/*
 * Copyright (C) ST-Ericsson SA 2010
 *
 * License Terms: GNU General Public License, version 2
 * Author: Rabin Vincent <rabin.vincent@stericsson.com> for ST-Ericsson
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/gpio.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/mfd/stmpe.h>

/*
 * These registers are modified under the irq bus lock and cached to avoid
 * unnecessary writes in bus_sync_unlock.
 */
enum { REG_RE, REG_FE, REG_IE };

#define CACHE_NR_REGS	3
#define CACHE_NR_BANKS	(STMPE_NR_GPIOS / 8)

struct stmpe_gpio {
	struct gpio_chip chip;
	struct stmpe *stmpe;
	struct device *dev;
	struct mutex irq_lock;

	int irq_base;
	unsigned norequest_mask;

	/* Caches of interrupt control registers for bus_lock */
	u8 regs[CACHE_NR_REGS][CACHE_NR_BANKS];
	u8 oldregs[CACHE_NR_REGS][CACHE_NR_BANKS];
};

static inline struct stmpe_gpio *to_stmpe_gpio(struct gpio_chip *chip)
{
	return container_of(chip, struct stmpe_gpio, chip);
}

static int stmpe_gpio_get(struct gpio_chip *chip, unsigned offset)
{
	struct stmpe_gpio *stmpe_gpio = to_stmpe_gpio(chip);
	struct stmpe *stmpe = stmpe_gpio->stmpe;
	u8 reg = stmpe->regs[STMPE_IDX_GPMR_LSB] - (offset / 8);
	u8 mask = 1 << (offset % 8);
	int ret;

	ret = stmpe_reg_read(stmpe, reg);
	if (ret < 0)
		return ret;

	return !!(ret & mask);
}

static void stmpe_gpio_set(struct gpio_chip *chip, unsigned offset, int val)
{
	struct stmpe_gpio *stmpe_gpio = to_stmpe_gpio(chip);
	struct stmpe *stmpe = stmpe_gpio->stmpe;
	int which = val ? STMPE_IDX_GPSR_LSB : STMPE_IDX_GPCR_LSB;
	u8 reg = stmpe->regs[which] - (offset / 8);
	u8 mask = 1 << (offset % 8);

	/*
	 * Some variants have single register for gpio set/clear functionality.
	 * For them we need to write 0 to clear and 1 to set.
	 */
	if (stmpe->regs[STMPE_IDX_GPSR_LSB] == stmpe->regs[STMPE_IDX_GPCR_LSB])
		stmpe_set_bits(stmpe, reg, mask, val ? mask : 0);
	else
		stmpe_reg_write(stmpe, reg, mask);
}

static int stmpe_gpio_direction_output(struct gpio_chip *chip,
					 unsigned offset, int val)
{
	struct stmpe_gpio *stmpe_gpio = to_stmpe_gpio(chip);
	struct stmpe *stmpe = stmpe_gpio->stmpe;
	u8 reg = stmpe->regs[STMPE_IDX_GPDR_LSB] - (offset / 8);
	u8 mask = 1 << (offset % 8);

	stmpe_gpio_set(chip, offset, val);

	return stmpe_set_bits(stmpe, reg, mask, mask);
}

static int stmpe_gpio_direction_input(struct gpio_chip *chip,
					unsigned offset)
{
	struct stmpe_gpio *stmpe_gpio = to_stmpe_gpio(chip);
	struct stmpe *stmpe = stmpe_gpio->stmpe;
	u8 reg = stmpe->regs[STMPE_IDX_GPDR_LSB] - (offset / 8);
	u8 mask = 1 << (offset % 8);

	return stmpe_set_bits(stmpe, reg, mask, 0);
}

static int stmpe_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
{
	struct stmpe_gpio *stmpe_gpio = to_stmpe_gpio(chip);

