/*
   *	nv_tco 0.01:	TCO timer driver for NV chipsets
   *
   *	(c) Copyright 2005 Google Inc., All Rights Reserved.
   *
   *	Based off i8xx_tco.c:
   *	(c) Copyright 2000 kernel concepts <nils@kernelconcepts.de>, All Rights
   *	Reserved.
   *				http://www.kernelconcepts.de
   *
   *	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.
   *
   *	TCO timer driver for NV chipsets
   *	based on softdog.c by Alan Cox <alan@redhat.com>
   */
  
  /*
   *	Includes, defines, variables, module parameters, ...
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/types.h>
  #include <linux/miscdevice.h>
  #include <linux/watchdog.h>
  #include <linux/init.h>
  #include <linux/fs.h>
  #include <linux/pci.h>
  #include <linux/ioport.h>
  #include <linux/jiffies.h>
  #include <linux/platform_device.h>
  #include <linux/uaccess.h>
  #include <linux/io.h>
  
  #include "nv_tco.h"
  
  /* Module and version information */
  #define TCO_VERSION "0.01"
  #define TCO_MODULE_NAME "NV_TCO"
  #define TCO_DRIVER_NAME   TCO_MODULE_NAME ", v" TCO_VERSION
  
  /* internal variables */
  static unsigned int tcobase;
  static DEFINE_SPINLOCK(tco_lock);	/* Guards the hardware */
  static unsigned long timer_alive;
  static char tco_expect_close;
  static struct pci_dev *tco_pci;
  
  /* the watchdog platform device */
  static struct platform_device *nv_tco_platform_device;
  
  /* module parameters */
  #define WATCHDOG_HEARTBEAT 30	/* 30 sec default heartbeat (2<heartbeat<39) */
  static int heartbeat = WATCHDOG_HEARTBEAT;  /* in seconds */
  module_param(heartbeat, int, 0);
  MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. (2<heartbeat<39, "
  			    "default=" __MODULE_STRING(WATCHDOG_HEARTBEAT) ")");
  
  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) ")");
  
  /*
   * Some TCO specific functions
   */
  static inline unsigned char seconds_to_ticks(int seconds)
  {
  	/* the internal timer is stored as ticks which decrement
  	 * every 0.6 seconds */
  	return (seconds * 10) / 6;
  }
  
  static void tco_timer_start(void)
  {
  	u32 val;
  	unsigned long flags;
  
  	spin_lock_irqsave(&tco_lock, flags);
  	val = inl(TCO_CNT(tcobase));
  	val &= ~TCO_CNT_TCOHALT;
  	outl(val, TCO_CNT(tcobase));
  	spin_unlock_irqrestore(&tco_lock, flags);
  }
  
  static void tco_timer_stop(void)
  {
  	u32 val;
  	unsigned long flags;
  
  	spin_lock_irqsave(&tco_lock, flags);
  	val = inl(TCO_CNT(tcobase));
  	val |= TCO_CNT_TCOHALT;
  	outl(val, TCO_CNT(tcobase));
  	spin_unlock_irqrestore(&tco_lock, flags);
  }
  
  static void tco_timer_keepalive(void)
  {
  	unsigned long flags;
  
  	spin_lock_irqsave(&tco_lock, flags);
  	outb(0x01, TCO_RLD(tcobase));
  	spin_unlock_irqrestore(&tco_lock, flags);
  }
  
  static int tco_timer_set_heartbeat(int t)
  {
  	int ret = 0;
  	unsigned char tmrval;
  	unsigned long flags;
  	u8 val;
  
  	/*
  	 * note seconds_to_ticks(t) > t, so if t > 0x3f, so is
  	 * tmrval=seconds_to_ticks(t).  Check that the count in seconds isn't
  	 * out of range on it's own (to avoid overflow in tmrval).
  	 */
  	if (t < 0 || t > 0x3f)
  		return -EINVAL;
  	tmrval = seconds_to_ticks(t);
  
  	/* "Values of 0h-3h are ignored and should not be attempted" */
  	if (tmrval > 0x3f || tmrval < 0x04)
  		return -EINVAL;
  
