/*
 * Ingenic JZ47xx GPIO driver
 *
 * Copyright (c) 2017 Paul Cercueil <paul@crapouillou.net>
 *
 * License terms: GNU General Public License (GPL) version 2
 */

#include <linux/gpio/driver.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/of_irq.h>
#include <linux/pinctrl/consumer.h>
#include <linux/regmap.h>

#define GPIO_PIN	0x00
#define GPIO_MSK	0x20

#define JZ4740_GPIO_DATA	0x10
#define JZ4740_GPIO_SELECT	0x50
#define JZ4740_GPIO_DIR		0x60
#define JZ4740_GPIO_TRIG	0x70
#define JZ4740_GPIO_FLAG	0x80

#define JZ4770_GPIO_INT		0x10
#define JZ4770_GPIO_PAT1	0x30
#define JZ4770_GPIO_PAT0	0x40
#define JZ4770_GPIO_FLAG	0x50

#define REG_SET(x) ((x) + 0x4)
#define REG_CLEAR(x) ((x) + 0x8)

enum jz_version {
	ID_JZ4740,
	ID_JZ4770,
	ID_JZ4780,
};

struct ingenic_gpio_chip {
	struct regmap *map;
	struct gpio_chip gc;
	struct irq_chip irq_chip;
	unsigned int irq, reg_base;
	enum jz_version version;
};

static u32 gpio_ingenic_read_reg(struct ingenic_gpio_chip *jzgc, u8 reg)
{
	unsigned int val;

	regmap_read(jzgc->map, jzgc->reg_base + reg, &val);

	return (u32) val;
}

static void gpio_ingenic_set_bit(struct ingenic_gpio_chip *jzgc,
		u8 reg, u8 offset, bool set)
{
	if (set)
		reg = REG_SET(reg);
	else
		reg = REG_CLEAR(reg);

	regmap_write(jzgc->map, jzgc->reg_base + reg, BIT(offset));
}

static inline bool gpio_get_value(struct ingenic_gpio_chip *jzgc, u8 offset)
{
	unsigned int val = gpio_ingenic_read_reg(jzgc, GPIO_PIN);

	return !!(val & BIT(offset));
}

static void gpio_set_value(struct ingenic_gpio_chip *jzgc, u8 offset, int value)
{
	if (jzgc->version >= ID_JZ4770)
		gpio_ingenic_set_bit(jzgc, JZ4770_GPIO_PAT0, offset, !!value);
	else
		gpio_ingenic_set_bit(jzgc, JZ4740_GPIO_DATA, offset, !!value);
}

static void irq_set_type(struct ingenic_gpio_chip *jzgc,
		u8 offset, unsigned int type)
{
	u8 reg1, reg2;

	if (jzgc->version >= ID_JZ4770) {
		reg1 = JZ4770_GPIO_PAT1;
		reg2 = JZ4770_GPIO_PAT0;
	} else {
		reg1 = JZ4740_GPIO_TRIG;
		reg2 = JZ4740_GPIO_DIR;
	}

	switch (type) {
	case IRQ_TYPE_EDGE_RISING:
		gpio_ingenic_set_bit(jzgc, reg2, offset, true);
		gpio_ingenic_set_bit(jzgc, reg1, offset, true);
		break;
	case IRQ_TYPE_EDGE_FALLING:
		gpio_ingenic_set_bit(jzgc, reg2, offset, false);
		gpio_ingenic_set_bit(jzgc, reg1, offset, true);
		break;
	case IRQ_TYPE_LEVEL_HIGH:
		gpio_ingenic_set_bit(jzgc, reg2, offset, true);
		gpio_ingenic_set_bit(jzgc, reg1, offset, false);
		break;
	case IRQ_TYPE_LEVEL_LOW:
	default:
		gpio_ingenic_set_bit(jzgc, reg2, offset, false);
		gpio_ingenic_set_bit(jzgc, reg1, offset, false);
		break;
	}
}

static void ingenic_gpio_irq_mask(struct irq_data *irqd)
{
	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
	struct ingenic_gpio_chip *jzgc = gpiochip_get_data(gc);

	gpio_ingenic_set_bit(jzgc, GPIO_MSK, irqd->hwirq, true);
}

static void ingenic_gpio_irq_unmask(struct irq_data *irqd)
{
	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
	struct ingenic_gpio_chip *jzgc = gpiochip_get_data(gc);

	gpio_ingenic_set_bit(jzgc, GPIO_MSK, irqd->hwirq, false);
}

static void ingenic_gpio_irq_enable(struct irq_data *irqd)
{
	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
	struct ingenic_gpio_chip *jzgc = gpiochip_get_data(gc);
	int irq = irqd->hwirq;

	if (jzgc->version >= ID_JZ4770)
		gpio_ingenic_set_bit(jzgc, JZ4770_GPIO_INT, irq, true);
	else
		gpio_ingenic_set_bit(jzgc, JZ4740_GPIO_SELECT, irq, true);

