// SPDX-License-Identifier: GPL-2.0+
/*
 *	Industrial Computer Source PCI-WDT500/501 driver
 *
 *	(c) Copyright 1996-1997 Alan Cox <alan@lxorguk.ukuu.org.uk>,
 *						All Rights Reserved.
 *
 *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
 *	warranty for any of this software. This material is provided
 *	"AS-IS" and at no charge.
 *
 *	(c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
 *
 *	Release 0.10.
 *
 *	Fixes
 *		Dave Gregorich	:	Modularisation and minor bugs
 *		Alan Cox	:	Added the watchdog ioctl() stuff
 *		Alan Cox	:	Fixed the reboot problem (as noted by
 *					Matt Crocker).
 *		Alan Cox	:	Added wdt= boot option
 *		Alan Cox	:	Cleaned up copy/user stuff
 *		Tim Hockin	:	Added insmod parameters, comment cleanup
 *					Parameterized timeout
 *		JP Nollmann	:	Added support for PCI wdt501p
 *		Alan Cox	:	Split ISA and PCI cards into two drivers
 *		Jeff Garzik	:	PCI cleanups
 *		Tigran Aivazian	:	Restructured wdtpci_init_one() to handle
 *					failures
 *		Joel Becker	:	Added WDIOC_GET/SETTIMEOUT
 *		Zwane Mwaikambo	:	Magic char closing, locking changes,
 *					cleanups
 *		Matt Domsch	:	nowayout module option
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/ioport.h>
#include <linux/delay.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/fs.h>
#include <linux/pci.h>
#include <linux/io.h>
#include <linux/uaccess.h>


#define WDT_IS_PCI
#include "wd501p.h"

/* We can only use 1 card due to the /dev/watchdog restriction */
static int dev_count;

static unsigned long open_lock;
static DEFINE_SPINLOCK(wdtpci_lock);
static char expect_close;

static resource_size_t io;
static int irq;

/* Default timeout */
#define WD_TIMO 60			/* Default heartbeat = 60 seconds */

static int heartbeat = WD_TIMO;
static int wd_heartbeat;
module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat,
		"Watchdog heartbeat in seconds. (0<heartbeat<65536, default="
				__MODULE_STRING(WD_TIMO) ")");

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
		"Watchdog cannot be stopped once started (default="
				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

/* Support for the Fan Tachometer on the PCI-WDT501 */
static int tachometer;
module_param(tachometer, int, 0);
MODULE_PARM_DESC(tachometer,
		"PCI-WDT501 Fan Tachometer support (0=disable, default=0)");

static int type = 500;
module_param(type, int, 0);
MODULE_PARM_DESC(type,
		"PCI-WDT501 Card type (500 or 501 , default=500)");

/*
 *	Programming support
 */

static void wdtpci_ctr_mode(int ctr, int mode)
{
	ctr <<= 6;
	ctr |= 0x30;
	ctr |= (mode << 1);
	outb(ctr, WDT_CR);
	udelay(8);
}

static void wdtpci_ctr_load(int ctr, int val)
{
	outb(val & 0xFF, WDT_COUNT0 + ctr);
	udelay(8);
	outb(val >> 8, WDT_COUNT0 + ctr);
	udelay(8);
}

/**
 *	wdtpci_start:
 *
 *	Start the watchdog driver.
 */

static int wdtpci_start(void)
{
	unsigned long flags;

	spin_lock_irqsave(&wdtpci_lock, flags);

	/*
	 * "pet" the watchdog, as Access says.
	 * This resets the clock outputs.
	 */
	inb(WDT_DC);			/* Disable watchdog */
	udelay(8);
	wdtpci_ctr_mode(2, 0);		/* Program CTR2 for Mode 0:
						Pulse on Terminal Count */
	outb(0, WDT_DC);		/* Enable watchdog */
	udelay(8);
	inb(WDT_DC);			/* Disable watchdog */
	udelay(8);
	outb(0, WDT_CLOCK);		/* 2.0833MHz clock */
	udelay(8);
	inb(WDT_BUZZER);		/* disable */
	udelay(8);
	inb(WDT_OPTONOTRST);		/* disable */
	udelay(8);
	inb(WDT_OPTORST);		/* disable */
	udelay(8);
	inb(WDT_PROGOUT);		/* disable */
	udelay(8);
	wdtpci_ctr_mode(0, 3);		/* Program CTR0 for Mode 3:
						Square Wave Generator */
	wdtpci_ctr_mode(1, 2);		/* Program CTR1 for Mode 2:
						Rate Generator */
	wdtpci_ctr_mode(2, 1);		/* Program CTR2 for Mode 1:
						Retriggerable One-Shot */
	wdtpci_ctr_load(0, 20833);	/* count at 100Hz */
	wdtpci_ctr_load(1, wd_heartbeat);/* Heartbeat */
	/* DO NOT LOAD CTR2 on PCI card! -- JPN */
	outb(0, WDT_DC);		/* Enable watchdog */
	udelay(8);