  	/* Write new heartbeat to watchdog */
  	spin_lock_irqsave(&tco_lock, flags);
  	val = inb(TCO_TMR(tcobase));
  	val &= 0xc0;
  	val |= tmrval;
  	outb(val, TCO_TMR(tcobase));
  	val = inb(TCO_TMR(tcobase));
  
  	if ((val & 0x3f) != tmrval)
  		ret = -EINVAL;
  	spin_unlock_irqrestore(&tco_lock, flags);
  
  	if (ret)
  		return ret;
  
  	heartbeat = t;
  	return 0;
  }
  
  /*
   *	/dev/watchdog handling
   */
  
  static int nv_tco_open(struct inode *inode, struct file *file)
  {
  	/* /dev/watchdog can only be opened once */
  	if (test_and_set_bit(0, &timer_alive))
  		return -EBUSY;
  
  	/* Reload and activate timer */
  	tco_timer_keepalive();
  	tco_timer_start();
  	return nonseekable_open(inode, file);
  }
  
  static int nv_tco_release(struct inode *inode, struct file *file)
  {
  	/* Shut off the timer */
  	if (tco_expect_close == 42) {
  		tco_timer_stop();
  	} else {
  		pr_crit("Unexpected close, not stopping watchdog!
  ");
  		tco_timer_keepalive();
  	}
  	clear_bit(0, &timer_alive);
  	tco_expect_close = 0;
  	return 0;
  }
  
  static ssize_t nv_tco_write(struct file *file, const char __user *data,
  			    size_t len, loff_t *ppos)
  {
  	/* See if we got the magic character 'V' and reload the timer */
  	if (len) {
  		if (!nowayout) {
  			size_t i;
  
  			/*
  			 * note: just in case someone wrote the magic character
  			 * five months ago...
  			 */
  			tco_expect_close = 0;
  
  			/*
  			 * scan to see whether or not we got the magic
  			 * character
  			 */
  			for (i = 0; i != len; i++) {
  				char c;
  				if (get_user(c, data + i))
  					return -EFAULT;
  				if (c == 'V')
  					tco_expect_close = 42;
  			}
  		}
  
  		/* someone wrote to us, we should reload the timer */
  		tco_timer_keepalive();
  	}
  	return len;
  }
  
  static long nv_tco_ioctl(struct file *file, unsigned int cmd,
  			 unsigned long arg)
  {
  	int new_options, retval = -EINVAL;
  	int new_heartbeat;
  	void __user *argp = (void __user *)arg;
  	int __user *p = argp;
  	static const struct watchdog_info ident = {
  		.options =		WDIOF_SETTIMEOUT |
  					WDIOF_KEEPALIVEPING |
  					WDIOF_MAGICCLOSE,
  		.firmware_version =	0,
  		.identity =		TCO_MODULE_NAME,
  	};
  
  	switch (cmd) {
  	case WDIOC_GETSUPPORT:
  		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
  	case WDIOC_GETSTATUS:
  	case WDIOC_GETBOOTSTATUS:
  		return put_user(0, p);
  	case WDIOC_SETOPTIONS:
  		if (get_user(new_options, p))
  			return -EFAULT;
  		if (new_options & WDIOS_DISABLECARD) {
  			tco_timer_stop();
  			retval = 0;
  		}
  		if (new_options & WDIOS_ENABLECARD) {
  			tco_timer_keepalive();
  			tco_timer_start();
  			retval = 0;
  		}
  		return retval;
  	case WDIOC_KEEPALIVE:
  		tco_timer_keepalive();
  		return 0;
  	case WDIOC_SETTIMEOUT:
  		if (get_user(new_heartbeat, p))
  			return -EFAULT;
  		if (tco_timer_set_heartbeat(new_heartbeat))
  			return -EINVAL;
  		tco_timer_keepalive();
  		/* Fall through */
  	case WDIOC_GETTIMEOUT:
  		return put_user(heartbeat, p);
  	default:
  		return -ENOTTY;
  	}
  }
  
  /*
   *	Kernel Interfaces
   */
  
  static const struct file_operations nv_tco_fops = {
  	.owner =		THIS_MODULE,
  	.llseek =		no_llseek,
  	.write =		nv_tco_write,
  	.unlocked_ioctl =	nv_tco_ioctl,
  	.open =			nv_tco_open,
  	.release =		nv_tco_release,
  };
  
  static struct miscdevice nv_tco_miscdev = {
  	.minor =	WATCHDOG_MINOR,
  	.name =		"watchdog",
  	.fops =		&nv_tco_fops,
  };
  
