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gpiolib.c

/* 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);
}

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