/*
   *	National Semiconductor PC87307/PC97307 (ala SC1200) WDT driver
   *	(c) Copyright 2002 Zwane Mwaikambo <zwane@commfireservices.com>,
   *			All Rights Reserved.
   *	Based on wdt.c and wdt977.c by Alan Cox and Woody Suwalski respectively.
   *
   *	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.
   *
   *	The author(s) of this software shall not be held liable for damages
   *	of any nature resulting due to the use of this software. This
   *	software is provided AS-IS with no warranties.
   *
   *	Changelog:
   *	20020220 Zwane Mwaikambo	Code based on datasheet, no hardware.
   *	20020221 Zwane Mwaikambo	Cleanups as suggested by Jeff Garzik
   *					and Alan Cox.
   *	20020222 Zwane Mwaikambo	Added probing.
   *	20020225 Zwane Mwaikambo	Added ISAPNP support.
   *	20020412 Rob Radez		Broke out start/stop functions
   *		 <rob@osinvestor.com>	Return proper status instead of
   *					temperature warning
   *					Add WDIOC_GETBOOTSTATUS and
   *					WDIOC_SETOPTIONS ioctls
   *					Fix CONFIG_WATCHDOG_NOWAYOUT
   *	20020530 Joel Becker		Add Matt Domsch's nowayout module
   *					option
   *	20030116 Adam Belay		Updated to the latest pnp code
   *
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/miscdevice.h>
  #include <linux/watchdog.h>
  #include <linux/ioport.h>
  #include <linux/spinlock.h>
  #include <linux/notifier.h>
  #include <linux/reboot.h>
  #include <linux/init.h>
  #include <linux/pnp.h>
  #include <linux/fs.h>
  #include <linux/semaphore.h>
  #include <linux/io.h>
  #include <linux/uaccess.h>
  
  #define SC1200_MODULE_VER	"build 20020303"
  #define SC1200_MODULE_NAME	"sc1200wdt"
  
  #define	MAX_TIMEOUT	255	/* 255 minutes */
  #define PMIR		(io)	/* Power Management Index Register */
  #define PMDR		(io+1)	/* Power Management Data Register */
  
  /* Data Register indexes */
  #define FER1		0x00	/* Function enable register 1 */
  #define FER2		0x01	/* Function enable register 2 */
  #define PMC1		0x02	/* Power Management Ctrl 1 */
  #define PMC2		0x03	/* Power Management Ctrl 2 */
  #define PMC3		0x04	/* Power Management Ctrl 3 */
  #define WDTO		0x05	/* Watchdog timeout register */
  #define	WDCF		0x06	/* Watchdog config register */
  #define WDST		0x07	/* Watchdog status register */
  
  /* WDCF bitfields - which devices assert WDO */
  #define KBC_IRQ		0x01	/* Keyboard Controller */
  #define MSE_IRQ		0x02	/* Mouse */
  #define UART1_IRQ	0x03	/* Serial0 */
  #define UART2_IRQ	0x04	/* Serial1 */
  /* 5 -7 are reserved */
  
  static int timeout = 1;
  static int io = -1;
  static int io_len = 2;		/* for non plug and play */
  static unsigned long open_flag;
  static char expect_close;
  static DEFINE_SPINLOCK(sc1200wdt_lock);	/* io port access serialisation */
  
  #if defined CONFIG_PNP
  static int isapnp = 1;
  static struct pnp_dev *wdt_dev;
  
  module_param(isapnp, int, 0);
  MODULE_PARM_DESC(isapnp,
  	"When set to 0 driver ISA PnP support will be disabled");
  #endif
  
  module_param(io, int, 0);
  MODULE_PARM_DESC(io, "io port");
  module_param(timeout, int, 0);
  MODULE_PARM_DESC(timeout, "range is 0-255 minutes, default is 1");
  
  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) ")");
  
  
  
  /* Read from Data Register */
  static inline void __sc1200wdt_read_data(unsigned char index,
  						unsigned char *data)
  {
  	outb_p(index, PMIR);
  	*data = inb(PMDR);
  }
  
  static void sc1200wdt_read_data(unsigned char index, unsigned char *data)
  {
  	spin_lock(&sc1200wdt_lock);
  	__sc1200wdt_read_data(index, data);
  	spin_unlock(&sc1200wdt_lock);
  }
  
  /* Write to Data Register */
  static inline void __sc1200wdt_write_data(unsigned char index,
  						unsigned char data)
  {
  	outb_p(index, PMIR);
  	outb(data, PMDR);
  }
  
  static inline void sc1200wdt_write_data(unsigned char index,
  						unsigned char data)
  {
  	spin_lock(&sc1200wdt_lock);
  	__sc1200wdt_write_data(index, data);
  	spin_unlock(&sc1200wdt_lock);
  }
  
  
  static void sc1200wdt_start(void)
  {
  	unsigned char reg;
  	spin_lock(&sc1200wdt_lock);
  
