gpio_extended.c

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/*
 * Generic PMC MSP71xx EXTENDED (EXD) GPIO handling. The extended gpio is
 * a set of hardware registers that have no need for explicit locking as
 * it is handled by unique method of writing individual set/clr bits.
 *
 * 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.
 *
 * @author Patrick Glass <[email protected]>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/gpio.h>
#include <linux/io.h>

#define MSP71XX_DATA_OFFSET(gpio)   (2 * (gpio))
#define MSP71XX_READ_OFFSET(gpio)   (MSP71XX_DATA_OFFSET(gpio) + 1)
#define MSP71XX_CFG_OUT_OFFSET(gpio)    (MSP71XX_DATA_OFFSET(gpio) + 16)
#define MSP71XX_CFG_IN_OFFSET(gpio) (MSP71XX_CFG_OUT_OFFSET(gpio) + 1)

#define MSP71XX_EXD_GPIO_BASE   0x0BC000000L

#define to_msp71xx_exd_gpio_chip(c) \
            container_of(c, struct msp71xx_exd_gpio_chip, chip)

/*
 * struct msp71xx_exd_gpio_chip - container for gpio chip and registers
 * @chip: chip structure for the specified gpio bank
 * @reg: register for control and data of gpio pin
 */
struct msp71xx_exd_gpio_chip {
    struct gpio_chip chip;
    void __iomem *reg;
};

/*
 * msp71xx_exd_gpio_get() - return the chip's gpio value
 * @chip: chip structure which controls the specified gpio
 * @offset: gpio whose value will be returned
 *
 * It will return 0 if gpio value is low and other if high.
 */
static int msp71xx_exd_gpio_get(struct gpio_chip *chip, unsigned offset)
{
    struct msp71xx_exd_gpio_chip *msp71xx_chip =
        to_msp71xx_exd_gpio_chip(chip);
    const unsigned bit = MSP71XX_READ_OFFSET(offset);

    return __raw_readl(msp71xx_chip->reg) & (1 << bit);
}

/*
 * msp71xx_exd_gpio_set() - set the output value for the gpio
 * @chip: chip structure who controls the specified gpio
 * @offset: gpio whose value will be assigned
 * @value: logic level to assign to the gpio initially
 *
 * This will set the gpio bit specified to the desired value. It will set the
 * gpio pin low if value is 0 otherwise it will be high.
 */
static void msp71xx_exd_gpio_set(struct gpio_chip *chip,
                 unsigned offset, int value)
{
    struct msp71xx_exd_gpio_chip *msp71xx_chip =
        to_msp71xx_exd_gpio_chip(chip);
    const unsigned bit = MSP71XX_DATA_OFFSET(offset);

    __raw_writel(1 << (bit + (value ? 1 : 0)), msp71xx_chip->reg);
}

/*
 * msp71xx_exd_direction_output() - declare the direction mode for a gpio
 * @chip: chip structure which controls the specified gpio
 * @offset: gpio whose value will be assigned
 * @value: logic level to assign to the gpio initially
 *
 * This call will set the mode for the @gpio to output. It will set the
 * gpio pin low if value is 0 otherwise it will be high.
 */
static int msp71xx_exd_direction_output(struct gpio_chip *chip,
                    unsigned offset, int value)
{
    struct msp71xx_exd_gpio_chip *msp71xx_chip =
        to_msp71xx_exd_gpio_chip(chip);

    msp71xx_exd_gpio_set(chip, offset, value);
    __raw_writel(1 << MSP71XX_CFG_OUT_OFFSET(offset), msp71xx_chip->reg);
    return 0;
}

/*
 * msp71xx_exd_direction_input() - declare the direction mode for a gpio
 * @chip: chip structure which controls the specified gpio
 * @offset: gpio whose to which the value will be assigned
 *
 * This call will set the mode for the @gpio to input.
 */
static int msp71xx_exd_direction_input(struct gpio_chip *chip, unsigned offset)
{
    struct msp71xx_exd_gpio_chip *msp71xx_chip =
        to_msp71xx_exd_gpio_chip(chip);

    __raw_writel(1 << MSP71XX_CFG_IN_OFFSET(offset), msp71xx_chip->reg);
    return 0;
}

#define MSP71XX_EXD_GPIO_BANK(name, exd_reg, base_gpio, num_gpio) \
{ \
    .chip = { \
        .label        = name, \
        .direction_input  = msp71xx_exd_direction_input, \
        .direction_output = msp71xx_exd_direction_output, \
        .get          = msp71xx_exd_gpio_get, \
        .set          = msp71xx_exd_gpio_set, \
        .base         = base_gpio, \
        .ngpio        = num_gpio, \
    }, \
    .reg    = (void __iomem *)(MSP71XX_EXD_GPIO_BASE + exd_reg), \
}

/*
 * struct msp71xx_exd_gpio_banks[] - container array of gpio banks
 * @chip: chip structure for the specified gpio bank
 * @reg: register for reading and writing the gpio pin value
 *
 * This array structure defines the extended gpio banks for the
 * PMC MIPS Processor. We specify the bank name, the data/config
 * register,the base starting gpio number, and the number of
 * gpios exposed by the bank of gpios.
 */
static struct msp71xx_exd_gpio_chip msp71xx_exd_gpio_banks[] = {

    MSP71XX_EXD_GPIO_BANK("GPIO_23_16", 0x188, 16, 8),
    MSP71XX_EXD_GPIO_BANK("GPIO_27_24", 0x18C, 24, 4),
};

void __init msp71xx_init_gpio_extended(void)
{
    int i;

    for (i = 0; i < ARRAY_SIZE(msp71xx_exd_gpio_banks); i++)
        gpiochip_add(&msp71xx_exd_gpio_banks[i].chip);
}