/*
 *	sp5100_tco :	TCO timer driver for sp5100 chipsets
 *
 *	(c) Copyright 2009 Google Inc., All Rights Reserved.
 *
 *	Based on 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.
 *
 *	See AMD Publication 43009 "AMD SB700/710/750 Register Reference Guide",
 *	    AMD Publication 45482 "AMD SB800-Series Southbridges Register
 *	                                                      Reference Guide"
 *	    AMD Publication 48751 "BIOS and Kernel Developer’s Guide (BKDG)
 *				for AMD Family 16h Models 00h-0Fh Processors"
 *	    AMD Publication 51192 "AMD Bolton FCH Register Reference Guide"
 *	    AMD Publication 52740 "BIOS and Kernel Developer’s Guide (BKDG)
 *				for AMD Family 16h Models 30h-3Fh Processors"
 */

/*
 *	Includes, defines, variables, module parameters, ...
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/init.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/pci.h>
#include <linux/platform_device.h>
#include <linux/types.h>
#include <linux/watchdog.h>

#include "sp5100_tco.h"

#define TCO_DRIVER_NAME	"sp5100-tco"

/* internal variables */

enum tco_reg_layout {
	sp5100, sb800, efch
};

struct sp5100_tco {
	struct watchdog_device wdd;
	void __iomem *tcobase;
	enum tco_reg_layout tco_reg_layout;
};

/* the watchdog platform device */
static struct platform_device *sp5100_tco_platform_device;
/* the associated PCI device */
static struct pci_dev *sp5100_tco_pci;

/* module parameters */

#define WATCHDOG_HEARTBEAT 60	/* 60 sec default heartbeat. */
static int heartbeat = WATCHDOG_HEARTBEAT;  /* in seconds */
module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. (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 enum tco_reg_layout tco_reg_layout(struct pci_dev *dev)
{
	if (dev->vendor == PCI_VENDOR_ID_ATI &&
	    dev->device == PCI_DEVICE_ID_ATI_SBX00_SMBUS &&
	    dev->revision < 0x40) {
		return sp5100;
	} else if (dev->vendor == PCI_VENDOR_ID_AMD &&
	    ((dev->device == PCI_DEVICE_ID_AMD_HUDSON2_SMBUS &&
	     dev->revision >= 0x41) ||
	    (dev->device == PCI_DEVICE_ID_AMD_KERNCZ_SMBUS &&
	     dev->revision >= 0x49))) {
		return efch;
	}
	return sb800;
}

static int tco_timer_start(struct watchdog_device *wdd)
{
	struct sp5100_tco *tco = watchdog_get_drvdata(wdd);
	u32 val;

	val = readl(SP5100_WDT_CONTROL(tco->tcobase));
	val |= SP5100_WDT_START_STOP_BIT;
	writel(val, SP5100_WDT_CONTROL(tco->tcobase));

	return 0;
}

static int tco_timer_stop(struct watchdog_device *wdd)
{
	struct sp5100_tco *tco = watchdog_get_drvdata(wdd);
	u32 val;

	val = readl(SP5100_WDT_CONTROL(tco->tcobase));
	val &= ~SP5100_WDT_START_STOP_BIT;
	writel(val, SP5100_WDT_CONTROL(tco->tcobase));

	return 0;
}

static int tco_timer_ping(struct watchdog_device *wdd)
{
	struct sp5100_tco *tco = watchdog_get_drvdata(wdd);
	u32 val;

	val = readl(SP5100_WDT_CONTROL(tco->tcobase));
	val |= SP5100_WDT_TRIGGER_BIT;
	writel(val, SP5100_WDT_CONTROL(tco->tcobase));

	return 0;
}

static int tco_timer_set_timeout(struct watchdog_device *wdd,
				 unsigned int t)
{
	struct sp5100_tco *tco = watchdog_get_drvdata(wdd);

