/*
 * GE PIO2 GPIO Driver
 *
 * Author: Martyn Welch <martyn.welch@ge.com>
 * 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/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/driver.h>
#include <linux/slab.h>
#include <linux/vme.h>

#include "vme_pio2.h"

static const char driver_name[] = "pio2_gpio";

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

                return 1;
        }

        if (card->bank[PIO2_CHANNEL_BANK[offset]].config != BOTH)
                return 1;

        return 0;
}

static void pio2_gpio_set(struct gpio_chip *chip,
                          unsigned int offset, int value)
{
        u8 reg;
        int retval;
        struct pio2_card *card = gpiochip_get_data(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 int offset)
{
        int data;
        struct pio2_card *card = gpiochip_get_data(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 runtime\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 int offset, int value)
{
        int data;
        struct pio2_card *card = gpiochip_get_data(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 runtime\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 pio2_gpio_init(struct pio2_card *card)
{
        int retval = 0;
        char *label;

        label = kasprintf(GFP_KERNEL,
                          "%s@%s", driver_name, dev_name(&card->vdev->dev));
        if (!label)
                return -ENOMEM;

        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_data(&card->gc, card);
        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;

        gpiochip_remove(&card->gc);
        kfree(label);
}