	return stmpe_gpio->irq_base + offset;
}

static int stmpe_gpio_request(struct gpio_chip *chip, unsigned offset)
{
	struct stmpe_gpio *stmpe_gpio = to_stmpe_gpio(chip);
	struct stmpe *stmpe = stmpe_gpio->stmpe;

	if (stmpe_gpio->norequest_mask & (1 << offset))
		return -EINVAL;

	return stmpe_set_altfunc(stmpe, 1 << offset, STMPE_BLOCK_GPIO);
}

static struct gpio_chip template_chip = {
	.label			= "stmpe",
	.owner			= THIS_MODULE,
	.direction_input	= stmpe_gpio_direction_input,
	.get			= stmpe_gpio_get,
	.direction_output	= stmpe_gpio_direction_output,
	.set			= stmpe_gpio_set,
	.to_irq			= stmpe_gpio_to_irq,
	.request		= stmpe_gpio_request,
	.can_sleep		= 1,
};

static int stmpe_gpio_irq_set_type(struct irq_data *d, unsigned int type)
{
	struct stmpe_gpio *stmpe_gpio = irq_data_get_irq_chip_data(d);
	int offset = d->irq - stmpe_gpio->irq_base;
	int regoffset = offset / 8;
	int mask = 1 << (offset % 8);

	if (type == IRQ_TYPE_LEVEL_LOW || type == IRQ_TYPE_LEVEL_HIGH)
		return -EINVAL;

	/* STMPE801 doesn't have RE and FE registers */
	if (stmpe_gpio->stmpe->partnum == STMPE801)
		return 0;

	if (type == IRQ_TYPE_EDGE_RISING)
		stmpe_gpio->regs[REG_RE][regoffset] |= mask;
	else
		stmpe_gpio->regs[REG_RE][regoffset] &= ~mask;

	if (type == IRQ_TYPE_EDGE_FALLING)
		stmpe_gpio->regs[REG_FE][regoffset] |= mask;
	else
		stmpe_gpio->regs[REG_FE][regoffset] &= ~mask;

	return 0;
}

static void stmpe_gpio_irq_lock(struct irq_data *d)
{
	struct stmpe_gpio *stmpe_gpio = irq_data_get_irq_chip_data(d);

	mutex_lock(&stmpe_gpio->irq_lock);
}

static void stmpe_gpio_irq_sync_unlock(struct irq_data *d)
{
	struct stmpe_gpio *stmpe_gpio = irq_data_get_irq_chip_data(d);
	struct stmpe *stmpe = stmpe_gpio->stmpe;
	int num_banks = DIV_ROUND_UP(stmpe->num_gpios, 8);
	static const u8 regmap[] = {
		[REG_RE]	= STMPE_IDX_GPRER_LSB,
		[REG_FE]	= STMPE_IDX_GPFER_LSB,
		[REG_IE]	= STMPE_IDX_IEGPIOR_LSB,
	};
	int i, j;

	for (i = 0; i < CACHE_NR_REGS; i++) {
		/* STMPE801 doesn't have RE and FE registers */
		if ((stmpe->partnum == STMPE801) &&
				(i != REG_IE))
			continue;

		for (j = 0; j < num_banks; j++) {
			u8 old = stmpe_gpio->oldregs[i][j];
			u8 new = stmpe_gpio->regs[i][j];

			if (new == old)
				continue;

			stmpe_gpio->oldregs[i][j] = new;
			stmpe_reg_write(stmpe, stmpe->regs[regmap[i]] - j, new);
		}
	}

	mutex_unlock(&stmpe_gpio->irq_lock);
}

static void stmpe_gpio_irq_mask(struct irq_data *d)
{
	struct stmpe_gpio *stmpe_gpio = irq_data_get_irq_chip_data(d);
	int offset = d->irq - stmpe_gpio->irq_base;
	int regoffset = offset / 8;
	int mask = 1 << (offset % 8);