  	__sc1200wdt_read_data(WDCF, &reg);
  	/* assert WDO when any of the following interrupts are triggered too */
  	reg |= (KBC_IRQ | MSE_IRQ | UART1_IRQ | UART2_IRQ);
  	__sc1200wdt_write_data(WDCF, reg);
  	/* set the timeout and get the ball rolling */
  	__sc1200wdt_write_data(WDTO, timeout);
  
  	spin_unlock(&sc1200wdt_lock);
  }
  
  static void sc1200wdt_stop(void)
  {
  	sc1200wdt_write_data(WDTO, 0);
  }
  
  /* This returns the status of the WDO signal, inactive high. */
  static inline int sc1200wdt_status(void)
  {
  	unsigned char ret;
  
  	sc1200wdt_read_data(WDST, &ret);
  	/* If the bit is inactive, the watchdog is enabled, so return
  	 * KEEPALIVEPING which is a bit of a kludge because there's nothing
  	 * else for enabled/disabled status
  	 */
  	return (ret & 0x01) ? 0 : WDIOF_KEEPALIVEPING;
  }
  
  static int sc1200wdt_open(struct inode *inode, struct file *file)
  {
  	/* allow one at a time */
  	if (test_and_set_bit(0, &open_flag))
  		return -EBUSY;
  
  	if (timeout > MAX_TIMEOUT)
  		timeout = MAX_TIMEOUT;
  
  	sc1200wdt_start();
  	pr_info("Watchdog enabled, timeout = %d min(s)", timeout);
  
  	return nonseekable_open(inode, file);
  }
  
  
  static long sc1200wdt_ioctl(struct file *file, unsigned int cmd,
  						unsigned long arg)
  {
  	int new_timeout;
  	void __user *argp = (void __user *)arg;
  	int __user *p = argp;
  	static const struct watchdog_info ident = {
  		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
  							WDIOF_MAGICCLOSE,
  		.firmware_version = 0,
  		.identity = "PC87307/PC97307",
  	};
  
  	switch (cmd) {
  	case WDIOC_GETSUPPORT:
  		if (copy_to_user(argp, &ident, sizeof(ident)))
  			return -EFAULT;
  		return 0;
  
  	case WDIOC_GETSTATUS:
  		return put_user(sc1200wdt_status(), p);
  
  	case WDIOC_GETBOOTSTATUS:
  		return put_user(0, p);
  
  	case WDIOC_SETOPTIONS:
  	{
  		int options, retval = -EINVAL;
  
  		if (get_user(options, p))
  			return -EFAULT;
  
  		if (options & WDIOS_DISABLECARD) {
  			sc1200wdt_stop();
  			retval = 0;
  		}
  
  		if (options & WDIOS_ENABLECARD) {
  			sc1200wdt_start();
  			retval = 0;
  		}
  
  		return retval;
  	}
  	case WDIOC_KEEPALIVE:
  		sc1200wdt_write_data(WDTO, timeout);
  		return 0;
  
  	case WDIOC_SETTIMEOUT:
  		if (get_user(new_timeout, p))
  			return -EFAULT;
  		/* the API states this is given in secs */
  		new_timeout /= 60;
  		if (new_timeout < 0 || new_timeout > MAX_TIMEOUT)
  			return -EINVAL;
  		timeout = new_timeout;
  		sc1200wdt_write_data(WDTO, timeout);
  		/* fall through and return the new timeout */
  
  	case WDIOC_GETTIMEOUT:
  		return put_user(timeout * 60, p);
  
  	default:
  		return -ENOTTY;
  	}
  }
  
  
  static int sc1200wdt_release(struct inode *inode, struct file *file)
  {
  	if (expect_close == 42) {
  		sc1200wdt_stop();
  		pr_info("Watchdog disabled
  ");
  	} else {
  		sc1200wdt_write_data(WDTO, timeout);
  		pr_crit("Unexpected close!, timeout = %d min(s)
  ", timeout);
  	}
  	clear_bit(0, &open_flag);
  	expect_close = 0;
  
  	return 0;
  }
  
  
  static ssize_t sc1200wdt_write(struct file *file, const char __user *data,
  						size_t len, loff_t *ppos)
  {
  	if (len) {
  		if (!nowayout) {
  			size_t i;
  
  			expect_close = 0;
  
  			for (i = 0; i != len; i++) {
  				char c;
  
  				if (get_user(c, data + i))
  					return -EFAULT;
  				if (c == 'V')
  					expect_close = 42;
  			}
  		}
  
  		sc1200wdt_write_data(WDTO, timeout);
  		return len;
  	}
  
  	return 0;
  }
  
  
  static int sc1200wdt_notify_sys(struct notifier_block *this,
  					unsigned long code, void *unused)
  {
  	if (code == SYS_DOWN || code == SYS_HALT)
  		sc1200wdt_stop();
  
  	return NOTIFY_DONE;
  }
  
  
  static struct notifier_block sc1200wdt_notifier = {
  	.notifier_call =	sc1200wdt_notify_sys,
  };
  
  static const struct file_operations sc1200wdt_fops = {
  	.owner		= THIS_MODULE,
  	.llseek		= no_llseek,
  	.write		= sc1200wdt_write,
  	.unlocked_ioctl = sc1200wdt_ioctl,
  	.open		= sc1200wdt_open,
  	.release	= sc1200wdt_release,
  };
  
