/*
 *  Atheros AR71XX/AR724X/AR913X GPIO API support
 *
 *  Copyright (C) 2015 Alban Bedel <albeu@free.fr>
 *  Copyright (C) 2010-2011 Jaiganesh Narayanan <jnarayanan@atheros.com>
 *  Copyright (C) 2008-2011 Gabor Juhos <juhosg@openwrt.org>
 *  Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
 *
 *  This program is free software; you can redistribute it and/or modify it
 *  under the terms of the GNU General Public License version 2 as published
 *  by the Free Software Foundation.
 */

#include <linux/gpio/driver.h>
#include <linux/platform_data/gpio-ath79.h>
#include <linux/of_device.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/irq.h>

#define AR71XX_GPIO_REG_OE		0x00
#define AR71XX_GPIO_REG_IN		0x04
#define AR71XX_GPIO_REG_SET		0x0c
#define AR71XX_GPIO_REG_CLEAR		0x10

#define AR71XX_GPIO_REG_INT_ENABLE	0x14
#define AR71XX_GPIO_REG_INT_TYPE	0x18
#define AR71XX_GPIO_REG_INT_POLARITY	0x1c
#define AR71XX_GPIO_REG_INT_PENDING	0x20
#define AR71XX_GPIO_REG_INT_MASK	0x24

struct ath79_gpio_ctrl {
	struct gpio_chip gc;
	void __iomem *base;
	spinlock_t lock;
	unsigned long both_edges;
};

static struct ath79_gpio_ctrl *irq_data_to_ath79_gpio(struct irq_data *data)
{
	struct gpio_chip *gc = irq_data_get_irq_chip_data(data);

	return container_of(gc, struct ath79_gpio_ctrl, gc);
}

static u32 ath79_gpio_read(struct ath79_gpio_ctrl *ctrl, unsigned reg)
{
	return readl(ctrl->base + reg);
}

static void ath79_gpio_write(struct ath79_gpio_ctrl *ctrl,
			unsigned reg, u32 val)
{
	return writel(val, ctrl->base + reg);
}

static bool ath79_gpio_update_bits(
	struct ath79_gpio_ctrl *ctrl, unsigned reg, u32 mask, u32 bits)
{
	u32 old_val, new_val;

	old_val = ath79_gpio_read(ctrl, reg);
	new_val = (old_val & ~mask) | (bits & mask);

	if (new_val != old_val)
		ath79_gpio_write(ctrl, reg, new_val);

	return new_val != old_val;
}

static void ath79_gpio_irq_unmask(struct irq_data *data)
{
	struct ath79_gpio_ctrl *ctrl = irq_data_to_ath79_gpio(data);
	u32 mask = BIT(irqd_to_hwirq(data));
	unsigned long flags;

	spin_lock_irqsave(&ctrl->lock, flags);
	ath79_gpio_update_bits(ctrl, AR71XX_GPIO_REG_INT_MASK, mask, mask);
	spin_unlock_irqrestore(&ctrl->lock, flags);
}

static void ath79_gpio_irq_mask(struct irq_data *data)
{
	struct ath79_gpio_ctrl *ctrl = irq_data_to_ath79_gpio(data);
	u32 mask = BIT(irqd_to_hwirq(data));
	unsigned long flags;

	spin_lock_irqsave(&ctrl->lock, flags);
	ath79_gpio_update_bits(ctrl, AR71XX_GPIO_REG_INT_MASK, mask, 0);
	spin_unlock_irqrestore(&ctrl->lock, flags);
}

static void ath79_gpio_irq_enable(struct irq_data *data)
{
	struct ath79_gpio_ctrl *ctrl = irq_data_to_ath79_gpio(data);
	u32 mask = BIT(irqd_to_hwirq(data));
	unsigned long flags;

	spin_lock_irqsave(&ctrl->lock, flags);
	ath79_gpio_update_bits(ctrl, AR71XX_GPIO_REG_INT_ENABLE, mask, mask);
	ath79_gpio_update_bits(ctrl, AR71XX_GPIO_REG_INT_MASK, mask, mask);
	spin_unlock_irqrestore(&ctrl->lock, flags);
}

