/*
 * Copyright 2015 IBM Corp.
 *
 * Joel Stanley <joel@jms.id.au>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/spinlock.h>
#include <linux/platform_device.h>
#include <linux/gpio/driver.h>
#include <linux/pinctrl/consumer.h>

struct aspeed_bank_props {
	unsigned int bank;
	u32 input;
	u32 output;
};

struct aspeed_gpio_config {
	unsigned int nr_gpios;
	const struct aspeed_bank_props *props;
};

struct aspeed_gpio {
	struct gpio_chip chip;
	spinlock_t lock;
	void __iomem *base;
	int irq;
	const struct aspeed_gpio_config *config;
};

struct aspeed_gpio_bank {
	uint16_t	val_regs;
	uint16_t	irq_regs;
	const char	names[4][3];
};

static const struct aspeed_gpio_bank aspeed_gpio_banks[] = {
	{
		.val_regs = 0x0000,
		.irq_regs = 0x0008,
		.names = { "A", "B", "C", "D" },
	},
	{
		.val_regs = 0x0020,
		.irq_regs = 0x0028,
		.names = { "E", "F", "G", "H" },
	},
	{
		.val_regs = 0x0070,
		.irq_regs = 0x0098,
		.names = { "I", "J", "K", "L" },
	},
	{
		.val_regs = 0x0078,
		.irq_regs = 0x00e8,
		.names = { "M", "N", "O", "P" },
	},
	{
		.val_regs = 0x0080,
		.irq_regs = 0x0118,
		.names = { "Q", "R", "S", "T" },
	},
	{
		.val_regs = 0x0088,
		.irq_regs = 0x0148,
		.names = { "U", "V", "W", "X" },
	},
	{
		.val_regs = 0x01E0,
		.irq_regs = 0x0178,
		.names = { "Y", "Z", "AA", "AB" },
	},
	{
		.val_regs = 0x01E8,
		.irq_regs = 0x01A8,
		.names = { "AC", "", "", "" },
	},
};

#define GPIO_BANK(x)	((x) >> 5)
#define GPIO_OFFSET(x)	((x) & 0x1f)
#define GPIO_BIT(x)	BIT(GPIO_OFFSET(x))

#define GPIO_DATA	0x00
#define GPIO_DIR	0x04

#define GPIO_IRQ_ENABLE	0x00
#define GPIO_IRQ_TYPE0	0x04
#define GPIO_IRQ_TYPE1	0x08
#define GPIO_IRQ_TYPE2	0x0c
#define GPIO_IRQ_STATUS	0x10

static const struct aspeed_gpio_bank *to_bank(unsigned int offset)
{
	unsigned int bank = GPIO_BANK(offset);

	WARN_ON(bank > ARRAY_SIZE(aspeed_gpio_banks));
	return &aspeed_gpio_banks[bank];
}

static inline bool is_bank_props_sentinel(const struct aspeed_bank_props *props)
{
	return !(props->input || props->output);
}

static inline const struct aspeed_bank_props *find_bank_props(
		struct aspeed_gpio *gpio, unsigned int offset)
{
	const struct aspeed_bank_props *props = gpio->config->props;

	while (!is_bank_props_sentinel(props)) {
		if (props->bank == GPIO_BANK(offset))
			return props;
		props++;
	}

	return NULL;
}

static inline bool have_gpio(struct aspeed_gpio *gpio, unsigned int offset)
{
	const struct aspeed_bank_props *props = find_bank_props(gpio, offset);
	const struct aspeed_gpio_bank *bank = to_bank(offset);
	unsigned int group = GPIO_OFFSET(offset) / 8;

	return bank->names[group][0] != '\0' &&
		(!props || ((props->input | props->output) & GPIO_BIT(offset)));
}

static inline bool have_input(struct aspeed_gpio *gpio, unsigned int offset)
{
	const struct aspeed_bank_props *props = find_bank_props(gpio, offset);

	return !props || (props->input & GPIO_BIT(offset));
}

#define have_irq(g, o) have_input((g), (o))

static inline bool have_output(struct aspeed_gpio *gpio, unsigned int offset)
{
	const struct aspeed_bank_props *props = find_bank_props(gpio, offset);

	return !props || (props->output & GPIO_BIT(offset));
}

static void __iomem *bank_val_reg(struct aspeed_gpio *gpio,
		const struct aspeed_gpio_bank *bank,
		unsigned int reg)
{
	return gpio->base + bank->val_regs + reg;
}

static void __iomem *bank_irq_reg(struct aspeed_gpio *gpio,
		const struct aspeed_gpio_bank *bank,
		unsigned int reg)
{
	return gpio->base + bank->irq_regs + reg;
}

