vme_pio2_gpio.c

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/*
 * GE PIO2 GPIO Driver
 *
 * Author: Martyn Welch <[email protected]>
 * Copyright 2009 GE Intelligent Platforms Embedded Systems, Inc.
 *
 * This program is free software; you can redistribute  it and/or modify it
 * under  the terms of  the GNU General  Public License as published by the
 * Free Software Foundation;  either version 2 of the  License, or (at your
 * option) any later version.
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/ctype.h>
#include <linux/gpio.h>
#include <linux/slab.h>
#include <linux/vme.h>

#include "vme_pio2.h"

static const char driver_name[] = "pio2_gpio";

static struct pio2_card *gpio_to_pio2_card(struct gpio_chip *chip)
{
    return container_of(chip, struct pio2_card, gc);
}

static int pio2_gpio_get(struct gpio_chip *chip, unsigned int offset)
{
    u8 reg;
    int retval;
    struct pio2_card *card = gpio_to_pio2_card(chip);

    if ((card->bank[PIO2_CHANNEL_BANK[offset]].config == OUTPUT) |
        (card->bank[PIO2_CHANNEL_BANK[offset]].config == NOFIT)) {

        dev_err(&card->vdev->dev, "Channel not available as input\n");
        return 0;
    }

    retval = vme_master_read(card->window, &reg, 1,
        PIO2_REGS_DATA[PIO2_CHANNEL_BANK[offset]]);
    if (retval < 0) {
        dev_err(&card->vdev->dev, "Unable to read from GPIO\n");
        return 0;
    }

    /*
     * Remember, input on channels configured as both input and output
     * are inverted!
     */
    if (reg & PIO2_CHANNEL_BIT[offset]) {
        if (card->bank[PIO2_CHANNEL_BANK[offset]].config != BOTH)
            return 0;
        else
            return 1;
    } else {
        if (card->bank[PIO2_CHANNEL_BANK[offset]].config != BOTH)
            return 1;
        else
            return 0;
    }
}

static void pio2_gpio_set(struct gpio_chip *chip, unsigned int offset,
    int value)
{
    u8 reg;
    int retval;
    struct pio2_card *card = gpio_to_pio2_card(chip);

    if ((card->bank[PIO2_CHANNEL_BANK[offset]].config == INPUT) |
        (card->bank[PIO2_CHANNEL_BANK[offset]].config == NOFIT)) {

        dev_err(&card->vdev->dev, "Channel not available as output\n");
        return;
    }

    if (value)
        reg = card->bank[PIO2_CHANNEL_BANK[offset]].value |
            PIO2_CHANNEL_BIT[offset];
    else
        reg = card->bank[PIO2_CHANNEL_BANK[offset]].value &
            ~PIO2_CHANNEL_BIT[offset];

    retval = vme_master_write(card->window, &reg, 1,
        PIO2_REGS_DATA[PIO2_CHANNEL_BANK[offset]]);
    if (retval < 0) {
        dev_err(&card->vdev->dev, "Unable to write to GPIO\n");
        return;
    }

    card->bank[PIO2_CHANNEL_BANK[offset]].value = reg;
}

/* Directionality configured at board build - send appropriate response */
static int pio2_gpio_dir_in(struct gpio_chip *chip, unsigned offset)
{
    int data;
    struct pio2_card *card = gpio_to_pio2_card(chip);

    if ((card->bank[PIO2_CHANNEL_BANK[offset]].config == OUTPUT) |
        (card->bank[PIO2_CHANNEL_BANK[offset]].config == NOFIT)) {
        dev_err(&card->vdev->dev,
            "Channel directionality not configurable at runtine\n");

        data = -EINVAL;
    } else {
        data = 0;
    }

    return data;
}

/* Directionality configured at board build - send appropriate response */
static int pio2_gpio_dir_out(struct gpio_chip *chip, unsigned offset, int value)
{
    int data;
    struct pio2_card *card = gpio_to_pio2_card(chip);

    if ((card->bank[PIO2_CHANNEL_BANK[offset]].config == INPUT) |
        (card->bank[PIO2_CHANNEL_BANK[offset]].config == NOFIT)) {
        dev_err(&card->vdev->dev,
            "Channel directionality not configurable at runtine\n");

        data = -EINVAL;
    } else {
        data = 0;
    }

    return data;
}

/*
 * We return whether this has been successful - this is used in the probe to
 * ensure we have a valid card.
 */
int pio2_gpio_reset(struct pio2_card *card)
{
    int retval = 0;
    int i, j;

    u8 data = 0;

    /* Zero output registers */
    for (i = 0; i < 4; i++) {
        retval = vme_master_write(card->window, &data, 1,
            PIO2_REGS_DATA[i]);
        if (retval < 0)
            return retval;
        card->bank[i].value = 0;
    }

    /* Set input interrupt masks */
    for (i = 0; i < 4; i++) {
        retval = vme_master_write(card->window, &data, 1,
            PIO2_REGS_INT_MASK[i * 2]);
        if (retval < 0)
            return retval;

        retval = vme_master_write(card->window, &data, 1,
            PIO2_REGS_INT_MASK[(i * 2) + 1]);
        if (retval < 0)
            return retval;

        for (j = 0; j < 8; j++)
            card->bank[i].irq[j] = NONE;
    }

    /* Ensure all I/O interrupts are cleared */
    for (i = 0; i < 4; i++) {
        do {
            retval = vme_master_read(card->window, &data, 1,
                PIO2_REGS_INT_STAT[i]);
            if (retval < 0)
                return retval;
        } while (data != 0);
    }

    return 0;
}

int __devinit pio2_gpio_init(struct pio2_card *card)
{
    int retval = 0;
    char *label;

    label = kmalloc(PIO2_NUM_CHANNELS, GFP_KERNEL);
    if (label == NULL) {
        dev_err(&card->vdev->dev, "Unable to allocate GPIO label\n");
        return -ENOMEM;
    }

    sprintf(label, "%s@%s", driver_name, dev_name(&card->vdev->dev));
    card->gc.label = label;

    card->gc.ngpio = PIO2_NUM_CHANNELS;
    /* Dynamic allocation of base */
    card->gc.base = -1;
    /* Setup pointers to chip functions */
    card->gc.direction_input = pio2_gpio_dir_in;
    card->gc.direction_output = pio2_gpio_dir_out;
    card->gc.get = pio2_gpio_get;
    card->gc.set = pio2_gpio_set;

    /* This function adds a memory mapped GPIO chip */
    retval = gpiochip_add(&(card->gc));
    if (retval) {
        dev_err(&card->vdev->dev, "Unable to register GPIO\n");
        kfree(card->gc.label);
    }

    return retval;
};

void pio2_gpio_exit(struct pio2_card *card)
{
    const char *label = card->gc.label;

    if (gpiochip_remove(&(card->gc)))
        dev_err(&card->vdev->dev, "Failed to remove GPIO");

    kfree(label);
}