/* Abilis Systems MODULE DESCRIPTION
 *
 * Copyright (C) Abilis Systems 2013
 *
 * Authors: Sascha Leuenberger <sascha.leuenberger@abilis.com>
 *          Christian Ruppert <christian.ruppert@abilis.com>
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/gpio.h>
#include <linux/slab.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/of_gpio.h>
#include <linux/spinlock.h>
#include <linux/bitops.h>
#include <linux/pinctrl/consumer.h>

#define TB10X_GPIO_DIR_IN	(0x00000000)
#define TB10X_GPIO_DIR_OUT	(0x00000001)
#define OFFSET_TO_REG_DDR	(0x00)
#define OFFSET_TO_REG_DATA	(0x04)
#define OFFSET_TO_REG_INT_EN	(0x08)
#define OFFSET_TO_REG_CHANGE	(0x0C)
#define OFFSET_TO_REG_WRMASK	(0x10)
#define OFFSET_TO_REG_INT_TYPE	(0x14)


/**
 * @spinlock: used for atomic read/modify/write of registers
 * @base: register base address
 * @domain: IRQ domain of GPIO generated interrupts managed by this controller
 * @irq: Interrupt line of parent interrupt controller
 * @gc: gpio_chip structure associated to this GPIO controller
 */
struct tb10x_gpio {
	spinlock_t spinlock;
	void __iomem *base;
	struct irq_domain *domain;
	int irq;
	struct gpio_chip gc;
};

static inline u32 tb10x_reg_read(struct tb10x_gpio *gpio, unsigned int offs)
{
	return ioread32(gpio->base + offs);
}

static inline void tb10x_reg_write(struct tb10x_gpio *gpio, unsigned int offs,
				u32 val)
{
	iowrite32(val, gpio->base + offs);
}

static inline void tb10x_set_bits(struct tb10x_gpio *gpio, unsigned int offs,
				u32 mask, u32 val)
{
	u32 r;
	unsigned long flags;

	spin_lock_irqsave(&gpio->spinlock, flags);

	r = tb10x_reg_read(gpio, offs);
	r = (r & ~mask) | (val & mask);

	tb10x_reg_write(gpio, offs, r);

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

static inline struct tb10x_gpio *to_tb10x_gpio(struct gpio_chip *chip)
{
	return container_of(chip, struct tb10x_gpio, gc);
}

static int tb10x_gpio_direction_in(struct gpio_chip *chip, unsigned offset)
{
	struct tb10x_gpio *tb10x_gpio = to_tb10x_gpio(chip);
	int mask = BIT(offset);
	int val = TB10X_GPIO_DIR_IN << offset;

	tb10x_set_bits(tb10x_gpio, OFFSET_TO_REG_DDR, mask, val);

	return 0;
}

static int tb10x_gpio_get(struct gpio_chip *chip, unsigned offset)
{
	struct tb10x_gpio *tb10x_gpio = to_tb10x_gpio(chip);
	int val;

	val = tb10x_reg_read(tb10x_gpio, OFFSET_TO_REG_DATA);

	if (val & BIT(offset))
		return 1;
	else
		return 0;
}

static void tb10x_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
{
	struct tb10x_gpio *tb10x_gpio = to_tb10x_gpio(chip);
	int mask = BIT(offset);
	int val = value << offset;

	tb10x_set_bits(tb10x_gpio, OFFSET_TO_REG_DATA, mask, val);
}

static int tb10x_gpio_direction_out(struct gpio_chip *chip,
					unsigned offset, int value)
{
	struct tb10x_gpio *tb10x_gpio = to_tb10x_gpio(chip);
	int mask = BIT(offset);
	int val = TB10X_GPIO_DIR_OUT << offset;

	tb10x_gpio_set(chip, offset, value);
	tb10x_set_bits(tb10x_gpio, OFFSET_TO_REG_DDR, mask, val);

	return 0;
}

static int tb10x_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
{
	struct tb10x_gpio *tb10x_gpio = to_tb10x_gpio(chip);

	return irq_create_mapping(tb10x_gpio->domain, offset);
}

static int tb10x_gpio_irq_set_type(struct irq_data *data, unsigned int type)
{
	if ((type & IRQF_TRIGGER_MASK) != IRQ_TYPE_EDGE_BOTH) {
		pr_err("Only (both) edge triggered interrupts supported.\n");
		return -EINVAL;
	}

	irqd_set_trigger_type(data, type);

	return IRQ_SET_MASK_OK;
}

static irqreturn_t tb10x_gpio_irq_cascade(int irq, void *data)
{
	struct tb10x_gpio *tb10x_gpio = data;
	u32 r = tb10x_reg_read(tb10x_gpio, OFFSET_TO_REG_CHANGE);
	u32 m = tb10x_reg_read(tb10x_gpio, OFFSET_TO_REG_INT_EN);
	const unsigned long bits = r & m;
	int i;

	for_each_set_bit(i, &bits, 32)
		generic_handle_irq(irq_find_mapping(tb10x_gpio->domain, i));

	return IRQ_HANDLED;
}

static int tb10x_gpio_probe(struct platform_device *pdev)
{
	struct tb10x_gpio *tb10x_gpio;
	struct resource *mem;
	struct device_node *dn = pdev->dev.of_node;
	int ret = -EBUSY;
	u32 ngpio;

	if (!dn)
		return -EINVAL;

	if (of_property_read_u32(dn, "abilis,ngpio", &ngpio))
		return -EINVAL;

	tb10x_gpio = devm_kzalloc(&pdev->dev, sizeof(*tb10x_gpio), GFP_KERNEL);
	if (tb10x_gpio == NULL)
		return -ENOMEM;

	spin_lock_init(&tb10x_gpio->spinlock);