static int aspeed_gpio_get(struct gpio_chip *gc, unsigned int offset)
{
	struct aspeed_gpio *gpio = gpiochip_get_data(gc);
	const struct aspeed_gpio_bank *bank = to_bank(offset);

	return !!(ioread32(bank_val_reg(gpio, bank, GPIO_DATA))
			& GPIO_BIT(offset));
}

static void __aspeed_gpio_set(struct gpio_chip *gc, unsigned int offset,
			      int val)
{
	struct aspeed_gpio *gpio = gpiochip_get_data(gc);
	const struct aspeed_gpio_bank *bank = to_bank(offset);
	void __iomem *addr;
	u32 reg;

	addr = bank_val_reg(gpio, bank, GPIO_DATA);
	reg = ioread32(addr);

	if (val)
		reg |= GPIO_BIT(offset);
	else
		reg &= ~GPIO_BIT(offset);

	iowrite32(reg, addr);
}

static void aspeed_gpio_set(struct gpio_chip *gc, unsigned int offset,
			    int val)
{
	struct aspeed_gpio *gpio = gpiochip_get_data(gc);
	unsigned long flags;

	spin_lock_irqsave(&gpio->lock, flags);

	__aspeed_gpio_set(gc, offset, val);

	spin_unlock_irqrestore(&gpio->lock, flags);
}

static int aspeed_gpio_dir_in(struct gpio_chip *gc, unsigned int offset)
{
	struct aspeed_gpio *gpio = gpiochip_get_data(gc);
	const struct aspeed_gpio_bank *bank = to_bank(offset);
	unsigned long flags;
	u32 reg;

	if (!have_input(gpio, offset))
		return -ENOTSUPP;

	spin_lock_irqsave(&gpio->lock, flags);

	reg = ioread32(bank_val_reg(gpio, bank, GPIO_DIR));
	iowrite32(reg & ~GPIO_BIT(offset), bank_val_reg(gpio, bank, GPIO_DIR));

	spin_unlock_irqrestore(&gpio->lock, flags);

	return 0;
}

static int aspeed_gpio_dir_out(struct gpio_chip *gc,
			       unsigned int offset, int val)
{
	struct aspeed_gpio *gpio = gpiochip_get_data(gc);
	const struct aspeed_gpio_bank *bank = to_bank(offset);
	unsigned long flags;
	u32 reg;

	if (!have_output(gpio, offset))
		return -ENOTSUPP;

	spin_lock_irqsave(&gpio->lock, flags);

	reg = ioread32(bank_val_reg(gpio, bank, GPIO_DIR));
	iowrite32(reg | GPIO_BIT(offset), bank_val_reg(gpio, bank, GPIO_DIR));

	__aspeed_gpio_set(gc, offset, val);

	spin_unlock_irqrestore(&gpio->lock, flags);

	return 0;
}

static int aspeed_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
{
	struct aspeed_gpio *gpio = gpiochip_get_data(gc);
	const struct aspeed_gpio_bank *bank = to_bank(offset);
	unsigned long flags;
	u32 val;

	if (!have_input(gpio, offset))
		return 0;

	if (!have_output(gpio, offset))
		return 1;

	spin_lock_irqsave(&gpio->lock, flags);

	val = ioread32(bank_val_reg(gpio, bank, GPIO_DIR)) & GPIO_BIT(offset);

	spin_unlock_irqrestore(&gpio->lock, flags);

	return !val;

}

static inline int irqd_to_aspeed_gpio_data(struct irq_data *d,
		struct aspeed_gpio **gpio,
		const struct aspeed_gpio_bank **bank,
		u32 *bit)
{
	int offset;
	struct aspeed_gpio *internal;

	offset = irqd_to_hwirq(d);

	internal = irq_data_get_irq_chip_data(d);

	/* This might be a bit of a questionable place to check */
	if (!have_irq(internal, offset))
		return -ENOTSUPP;

	*gpio = internal;
	*bank = to_bank(offset);
	*bit = GPIO_BIT(offset);

	return 0;
}

static void aspeed_gpio_irq_ack(struct irq_data *d)
{
	const struct aspeed_gpio_bank *bank;
	struct aspeed_gpio *gpio;
	unsigned long flags;
	void __iomem *status_addr;
	u32 bit;
	int rc;

	rc = irqd_to_aspeed_gpio_data(d, &gpio, &bank, &bit);
	if (rc)
		return;

	status_addr = bank_irq_reg(gpio, bank, GPIO_IRQ_STATUS);

	spin_lock_irqsave(&gpio->lock, flags);
	iowrite32(bit, status_addr);
	spin_unlock_irqrestore(&gpio->lock, flags);
}

