/*
 * GE PIO2 6U VME I/O 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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#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/ctype.h>
#include <linux/gpio.h>
#include <linux/slab.h>
#include <linux/vme.h>

#include "vme_pio2.h"


static const char driver_name[] = "pio2";

static int bus[PIO2_CARDS_MAX];
static int bus_num;
static long base[PIO2_CARDS_MAX];
static int base_num;
static int vector[PIO2_CARDS_MAX];
static int vector_num;
static int level[PIO2_CARDS_MAX];
static int level_num;
static char *variant[PIO2_CARDS_MAX];
static int variant_num;

static bool loopback;

static int pio2_match(struct vme_dev *);
static int pio2_probe(struct vme_dev *);
static int pio2_remove(struct vme_dev *);

static int pio2_get_led(struct pio2_card *card)
{
        /* Can't read hardware, state saved in structure */
        return card->led;
}

static int pio2_set_led(struct pio2_card *card, int state)
{
        u8 reg;
        int retval;

        reg = card->irq_level;

        /* Register state inverse of led state */
        if (!state)
                reg |= PIO2_LED;

        if (loopback)
                reg |= PIO2_LOOP;

        retval = vme_master_write(card->window, &reg, 1, PIO2_REGS_CTRL);
        if (retval < 0)
                return retval;

        card->led = state ? 1 : 0;

        return 0;
}

static void pio2_int(int level, int vector, void *ptr)
{
        int vec, i, channel, retval;
        u8 reg;
        struct pio2_card *card  = ptr;

        vec = vector & ~PIO2_VME_VECTOR_MASK;

        switch (vec) {
        case 0:
                dev_warn(&card->vdev->dev, "Spurious Interrupt\n");
                break;
        case 1:
        case 2:
        case 3:
        case 4:
                /* Channels 0 to 7 */
                retval = vme_master_read(card->window, &reg, 1,
                        PIO2_REGS_INT_STAT[vec - 1]);
                if (retval < 0) {
                        dev_err(&card->vdev->dev,
                                "Unable to read IRQ status register\n");
                        return;
                }
                for (i = 0; i < 8; i++) {
                        channel = ((vec - 1) * 8) + i;
                        if (reg & PIO2_CHANNEL_BIT[channel])
                                dev_info(&card->vdev->dev,
                                        "Interrupt on I/O channel %d\n",
                                        channel);
                }
                break;
        case 5:
        case 6:
        case 7:
        case 8:
        case 9:
        case 10:
                /* Counters are dealt with by their own handler */
                dev_err(&card->vdev->dev,
                        "Counter interrupt\n");
                break;
        }
}


/*
 * We return whether this has been successful - this is used in the probe to
 * ensure we have a valid card.
 */
static int pio2_reset_card(struct pio2_card *card)
{
        int retval = 0;
        u8 data = 0;

        /* Clear main register*/
        retval = vme_master_write(card->window, &data, 1, PIO2_REGS_CTRL);
        if (retval < 0)
                return retval;

        /* Clear VME vector */
        retval = vme_master_write(card->window, &data, 1, PIO2_REGS_VME_VECTOR);
        if (retval < 0)
                return retval;

        /* Reset GPIO */
        retval = pio2_gpio_reset(card);
        if (retval < 0)
                return retval;

        /* Reset counters */
        retval = pio2_cntr_reset(card);
        if (retval < 0)
                return retval;

        return 0;
}

static struct vme_driver pio2_driver = {
        .name = driver_name,
        .match = pio2_match,
        .probe = pio2_probe,
        .remove = pio2_remove,
};


static int __init pio2_init(void)
{
        if (bus_num == 0) {
                pr_err("No cards, skipping registration\n");
                return -ENODEV;
        }

        if (bus_num > PIO2_CARDS_MAX) {
                pr_err("Driver only able to handle %d PIO2 Cards\n",
                       PIO2_CARDS_MAX);
                bus_num = PIO2_CARDS_MAX;
        }

        /* Register the PIO2 driver */
        return  vme_register_driver(&pio2_driver, bus_num);
}

static int pio2_match(struct vme_dev *vdev)
{

        if (vdev->num >= bus_num) {
                dev_err(&vdev->dev,
                        "The enumeration of the VMEbus to which the board is connected must be specified");
                return 0;
        }

        if (vdev->num >= base_num) {
                dev_err(&vdev->dev,
                        "The VME address for the cards registers must be specified");
                return 0;
        }

        if (vdev->num >= vector_num) {
                dev_err(&vdev->dev,
                        "The IRQ vector used by the card must be specified");
                return 0;
        }

        if (vdev->num >= level_num) {
                dev_err(&vdev->dev,
                        "The IRQ level used by the card must be specified");
                return 0;
        }