  /*
   * Data for PCI driver interface
   *
   * This data only exists for exporting the supported
   * PCI ids via MODULE_DEVICE_TABLE.  We do not actually
   * register a pci_driver, because someone else might one day
   * want to register another driver on the same PCI id.
   */
  static const struct pci_device_id tco_pci_tbl[] = {
  	{ PCI_VENDOR_ID_NVIDIA, PCI_DEVICE_ID_NVIDIA_NFORCE_MCP51_SMBUS,
  	  PCI_ANY_ID, PCI_ANY_ID, },
  	{ PCI_VENDOR_ID_NVIDIA, PCI_DEVICE_ID_NVIDIA_NFORCE_MCP55_SMBUS,
  	  PCI_ANY_ID, PCI_ANY_ID, },
  	{ 0, },			/* End of list */
  };
  MODULE_DEVICE_TABLE(pci, tco_pci_tbl);
  
  /*
   *	Init & exit routines
   */
  
  static unsigned char nv_tco_getdevice(void)
  {
  	struct pci_dev *dev = NULL;
  	u32 val;
  
  	/* Find the PCI device */
  	for_each_pci_dev(dev) {
  		if (pci_match_id(tco_pci_tbl, dev) != NULL) {
  			tco_pci = dev;
  			break;
  		}
  	}
  
  	if (!tco_pci)
  		return 0;
  
  	/* Find the base io port */
  	pci_read_config_dword(tco_pci, 0x64, &val);
  	val &= 0xffff;
  	if (val == 0x0001 || val == 0x0000) {
  		/* Something is wrong here, bar isn't setup */
  		pr_err("failed to get tcobase address
  ");
  		return 0;
  	}
  	val &= 0xff00;
  	tcobase = val + 0x40;
  
  	if (!request_region(tcobase, 0x10, "NV TCO")) {
  		pr_err("I/O address 0x%04x already in use
  ", tcobase);
  		return 0;
  	}
  
  	/* Set a reasonable heartbeat before we stop the timer */
  	tco_timer_set_heartbeat(30);
  
  	/*
  	 * Stop the TCO before we change anything so we don't race with
  	 * a zeroed timer.
  	 */
  	tco_timer_keepalive();
  	tco_timer_stop();
  
  	/* Disable SMI caused by TCO */
  	if (!request_region(MCP51_SMI_EN(tcobase), 4, "NV TCO")) {
  		pr_err("I/O address 0x%04x already in use
  ",
  		       MCP51_SMI_EN(tcobase));
  		goto out;
  	}
  	val = inl(MCP51_SMI_EN(tcobase));
  	val &= ~MCP51_SMI_EN_TCO;
  	outl(val, MCP51_SMI_EN(tcobase));
  	val = inl(MCP51_SMI_EN(tcobase));
  	release_region(MCP51_SMI_EN(tcobase), 4);
  	if (val & MCP51_SMI_EN_TCO) {
  		pr_err("Could not disable SMI caused by TCO
  ");
  		goto out;
  	}
  
  	/* Check chipset's NO_REBOOT bit */
  	pci_read_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, &val);
  	val |= MCP51_SMBUS_SETUP_B_TCO_REBOOT;
  	pci_write_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, val);
  	pci_read_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, &val);
  	if (!(val & MCP51_SMBUS_SETUP_B_TCO_REBOOT)) {
  		pr_err("failed to reset NO_REBOOT flag, reboot disabled by hardware
  ");
  		goto out;
  	}
  
  	return 1;
  out:
  	release_region(tcobase, 0x10);
  	return 0;
  }
  
  static int nv_tco_init(struct platform_device *dev)
  {
  	int ret;
  
  	/* Check whether or not the hardware watchdog is there */
  	if (!nv_tco_getdevice())
  		return -ENODEV;
  
  	/* Check to see if last reboot was due to watchdog timeout */
  	pr_info("Watchdog reboot %sdetected
  ",
  		inl(TCO_STS(tcobase)) & TCO_STS_TCO2TO_STS ? "" : "not ");
  
