/* drivers/gpio/gpio-vt8500.c
 *
 * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
 * Based on arch/arm/mach-vt8500/gpio.c:
 * - Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * 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.
 *
 */

#include <linux/module.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/gpio.h>
#include <linux/platform_device.h>
#include <linux/bitops.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/of_device.h>

/*
	We handle GPIOs by bank, each bank containing up to 32 GPIOs covered
	by one set of registers (although not all may be valid).

	Because different SoC's have different register offsets, we pass the
	register offsets as data in vt8500_gpio_dt_ids[].

	A value of NO_REG is used to indicate that this register is not
	supported. Only used for ->en at the moment.
*/

#define NO_REG	0xFFFF

/*
 * struct vt8500_gpio_bank_regoffsets
 * @en: offset to enable register of the bank
 * @dir: offset to direction register of the bank
 * @data_out: offset to the data out register of the bank
 * @data_in: offset to the data in register of the bank
 * @ngpio: highest valid pin in this bank
 */

struct vt8500_gpio_bank_regoffsets {
	unsigned int	en;
	unsigned int	dir;
	unsigned int	data_out;
	unsigned int	data_in;
	unsigned char	ngpio;
};

struct vt8500_gpio_data {
	unsigned int				num_banks;
	struct vt8500_gpio_bank_regoffsets	banks[];
};

#define VT8500_BANK(__en, __dir, __out, __in, __ngpio)		\
{								\
	.en = __en,						\
	.dir = __dir,						\
	.data_out = __out,					\
	.data_in = __in,					\
	.ngpio = __ngpio,					\
}

static struct vt8500_gpio_data vt8500_data = {
	.num_banks	= 7,
	.banks	= {
		VT8500_BANK(0x00, 0x20, 0x40, 0x60, 26),
		VT8500_BANK(0x04, 0x24, 0x44, 0x64, 28),
		VT8500_BANK(0x08, 0x28, 0x48, 0x68, 31),
		VT8500_BANK(0x0C, 0x2C, 0x4C, 0x6C, 19),
		VT8500_BANK(0x10, 0x30, 0x50, 0x70, 19),
		VT8500_BANK(0x14, 0x34, 0x54, 0x74, 23),
		VT8500_BANK(NO_REG, 0x3C, 0x5C, 0x7C, 9),
	},
};

static struct vt8500_gpio_data wm8505_data = {
	.num_banks	= 10,
	.banks	= {
		VT8500_BANK(0x40, 0x68, 0x90, 0xB8, 8),
		VT8500_BANK(0x44, 0x6C, 0x94, 0xBC, 32),
		VT8500_BANK(0x48, 0x70, 0x98, 0xC0, 6),
		VT8500_BANK(0x4C, 0x74, 0x9C, 0xC4, 16),
		VT8500_BANK(0x50, 0x78, 0xA0, 0xC8, 25),
		VT8500_BANK(0x54, 0x7C, 0xA4, 0xCC, 5),
		VT8500_BANK(0x58, 0x80, 0xA8, 0xD0, 5),
		VT8500_BANK(0x5C, 0x84, 0xAC, 0xD4, 12),
		VT8500_BANK(0x60, 0x88, 0xB0, 0xD8, 16),
		VT8500_BANK(0x64, 0x8C, 0xB4, 0xDC, 22),
	},
};

/*
 * No information about which bits are valid so we just make
 * them all available until its figured out.
 */
static struct vt8500_gpio_data wm8650_data = {
	.num_banks	= 9,
	.banks	= {
		VT8500_BANK(0x40, 0x80, 0xC0, 0x00, 32),
		VT8500_BANK(0x44, 0x84, 0xC4, 0x04, 32),
		VT8500_BANK(0x48, 0x88, 0xC8, 0x08, 32),
		VT8500_BANK(0x4C, 0x8C, 0xCC, 0x0C, 32),
		VT8500_BANK(0x50, 0x90, 0xD0, 0x10, 32),
		VT8500_BANK(0x54, 0x94, 0xD4, 0x14, 32),
		VT8500_BANK(0x58, 0x98, 0xD8, 0x18, 32),
		VT8500_BANK(0x5C, 0x9C, 0xDC, 0x1C, 32),
		VT8500_BANK(0x7C, 0xBC, 0xFC, 0x3C, 32),
	},
};

struct vt8500_gpio_chip {
	struct gpio_chip		chip;

	const struct vt8500_gpio_bank_regoffsets *regs;
	void __iomem	*base;
};


#define to_vt8500(__chip) container_of(__chip, struct vt8500_gpio_chip, chip)

static int vt8500_gpio_request(struct gpio_chip *chip, unsigned offset)
{
	u32 val;
	struct vt8500_gpio_chip *vt8500_chip = to_vt8500(chip);

	if (vt8500_chip->regs->en == NO_REG)
		return 0;

	val = readl_relaxed(vt8500_chip->base + vt8500_chip->regs->en);
	val |= BIT(offset);
	writel_relaxed(val, vt8500_chip->base + vt8500_chip->regs->en);

	return 0;
}

static void vt8500_gpio_free(struct gpio_chip *chip, unsigned offset)
{
	struct vt8500_gpio_chip *vt8500_chip = to_vt8500(chip);
	u32 val;

	if (vt8500_chip->regs->en == NO_REG)
		return;

	val = readl_relaxed(vt8500_chip->base + vt8500_chip->regs->en);
	val &= ~BIT(offset);
	writel_relaxed(val, vt8500_chip->base + vt8500_chip->regs->en);
}

