// SPDX-License-Identifier: GPL-2.0
/*
 * Broadcom STB generic reset controller for SW_INIT style reset controller
 *
 * Author: Florian Fainelli <f.fainelli@gmail.com>
 * Copyright (C) 2018 Broadcom
 */
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/reset-controller.h>
#include <linux/types.h>

struct brcmstb_reset {
	void __iomem *base;
	struct reset_controller_dev rcdev;
};

#define SW_INIT_SET		0x00
#define SW_INIT_CLEAR		0x04
#define SW_INIT_STATUS		0x08

#define SW_INIT_BIT(id)		BIT((id) & 0x1f)
#define SW_INIT_BANK(id)	((id) >> 5)

/* A full bank contains extra registers that we are not utilizing but still
 * qualify as a single bank.
 */
#define SW_INIT_BANK_SIZE	0x18

static inline
struct brcmstb_reset *to_brcmstb(struct reset_controller_dev *rcdev)
{
	return container_of(rcdev, struct brcmstb_reset, rcdev);
}

static int brcmstb_reset_assert(struct reset_controller_dev *rcdev,
				unsigned long id)
{
	unsigned int off = SW_INIT_BANK(id) * SW_INIT_BANK_SIZE;
	struct brcmstb_reset *priv = to_brcmstb(rcdev);

	writel_relaxed(SW_INIT_BIT(id), priv->base + off + SW_INIT_SET);

	return 0;
}

static int brcmstb_reset_deassert(struct reset_controller_dev *rcdev,
				  unsigned long id)
{
	unsigned int off = SW_INIT_BANK(id) * SW_INIT_BANK_SIZE;
	struct brcmstb_reset *priv = to_brcmstb(rcdev);

	writel_relaxed(SW_INIT_BIT(id), priv->base + off + SW_INIT_CLEAR);
	/* Maximum reset delay after de-asserting a line and seeing block
	 * operation is typically 14us for the worst case, build some slack
	 * here.
	 */
	usleep_range(100, 200);

	return 0;
}

static int brcmstb_reset_status(struct reset_controller_dev *rcdev,
				unsigned long id)
{
	unsigned int off = SW_INIT_BANK(id) * SW_INIT_BANK_SIZE;
	struct brcmstb_reset *priv = to_brcmstb(rcdev);

	return readl_relaxed(priv->base + off + SW_INIT_STATUS) &
			     SW_INIT_BIT(id);
}

static const struct reset_control_ops brcmstb_reset_ops = {
	.assert	= brcmstb_reset_assert,
	.deassert = brcmstb_reset_deassert,
	.status = brcmstb_reset_status,
};

static int brcmstb_reset_probe(struct platform_device *pdev)
{
	struct device *kdev = &pdev->dev;
	struct brcmstb_reset *priv;
	struct resource *res;

	priv = devm_kzalloc(kdev, sizeof(*priv), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!IS_ALIGNED(res->start, SW_INIT_BANK_SIZE) ||
	    !IS_ALIGNED(resource_size(res), SW_INIT_BANK_SIZE)) {
		dev_err(kdev, "incorrect register range\n");
		return -EINVAL;
	}

	priv->base = devm_ioremap_resource(kdev, res);
	if (IS_ERR(priv->base))
		return PTR_ERR(priv->base);

	dev_set_drvdata(kdev, priv);

	priv->rcdev.owner = THIS_MODULE;
	priv->rcdev.nr_resets = DIV_ROUND_DOWN_ULL(resource_size(res),
						   SW_INIT_BANK_SIZE) * 32;
	priv->rcdev.ops = &brcmstb_reset_ops;
	priv->rcdev.of_node = kdev->of_node;
	/* Use defaults: 1 cell and simple xlate function */

	return devm_reset_controller_register(kdev, &priv->rcdev);
}

static const struct of_device_id brcmstb_reset_of_match[] = {
	{ .compatible = "brcm,brcmstb-reset" },
	{ /* sentinel */ }
};

static struct platform_driver brcmstb_reset_driver = {
	.probe	= brcmstb_reset_probe,
	.driver	= {
		.name = "brcmstb-reset",
		.of_match_table = brcmstb_reset_of_match,
	},
};
module_platform_driver(brcmstb_reset_driver);

MODULE_AUTHOR("Broadcom");
MODULE_DESCRIPTION("Broadcom STB reset controller");
MODULE_LICENSE("GPL");