linux/drivers/reset/reset-zx2967.c

/*
 * ZTE's zx2967 family reset controller driver
 *
 * Copyright (C) 2017 ZTE Ltd.
 *
 * Author: Baoyou Xie <baoyou.xie@linaro.org>
 *
 * License terms: GNU General Public License (GPL) version 2
 */

#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/reset-controller.h>

struct zx2967_reset {
	void __iomem			*reg_base;
	spinlock_t			lock;
	struct reset_controller_dev	rcdev;
};

static int zx2967_reset_act(struct reset_controller_dev *rcdev,
			    unsigned long id, bool assert)
{
	struct zx2967_reset *reset = NULL;
	int bank = id / 32;
	int offset = id % 32;
	u32 reg;
	unsigned long flags;

	reset = container_of(rcdev, struct zx2967_reset, rcdev);

	spin_lock_irqsave(&reset->lock, flags);

	reg = readl_relaxed(reset->reg_base + (bank * 4));
	if (assert)
		reg &= ~BIT(offset);
	else
		reg |= BIT(offset);
	writel_relaxed(reg, reset->reg_base + (bank * 4));

	spin_unlock_irqrestore(&reset->lock, flags);

	return 0;
}

static int zx2967_reset_assert(struct reset_controller_dev *rcdev,
			       unsigned long id)
{
	return zx2967_reset_act(rcdev, id, true);
}

static int zx2967_reset_deassert(struct reset_controller_dev *rcdev,
				 unsigned long id)
{
	return zx2967_reset_act(rcdev, id, false);
}

static const struct reset_control_ops zx2967_reset_ops = {
	.assert		= zx2967_reset_assert,
	.deassert	= zx2967_reset_deassert,
};

static int zx2967_reset_probe(struct platform_device *pdev)
{
	struct zx2967_reset *reset;
	struct resource *res;

	reset = devm_kzalloc(&pdev->dev, sizeof(*reset), GFP_KERNEL);
	if (!reset)
		return -ENOMEM;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	reset->reg_base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(reset->reg_base))
		return PTR_ERR(reset->reg_base);

	spin_lock_init(&reset->lock);

	reset->rcdev.owner = THIS_MODULE;
	reset->rcdev.nr_resets = resource_size(res) * 8;
	reset->rcdev.ops = &zx2967_reset_ops;
	reset->rcdev.of_node = pdev->dev.of_node;

	return devm_reset_controller_register(&pdev->dev, &reset->rcdev);
}

static const struct of_device_id zx2967_reset_dt_ids[] = {
	 { .compatible = "zte,zx296718-reset", },
	 {},
};

static struct platform_driver zx2967_reset_driver = {
	.probe	= zx2967_reset_probe,
	.driver = {
		.name		= "zx2967-reset",
		.of_match_table	= zx2967_reset_dt_ids,
	},
};
builtin_platform_driver(zx2967_reset_driver);