        if (vdev->num >= variant_num) {
                dev_err(&vdev->dev, "The variant of the card must be specified");
                return 0;
        }

        return 1;
}

static int pio2_probe(struct vme_dev *vdev)
{
        struct pio2_card *card;
        int retval;
        int i;
        u8 reg;
        int vec;

        card = kzalloc(sizeof(struct pio2_card), GFP_KERNEL);
        if (card == NULL) {
                retval = -ENOMEM;
                goto err_struct;
        }

        card->id = vdev->num;
        card->bus = bus[card->id];
        card->base = base[card->id];
        card->irq_vector = vector[card->id];
        card->irq_level = level[card->id] & PIO2_VME_INT_MASK;
        strncpy(card->variant, variant[card->id], PIO2_VARIANT_LENGTH);
        card->vdev = vdev;

        for (i = 0; i < PIO2_VARIANT_LENGTH; i++) {

                if (isdigit(card->variant[i]) == 0) {
                        dev_err(&card->vdev->dev, "Variant invalid\n");
                        retval = -EINVAL;
                        goto err_variant;
                }
        }

        /*
         * Bottom 4 bits of VME interrupt vector used to determine source,
         * provided vector should only use upper 4 bits.
         */
        if (card->irq_vector & ~PIO2_VME_VECTOR_MASK) {
                dev_err(&card->vdev->dev,
                        "Invalid VME IRQ Vector, vector must not use lower 4 bits\n");
                retval = -EINVAL;
                goto err_vector;
        }

        /*
         * There is no way to determine the build variant or whether each bank
         * is input, output or both at run time. The inputs are also inverted
         * if configured as both.
         *
         * We pass in the board variant and use that to determine the
         * configuration of the banks.
         */
        for (i = 1; i < PIO2_VARIANT_LENGTH; i++) {
                switch (card->variant[i]) {
                case '0':
                        card->bank[i-1].config = NOFIT;
                        break;
                case '1':
                case '2':
                case '3':
                case '4':
                        card->bank[i-1].config = INPUT;
                        break;
                case '5':
                        card->bank[i-1].config = OUTPUT;
                        break;
                case '6':
                case '7':
                case '8':
                case '9':
                        card->bank[i-1].config = BOTH;
                        break;
                }
        }

        /* Get a master window and position over regs */
        card->window = vme_master_request(vdev, VME_A24, VME_SCT, VME_D16);
        if (card->window == NULL) {
                dev_err(&card->vdev->dev,
                        "Unable to assign VME master resource\n");
                retval = -EIO;
                goto err_window;
        }

        retval = vme_master_set(card->window, 1, card->base, 0x10000, VME_A24,
                (VME_SCT | VME_USER | VME_DATA), VME_D16);
        if (retval) {
                dev_err(&card->vdev->dev,
                        "Unable to configure VME master resource\n");
                goto err_set;
        }

        /*
         * There is also no obvious register which we can probe to determine
         * whether the provided base is valid. If we can read the "ID Register"
         * offset and the reset function doesn't error, assume we have a valid
         * location.
         */
        retval = vme_master_read(card->window, &reg, 1, PIO2_REGS_ID);
        if (retval < 0) {
                dev_err(&card->vdev->dev, "Unable to read from device\n");
                goto err_read;
        }

        dev_dbg(&card->vdev->dev, "ID Register:%x\n", reg);

        /*
         * Ensure all the I/O is cleared. We can't read back the states, so
         * this is the only method we have to ensure that the I/O is in a known
         * state.
         */
        retval = pio2_reset_card(card);
        if (retval) {
                dev_err(&card->vdev->dev,
                        "Failed to reset card, is location valid?");
                retval = -ENODEV;
                goto err_reset;
        }

        /* Configure VME Interrupts */
        reg = card->irq_level;
        if (pio2_get_led(card))
                reg |= PIO2_LED;
        if (loopback)
                reg |= PIO2_LOOP;
        retval = vme_master_write(card->window, &reg, 1, PIO2_REGS_CTRL);
        if (retval < 0)
                return retval;

        /* Set VME vector */
        retval = vme_master_write(card->window, &card->irq_vector, 1,
                PIO2_REGS_VME_VECTOR);
        if (retval < 0)
                return retval;

        /* Attach spurious interrupt handler. */
        vec = card->irq_vector | PIO2_VME_VECTOR_SPUR;

        retval = vme_irq_request(vdev, card->irq_level, vec,
                &pio2_int, (void *)card);
        if (retval < 0) {
                dev_err(&card->vdev->dev,
                        "Unable to attach VME interrupt vector0x%x, level 0x%x\n",
                         vec, card->irq_level);
                goto err_irq;
        }