	/* Write new heartbeat to watchdog */
	writel(t, SP5100_WDT_COUNT(tco->tcobase));

	wdd->timeout = t;

	return 0;
}

static u8 sp5100_tco_read_pm_reg8(u8 index)
{
	outb(index, SP5100_IO_PM_INDEX_REG);
	return inb(SP5100_IO_PM_DATA_REG);
}

static void sp5100_tco_update_pm_reg8(u8 index, u8 reset, u8 set)
{
	u8 val;

	outb(index, SP5100_IO_PM_INDEX_REG);
	val = inb(SP5100_IO_PM_DATA_REG);
	val &= reset;
	val |= set;
	outb(val, SP5100_IO_PM_DATA_REG);
}

static void tco_timer_enable(struct sp5100_tco *tco)
{
	u32 val;

	switch (tco->tco_reg_layout) {
	case sb800:
		/* For SB800 or later */
		/* Set the Watchdog timer resolution to 1 sec */
		sp5100_tco_update_pm_reg8(SB800_PM_WATCHDOG_CONFIG,
					  0xff, SB800_PM_WATCHDOG_SECOND_RES);

		/* Enable watchdog decode bit and watchdog timer */
		sp5100_tco_update_pm_reg8(SB800_PM_WATCHDOG_CONTROL,
					  ~SB800_PM_WATCHDOG_DISABLE,
					  SB800_PCI_WATCHDOG_DECODE_EN);
		break;
	case sp5100:
		/* For SP5100 or SB7x0 */
		/* Enable watchdog decode bit */
		pci_read_config_dword(sp5100_tco_pci,
				      SP5100_PCI_WATCHDOG_MISC_REG,
				      &val);

		val |= SP5100_PCI_WATCHDOG_DECODE_EN;

		pci_write_config_dword(sp5100_tco_pci,
				       SP5100_PCI_WATCHDOG_MISC_REG,
				       val);

		/* Enable Watchdog timer and set the resolution to 1 sec */
		sp5100_tco_update_pm_reg8(SP5100_PM_WATCHDOG_CONTROL,
					  ~SP5100_PM_WATCHDOG_DISABLE,
					  SP5100_PM_WATCHDOG_SECOND_RES);
		break;
	case efch:
		/* Set the Watchdog timer resolution to 1 sec and enable */
		sp5100_tco_update_pm_reg8(EFCH_PM_DECODEEN3,
					  ~EFCH_PM_WATCHDOG_DISABLE,
					  EFCH_PM_DECODEEN_SECOND_RES);
		break;
	}
}

static u32 sp5100_tco_read_pm_reg32(u8 index)
{
	u32 val = 0;
	int i;

	for (i = 3; i >= 0; i--)
		val = (val << 8) + sp5100_tco_read_pm_reg8(index + i);

	return val;
}

static int sp5100_tco_setupdevice(struct device *dev,
				  struct watchdog_device *wdd)
{
	struct sp5100_tco *tco = watchdog_get_drvdata(wdd);
	const char *dev_name;
	u32 mmio_addr = 0, val;
	int ret;

	/* Request the IO ports used by this driver */
	if (!request_muxed_region(SP5100_IO_PM_INDEX_REG,
				  SP5100_PM_IOPORTS_SIZE, "sp5100_tco")) {
		dev_err(dev, "I/O address 0x%04x already in use\n",
			SP5100_IO_PM_INDEX_REG);
		return -EBUSY;
	}

	/*
	 * Determine type of southbridge chipset.
	 */
	switch (tco->tco_reg_layout) {
	case sp5100:
		dev_name = SP5100_DEVNAME;
		mmio_addr = sp5100_tco_read_pm_reg32(SP5100_PM_WATCHDOG_BASE) &
								0xfffffff8;
		break;
	case sb800:
		dev_name = SB800_DEVNAME;
		mmio_addr = sp5100_tco_read_pm_reg32(SB800_PM_WATCHDOG_BASE) &
								0xfffffff8;
		break;
	case efch:
		dev_name = SB800_DEVNAME;
		val = sp5100_tco_read_pm_reg8(EFCH_PM_DECODEEN);
		if (val & EFCH_PM_DECODEEN_WDT_TMREN)
			mmio_addr = EFCH_PM_WDT_ADDR;
		break;
	default:
		return -ENODEV;
	}