	spin_unlock_irqrestore(&wdtpci_lock, flags);
	return 0;
}

/**
 *	wdtpci_stop:
 *
 *	Stop the watchdog driver.
 */

static int wdtpci_stop(void)
{
	unsigned long flags;

	/* Turn the card off */
	spin_lock_irqsave(&wdtpci_lock, flags);
	inb(WDT_DC);			/* Disable watchdog */
	udelay(8);
	wdtpci_ctr_load(2, 0);		/* 0 length reset pulses now */
	spin_unlock_irqrestore(&wdtpci_lock, flags);
	return 0;
}

/**
 *	wdtpci_ping:
 *
 *	Reload counter one with the watchdog heartbeat. We don't bother
 *	reloading the cascade counter.
 */

static int wdtpci_ping(void)
{
	unsigned long flags;

	spin_lock_irqsave(&wdtpci_lock, flags);
	/* Write a watchdog value */
	inb(WDT_DC);			/* Disable watchdog */
	udelay(8);
	wdtpci_ctr_mode(1, 2);		/* Re-Program CTR1 for Mode 2:
							Rate Generator */
	wdtpci_ctr_load(1, wd_heartbeat);/* Heartbeat */
	outb(0, WDT_DC);		/* Enable watchdog */
	udelay(8);
	spin_unlock_irqrestore(&wdtpci_lock, flags);
	return 0;
}

/**
 *	wdtpci_set_heartbeat:
 *	@t:		the new heartbeat value that needs to be set.
 *
 *	Set a new heartbeat value for the watchdog device. If the heartbeat
 *	value is incorrect we keep the old value and return -EINVAL.
 *	If successful we return 0.
 */
static int wdtpci_set_heartbeat(int t)
{
	/* Arbitrary, can't find the card's limits */
	if (t < 1 || t > 65535)
		return -EINVAL;

	heartbeat = t;
	wd_heartbeat = t * 100;
	return 0;
}

/**
 *	wdtpci_get_status:
 *	@status:		the new status.
 *
 *	Extract the status information from a WDT watchdog device. There are
 *	several board variants so we have to know which bits are valid. Some
 *	bits default to one and some to zero in order to be maximally painful.
 *
 *	we then map the bits onto the status ioctl flags.
 */

static int wdtpci_get_status(int *status)
{
	unsigned char new_status;
	unsigned long flags;

	spin_lock_irqsave(&wdtpci_lock, flags);
	new_status = inb(WDT_SR);
	spin_unlock_irqrestore(&wdtpci_lock, flags);

	*status = 0;
	if (new_status & WDC_SR_ISOI0)
		*status |= WDIOF_EXTERN1;
	if (new_status & WDC_SR_ISII1)
		*status |= WDIOF_EXTERN2;
	if (type == 501) {
		if (!(new_status & WDC_SR_TGOOD))
			*status |= WDIOF_OVERHEAT;
		if (!(new_status & WDC_SR_PSUOVER))
			*status |= WDIOF_POWEROVER;
		if (!(new_status & WDC_SR_PSUUNDR))
			*status |= WDIOF_POWERUNDER;
		if (tachometer) {
			if (!(new_status & WDC_SR_FANGOOD))
				*status |= WDIOF_FANFAULT;
		}
	}
	return 0;
}

/**
 *	wdtpci_get_temperature:
 *
 *	Reports the temperature in degrees Fahrenheit. The API is in
 *	farenheit. It was designed by an imperial measurement luddite.
 */

static int wdtpci_get_temperature(int *temperature)
{
	unsigned short c;
	unsigned long flags;
	spin_lock_irqsave(&wdtpci_lock, flags);
	c = inb(WDT_RT);
	udelay(8);
	spin_unlock_irqrestore(&wdtpci_lock, flags);
	*temperature = (c * 11 / 15) + 7;
	return 0;
}

