rcdev,
 47				unsigned long id)
 48{
 49	struct stm32_reset_data *data = container_of(rcdev,
 50						     struct stm32_reset_data,
 51						     rcdev);
 52	int bank = id / BITS_PER_LONG;
 53	int offset = id % BITS_PER_LONG;
 54	unsigned long flags;
 55	u32 reg;
 56
 57	spin_lock_irqsave(&data->lock, flags);
 58
 59	reg = readl(data->membase + (bank * 4));
 60	writel(reg & ~BIT(offset), data->membase + (bank * 4));
 61
 62	spin_unlock_irqrestore(&data->lock, flags);
 63
 64	return 0;
 65}
 66
 67static const struct reset_control_ops stm32_reset_ops = {
 68	.assert		= stm32_reset_assert,
 69	.deassert	= stm32_reset_deassert,
 70};
 71
 72static const struct of_device_id stm32_reset_dt_ids[] = {
 73	 { .compatible = "st,stm32-rcc", },
 74	 { /* sentinel */ },
 75};
 76
 77static int stm32_reset_probe(struct platform_device *pdev)
 78{
 79	struct stm32_reset_data *data;
 80	struct resource *res;
 81
 82	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 83	if (!data)
 84		return -ENOMEM;
 85
 86	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 87	data->membase = devm_ioremap_resource(&pdev->dev, res);
 88	if (IS_ERR(data->membase))
 89		return PTR_ERR(data->membase);
 90
 91	spin_lock_init(&data->lock);
 92
 93	data->rcdev.owner = THIS_MODULE;
 94	data->rcdev.nr_resets = resource_size(res) * 8;
 95	data->rcdev.ops = &stm32_reset_ops;
 96	data->rcdev.of_node = pdev->dev.of_node;
 97
 98	return devm_reset_controller_register(&pdev->dev, &data->rcdev);
 99}
100
101static struct platform_driver stm32_reset_driver = {
102	.probe	= stm32_reset_probe,
103	.driver = {
104		.name		= "stm32-rcc-reset",
105		.of_match_table	= stm32_reset_dt_ids,
106	},
107};
108builtin_platform_driver(stm32_reset_driver);