	stmpe_gpio->regs[REG_IE][regoffset] &= ~mask;
}

static void stmpe_gpio_irq_unmask(struct irq_data *d)
{
	struct stmpe_gpio *stmpe_gpio = irq_data_get_irq_chip_data(d);
	int offset = d->irq - stmpe_gpio->irq_base;
	int regoffset = offset / 8;
	int mask = 1 << (offset % 8);

	stmpe_gpio->regs[REG_IE][regoffset] |= mask;
}

static struct irq_chip stmpe_gpio_irq_chip = {
	.name			= "stmpe-gpio",
	.irq_bus_lock		= stmpe_gpio_irq_lock,
	.irq_bus_sync_unlock	= stmpe_gpio_irq_sync_unlock,
	.irq_mask		= stmpe_gpio_irq_mask,
	.irq_unmask		= stmpe_gpio_irq_unmask,
	.irq_set_type		= stmpe_gpio_irq_set_type,
};

static irqreturn_t stmpe_gpio_irq(int irq, void *dev)
{
	struct stmpe_gpio *stmpe_gpio = dev;
	struct stmpe *stmpe = stmpe_gpio->stmpe;
	u8 statmsbreg = stmpe->regs[STMPE_IDX_ISGPIOR_MSB];
	int num_banks = DIV_ROUND_UP(stmpe->num_gpios, 8);
	u8 status[num_banks];
	int ret;
	int i;

	ret = stmpe_block_read(stmpe, statmsbreg, num_banks, status);
	if (ret < 0)
		return IRQ_NONE;

	for (i = 0; i < num_banks; i++) {
		int bank = num_banks - i - 1;
		unsigned int enabled = stmpe_gpio->regs[REG_IE][bank];
		unsigned int stat = status[i];

		stat &= enabled;
		if (!stat)
			continue;

		while (stat) {
			int bit = __ffs(stat);
			int line = bank * 8 + bit;

			handle_nested_irq(stmpe_gpio->irq_base + line);
			stat &= ~(1 << bit);
		}

		stmpe_reg_write(stmpe, statmsbreg + i, status[i]);

		/* Edge detect register is not present on 801 */
		if (stmpe->partnum != STMPE801)
			stmpe_reg_write(stmpe, stmpe->regs[STMPE_IDX_GPEDR_MSB]
					+ i, status[i]);
	}

	return IRQ_HANDLED;
}

static int __devinit stmpe_gpio_irq_init(struct stmpe_gpio *stmpe_gpio)
{
	int base = stmpe_gpio->irq_base;
	int irq;

	for (irq = base; irq < base + stmpe_gpio->chip.ngpio; irq++) {
		irq_set_chip_data(irq, stmpe_gpio);
		irq_set_chip_and_handler(irq, &stmpe_gpio_irq_chip,
					 handle_simple_irq);
		irq_set_nested_thread(irq, 1);
#ifdef CONFIG_ARM
		set_irq_flags(irq, IRQF_VALID);
#else
		irq_set_noprobe(irq);
#endif
	}

	return 0;
}

static void stmpe_gpio_irq_remove(struct stmpe_gpio *stmpe_gpio)
{
	int base = stmpe_gpio->irq_base;
	int irq;

	for (irq = base; irq < base + stmpe_gpio->chip.ngpio; irq++) {
#ifdef CONFIG_ARM
		set_irq_flags(irq, 0);
#endif
		irq_set_chip_and_handler(irq, NULL, NULL);
		irq_set_chip_data(irq, NULL);
	}
}

static int __devinit stmpe_gpio_probe(struct platform_device *pdev)
{
	struct stmpe *stmpe = dev_get_drvdata(pdev->dev.parent);
	struct stmpe_gpio_platform_data *pdata;
	struct stmpe_gpio *stmpe_gpio;
	int ret;
	int irq = 0;

	pdata = stmpe->pdata->gpio;

	irq = platform_get_irq(pdev, 0);

	stmpe_gpio = kzalloc(sizeof(struct stmpe_gpio), GFP_KERNEL);
	if (!stmpe_gpio)
		return -ENOMEM;