static void aspeed_gpio_irq_set_mask(struct irq_data *d, bool set)
{
	const struct aspeed_gpio_bank *bank;
	struct aspeed_gpio *gpio;
	unsigned long flags;
	u32 reg, bit;
	void __iomem *addr;
	int rc;

	rc = irqd_to_aspeed_gpio_data(d, &gpio, &bank, &bit);
	if (rc)
		return;

	addr = bank_irq_reg(gpio, bank, GPIO_IRQ_ENABLE);

	spin_lock_irqsave(&gpio->lock, flags);

	reg = ioread32(addr);
	if (set)
		reg |= bit;
	else
		reg &= bit;
	iowrite32(reg, addr);

	spin_unlock_irqrestore(&gpio->lock, flags);
}

static void aspeed_gpio_irq_mask(struct irq_data *d)
{
	aspeed_gpio_irq_set_mask(d, false);
}

static void aspeed_gpio_irq_unmask(struct irq_data *d)
{
	aspeed_gpio_irq_set_mask(d, true);
}

static int aspeed_gpio_set_type(struct irq_data *d, unsigned int type)
{
	u32 type0 = 0;
	u32 type1 = 0;
	u32 type2 = 0;
	u32 bit, reg;
	const struct aspeed_gpio_bank *bank;
	irq_flow_handler_t handler;
	struct aspeed_gpio *gpio;
	unsigned long flags;
	void __iomem *addr;
	int rc;

	rc = irqd_to_aspeed_gpio_data(d, &gpio, &bank, &bit);
	if (rc)
		return -EINVAL;

	switch (type & IRQ_TYPE_SENSE_MASK) {
	case IRQ_TYPE_EDGE_BOTH:
		type2 |= bit;
	case IRQ_TYPE_EDGE_RISING:
		type0 |= bit;
	case IRQ_TYPE_EDGE_FALLING:
		handler = handle_edge_irq;
		break;
	case IRQ_TYPE_LEVEL_HIGH:
		type0 |= bit;
	case IRQ_TYPE_LEVEL_LOW:
		type1 |= bit;
		handler = handle_level_irq;
		break;
	default:
		return -EINVAL;
	}

	spin_lock_irqsave(&gpio->lock, flags);

	addr = bank_irq_reg(gpio, bank, GPIO_IRQ_TYPE0);
	reg = ioread32(addr);
	reg = (reg & ~bit) | type0;
	iowrite32(reg, addr);

	addr = bank_irq_reg(gpio, bank, GPIO_IRQ_TYPE1);
	reg = ioread32(addr);
	reg = (reg & ~bit) | type1;
	iowrite32(reg, addr);

	addr = bank_irq_reg(gpio, bank, GPIO_IRQ_TYPE2);
	reg = ioread32(addr);
	reg = (reg & ~bit) | type2;
	iowrite32(reg, addr);

	spin_unlock_irqrestore(&gpio->lock, flags);

	irq_set_handler_locked(d, handler);

	return 0;
}

static void aspeed_gpio_irq_handler(struct irq_desc *desc)
{
	struct gpio_chip *gc = irq_desc_get_handler_data(desc);
	struct irq_chip *ic = irq_desc_get_chip(desc);
	struct aspeed_gpio *data = gpiochip_get_data(gc);
	unsigned int i, p, girq;
	unsigned long reg;

	chained_irq_enter(ic, desc);

	for (i = 0; i < ARRAY_SIZE(aspeed_gpio_banks); i++) {
		const struct aspeed_gpio_bank *bank = &aspeed_gpio_banks[i];

		reg = ioread32(bank_irq_reg(data, bank, GPIO_IRQ_STATUS));

		for_each_set_bit(p, &reg, 32) {
			girq = irq_find_mapping(gc->irqdomain, i * 32 + p);
			generic_handle_irq(girq);
		}

	}

	chained_irq_exit(ic, desc);
}

static struct irq_chip aspeed_gpio_irqchip = {
	.name		= "aspeed-gpio",
	.irq_ack	= aspeed_gpio_irq_ack,
	.irq_mask	= aspeed_gpio_irq_mask,
	.irq_unmask	= aspeed_gpio_irq_unmask,
	.irq_set_type	= aspeed_gpio_set_type,
};

static void set_irq_valid_mask(struct aspeed_gpio *gpio)
{
	const struct aspeed_bank_props *props = gpio->config->props;

	while (!is_bank_props_sentinel(props)) {
		unsigned int offset;
		const unsigned long int input = props->input;

