// SPDX-License-Identifier: GPL-2.0+
/* Microchip Sparx5 Switch Reset driver
 *
 * Copyright (c) 2020 Microchip Technology Inc. and its subsidiaries.
 *
 * The Sparx5 Chip Register Model can be browsed at this location:
 * https://github.com/microchip-ung/sparx-5_reginfo
 */
#include <linux/mfd/syscon.h>
#include <linux/of_device.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/reset-controller.h>

#define PROTECT_REG    0x84
#define PROTECT_BIT    BIT(10)
#define SOFT_RESET_REG 0x00
#define SOFT_RESET_BIT BIT(1)

struct mchp_reset_context {
	struct regmap *cpu_ctrl;
	struct regmap *gcb_ctrl;
	struct reset_controller_dev rcdev;
};

static struct regmap_config sparx5_reset_regmap_config = {
	.reg_bits	= 32,
	.val_bits	= 32,
	.reg_stride	= 4,
};

static int sparx5_switch_reset(struct reset_controller_dev *rcdev,
			       unsigned long id)
{
	struct mchp_reset_context *ctx =
		container_of(rcdev, struct mchp_reset_context, rcdev);
	u32 val;

	/* Make sure the core is PROTECTED from reset */
	regmap_update_bits(ctx->cpu_ctrl, PROTECT_REG, PROTECT_BIT, PROTECT_BIT);

	/* Start soft reset */
	regmap_write(ctx->gcb_ctrl, SOFT_RESET_REG, SOFT_RESET_BIT);

	/* Wait for soft reset done */
	return regmap_read_poll_timeout(ctx->gcb_ctrl, SOFT_RESET_REG, val,
					(val & SOFT_RESET_BIT) == 0,
					1, 100);
}

static const struct reset_control_ops sparx5_reset_ops = {
	.reset = sparx5_switch_reset,
};

static int mchp_sparx5_map_syscon(struct platform_device *pdev, char *name,
				  struct regmap **target)
{
	struct device_node *syscon_np;
	struct regmap *regmap;
	int err;

	syscon_np = of_parse_phandle(pdev->dev.of_node, name, 0);
	if (!syscon_np)
		return -ENODEV;
	regmap = syscon_node_to_regmap(syscon_np);
	of_node_put(syscon_np);
	if (IS_ERR(regmap)) {
		err = PTR_ERR(regmap);
		dev_err(&pdev->dev, "No '%s' map: %d\n", name, err);
		return err;
	}
	*target = regmap;
	return 0;
}

static int mchp_sparx5_map_io(struct platform_device *pdev, int index,
			      struct regmap **target)
{
	struct resource *res;
	struct regmap *map;
	void __iomem *mem;

	mem = devm_platform_get_and_ioremap_resource(pdev, index, &res);
	if (IS_ERR(mem)) {
		dev_err(&pdev->dev, "Could not map resource %d\n", index);
		return PTR_ERR(mem);
	}
	sparx5_reset_regmap_config.name = res->name;
	map = devm_regmap_init_mmio(&pdev->dev, mem, &sparx5_reset_regmap_config);
	if (IS_ERR(map))
		return PTR_ERR(map);
	*target = map;
	return 0;
}

static int mchp_sparx5_reset_probe(struct platform_device *pdev)
{
	struct device_node *dn = pdev->dev.of_node;
	struct mchp_reset_context *ctx;
	int err;

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

	err = mchp_sparx5_map_syscon(pdev, "cpu-syscon", &ctx->cpu_ctrl);
	if (err)
		return err;
	err = mchp_sparx5_map_io(pdev, 0, &ctx->gcb_ctrl);
	if (err)
		return err;

	ctx->rcdev.owner = THIS_MODULE;
	ctx->rcdev.nr_resets = 1;
	ctx->rcdev.ops = &sparx5_reset_ops;
	ctx->rcdev.of_node = dn;

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

static const struct of_device_id mchp_sparx5_reset_of_match[] = {
	{
		.compatible = "microchip,sparx5-switch-reset",
	},
	{ }
};

static struct platform_driver mchp_sparx5_reset_driver = {
	.probe = mchp_sparx5_reset_probe,
	.driver = {
		.name = "sparx5-switch-reset",
		.of_match_table = mchp_sparx5_reset_of_match,
	},
};

static int __init mchp_sparx5_reset_init(void)
{
	return platform_driver_register(&mchp_sparx5_reset_driver);
}

postcore_initcall(mchp_sparx5_reset_init);

MODULE_DESCRIPTION("Microchip Sparx5 switch reset driver");
MODULE_AUTHOR("Steen Hegelund <steen.hegelund@microchip.com>");
MODULE_LICENSE("Dual MIT/GPL");