	/* Check MMIO address conflict */
	if (!mmio_addr ||
	    !devm_request_mem_region(dev, mmio_addr, SP5100_WDT_MEM_MAP_SIZE,
				     dev_name)) {
		if (mmio_addr)
			dev_dbg(dev, "MMIO address 0x%08x already in use\n",
				mmio_addr);
		switch (tco->tco_reg_layout) {
		case sp5100:
			/*
			 * Secondly, Find the watchdog timer MMIO address
			 * from SBResource_MMIO register.
			 */
			/* Read SBResource_MMIO from PCI config(PCI_Reg: 9Ch) */
			pci_read_config_dword(sp5100_tco_pci,
					      SP5100_SB_RESOURCE_MMIO_BASE,
					      &mmio_addr);
			if ((mmio_addr & (SB800_ACPI_MMIO_DECODE_EN |
					  SB800_ACPI_MMIO_SEL)) !=
						  SB800_ACPI_MMIO_DECODE_EN) {
				ret = -ENODEV;
				goto unreg_region;
			}
			mmio_addr &= ~0xFFF;
			mmio_addr += SB800_PM_WDT_MMIO_OFFSET;
			break;
		case sb800:
			/* Read SBResource_MMIO from AcpiMmioEn(PM_Reg: 24h) */
			mmio_addr =
				sp5100_tco_read_pm_reg32(SB800_PM_ACPI_MMIO_EN);
			if ((mmio_addr & (SB800_ACPI_MMIO_DECODE_EN |
					  SB800_ACPI_MMIO_SEL)) !=
						  SB800_ACPI_MMIO_DECODE_EN) {
				ret = -ENODEV;
				goto unreg_region;
			}
			mmio_addr &= ~0xFFF;
			mmio_addr += SB800_PM_WDT_MMIO_OFFSET;
			break;
		case efch:
			val = sp5100_tco_read_pm_reg8(EFCH_PM_ISACONTROL);
			if (!(val & EFCH_PM_ISACONTROL_MMIOEN)) {
				ret = -ENODEV;
				goto unreg_region;
			}
			mmio_addr = EFCH_PM_ACPI_MMIO_ADDR +
				    EFCH_PM_ACPI_MMIO_WDT_OFFSET;
			break;
		}
		dev_dbg(dev, "Got 0x%08x from SBResource_MMIO register\n",
			mmio_addr);
		if (!devm_request_mem_region(dev, mmio_addr,
					     SP5100_WDT_MEM_MAP_SIZE,
					     dev_name)) {
			dev_dbg(dev, "MMIO address 0x%08x already in use\n",
				mmio_addr);
			ret = -EBUSY;
			goto unreg_region;
		}
	}

	tco->tcobase = devm_ioremap(dev, mmio_addr, SP5100_WDT_MEM_MAP_SIZE);
	if (!tco->tcobase) {
		dev_err(dev, "failed to get tcobase address\n");
		ret = -ENOMEM;
		goto unreg_region;
	}

	dev_info(dev, "Using 0x%08x for watchdog MMIO address\n", mmio_addr);

	/* Setup the watchdog timer */
	tco_timer_enable(tco);

	val = readl(SP5100_WDT_CONTROL(tco->tcobase));
	if (val & SP5100_WDT_DISABLED) {
		dev_err(dev, "Watchdog hardware is disabled\n");
		ret = -ENODEV;
		goto unreg_region;
	}

	/*
	 * Save WatchDogFired status, because WatchDogFired flag is
	 * cleared here.
	 */
	if (val & SP5100_WDT_FIRED)
		wdd->bootstatus = WDIOF_CARDRESET;
	/* Set watchdog action to reset the system */
	val &= ~SP5100_WDT_ACTION_RESET;
	writel(val, SP5100_WDT_CONTROL(tco->tcobase));

	/* Set a reasonable heartbeat before we stop the timer */
	tco_timer_set_timeout(wdd, wdd->timeout);