	ingenic_gpio_irq_unmask(irqd);
}

static void ingenic_gpio_irq_disable(struct irq_data *irqd)
{
	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
	struct ingenic_gpio_chip *jzgc = gpiochip_get_data(gc);
	int irq = irqd->hwirq;

	ingenic_gpio_irq_mask(irqd);

	if (jzgc->version >= ID_JZ4770)
		gpio_ingenic_set_bit(jzgc, JZ4770_GPIO_INT, irq, false);
	else
		gpio_ingenic_set_bit(jzgc, JZ4740_GPIO_SELECT, irq, false);
}

static void ingenic_gpio_irq_ack(struct irq_data *irqd)
{
	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
	struct ingenic_gpio_chip *jzgc = gpiochip_get_data(gc);
	int irq = irqd->hwirq;
	bool high;

	if (irqd_get_trigger_type(irqd) == IRQ_TYPE_EDGE_BOTH) {
		/*
		 * Switch to an interrupt for the opposite edge to the one that
		 * triggered the interrupt being ACKed.
		 */
		high = gpio_get_value(jzgc, irq);
		if (high)
			irq_set_type(jzgc, irq, IRQ_TYPE_EDGE_FALLING);
		else
			irq_set_type(jzgc, irq, IRQ_TYPE_EDGE_RISING);
	}

	if (jzgc->version >= ID_JZ4770)
		gpio_ingenic_set_bit(jzgc, JZ4770_GPIO_FLAG, irq, false);
	else
		gpio_ingenic_set_bit(jzgc, JZ4740_GPIO_DATA, irq, true);
}

static int ingenic_gpio_irq_set_type(struct irq_data *irqd, unsigned int type)
{
	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
	struct ingenic_gpio_chip *jzgc = gpiochip_get_data(gc);

	switch (type) {
	case IRQ_TYPE_EDGE_BOTH:
	case IRQ_TYPE_EDGE_RISING:
	case IRQ_TYPE_EDGE_FALLING:
		irq_set_handler_locked(irqd, handle_edge_irq);
		break;
	case IRQ_TYPE_LEVEL_HIGH:
	case IRQ_TYPE_LEVEL_LOW:
		irq_set_handler_locked(irqd, handle_level_irq);
		break;
	default:
		irq_set_handler_locked(irqd, handle_bad_irq);
	}

	if (type == IRQ_TYPE_EDGE_BOTH) {
		/*
		 * The hardware does not support interrupts on both edges. The
		 * best we can do is to set up a single-edge interrupt and then
		 * switch to the opposing edge when ACKing the interrupt.
		 */
		bool high = gpio_get_value(jzgc, irqd->hwirq);

		type = high ? IRQ_TYPE_EDGE_FALLING : IRQ_TYPE_EDGE_RISING;
	}

	irq_set_type(jzgc, irqd->hwirq, type);
	return 0;
}

static int ingenic_gpio_irq_set_wake(struct irq_data *irqd, unsigned int on)
{
	struct gpio_chip *gc = irq_data_get_irq_chip_data(irqd);
	struct ingenic_gpio_chip *jzgc = gpiochip_get_data(gc);

	return irq_set_irq_wake(jzgc->irq, on);
}

static void ingenic_gpio_irq_handler(struct irq_desc *desc)
{
	struct gpio_chip *gc = irq_desc_get_handler_data(desc);
	struct ingenic_gpio_chip *jzgc = gpiochip_get_data(gc);
	struct irq_chip *irq_chip = irq_data_get_irq_chip(&desc->irq_data);
	unsigned long flag, i;

	chained_irq_enter(irq_chip, desc);

	if (jzgc->version >= ID_JZ4770)
		flag = gpio_ingenic_read_reg(jzgc, JZ4770_GPIO_FLAG);
	else
		flag = gpio_ingenic_read_reg(jzgc, JZ4740_GPIO_FLAG);

	for_each_set_bit(i, &flag, 32)
		generic_handle_irq(irq_linear_revmap(gc->irq.domain, i));
	chained_irq_exit(irq_chip, desc);
}

static void ingenic_gpio_set(struct gpio_chip *gc,
		unsigned int offset, int value)
{
	struct ingenic_gpio_chip *jzgc = gpiochip_get_data(gc);

	gpio_set_value(jzgc, offset, value);
}

static int ingenic_gpio_get(struct gpio_chip *gc, unsigned int offset)
{
	struct ingenic_gpio_chip *jzgc = gpiochip_get_data(gc);

	return (int) gpio_get_value(jzgc, offset);
}

static int ingenic_gpio_direction_input(struct gpio_chip *gc,
		unsigned int offset)
{
	return pinctrl_gpio_direction_input(gc->base + offset);
}

