// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2019 Bootlin
 * Author: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
 */

#include <linux/err.h>
#include <linux/gpio/driver.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/mfd/syscon.h>

#define LOGICVC_CTRL_REG		0x40
#define LOGICVC_CTRL_GPIO_SHIFT		11
#define LOGICVC_CTRL_GPIO_BITS		5

#define LOGICVC_POWER_CTRL_REG		0x78
#define LOGICVC_POWER_CTRL_GPIO_SHIFT	0
#define LOGICVC_POWER_CTRL_GPIO_BITS	4

struct logicvc_gpio {
	struct gpio_chip chip;
	struct regmap *regmap;
};

static void logicvc_gpio_offset(struct logicvc_gpio *logicvc, unsigned offset,
				unsigned int *reg, unsigned int *bit)
{
	if (offset >= LOGICVC_CTRL_GPIO_BITS) {
		*reg = LOGICVC_POWER_CTRL_REG;

		/* To the (virtual) power ctrl offset. */
		offset -= LOGICVC_CTRL_GPIO_BITS;
		/* To the actual bit offset in reg. */
		offset += LOGICVC_POWER_CTRL_GPIO_SHIFT;
	} else {
		*reg = LOGICVC_CTRL_REG;

		/* To the actual bit offset in reg. */
		offset += LOGICVC_CTRL_GPIO_SHIFT;
	}

	*bit = BIT(offset);
}

static int logicvc_gpio_get(struct gpio_chip *chip, unsigned offset)
{
	struct logicvc_gpio *logicvc = gpiochip_get_data(chip);
	unsigned int reg, bit, value;
	int ret;

	logicvc_gpio_offset(logicvc, offset, &reg, &bit);

	ret = regmap_read(logicvc->regmap, reg, &value);
	if (ret)
		return ret;

	return !!(value & bit);
}

static void logicvc_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
{
	struct logicvc_gpio *logicvc = gpiochip_get_data(chip);
	unsigned int reg, bit;

	logicvc_gpio_offset(logicvc, offset, &reg, &bit);

	regmap_update_bits(logicvc->regmap, reg, bit, value ? bit : 0);
}

static int logicvc_gpio_direction_output(struct gpio_chip *chip,
					 unsigned offset, int value)
{
	/* Pins are always configured as output, so just set the value. */
	logicvc_gpio_set(chip, offset, value);

	return 0;
}

static struct regmap_config logicvc_gpio_regmap_config = {
	.reg_bits	= 32,
	.val_bits	= 32,
	.reg_stride	= 4,
	.name		= "logicvc-gpio",
};

static int logicvc_gpio_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct device_node *of_node = dev->of_node;
	struct logicvc_gpio *logicvc;
	int ret;

	logicvc = devm_kzalloc(dev, sizeof(*logicvc), GFP_KERNEL);
	if (!logicvc)
		return -ENOMEM;

	/* Try to get regmap from parent first. */
	logicvc->regmap = syscon_node_to_regmap(of_node->parent);

	/* Grab our own regmap if that fails. */
	if (IS_ERR(logicvc->regmap)) {
		struct resource res;
		void __iomem *base;

		ret = of_address_to_resource(of_node, 0, &res);
		if (ret) {
			dev_err(dev, "Failed to get resource from address\n");
			return ret;
		}

		base = devm_ioremap_resource(dev, &res);
		if (IS_ERR(base))
			return PTR_ERR(base);

		logicvc_gpio_regmap_config.max_register = resource_size(&res) -
			logicvc_gpio_regmap_config.reg_stride;

		logicvc->regmap =
			devm_regmap_init_mmio(dev, base,
					      &logicvc_gpio_regmap_config);
		if (IS_ERR(logicvc->regmap)) {
			dev_err(dev, "Failed to create regmap for I/O\n");
			return PTR_ERR(logicvc->regmap);
		}
	}

	logicvc->chip.parent = dev;
	logicvc->chip.owner = THIS_MODULE;
	logicvc->chip.label = dev_name(dev);
	logicvc->chip.base = -1;
	logicvc->chip.ngpio = LOGICVC_CTRL_GPIO_BITS +
			      LOGICVC_POWER_CTRL_GPIO_BITS;
	logicvc->chip.get = logicvc_gpio_get;
	logicvc->chip.set = logicvc_gpio_set;
	logicvc->chip.direction_output = logicvc_gpio_direction_output;

	return devm_gpiochip_add_data(dev, &logicvc->chip, logicvc);
}

static const struct of_device_id logicivc_gpio_of_table[] = {
	{
		.compatible	= "xylon,logicvc-3.02.a-gpio",
	},
	{ }
};

MODULE_DEVICE_TABLE(of, logicivc_gpio_of_table);

static struct platform_driver logicvc_gpio_driver = {
	.driver	= {
		.name		= "gpio-logicvc",
		.of_match_table	= logicivc_gpio_of_table,
	},
	.probe	= logicvc_gpio_probe,
};

module_platform_driver(logicvc_gpio_driver);

MODULE_AUTHOR("Paul Kocialkowski <paul.kocialkowski@bootlin.com>");
MODULE_DESCRIPTION("Xylon LogiCVC GPIO driver");
MODULE_LICENSE("GPL");