/**
 *	wdtpci_interrupt:
 *	@irq:		Interrupt number
 *	@dev_id:	Unused as we don't allow multiple devices.
 *
 *	Handle an interrupt from the board. These are raised when the status
 *	map changes in what the board considers an interesting way. That means
 *	a failure condition occurring.
 */

static irqreturn_t wdtpci_interrupt(int irq, void *dev_id)
{
	/*
	 *	Read the status register see what is up and
	 *	then printk it.
	 */
	unsigned char status;

	spin_lock(&wdtpci_lock);

	status = inb(WDT_SR);
	udelay(8);

	pr_crit("status %d\n", status);

	if (type == 501) {
		if (!(status & WDC_SR_TGOOD)) {
			pr_crit("Overheat alarm (%d)\n", inb(WDT_RT));
			udelay(8);
		}
		if (!(status & WDC_SR_PSUOVER))
			pr_crit("PSU over voltage\n");
		if (!(status & WDC_SR_PSUUNDR))
			pr_crit("PSU under voltage\n");
		if (tachometer) {
			if (!(status & WDC_SR_FANGOOD))
				pr_crit("Possible fan fault\n");
		}
	}
	if (!(status & WDC_SR_WCCR)) {
#ifdef SOFTWARE_REBOOT
#ifdef ONLY_TESTING
		pr_crit("Would Reboot\n");
#else
		pr_crit("Initiating system reboot\n");
		emergency_restart();
#endif
#else
		pr_crit("Reset in 5ms\n");
#endif
	}
	spin_unlock(&wdtpci_lock);
	return IRQ_HANDLED;
}


/**
 *	wdtpci_write:
 *	@file: file handle to the watchdog
 *	@buf: buffer to write (unused as data does not matter here
 *	@count: count of bytes
 *	@ppos: pointer to the position to write. No seeks allowed
 *
 *	A write to a watchdog device is defined as a keepalive signal. Any
 *	write of data will do, as we we don't define content meaning.
 */

static ssize_t wdtpci_write(struct file *file, const char __user *buf,
						size_t count, loff_t *ppos)
{
	if (count) {
		if (!nowayout) {
			size_t i;

			/* In case it was set long ago */
			expect_close = 0;

			for (i = 0; i != count; i++) {
				char c;
				if (get_user(c, buf + i))
					return -EFAULT;
				if (c == 'V')
					expect_close = 42;
			}
		}
		wdtpci_ping();
	}
	return count;
}

/**
 *	wdtpci_ioctl:
 *	@file: file handle to the device
 *	@cmd: watchdog command
 *	@arg: argument pointer
 *
 *	The watchdog API defines a common set of functions for all watchdogs
 *	according to their available features. We only actually usefully support
 *	querying capabilities and current status.
 */

static long wdtpci_ioctl(struct file *file, unsigned int cmd,
							unsigned long arg)
{
	void __user *argp = (void __user *)arg;
	int __user *p = argp;
	int new_heartbeat;
	int status;

	struct watchdog_info ident = {
		.options =		WDIOF_SETTIMEOUT|
					WDIOF_MAGICCLOSE|
					WDIOF_KEEPALIVEPING,
		.firmware_version =	1,
		.identity =		"PCI-WDT500/501",
	};

	/* Add options according to the card we have */
	ident.options |= (WDIOF_EXTERN1|WDIOF_EXTERN2);
	if (type == 501) {
		ident.options |= (WDIOF_OVERHEAT|WDIOF_POWERUNDER|
							WDIOF_POWEROVER);
		if (tachometer)
			ident.options |= WDIOF_FANFAULT;
	}

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
	case WDIOC_GETSTATUS:
		wdtpci_get_status(&status);
		return put_user(status, p);
	case WDIOC_GETBOOTSTATUS:
		return put_user(0, p);
	case WDIOC_KEEPALIVE:
		wdtpci_ping();
		return 0;
	case WDIOC_SETTIMEOUT:
		if (get_user(new_heartbeat, p))
			return -EFAULT;
		if (wdtpci_set_heartbeat(new_heartbeat))
			return -EINVAL;
		wdtpci_ping();
		fallthrough;
	case WDIOC_GETTIMEOUT:
		return put_user(heartbeat, p);
	default:
		return -ENOTTY;
	}
}

