// SPDX-License-Identifier: GPL-2.0+
/*
 * COMEDI driver for the watchdog subdevice found on some addi-data boards
 * Copyright (c) 2013 H Hartley Sweeten <hsweeten@visionengravers.com>
 *
 * Based on implementations in various addi-data COMEDI drivers.
 *
 * COMEDI - Linux Control and Measurement Device Interface
 * Copyright (C) 1998 David A. Schleef <ds@schleef.org>
 */

#include <linux/module.h>
#include <linux/comedi/comedidev.h>
#include "addi_tcw.h"
#include "addi_watchdog.h"

struct addi_watchdog_private {
        unsigned long iobase;
        unsigned int wdog_ctrl;
};

/*
 * The watchdog subdevice is configured with two INSN_CONFIG instructions:
 *
 * Enable the watchdog and set the reload timeout:
 *      data[0] = INSN_CONFIG_ARM
 *      data[1] = timeout reload value
 *
 * Disable the watchdog:
 *      data[0] = INSN_CONFIG_DISARM
 */
static int addi_watchdog_insn_config(struct comedi_device *dev,
                                     struct comedi_subdevice *s,
                                     struct comedi_insn *insn,
                                     unsigned int *data)
{
        struct addi_watchdog_private *spriv = s->private;
        unsigned int reload;

        switch (data[0]) {
        case INSN_CONFIG_ARM:
                spriv->wdog_ctrl = ADDI_TCW_CTRL_ENA;
                reload = data[1] & s->maxdata;
                outl(reload, spriv->iobase + ADDI_TCW_RELOAD_REG);

                /* Time base is 20ms, let the user know the timeout */
                dev_info(dev->class_dev, "watchdog enabled, timeout:%dms\n",
                         20 * reload + 20);
                break;
        case INSN_CONFIG_DISARM:
                spriv->wdog_ctrl = 0;
                break;
        default:
                return -EINVAL;
        }

        outl(spriv->wdog_ctrl, spriv->iobase + ADDI_TCW_CTRL_REG);

        return insn->n;
}

static int addi_watchdog_insn_read(struct comedi_device *dev,
                                   struct comedi_subdevice *s,
                                   struct comedi_insn *insn,
                                   unsigned int *data)
{
        struct addi_watchdog_private *spriv = s->private;
        int i;

        for (i = 0; i < insn->n; i++)
                data[i] = inl(spriv->iobase + ADDI_TCW_STATUS_REG);

        return insn->n;
}

static int addi_watchdog_insn_write(struct comedi_device *dev,
                                    struct comedi_subdevice *s,
                                    struct comedi_insn *insn,
                                    unsigned int *data)
{
        struct addi_watchdog_private *spriv = s->private;
        int i;

        if (spriv->wdog_ctrl == 0) {
                dev_warn(dev->class_dev, "watchdog is disabled\n");
                return -EINVAL;
        }

        /* "ping" the watchdog */
        for (i = 0; i < insn->n; i++) {
                outl(spriv->wdog_ctrl | ADDI_TCW_CTRL_TRIG,
                     spriv->iobase + ADDI_TCW_CTRL_REG);
        }

        return insn->n;
}

void addi_watchdog_reset(unsigned long iobase)
{
        outl(0x0, iobase + ADDI_TCW_CTRL_REG);
        outl(0x0, iobase + ADDI_TCW_RELOAD_REG);
}
EXPORT_SYMBOL_GPL(addi_watchdog_reset);

int addi_watchdog_init(struct comedi_subdevice *s, unsigned long iobase)
{
        struct addi_watchdog_private *spriv;

        spriv = comedi_alloc_spriv(s, sizeof(*spriv));
        if (!spriv)
                return -ENOMEM;

        spriv->iobase = iobase;

        s->type         = COMEDI_SUBD_TIMER;
        s->subdev_flags = SDF_WRITABLE;
        s->n_chan       = 1;
        s->maxdata      = 0xff;
        s->insn_config  = addi_watchdog_insn_config;
        s->insn_read    = addi_watchdog_insn_read;
        s->insn_write   = addi_watchdog_insn_write;

        return 0;
}
EXPORT_SYMBOL_GPL(addi_watchdog_init);

static int __init addi_watchdog_module_init(void)
{
        return 0;
}
module_init(addi_watchdog_module_init);

static void __exit addi_watchdog_module_exit(void)
{
}
module_exit(addi_watchdog_module_exit);

MODULE_DESCRIPTION("ADDI-DATA Watchdog subdevice");
MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
MODULE_LICENSE("GPL");