#include <linux/device.h>
#include <linux/module.h>
#include <linux/of_platform.h>
#include <linux/regmap.h>
#include <linux/reset-controller.h>

#define RESET_REG_0 0x0

struct cds9k_reset_priv {
	struct reset_controller_dev rcdev;
	struct regmap *regmap;
	u32 base;
};

static int cds9k_reset_reset(struct reset_controller_dev *rcdev, unsigned long id)
{
	struct cds9k_reset_priv *priv = container_of(rcdev, struct cds9k_reset_priv, rcdev);

	/* reset sequence: put 0xDEAD into reg 0 for 250 ms */
	struct reg_sequence reset_sequence[] = {
		{ priv->base + RESET_REG_0, 0xDEAD, 1500 },
		{ priv->base + RESET_REG_0, 0x0000 },
	};

	if (id != 0)
		return -EINVAL;

	return regmap_multi_reg_write(priv->regmap, reset_sequence, ARRAY_SIZE(reset_sequence));
}

static int cds9k_reset_xlate(struct reset_controller_dev *rcdev,
                             const struct of_phandle_args *spec)
{
	/* single reset */
	return 0;
}

static const struct reset_control_ops cds9k_reset_ops = {
	.reset = cds9k_reset_reset,
};

static int cds9k_reset_probe(struct platform_device *pdev)
{
	struct cds9k_reset_priv *priv;
	int ret;

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

	platform_set_drvdata(pdev, priv);

	ret = device_property_read_u32(&pdev->dev, "reg", &priv->base);
	if (ret)
		return -EINVAL;

	if (!pdev->dev.parent)
		return -ENODEV;

	priv->regmap = dev_get_regmap(pdev->dev.parent, NULL);
	if (!priv->regmap)
		return -ENODEV;

	priv->rcdev.ops = &cds9k_reset_ops;
	priv->rcdev.owner = pdev->dev.driver->owner;
	priv->rcdev.of_node = pdev->dev.of_node;
	priv->rcdev.nr_resets = 1;
	priv->rcdev.of_reset_n_cells = 0;
	priv->rcdev.of_xlate = cds9k_reset_xlate;

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

static struct of_device_id cds9k_reset_of_match[] = {
	{ .compatible = "david,cds9k-reset" },
	{}
};
MODULE_DEVICE_TABLE(of, cds9k_reset_of_match);

static struct platform_driver cds9k_reset = {
	.driver = {
		.name = "cds9k-reset",
		.of_match_table = cds9k_reset_of_match,
	},
	.probe = cds9k_reset_probe
};
module_platform_driver(cds9k_reset);

MODULE_AUTHOR("David Phillips <david@yeah.nah.nz>");
MODULE_DESCRIPTION("Reset driver for the CDS9K board controller");
MODULE_LICENSE("GPL v2");