/**
 *	wdtpci_open:
 *	@inode: inode of device
 *	@file: file handle to device
 *
 *	The watchdog device has been opened. The watchdog device is single
 *	open and on opening we load the counters. Counter zero is a 100Hz
 *	cascade, into counter 1 which downcounts to reboot. When the counter
 *	triggers counter 2 downcounts the length of the reset pulse which
 *	set set to be as long as possible.
 */

static int wdtpci_open(struct inode *inode, struct file *file)
{
	if (test_and_set_bit(0, &open_lock))
		return -EBUSY;

	if (nowayout)
		__module_get(THIS_MODULE);
	/*
	 *	Activate
	 */
	wdtpci_start();
	return stream_open(inode, file);
}

/**
 *	wdtpci_release:
 *	@inode: inode to board
 *	@file: file handle to board
 *
 *	The watchdog has a configurable API. There is a religious dispute
 *	between people who want their watchdog to be able to shut down and
 *	those who want to be sure if the watchdog manager dies the machine
 *	reboots. In the former case we disable the counters, in the latter
 *	case you have to open it again very soon.
 */

static int wdtpci_release(struct inode *inode, struct file *file)
{
	if (expect_close == 42) {
		wdtpci_stop();
	} else {
		pr_crit("Unexpected close, not stopping timer!\n");
		wdtpci_ping();
	}
	expect_close = 0;
	clear_bit(0, &open_lock);
	return 0;
}

/**
 *	wdtpci_temp_read:
 *	@file: file handle to the watchdog board
 *	@buf: buffer to write 1 byte into
 *	@count: length of buffer
 *	@ptr: offset (no seek allowed)
 *
 *	Read reports the temperature in degrees Fahrenheit. The API is in
 *	fahrenheit. It was designed by an imperial measurement luddite.
 */

static ssize_t wdtpci_temp_read(struct file *file, char __user *buf,
						size_t count, loff_t *ptr)
{
	int temperature;

	if (wdtpci_get_temperature(&temperature))
		return -EFAULT;

	if (copy_to_user(buf, &temperature, 1))
		return -EFAULT;

	return 1;
}

/**
 *	wdtpci_temp_open:
 *	@inode: inode of device
 *	@file: file handle to device
 *
 *	The temperature device has been opened.
 */

static int wdtpci_temp_open(struct inode *inode, struct file *file)
{
	return stream_open(inode, file);
}

/**
 *	wdtpci_temp_release:
 *	@inode: inode to board
 *	@file: file handle to board
 *
 *	The temperature device has been closed.
 */

static int wdtpci_temp_release(struct inode *inode, struct file *file)
{
	return 0;
}

/**
 *	wdtpci_notify_sys:
 *	@this: our notifier block
 *	@code: the event being reported
 *	@unused: unused
 *
 *	Our notifier is called on system shutdowns. We want to turn the card
 *	off at reboot otherwise the machine will reboot again during memory
 *	test or worse yet during the following fsck. This would suck, in fact
 *	trust me - if it happens it does suck.
 */

static int wdtpci_notify_sys(struct notifier_block *this, unsigned long code,
							void *unused)
{
	if (code == SYS_DOWN || code == SYS_HALT)
		wdtpci_stop();
	return NOTIFY_DONE;
}

/*
 *	Kernel Interfaces
 */


static const struct file_operations wdtpci_fops = {
	.owner		= THIS_MODULE,
	.write		= wdtpci_write,
	.unlocked_ioctl	= wdtpci_ioctl,
	.compat_ioctl	= compat_ptr_ioctl,
	.open		= wdtpci_open,
	.release	= wdtpci_release,
};

static struct miscdevice wdtpci_miscdev = {
	.minor	= WATCHDOG_MINOR,
	.name	= "watchdog",
	.fops	= &wdtpci_fops,
};

static const struct file_operations wdtpci_temp_fops = {
	.owner		= THIS_MODULE,
	.read		= wdtpci_temp_read,
	.open		= wdtpci_temp_open,
	.release	= wdtpci_temp_release,
};

static struct miscdevice temp_miscdev = {
	.minor	= TEMP_MINOR,
	.name	= "temperature",
	.fops	= &wdtpci_temp_fops,
};