static int vt8500_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
{
	struct vt8500_gpio_chip *vt8500_chip = to_vt8500(chip);

	u32 val = readl_relaxed(vt8500_chip->base + vt8500_chip->regs->dir);
	val &= ~BIT(offset);
	writel_relaxed(val, vt8500_chip->base + vt8500_chip->regs->dir);

	return 0;
}

static int vt8500_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
								int value)
{
	struct vt8500_gpio_chip *vt8500_chip = to_vt8500(chip);

	u32 val = readl_relaxed(vt8500_chip->base + vt8500_chip->regs->dir);
	val |= BIT(offset);
	writel_relaxed(val, vt8500_chip->base + vt8500_chip->regs->dir);

	if (value) {
		val = readl_relaxed(vt8500_chip->base +
						vt8500_chip->regs->data_out);
		val |= BIT(offset);
		writel_relaxed(val, vt8500_chip->base +
						vt8500_chip->regs->data_out);
	}
	return 0;
}

static int vt8500_gpio_get_value(struct gpio_chip *chip, unsigned offset)
{
	struct vt8500_gpio_chip *vt8500_chip = to_vt8500(chip);

	return (readl_relaxed(vt8500_chip->base + vt8500_chip->regs->data_in) >>
								offset) & 1;
}

static void vt8500_gpio_set_value(struct gpio_chip *chip, unsigned offset,
								int value)
{
	struct vt8500_gpio_chip *vt8500_chip = to_vt8500(chip);

	u32 val = readl_relaxed(vt8500_chip->base +
						vt8500_chip->regs->data_out);
	if (value)
		val |= BIT(offset);
	else
		val &= ~BIT(offset);

	writel_relaxed(val, vt8500_chip->base + vt8500_chip->regs->data_out);
}

static int vt8500_of_xlate(struct gpio_chip *gc,
			    const struct of_phandle_args *gpiospec, u32 *flags)
{
	/* bank if specificed in gpiospec->args[0] */
	if (flags)
		*flags = gpiospec->args[2];

	return gpiospec->args[1];
}

static int vt8500_add_chips(struct platform_device *pdev, void __iomem *base,
				const struct vt8500_gpio_data *data)
{
	struct vt8500_gpio_chip *vtchip;
	struct gpio_chip *chip;
	int i;
	int pin_cnt = 0;

	vtchip = devm_kzalloc(&pdev->dev,
			sizeof(struct vt8500_gpio_chip) * data->num_banks,
			GFP_KERNEL);
	if (!vtchip) {
		pr_err("%s: failed to allocate chip memory\n", __func__);
		return -ENOMEM;
	}

	for (i = 0; i < data->num_banks; i++) {
		vtchip[i].base = base;
		vtchip[i].regs = &data->banks[i];

		chip = &vtchip[i].chip;

		chip->of_xlate = vt8500_of_xlate;
		chip->of_gpio_n_cells = 3;
		chip->of_node = pdev->dev.of_node;

		chip->request = vt8500_gpio_request;
		chip->free = vt8500_gpio_free;
		chip->direction_input = vt8500_gpio_direction_input;
		chip->direction_output = vt8500_gpio_direction_output;
		chip->get = vt8500_gpio_get_value;
		chip->set = vt8500_gpio_set_value;
		chip->can_sleep = 0;
		chip->base = pin_cnt;
		chip->ngpio = data->banks[i].ngpio;

		pin_cnt += data->banks[i].ngpio;

		gpiochip_add(chip);
	}
	return 0;
}

static struct of_device_id vt8500_gpio_dt_ids[] = {
	{ .compatible = "via,vt8500-gpio", .data = &vt8500_data, },
	{ .compatible = "wm,wm8505-gpio", .data = &wm8505_data, },
	{ .compatible = "wm,wm8650-gpio", .data = &wm8650_data, },
	{ /* Sentinel */ },
};

static int __devinit vt8500_gpio_probe(struct platform_device *pdev)
{
	void __iomem *gpio_base;
	struct device_node *np;
	const struct of_device_id *of_id =
				of_match_device(vt8500_gpio_dt_ids, &pdev->dev);

	if (!of_id) {
		dev_err(&pdev->dev, "Failed to find gpio controller\n");
		return -ENODEV;
	}

	np = pdev->dev.of_node;
	if (!np) {
		dev_err(&pdev->dev, "Missing GPIO description in devicetree\n");
		return -EFAULT;
	}

	gpio_base = of_iomap(np, 0);
	if (!gpio_base) {
		dev_err(&pdev->dev, "Unable to map GPIO registers\n");
		of_node_put(np);
		return -ENOMEM;
	}

	vt8500_add_chips(pdev, gpio_base, of_id->data);

	return 0;
}

static struct platform_driver vt8500_gpio_driver = {
	.probe		= vt8500_gpio_probe,
	.driver		= {
		.name	= "vt8500-gpio",
		.owner	= THIS_MODULE,
		.of_match_table = vt8500_gpio_dt_ids,
	},
};

module_platform_driver(vt8500_gpio_driver);

MODULE_DESCRIPTION("VT8500 GPIO Driver");
MODULE_AUTHOR("Tony Prisk <linux@prisktech.co.nz>");
MODULE_LICENSE("GPL v2");
MODULE_DEVICE_TABLE(of, vt8500_gpio_dt_ids);