  static struct miscdevice sc1200wdt_miscdev = {
  	.minor		= WATCHDOG_MINOR,
  	.name		= "watchdog",
  	.fops		= &sc1200wdt_fops,
  };
  
  
  static int __init sc1200wdt_probe(void)
  {
  	/* The probe works by reading the PMC3 register's default value of 0x0e
  	 * there is one caveat, if the device disables the parallel port or any
  	 * of the UARTs we won't be able to detect it.
  	 * NB. This could be done with accuracy by reading the SID registers,
  	 * but we don't have access to those io regions.
  	 */
  
  	unsigned char reg;
  
  	sc1200wdt_read_data(PMC3, &reg);
  	reg &= 0x0f;		/* we don't want the UART busy bits */
  	return (reg == 0x0e) ? 0 : -ENODEV;
  }
  
  
  #if defined CONFIG_PNP
  
  static struct pnp_device_id scl200wdt_pnp_devices[] = {
  	/* National Semiconductor PC87307/PC97307 watchdog component */
  	{.id = "NSC0800", .driver_data = 0},
  	{.id = ""},
  };
  
  static int scl200wdt_pnp_probe(struct pnp_dev *dev,
  					const struct pnp_device_id *dev_id)
  {
  	/* this driver only supports one card at a time */
  	if (wdt_dev || !isapnp)
  		return -EBUSY;
  
  	wdt_dev = dev;
  	io = pnp_port_start(wdt_dev, 0);
  	io_len = pnp_port_len(wdt_dev, 0);
  
  	if (!request_region(io, io_len, SC1200_MODULE_NAME)) {
  		pr_err("Unable to register IO port %#x
  ", io);
  		return -EBUSY;
  	}
  
  	pr_info("PnP device found at io port %#x/%d
  ", io, io_len);
  	return 0;
  }
  
  static void scl200wdt_pnp_remove(struct pnp_dev *dev)
  {
  	if (wdt_dev) {
  		release_region(io, io_len);
  		wdt_dev = NULL;
  	}
  }
  
  static struct pnp_driver scl200wdt_pnp_driver = {
  	.name		= "scl200wdt",
  	.id_table	= scl200wdt_pnp_devices,
  	.probe		= scl200wdt_pnp_probe,
  	.remove		= scl200wdt_pnp_remove,
  };
  
  #endif /* CONFIG_PNP */
  
  
  static int __init sc1200wdt_init(void)
  {
  	int ret;
  
  	pr_info("%s
  ", SC1200_MODULE_VER);
  
  #if defined CONFIG_PNP
  	if (isapnp) {
  		ret = pnp_register_driver(&scl200wdt_pnp_driver);
  		if (ret)
  			goto out_clean;
  	}
  #endif
  
  	if (io == -1) {
  		pr_err("io parameter must be specified
  ");
  		ret = -EINVAL;
  		goto out_pnp;
  	}
  
  #if defined CONFIG_PNP
  	/* now that the user has specified an IO port and we haven't detected
  	 * any devices, disable pnp support */
  	if (isapnp)
  		pnp_unregister_driver(&scl200wdt_pnp_driver);
  	isapnp = 0;
  #endif
  
  	if (!request_region(io, io_len, SC1200_MODULE_NAME)) {
  		pr_err("Unable to register IO port %#x
  ", io);
  		ret = -EBUSY;
  		goto out_pnp;
  	}
  
  	ret = sc1200wdt_probe();
  	if (ret)
  		goto out_io;
  
  	ret = register_reboot_notifier(&sc1200wdt_notifier);
  	if (ret) {
  		pr_err("Unable to register reboot notifier err = %d
  ", ret);
  		goto out_io;
  	}
  
  	ret = misc_register(&sc1200wdt_miscdev);
  	if (ret) {
  		pr_err("Unable to register miscdev on minor %d
  ",
  		       WATCHDOG_MINOR);
  		goto out_rbt;
  	}
  
  	/* ret = 0 */
  
  out_clean:
  	return ret;
  
  out_rbt:
  	unregister_reboot_notifier(&sc1200wdt_notifier);
  
  out_io:
  	release_region(io, io_len);
  
  out_pnp:
  #if defined CONFIG_PNP
  	if (isapnp)
  		pnp_unregister_driver(&scl200wdt_pnp_driver);
  #endif
  	goto out_clean;
  }
  
  
  static void __exit sc1200wdt_exit(void)
  {
  	misc_deregister(&sc1200wdt_miscdev);
  	unregister_reboot_notifier(&sc1200wdt_notifier);
  
  #if defined CONFIG_PNP
  	if (isapnp)
  		pnp_unregister_driver(&scl200wdt_pnp_driver);
  	else
  #endif
  	release_region(io, io_len);
  }
  
  module_init(sc1200wdt_init);
  module_exit(sc1200wdt_exit);
  
  MODULE_AUTHOR("Zwane Mwaikambo <zwane@commfireservices.com>");
  MODULE_DESCRIPTION(
  	"Driver for National Semiconductor PC87307/PC97307 watchdog component");
  MODULE_LICENSE("GPL");