/*
 *	The WDT card needs to learn about soft shutdowns in order to
 *	turn the timebomb registers off.
 */

static struct notifier_block wdtpci_notifier = {
	.notifier_call = wdtpci_notify_sys,
};


static int wdtpci_init_one(struct pci_dev *dev,
					const struct pci_device_id *ent)
{
	int ret = -EIO;

	dev_count++;
	if (dev_count > 1) {
		pr_err("This driver only supports one device\n");
		return -ENODEV;
	}

	if (type != 500 && type != 501) {
		pr_err("unknown card type '%d'\n", type);
		return -ENODEV;
	}

	if (pci_enable_device(dev)) {
		pr_err("Not possible to enable PCI Device\n");
		return -ENODEV;
	}

	if (pci_resource_start(dev, 2) == 0x0000) {
		pr_err("No I/O-Address for card detected\n");
		ret = -ENODEV;
		goto out_pci;
	}

	if (pci_request_region(dev, 2, "wdt_pci")) {
		pr_err("I/O address 0x%llx already in use\n",
		       (unsigned long long)pci_resource_start(dev, 2));
		goto out_pci;
	}

	irq = dev->irq;
	io = pci_resource_start(dev, 2);

	if (request_irq(irq, wdtpci_interrupt, IRQF_SHARED,
			 "wdt_pci", &wdtpci_miscdev)) {
		pr_err("IRQ %d is not free\n", irq);
		goto out_reg;
	}

	pr_info("PCI-WDT500/501 (PCI-WDG-CSM) driver 0.10 at 0x%llx (Interrupt %d)\n",
		(unsigned long long)io, irq);

	/* Check that the heartbeat value is within its range;
	   if not reset to the default */
	if (wdtpci_set_heartbeat(heartbeat)) {
		wdtpci_set_heartbeat(WD_TIMO);
		pr_info("heartbeat value must be 0 < heartbeat < 65536, using %d\n",
			WD_TIMO);
	}

	ret = register_reboot_notifier(&wdtpci_notifier);
	if (ret) {
		pr_err("cannot register reboot notifier (err=%d)\n", ret);
		goto out_irq;
	}

	if (type == 501) {
		ret = misc_register(&temp_miscdev);
		if (ret) {
			pr_err("cannot register miscdev on minor=%d (err=%d)\n",
			       TEMP_MINOR, ret);
			goto out_rbt;
		}
	}

	ret = misc_register(&wdtpci_miscdev);
	if (ret) {
		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
		       WATCHDOG_MINOR, ret);
		goto out_misc;
	}

	pr_info("initialized. heartbeat=%d sec (nowayout=%d)\n",
		heartbeat, nowayout);
	if (type == 501)
		pr_info("Fan Tachometer is %s\n",
			tachometer ? "Enabled" : "Disabled");

	ret = 0;
out:
	return ret;

out_misc:
	if (type == 501)
		misc_deregister(&temp_miscdev);
out_rbt:
	unregister_reboot_notifier(&wdtpci_notifier);
out_irq:
	free_irq(irq, &wdtpci_miscdev);
out_reg:
	pci_release_region(dev, 2);
out_pci:
	pci_disable_device(dev);
	goto out;
}


static void wdtpci_remove_one(struct pci_dev *pdev)
{
	/* here we assume only one device will ever have
	 * been picked up and registered by probe function */
	misc_deregister(&wdtpci_miscdev);
	if (type == 501)
		misc_deregister(&temp_miscdev);
	unregister_reboot_notifier(&wdtpci_notifier);
	free_irq(irq, &wdtpci_miscdev);
	pci_release_region(pdev, 2);
	pci_disable_device(pdev);
	dev_count--;
}


static const struct pci_device_id wdtpci_pci_tbl[] = {
	{
		.vendor	   = PCI_VENDOR_ID_ACCESSIO,
		.device	   = PCI_DEVICE_ID_ACCESSIO_WDG_CSM,
		.subvendor = PCI_ANY_ID,
		.subdevice = PCI_ANY_ID,
	},
	{ 0, }, /* terminate list */
};
MODULE_DEVICE_TABLE(pci, wdtpci_pci_tbl);


static struct pci_driver wdtpci_driver = {
	.name		= "wdt_pci",
	.id_table	= wdtpci_pci_tbl,
	.probe		= wdtpci_init_one,
	.remove		= wdtpci_remove_one,
};

module_pci_driver(wdtpci_driver);

MODULE_AUTHOR("JP Nollmann, Alan Cox");
MODULE_DESCRIPTION("Driver for the ICS PCI-WDT500/501 watchdog cards");
MODULE_LICENSE("GPL");