static int ingenic_gpio_direction_output(struct gpio_chip *gc,
		unsigned int offset, int value)
{
	ingenic_gpio_set(gc, offset, value);
	return pinctrl_gpio_direction_output(gc->base + offset);
}

static const struct of_device_id ingenic_gpio_of_match[] = {
	{ .compatible = "ingenic,jz4740-gpio", .data = (void *)ID_JZ4740 },
	{ .compatible = "ingenic,jz4770-gpio", .data = (void *)ID_JZ4770 },
	{ .compatible = "ingenic,jz4780-gpio", .data = (void *)ID_JZ4780 },
	{},
};
MODULE_DEVICE_TABLE(of, ingenic_gpio_of_match);

static int ingenic_gpio_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	const struct of_device_id *of_id = of_match_device(
			ingenic_gpio_of_match, dev);
	struct ingenic_gpio_chip *jzgc;
	u32 bank;
	int err;

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

	jzgc->map = dev_get_drvdata(dev->parent);
	if (!jzgc->map) {
		dev_err(dev, "Cannot get parent regmap\n");
		return -ENXIO;
	}

	err = of_property_read_u32(dev->of_node, "reg", &bank);
	if (err) {
		dev_err(dev, "Cannot read \"reg\" property: %i\n", err);
		return err;
	}

	jzgc->reg_base = bank * 0x100;

	jzgc->gc.label = devm_kasprintf(dev, GFP_KERNEL, "GPIO%c", 'A' + bank);
	if (!jzgc->gc.label)
		return -ENOMEM;

	/* DO NOT EXPAND THIS: FOR BACKWARD GPIO NUMBERSPACE COMPATIBIBILITY
	 * ONLY: WORK TO TRANSITION CONSUMERS TO USE THE GPIO DESCRIPTOR API IN
	 * <linux/gpio/consumer.h> INSTEAD.
	 */
	jzgc->gc.base = bank * 32;

	jzgc->gc.ngpio = 32;
	jzgc->gc.parent = dev;
	jzgc->gc.of_node = dev->of_node;
	jzgc->gc.owner = THIS_MODULE;
	jzgc->version = (enum jz_version)of_id->data;

	jzgc->gc.set = ingenic_gpio_set;
	jzgc->gc.get = ingenic_gpio_get;
	jzgc->gc.direction_input = ingenic_gpio_direction_input;
	jzgc->gc.direction_output = ingenic_gpio_direction_output;

	if (of_property_read_bool(dev->of_node, "gpio-ranges")) {
		jzgc->gc.request = gpiochip_generic_request;
		jzgc->gc.free = gpiochip_generic_free;
	}

	err = devm_gpiochip_add_data(dev, &jzgc->gc, jzgc);
	if (err)
		return err;

	jzgc->irq = irq_of_parse_and_map(dev->of_node, 0);
	if (!jzgc->irq)
		return -EINVAL;

	jzgc->irq_chip.name = jzgc->gc.label;
	jzgc->irq_chip.irq_enable = ingenic_gpio_irq_enable;
	jzgc->irq_chip.irq_disable = ingenic_gpio_irq_disable;
	jzgc->irq_chip.irq_unmask = ingenic_gpio_irq_unmask;
	jzgc->irq_chip.irq_mask = ingenic_gpio_irq_mask;
	jzgc->irq_chip.irq_ack = ingenic_gpio_irq_ack;
	jzgc->irq_chip.irq_set_type = ingenic_gpio_irq_set_type;
	jzgc->irq_chip.irq_set_wake = ingenic_gpio_irq_set_wake;
	jzgc->irq_chip.flags = IRQCHIP_MASK_ON_SUSPEND;

	err = gpiochip_irqchip_add(&jzgc->gc, &jzgc->irq_chip, 0,
			handle_level_irq, IRQ_TYPE_NONE);
	if (err)
		return err;

	gpiochip_set_chained_irqchip(&jzgc->gc, &jzgc->irq_chip,
			jzgc->irq, ingenic_gpio_irq_handler);
	return 0;
}

static int ingenic_gpio_remove(struct platform_device *pdev)
{
	return 0;
}

static struct platform_driver ingenic_gpio_driver = {
	.driver = {
		.name = "gpio-ingenic",
		.of_match_table = of_match_ptr(ingenic_gpio_of_match),
	},
	.probe = ingenic_gpio_probe,
	.remove = ingenic_gpio_remove,
};

static int __init ingenic_gpio_drv_register(void)
{
	return platform_driver_register(&ingenic_gpio_driver);
}
subsys_initcall(ingenic_gpio_drv_register);

static void __exit ingenic_gpio_drv_unregister(void)
{
	platform_driver_unregister(&ingenic_gpio_driver);
}
module_exit(ingenic_gpio_drv_unregister);

MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
MODULE_DESCRIPTION("Ingenic JZ47xx GPIO driver");
MODULE_LICENSE("GPL");