/*
 * 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_gpio {
	struct gpio_chip chip;
	spinlock_t lock;
	void __iomem *base;
	int irq;
};

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

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' },
	},
	/*
	 * A bank exists for { 'Y', 'Z', "AA", "AB" }, but is not implemented.
	 * Only half of GPIOs Y support interrupt configuration, and none of Z,
	 * AA or AB do as they are output only.
	 */
};

#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 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;

	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;

	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;

	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;

	offset = irqd_to_hwirq(d);

	*gpio = irq_data_get_irq_chip_data(d);
	*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 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;

	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)
{
	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);
}

static int __init aspeed_gpio_probe(struct platform_device *pdev)
{
	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);
	if (!res)
		return -ENXIO;

	gpio->base = devm_ioremap_resource(&pdev->dev, res);
	if (!gpio->base)
		return -ENOMEM;

	spin_lock_init(&gpio->lock);

	gpio->chip.ngpio = ARRAY_SIZE(aspeed_gpio_banks) * 32;

	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;

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

	return aspeed_gpio_setup_irqs(gpio, pdev);
}

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

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");