static void ath79_gpio_irq_disable(struct irq_data *data)
{
	struct ath79_gpio_ctrl *ctrl = irq_data_to_ath79_gpio(data);
	u32 mask = BIT(irqd_to_hwirq(data));
	unsigned long flags;

	spin_lock_irqsave(&ctrl->lock, flags);
	ath79_gpio_update_bits(ctrl, AR71XX_GPIO_REG_INT_MASK, mask, 0);
	ath79_gpio_update_bits(ctrl, AR71XX_GPIO_REG_INT_ENABLE, mask, 0);
	spin_unlock_irqrestore(&ctrl->lock, flags);
}

static int ath79_gpio_irq_set_type(struct irq_data *data,
				unsigned int flow_type)
{
	struct ath79_gpio_ctrl *ctrl = irq_data_to_ath79_gpio(data);
	u32 mask = BIT(irqd_to_hwirq(data));
	u32 type = 0, polarity = 0;
	unsigned long flags;
	bool disabled;

	switch (flow_type) {
	case IRQ_TYPE_EDGE_RISING:
		polarity |= mask;
	case IRQ_TYPE_EDGE_FALLING:
	case IRQ_TYPE_EDGE_BOTH:
		break;

	case IRQ_TYPE_LEVEL_HIGH:
		polarity |= mask;
	case IRQ_TYPE_LEVEL_LOW:
		type |= mask;
		break;

	default:
		return -EINVAL;
	}

	spin_lock_irqsave(&ctrl->lock, flags);

	if (flow_type == IRQ_TYPE_EDGE_BOTH) {
		ctrl->both_edges |= mask;
		polarity = ~ath79_gpio_read(ctrl, AR71XX_GPIO_REG_IN);
	} else {
		ctrl->both_edges &= ~mask;
	}

	/* As the IRQ configuration can't be loaded atomically we
	 * have to disable the interrupt while the configuration state
	 * is invalid.
	 */
	disabled = ath79_gpio_update_bits(
		ctrl, AR71XX_GPIO_REG_INT_ENABLE, mask, 0);

	ath79_gpio_update_bits(
		ctrl, AR71XX_GPIO_REG_INT_TYPE, mask, type);
	ath79_gpio_update_bits(
		ctrl, AR71XX_GPIO_REG_INT_POLARITY, mask, polarity);

	if (disabled)
		ath79_gpio_update_bits(
			ctrl, AR71XX_GPIO_REG_INT_ENABLE, mask, mask);

	spin_unlock_irqrestore(&ctrl->lock, flags);

	return 0;
}

static struct irq_chip ath79_gpio_irqchip = {
	.name = "gpio-ath79",
	.irq_enable = ath79_gpio_irq_enable,
	.irq_disable = ath79_gpio_irq_disable,
	.irq_mask = ath79_gpio_irq_mask,
	.irq_unmask = ath79_gpio_irq_unmask,
	.irq_set_type = ath79_gpio_irq_set_type,
};

static void ath79_gpio_irq_handler(struct irq_desc *desc)
{
	struct gpio_chip *gc = irq_desc_get_handler_data(desc);
	struct irq_chip *irqchip = irq_desc_get_chip(desc);
	struct ath79_gpio_ctrl *ctrl =
		container_of(gc, struct ath79_gpio_ctrl, gc);
	unsigned long flags, pending;
	u32 both_edges, state;
	int irq;

	chained_irq_enter(irqchip, desc);

	spin_lock_irqsave(&ctrl->lock, flags);

	pending = ath79_gpio_read(ctrl, AR71XX_GPIO_REG_INT_PENDING);