        /* Attach GPIO interrupt handlers. */
        for (i = 0; i < 4; i++) {
                vec = card->irq_vector | PIO2_VECTOR_BANK[i];

                retval = vme_irq_request(vdev, card->irq_level, vec,
                        &pio2_int, (void *)card);
                if (retval < 0) {
                        dev_err(&card->vdev->dev,
                                "Unable to attach VME interrupt vector0x%x, level 0x%x\n",
                                 vec, card->irq_level);
                        goto err_gpio_irq;
                }
        }

        /* Attach counter interrupt handlers. */
        for (i = 0; i < 6; i++) {
                vec = card->irq_vector | PIO2_VECTOR_CNTR[i];

                retval = vme_irq_request(vdev, card->irq_level, vec,
                        &pio2_int, (void *)card);
                if (retval < 0) {
                        dev_err(&card->vdev->dev,
                                "Unable to attach VME interrupt vector0x%x, level 0x%x\n",
                                vec, card->irq_level);
                        goto err_cntr_irq;
                }
        }

        /* Register IO */
        retval = pio2_gpio_init(card);
        if (retval < 0) {
                dev_err(&card->vdev->dev,
                        "Unable to register with GPIO framework\n");
                goto err_gpio;
        }

        /* Set LED - This also sets interrupt level */
        retval = pio2_set_led(card, 0);
        if (retval < 0) {
                dev_err(&card->vdev->dev, "Unable to set LED\n");
                goto err_led;
        }

        dev_set_drvdata(&card->vdev->dev, card);

        dev_info(&card->vdev->dev,
                "PIO2 (variant %s) configured at 0x%lx\n", card->variant,
                card->base);

        return 0;

err_led:
        pio2_gpio_exit(card);
err_gpio:
        i = 6;
err_cntr_irq:
        while (i > 0) {
                i--;
                vec = card->irq_vector | PIO2_VECTOR_CNTR[i];
                vme_irq_free(vdev, card->irq_level, vec);
        }

        i = 4;
err_gpio_irq:
        while (i > 0) {
                i--;
                vec = card->irq_vector | PIO2_VECTOR_BANK[i];
                vme_irq_free(vdev, card->irq_level, vec);
        }

        vec = (card->irq_vector & PIO2_VME_VECTOR_MASK) | PIO2_VME_VECTOR_SPUR;
        vme_irq_free(vdev, card->irq_level, vec);
err_irq:
         pio2_reset_card(card);
err_reset:
err_read:
        vme_master_set(card->window, 0, 0, 0, VME_A16, 0, VME_D16);
err_set:
        vme_master_free(card->window);
err_window:
err_vector:
err_variant:
        kfree(card);
err_struct:
        return retval;
}

static int pio2_remove(struct vme_dev *vdev)
{
        int vec;
        int i;

        struct pio2_card *card = dev_get_drvdata(&vdev->dev);

        pio2_gpio_exit(card);

        for (i = 0; i < 6; i++) {
                vec = card->irq_vector | PIO2_VECTOR_CNTR[i];
                vme_irq_free(vdev, card->irq_level, vec);
        }

        for (i = 0; i < 4; i++) {
                vec = card->irq_vector | PIO2_VECTOR_BANK[i];
                vme_irq_free(vdev, card->irq_level, vec);
        }

        vec = (card->irq_vector & PIO2_VME_VECTOR_MASK) | PIO2_VME_VECTOR_SPUR;
        vme_irq_free(vdev, card->irq_level, vec);

        pio2_reset_card(card);

        vme_master_set(card->window, 0, 0, 0, VME_A16, 0, VME_D16);

        vme_master_free(card->window);

        kfree(card);

        return 0;
}

static void __exit pio2_exit(void)
{
        vme_unregister_driver(&pio2_driver);
}


/* These are required for each board */
MODULE_PARM_DESC(bus, "Enumeration of VMEbus to which the board is connected");
module_param_array(bus, int, &bus_num, S_IRUGO);

MODULE_PARM_DESC(base, "Base VME address for PIO2 Registers");
module_param_array(base, long, &base_num, S_IRUGO);

MODULE_PARM_DESC(vector, "VME IRQ Vector (Lower 4 bits masked)");
module_param_array(vector, int, &vector_num, S_IRUGO);

MODULE_PARM_DESC(level, "VME IRQ Level");
module_param_array(level, int, &level_num, S_IRUGO);

MODULE_PARM_DESC(variant, "Last 4 characters of PIO2 board variant");
module_param_array(variant, charp, &variant_num, S_IRUGO);

/* This is for debugging */
MODULE_PARM_DESC(loopback, "Enable loopback mode on all cards");
module_param(loopback, bool, S_IRUGO);

MODULE_DESCRIPTION("GE PIO2 6U VME I/O Driver");
MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com");
MODULE_LICENSE("GPL");

module_init(pio2_init);
module_exit(pio2_exit);