	mutex_init(&stmpe_gpio->irq_lock);

	stmpe_gpio->dev = &pdev->dev;
	stmpe_gpio->stmpe = stmpe;
	stmpe_gpio->norequest_mask = pdata ? pdata->norequest_mask : 0;

	stmpe_gpio->chip = template_chip;
	stmpe_gpio->chip.ngpio = stmpe->num_gpios;
	stmpe_gpio->chip.dev = &pdev->dev;
	stmpe_gpio->chip.base = pdata ? pdata->gpio_base : -1;

	if (irq >= 0)
		stmpe_gpio->irq_base = stmpe->irq_base + STMPE_INT_GPIO(0);
	else
		dev_info(&pdev->dev,
			"device configured in no-irq mode; "
			"irqs are not available\n");

	ret = stmpe_enable(stmpe, STMPE_BLOCK_GPIO);
	if (ret)
		goto out_free;

	if (irq >= 0) {
		ret = stmpe_gpio_irq_init(stmpe_gpio);
		if (ret)
			goto out_disable;

		ret = request_threaded_irq(irq, NULL, stmpe_gpio_irq,
				IRQF_ONESHOT, "stmpe-gpio", stmpe_gpio);
		if (ret) {
			dev_err(&pdev->dev, "unable to get irq: %d\n", ret);
			goto out_removeirq;
		}
	}

	ret = gpiochip_add(&stmpe_gpio->chip);
	if (ret) {
		dev_err(&pdev->dev, "unable to add gpiochip: %d\n", ret);
		goto out_freeirq;
	}

	if (pdata && pdata->setup)
		pdata->setup(stmpe, stmpe_gpio->chip.base);

	platform_set_drvdata(pdev, stmpe_gpio);

	return 0;

out_freeirq:
	if (irq >= 0)
		free_irq(irq, stmpe_gpio);
out_removeirq:
	if (irq >= 0)
		stmpe_gpio_irq_remove(stmpe_gpio);
out_disable:
	stmpe_disable(stmpe, STMPE_BLOCK_GPIO);
out_free:
	kfree(stmpe_gpio);
	return ret;
}

static int __devexit stmpe_gpio_remove(struct platform_device *pdev)
{
	struct stmpe_gpio *stmpe_gpio = platform_get_drvdata(pdev);
	struct stmpe *stmpe = stmpe_gpio->stmpe;
	struct stmpe_gpio_platform_data *pdata = stmpe->pdata->gpio;
	int irq = platform_get_irq(pdev, 0);
	int ret;

	if (pdata && pdata->remove)
		pdata->remove(stmpe, stmpe_gpio->chip.base);

	ret = gpiochip_remove(&stmpe_gpio->chip);
	if (ret < 0) {
		dev_err(stmpe_gpio->dev,
			"unable to remove gpiochip: %d\n", ret);
		return ret;
	}

	stmpe_disable(stmpe, STMPE_BLOCK_GPIO);

	if (irq >= 0) {
		free_irq(irq, stmpe_gpio);
		stmpe_gpio_irq_remove(stmpe_gpio);
	}
	platform_set_drvdata(pdev, NULL);
	kfree(stmpe_gpio);

	return 0;
}

static struct platform_driver stmpe_gpio_driver = {
	.driver.name	= "stmpe-gpio",
	.driver.owner	= THIS_MODULE,
	.probe		= stmpe_gpio_probe,
	.remove		= __devexit_p(stmpe_gpio_remove),
};

static int __init stmpe_gpio_init(void)
{
	return platform_driver_register(&stmpe_gpio_driver);
}
subsys_initcall(stmpe_gpio_init);

static void __exit stmpe_gpio_exit(void)
{
	platform_driver_unregister(&stmpe_gpio_driver);
}
module_exit(stmpe_gpio_exit);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("STMPExxxx GPIO driver");
MODULE_AUTHOR("Rabin Vincent <rabin.vincent@stericsson.com>");