	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	tb10x_gpio->base = devm_ioremap_resource(&pdev->dev, mem);
	if (IS_ERR(tb10x_gpio->base))
		return PTR_ERR(tb10x_gpio->base);

	tb10x_gpio->gc.label		= of_node_full_name(dn);
	tb10x_gpio->gc.dev		= &pdev->dev;
	tb10x_gpio->gc.owner		= THIS_MODULE;
	tb10x_gpio->gc.direction_input	= tb10x_gpio_direction_in;
	tb10x_gpio->gc.get		= tb10x_gpio_get;
	tb10x_gpio->gc.direction_output	= tb10x_gpio_direction_out;
	tb10x_gpio->gc.set		= tb10x_gpio_set;
	tb10x_gpio->gc.request		= gpiochip_generic_request;
	tb10x_gpio->gc.free		= gpiochip_generic_free;
	tb10x_gpio->gc.base		= -1;
	tb10x_gpio->gc.ngpio		= ngpio;
	tb10x_gpio->gc.can_sleep	= false;


	ret = gpiochip_add(&tb10x_gpio->gc);
	if (ret < 0) {
		dev_err(&pdev->dev, "Could not add gpiochip.\n");
		goto fail_gpiochip_registration;
	}

	platform_set_drvdata(pdev, tb10x_gpio);

	if (of_find_property(dn, "interrupt-controller", NULL)) {
		struct irq_chip_generic *gc;

		ret = platform_get_irq(pdev, 0);
		if (ret < 0) {
			dev_err(&pdev->dev, "No interrupt specified.\n");
			goto fail_get_irq;
		}

		tb10x_gpio->gc.to_irq	= tb10x_gpio_to_irq;
		tb10x_gpio->irq		= ret;

		ret = devm_request_irq(&pdev->dev, ret, tb10x_gpio_irq_cascade,
				IRQF_TRIGGER_NONE | IRQF_SHARED,
				dev_name(&pdev->dev), tb10x_gpio);
		if (ret != 0)
			goto fail_request_irq;

		tb10x_gpio->domain = irq_domain_add_linear(dn,
						tb10x_gpio->gc.ngpio,
						&irq_generic_chip_ops, NULL);
		if (!tb10x_gpio->domain) {
			ret = -ENOMEM;
			goto fail_irq_domain;
		}

		ret = irq_alloc_domain_generic_chips(tb10x_gpio->domain,
				tb10x_gpio->gc.ngpio, 1, tb10x_gpio->gc.label,
				handle_edge_irq, IRQ_NOREQUEST, IRQ_NOPROBE,
				IRQ_GC_INIT_MASK_CACHE);
		if (ret)
			goto fail_irq_domain;

		gc = tb10x_gpio->domain->gc->gc[0];
		gc->reg_base                         = tb10x_gpio->base;
		gc->chip_types[0].type               = IRQ_TYPE_EDGE_BOTH;
		gc->chip_types[0].chip.irq_ack       = irq_gc_ack_set_bit;
		gc->chip_types[0].chip.irq_mask      = irq_gc_mask_clr_bit;
		gc->chip_types[0].chip.irq_unmask    = irq_gc_mask_set_bit;
		gc->chip_types[0].chip.irq_set_type  = tb10x_gpio_irq_set_type;
		gc->chip_types[0].regs.ack           = OFFSET_TO_REG_CHANGE;
		gc->chip_types[0].regs.mask          = OFFSET_TO_REG_INT_EN;
	}

	return 0;

fail_irq_domain:
fail_request_irq:
fail_get_irq:
	gpiochip_remove(&tb10x_gpio->gc);
fail_gpiochip_registration:
fail_ioremap:
	return ret;
}

static int tb10x_gpio_remove(struct platform_device *pdev)
{
	struct tb10x_gpio *tb10x_gpio = platform_get_drvdata(pdev);

	if (tb10x_gpio->gc.to_irq) {
		irq_remove_generic_chip(tb10x_gpio->domain->gc->gc[0],
					BIT(tb10x_gpio->gc.ngpio) - 1, 0, 0);
		kfree(tb10x_gpio->domain->gc);
		irq_domain_remove(tb10x_gpio->domain);
	}
	gpiochip_remove(&tb10x_gpio->gc);

	return 0;
}

static const struct of_device_id tb10x_gpio_dt_ids[] = {
	{ .compatible = "abilis,tb10x-gpio" },
	{ }
};
MODULE_DEVICE_TABLE(of, tb10x_gpio_dt_ids);

static struct platform_driver tb10x_gpio_driver = {
	.probe		= tb10x_gpio_probe,
	.remove		= tb10x_gpio_remove,
	.driver = {
		.name	= "tb10x-gpio",
		.of_match_table = tb10x_gpio_dt_ids,
	}
};

module_platform_driver(tb10x_gpio_driver);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("tb10x gpio.");
MODULE_VERSION("0.0.1");