/* arch/arm/plat-samsung/gpiolib.c
 *
 * Copyright 2008 Openmoko, Inc.
 * Copyright 2008 Simtec Electronics
 *      Ben Dooks <ben@simtec.co.uk>
 *      http://armlinux.simtec.co.uk/
 *
 * Copyright (c) 2009 Samsung Electronics Co., Ltd.
 *              http://www.samsung.com/
 *
 * SAMSUNG - GPIOlib support
 *
 * 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/kernel.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <linux/gpio.h>
#include <plat/gpio-core.h>
#include <plat/gpio-cfg.h>
#include <plat/gpio-cfg-helpers.h>

#ifndef DEBUG_GPIO
#define gpio_dbg(x...) do { } while (0)
#else
#define gpio_dbg(x...) printk(KERN_DEBUG x)
#endif

/* The samsung_gpiolib_4bit routines are to control the gpio banks where
 * the gpio configuration register (GPxCON) has 4 bits per GPIO, as the
 * following example:
 *
 * base + 0x00: Control register, 4 bits per gpio
 *              gpio n: 4 bits starting at (4*n)
 *              0000 = input, 0001 = output, others mean special-function
 * base + 0x04: Data register, 1 bit per gpio
 *              bit n: data bit n
 *
 * Note, since the data register is one bit per gpio and is at base + 0x4
 * we can use s3c_gpiolib_get and s3c_gpiolib_set to change the state of
 * the output.
*/

static int samsung_gpiolib_4bit_input(struct gpio_chip *chip,
                                      unsigned int offset)
{
        struct s3c_gpio_chip *ourchip = to_s3c_gpio(chip);
        void __iomem *base = ourchip->base;
        unsigned long con;

        con = __raw_readl(base + GPIOCON_OFF);
        con &= ~(0xf << con_4bit_shift(offset));
        __raw_writel(con, base + GPIOCON_OFF);

        gpio_dbg("%s: %p: CON now %08lx\n", __func__, base, con);

        return 0;
}

static int samsung_gpiolib_4bit_output(struct gpio_chip *chip,
                                       unsigned int offset, int value)
{
        struct s3c_gpio_chip *ourchip = to_s3c_gpio(chip);
        void __iomem *base = ourchip->base;
        unsigned long con;
        unsigned long dat;

        con = __raw_readl(base + GPIOCON_OFF);
        con &= ~(0xf << con_4bit_shift(offset));
        con |= 0x1 << con_4bit_shift(offset);

        dat = __raw_readl(base + GPIODAT_OFF);

        if (value)
                dat |= 1 << offset;
        else
                dat &= ~(1 << offset);

        __raw_writel(dat, base + GPIODAT_OFF);
        __raw_writel(con, base + GPIOCON_OFF);
        __raw_writel(dat, base + GPIODAT_OFF);

        gpio_dbg("%s: %p: CON %08lx, DAT %08lx\n", __func__, base, con, dat);

        return 0;
}

/* The next set of routines are for the case where the GPIO configuration
 * registers are 4 bits per GPIO but there is more than one register (the
 * bank has more than 8 GPIOs.
 *
 * This case is the similar to the 4 bit case, but the registers are as
 * follows:
 *
 * base + 0x00: Control register, 4 bits per gpio (lower 8 GPIOs)
 *              gpio n: 4 bits starting at (4*n)
 *              0000 = input, 0001 = output, others mean special-function
 * base + 0x04: Control register, 4 bits per gpio (up to 8 additions GPIOs)
 *              gpio n: 4 bits starting at (4*n)
 *              0000 = input, 0001 = output, others mean special-function
 * base + 0x08: Data register, 1 bit per gpio
 *              bit n: data bit n
 *
 * To allow us to use the s3c_gpiolib_get and s3c_gpiolib_set routines we
 * store the 'base + 0x4' address so that these routines see the data
 * register at ourchip->base + 0x04.
 */

static int samsung_gpiolib_4bit2_input(struct gpio_chip *chip,
                                       unsigned int offset)
{
        struct s3c_gpio_chip *ourchip = to_s3c_gpio(chip);
        void __iomem *base = ourchip->base;
        void __iomem *regcon = base;
        unsigned long con;

        if (offset > 7)
                offset -= 8;
        else
                regcon -= 4;

        con = __raw_readl(regcon);
        con &= ~(0xf << con_4bit_shift(offset));
        __raw_writel(con, regcon);

        gpio_dbg("%s: %p: CON %08lx\n", __func__, base, con);

        return 0;
}

static int samsung_gpiolib_4bit2_output(struct gpio_chip *chip,
                                        unsigned int offset, int value)
{
        struct s3c_gpio_chip *ourchip = to_s3c_gpio(chip);
        void __iomem *base = ourchip->base;
        void __iomem *regcon = base;
        unsigned long con;
        unsigned long dat;
        unsigned con_offset = offset;

        if (con_offset > 7)
                con_offset -= 8;
        else
                regcon -= 4;

        con = __raw_readl(regcon);
        con &= ~(0xf << con_4bit_shift(con_offset));
        con |= 0x1 << con_4bit_shift(con_offset);

        dat = __raw_readl(base + GPIODAT_OFF);

        if (value)
                dat |= 1 << offset;
        else
                dat &= ~(1 << offset);

        __raw_writel(dat, base + GPIODAT_OFF);
        __raw_writel(con, regcon);
        __raw_writel(dat, base + GPIODAT_OFF);

        gpio_dbg("%s: %p: CON %08lx, DAT %08lx\n", __func__, base, con, dat);

        return 0;
}

void __init samsung_gpiolib_add_4bit(struct s3c_gpio_chip *chip)
{
        chip->chip.direction_input = samsung_gpiolib_4bit_input;
        chip->chip.direction_output = samsung_gpiolib_4bit_output;
        chip->pm = __gpio_pm(&s3c_gpio_pm_4bit);
}

void __init samsung_gpiolib_add_4bit2(struct s3c_gpio_chip *chip)
{
        chip->chip.direction_input = samsung_gpiolib_4bit2_input;
        chip->chip.direction_output = samsung_gpiolib_4bit2_output;
        chip->pm = __gpio_pm(&s3c_gpio_pm_4bit);
}

void __init samsung_gpiolib_add_4bit_chips(struct s3c_gpio_chip *chip,
                                           int nr_chips)
{
        for (; nr_chips > 0; nr_chips--, chip++) {
                samsung_gpiolib_add_4bit(chip);
                s3c_gpiolib_add(chip);
        }
}

void __init samsung_gpiolib_add_4bit2_chips(struct s3c_gpio_chip *chip,
                                            int nr_chips)
{
        for (; nr_chips > 0; nr_chips--, chip++) {
                samsung_gpiolib_add_4bit2(chip);
                s3c_gpiolib_add(chip);
        }
}

void __init samsung_gpiolib_add_2bit_chips(struct s3c_gpio_chip *chip,
                                           int nr_chips)
{
        for (; nr_chips > 0; nr_chips--, chip++)
                s3c_gpiolib_add(chip);
}