	/* Update the polarity of the both edges irqs */
	both_edges = ctrl->both_edges & pending;
	if (both_edges) {
		state = ath79_gpio_read(ctrl, AR71XX_GPIO_REG_IN);
		ath79_gpio_update_bits(ctrl, AR71XX_GPIO_REG_INT_POLARITY,
				both_edges, ~state);
	}

	spin_unlock_irqrestore(&ctrl->lock, flags);

	if (pending) {
		for_each_set_bit(irq, &pending, gc->ngpio)
			generic_handle_irq(
				irq_linear_revmap(gc->irqdomain, irq));
	}

	chained_irq_exit(irqchip, desc);
}

static const struct of_device_id ath79_gpio_of_match[] = {
	{ .compatible = "qca,ar7100-gpio" },
	{ .compatible = "qca,ar9340-gpio" },
	{},
};

static int ath79_gpio_probe(struct platform_device *pdev)
{
	struct ath79_gpio_platform_data *pdata = dev_get_platdata(&pdev->dev);
	struct device_node *np = pdev->dev.of_node;
	struct ath79_gpio_ctrl *ctrl;
	struct resource *res;
	u32 ath79_gpio_count;
	bool oe_inverted;
	int err;

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

	if (np) {
		err = of_property_read_u32(np, "ngpios", &ath79_gpio_count);
		if (err) {
			dev_err(&pdev->dev, "ngpios property is not valid\n");
			return err;
		}
		oe_inverted = of_device_is_compatible(np, "qca,ar9340-gpio");
	} else if (pdata) {
		ath79_gpio_count = pdata->ngpios;
		oe_inverted = pdata->oe_inverted;
	} else {
		dev_err(&pdev->dev, "No DT node or platform data found\n");
		return -EINVAL;
	}

	if (ath79_gpio_count >= 32) {
		dev_err(&pdev->dev, "ngpios must be less than 32\n");
		return -EINVAL;
	}

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	ctrl->base = devm_ioremap_nocache(
		&pdev->dev, res->start, resource_size(res));
	if (!ctrl->base)
		return -ENOMEM;

	spin_lock_init(&ctrl->lock);
	err = bgpio_init(&ctrl->gc, &pdev->dev, 4,
			ctrl->base + AR71XX_GPIO_REG_IN,
			ctrl->base + AR71XX_GPIO_REG_SET,
			ctrl->base + AR71XX_GPIO_REG_CLEAR,
			oe_inverted ? NULL : ctrl->base + AR71XX_GPIO_REG_OE,
			oe_inverted ? ctrl->base + AR71XX_GPIO_REG_OE : NULL,
			0);
	if (err) {
		dev_err(&pdev->dev, "bgpio_init failed\n");
		return err;
	}
	/* Use base 0 to stay compatible with legacy platforms */
	ctrl->gc.base = 0;

	err = gpiochip_add_data(&ctrl->gc, ctrl);
	if (err) {
		dev_err(&pdev->dev,
			"cannot add AR71xx GPIO chip, error=%d", err);
		return err;
	}

	if (np && !of_property_read_bool(np, "interrupt-controller"))
		return 0;

	err = gpiochip_irqchip_add(&ctrl->gc, &ath79_gpio_irqchip, 0,
				handle_simple_irq, IRQ_TYPE_NONE);
	if (err) {
		dev_err(&pdev->dev, "failed to add gpiochip_irqchip\n");
		goto gpiochip_remove;
	}

	gpiochip_set_chained_irqchip(&ctrl->gc, &ath79_gpio_irqchip,
				platform_get_irq(pdev, 0),
				ath79_gpio_irq_handler);

	return 0;

gpiochip_remove:
	gpiochip_remove(&ctrl->gc);
	return err;
}

static int ath79_gpio_remove(struct platform_device *pdev)
{
	struct ath79_gpio_ctrl *ctrl = platform_get_drvdata(pdev);

	gpiochip_remove(&ctrl->gc);
	return 0;
}

static struct platform_driver ath79_gpio_driver = {
	.driver = {
		.name = "ath79-gpio",
		.of_match_table	= ath79_gpio_of_match,
	},
	.probe = ath79_gpio_probe,
	.remove = ath79_gpio_remove,
};

module_platform_driver(ath79_gpio_driver);