  	/* Clear out the old status */
  	outl(TCO_STS_RESET, TCO_STS(tcobase));
  
  	/*
  	 * Check that the heartbeat value is within it's range.
  	 * If not, reset to the default.
  	 */
  	if (tco_timer_set_heartbeat(heartbeat)) {
  		heartbeat = WATCHDOG_HEARTBEAT;
  		tco_timer_set_heartbeat(heartbeat);
  		pr_info("heartbeat value must be 2<heartbeat<39, using %d
  ",
  			heartbeat);
  	}
  
  	ret = misc_register(&nv_tco_miscdev);
  	if (ret != 0) {
  		pr_err("cannot register miscdev on minor=%d (err=%d)
  ",
  		       WATCHDOG_MINOR, ret);
  		goto unreg_region;
  	}
  
  	clear_bit(0, &timer_alive);
  
  	tco_timer_stop();
  
  	pr_info("initialized (0x%04x). heartbeat=%d sec (nowayout=%d)
  ",
  		tcobase, heartbeat, nowayout);
  
  	return 0;
  
  unreg_region:
  	release_region(tcobase, 0x10);
  	return ret;
  }
  
  static void nv_tco_cleanup(void)
  {
  	u32 val;
  
  	/* Stop the timer before we leave */
  	if (!nowayout)
  		tco_timer_stop();
  
  	/* Set the NO_REBOOT bit to prevent later reboots, just for sure */
  	pci_read_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, &val);
  	val &= ~MCP51_SMBUS_SETUP_B_TCO_REBOOT;
  	pci_write_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, val);
  	pci_read_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, &val);
  	if (val & MCP51_SMBUS_SETUP_B_TCO_REBOOT) {
  		pr_crit("Couldn't unset REBOOT bit.  Machine may soon reset
  ");
  	}
  
  	/* Deregister */
  	misc_deregister(&nv_tco_miscdev);
  	release_region(tcobase, 0x10);
  }
  
  static int nv_tco_remove(struct platform_device *dev)
  {
  	if (tcobase)
  		nv_tco_cleanup();
  
  	return 0;
  }
  
  static void nv_tco_shutdown(struct platform_device *dev)
  {
  	u32 val;
  
  	tco_timer_stop();
  
  	/* Some BIOSes fail the POST (once) if the NO_REBOOT flag is not
  	 * unset during shutdown. */
  	pci_read_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, &val);
  	val &= ~MCP51_SMBUS_SETUP_B_TCO_REBOOT;
  	pci_write_config_dword(tco_pci, MCP51_SMBUS_SETUP_B, val);
  }
  
  static struct platform_driver nv_tco_driver = {
  	.probe		= nv_tco_init,
  	.remove		= nv_tco_remove,
  	.shutdown	= nv_tco_shutdown,
  	.driver		= {
  		.owner	= THIS_MODULE,
  		.name	= TCO_MODULE_NAME,
  	},
  };
  
  static int __init nv_tco_init_module(void)
  {
  	int err;
  
  	pr_info("NV TCO WatchDog Timer Driver v%s
  ", TCO_VERSION);
  
  	err = platform_driver_register(&nv_tco_driver);
  	if (err)
  		return err;
  
  	nv_tco_platform_device = platform_device_register_simple(
  					TCO_MODULE_NAME, -1, NULL, 0);
  	if (IS_ERR(nv_tco_platform_device)) {
  		err = PTR_ERR(nv_tco_platform_device);
  		goto unreg_platform_driver;
  	}
  
  	return 0;
  
  unreg_platform_driver:
  	platform_driver_unregister(&nv_tco_driver);
  	return err;
  }
  
  static void __exit nv_tco_cleanup_module(void)
  {
  	platform_device_unregister(nv_tco_platform_device);
  	platform_driver_unregister(&nv_tco_driver);
  	pr_info("NV TCO Watchdog Module Unloaded
  ");
  }
  
  module_init(nv_tco_init_module);
  module_exit(nv_tco_cleanup_module);
  
  MODULE_AUTHOR("Mike Waychison");
  MODULE_DESCRIPTION("TCO timer driver for NV chipsets");
  MODULE_LICENSE("GPL");