		/* Pretty crummy approach, but similar to GPIO core */
		for_each_clear_bit(offset, &input, 32) {
			unsigned int i = props->bank * 32 + offset;

			if (i >= gpio->config->nr_gpios)
				break;

			clear_bit(i, gpio->chip.irq_valid_mask);
		}

		props++;
	}
}

static int aspeed_gpio_setup_irqs(struct aspeed_gpio *gpio,
		struct platform_device *pdev)
{
	int rc;

	rc = platform_get_irq(pdev, 0);
	if (rc < 0)
		return rc;

	gpio->irq = rc;

	set_irq_valid_mask(gpio);

	rc = gpiochip_irqchip_add(&gpio->chip, &aspeed_gpio_irqchip,
			0, handle_bad_irq, IRQ_TYPE_NONE);
	if (rc) {
		dev_info(&pdev->dev, "Could not add irqchip\n");
		return rc;
	}

	gpiochip_set_chained_irqchip(&gpio->chip, &aspeed_gpio_irqchip,
				     gpio->irq, aspeed_gpio_irq_handler);

	return 0;
}

static int aspeed_gpio_request(struct gpio_chip *chip, unsigned int offset)
{
	if (!have_gpio(gpiochip_get_data(chip), offset))
		return -ENODEV;

	return pinctrl_request_gpio(chip->base + offset);
}

static void aspeed_gpio_free(struct gpio_chip *chip, unsigned int offset)
{
	pinctrl_free_gpio(chip->base + offset);
}

/*
 * Any banks not specified in a struct aspeed_bank_props array are assumed to
 * have the properties:
 *
 *     { .input = 0xffffffff, .output = 0xffffffff }
 */

static const struct aspeed_bank_props ast2400_bank_props[] = {
	/*     input	  output   */
	{ 5, 0xffffffff, 0x0000ffff }, /* U/V/W/X */
	{ 6, 0x0000000f, 0x0fffff0f }, /* Y/Z/AA/AB, two 4-GPIO holes */
	{ },
};

static const struct aspeed_gpio_config ast2400_config =
	/* 220 for simplicity, really 216 with two 4-GPIO holes, four at end */
	{ .nr_gpios = 220, .props = ast2400_bank_props, };

static const struct aspeed_bank_props ast2500_bank_props[] = {
	/*     input	  output   */
	{ 5, 0xffffffff, 0x0000ffff }, /* U/V/W/X */
	{ 6, 0x0fffffff, 0x0fffffff }, /* Y/Z/AA/AB, 4-GPIO hole */
	{ 7, 0x000000ff, 0x000000ff }, /* AC */
	{ },
};

static const struct aspeed_gpio_config ast2500_config =
	/* 232 for simplicity, actual number is 228 (4-GPIO hole in GPIOAB) */
	{ .nr_gpios = 232, .props = ast2500_bank_props, };

static const struct of_device_id aspeed_gpio_of_table[] = {
	{ .compatible = "aspeed,ast2400-gpio", .data = &ast2400_config, },
	{ .compatible = "aspeed,ast2500-gpio", .data = &ast2500_config, },
	{}
};
MODULE_DEVICE_TABLE(of, aspeed_gpio_of_table);

static int __init aspeed_gpio_probe(struct platform_device *pdev)
{
	const struct of_device_id *gpio_id;
	struct aspeed_gpio *gpio;
	struct resource *res;
	int rc;

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

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	gpio->base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(gpio->base))
		return PTR_ERR(gpio->base);

	spin_lock_init(&gpio->lock);

	gpio_id = of_match_node(aspeed_gpio_of_table, pdev->dev.of_node);
	if (!gpio_id)
		return -EINVAL;

	gpio->config = gpio_id->data;

	gpio->chip.ngpio = gpio->config->nr_gpios;
	gpio->chip.parent = &pdev->dev;
	gpio->chip.direction_input = aspeed_gpio_dir_in;
	gpio->chip.direction_output = aspeed_gpio_dir_out;
	gpio->chip.get_direction = aspeed_gpio_get_direction;
	gpio->chip.request = aspeed_gpio_request;
	gpio->chip.free = aspeed_gpio_free;
	gpio->chip.get = aspeed_gpio_get;
	gpio->chip.set = aspeed_gpio_set;
	gpio->chip.label = dev_name(&pdev->dev);
	gpio->chip.base = -1;
	gpio->chip.irq_need_valid_mask = true;

	rc = devm_gpiochip_add_data(&pdev->dev, &gpio->chip, gpio);
	if (rc < 0)
		return rc;

	return aspeed_gpio_setup_irqs(gpio, pdev);
}

static struct platform_driver aspeed_gpio_driver = {
	.driver = {
		.name = KBUILD_MODNAME,
		.of_match_table = aspeed_gpio_of_table,
	},
};

module_platform_driver_probe(aspeed_gpio_driver, aspeed_gpio_probe);

MODULE_DESCRIPTION("Aspeed GPIO Driver");
MODULE_LICENSE("GPL");