	/*
	 * Stop the TCO before we change anything so we don't race with
	 * a zeroed timer.
	 */
	tco_timer_stop(wdd);

	release_region(SP5100_IO_PM_INDEX_REG, SP5100_PM_IOPORTS_SIZE);

	return 0;

unreg_region:
	release_region(SP5100_IO_PM_INDEX_REG, SP5100_PM_IOPORTS_SIZE);
	return ret;
}

static struct watchdog_info sp5100_tco_wdt_info = {
	.identity = "SP5100 TCO timer",
	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
};

static const struct watchdog_ops sp5100_tco_wdt_ops = {
	.owner = THIS_MODULE,
	.start = tco_timer_start,
	.stop = tco_timer_stop,
	.ping = tco_timer_ping,
	.set_timeout = tco_timer_set_timeout,
};

static int sp5100_tco_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct watchdog_device *wdd;
	struct sp5100_tco *tco;
	int ret;

	tco = devm_kzalloc(dev, sizeof(*tco), GFP_KERNEL);
	if (!tco)
		return -ENOMEM;

	tco->tco_reg_layout = tco_reg_layout(sp5100_tco_pci);

	wdd = &tco->wdd;
	wdd->parent = dev;
	wdd->info = &sp5100_tco_wdt_info;
	wdd->ops = &sp5100_tco_wdt_ops;
	wdd->timeout = WATCHDOG_HEARTBEAT;
	wdd->min_timeout = 1;
	wdd->max_timeout = 0xffff;

	if (watchdog_init_timeout(wdd, heartbeat, NULL))
		dev_info(dev, "timeout value invalid, using %d\n",
			 wdd->timeout);
	watchdog_set_nowayout(wdd, nowayout);
	watchdog_stop_on_reboot(wdd);
	watchdog_stop_on_unregister(wdd);
	watchdog_set_drvdata(wdd, tco);

	ret = sp5100_tco_setupdevice(dev, wdd);
	if (ret)
		return ret;

	ret = devm_watchdog_register_device(dev, wdd);
	if (ret) {
		dev_err(dev, "cannot register watchdog device (err=%d)\n", ret);
		return ret;
	}

	/* Show module parameters */
	dev_info(dev, "initialized. heartbeat=%d sec (nowayout=%d)\n",
		 wdd->timeout, nowayout);

	return 0;
}

static struct platform_driver sp5100_tco_driver = {
	.probe		= sp5100_tco_probe,
	.driver		= {
		.name	= TCO_DRIVER_NAME,
	},
};

/*
 * 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
 * want to register another driver on the same PCI id.
 */
static const struct pci_device_id sp5100_tco_pci_tbl[] = {
	{ PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_SBX00_SMBUS, PCI_ANY_ID,
	  PCI_ANY_ID, },
	{ PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_HUDSON2_SMBUS, PCI_ANY_ID,
	  PCI_ANY_ID, },
	{ PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_KERNCZ_SMBUS, PCI_ANY_ID,
	  PCI_ANY_ID, },
	{ 0, },			/* End of list */
};
MODULE_DEVICE_TABLE(pci, sp5100_tco_pci_tbl);

static int __init sp5100_tco_init(void)
{
	struct pci_dev *dev = NULL;
	int err;

	/* Match the PCI device */
	for_each_pci_dev(dev) {
		if (pci_match_id(sp5100_tco_pci_tbl, dev) != NULL) {
			sp5100_tco_pci = dev;
			break;
		}
	}

	if (!sp5100_tco_pci)
		return -ENODEV;

	pr_info("SP5100/SB800 TCO WatchDog Timer Driver\n");

	err = platform_driver_register(&sp5100_tco_driver);
	if (err)
		return err;

	sp5100_tco_platform_device =
		platform_device_register_simple(TCO_DRIVER_NAME, -1, NULL, 0);
	if (IS_ERR(sp5100_tco_platform_device)) {
		err = PTR_ERR(sp5100_tco_platform_device);
		goto unreg_platform_driver;
	}

	return 0;

unreg_platform_driver:
	platform_driver_unregister(&sp5100_tco_driver);
	return err;
}

static void __exit sp5100_tco_exit(void)
{
	platform_device_unregister(sp5100_tco_platform_device);
	platform_driver_unregister(&sp5100_tco_driver);
}

module_init(sp5100_tco_init);
module_exit(sp5100_tco_exit);

MODULE_AUTHOR("Priyanka Gupta");
MODULE_DESCRIPTION("TCO timer driver for SP5100/SB800 chipset");
MODULE_LICENSE("GPL");
