watchdog: sp5100_tco: Remove code that may cause a boot failure

A problem was found on PC's with the SB700 chipset: The PC fails to
load BIOS after running the 3.8.x kernel until the power is completely
cut off. It occurs in all 3.8.x versions and the mainline version as of
2/4. The issue does not occur with the 3.7.x builds.

There are two methods for accessing the watchdog registers.

1. Re-programming a resource address obtained by allocate_resource()
to chipset.
2. Use the direct memory-mapped IO access.

The method 1 can be used by all the chipsets (SP5100, SB7x0, SB8x0 or
later). However, experience shows that only PC with the SB8x0 (or
later) chipsets can use the method 2.

This patch removes the method 1, because the critical problem was found.
That's why the watchdog timer was able to be used on SP5100 and SB7x0
chipsets until now.

Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1116835
Link: https://lkml.org/lkml/2013/2/14/271

Signed-off-by: Takahisa Tanaka <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>
Cc: stable <[e-mail]>

drivers/watchdog/sp5100_tco.c

···
 #include "sp5100_tco.h"
 
 /* Module and version information */
-#define TCO_VERSION "0.03"
+#define TCO_VERSION "0.05"
 #define TCO_MODULE_NAME "SP5100 TCO timer"
 #define TCO_DRIVER_NAME   TCO_MODULE_NAME ", v" TCO_VERSION
 
 /* internal variables */
 static u32 tcobase_phys;
-static u32 resbase_phys;
 static u32 tco_wdt_fired;
 static void __iomem *tcobase;
 static unsigned int pm_iobase;
···
 static unsigned long timer_alive;
 static char tco_expect_close;
 static struct pci_dev *sp5100_tco_pci;
-static struct resource wdt_res = {
-	.name = "Watchdog Timer",
-	.flags = IORESOURCE_MEM,
-};
 
 /* the watchdog platform device */
 static struct platform_device *sp5100_tco_platform_device;
···
 module_param(nowayout, bool, 0);
 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started."
 		" (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
-
-static unsigned int force_addr;
-module_param(force_addr, uint, 0);
-MODULE_PARM_DESC(force_addr, "Force the use of specified MMIO address."
-		" ONLY USE THIS PARAMETER IF YOU REALLY KNOW"
-		" WHAT YOU ARE DOING (default=none)");
 
 /*
  * Some TCO specific functions
···
 		val = inb(SP5100_IO_PM_DATA_REG);
 		val |= SP5100_PM_WATCHDOG_SECOND_RES;
 		val &= ~SP5100_PM_WATCHDOG_DISABLE;
-		outb(val, SP5100_IO_PM_DATA_REG);
-	}
-}
-
-static void tco_timer_disable(void)
-{
-	int val;
-
-	if (sp5100_tco_pci->revision >= 0x40) {
-		/* For SB800 or later */
-		/* Enable watchdog decode bit and Disable watchdog timer */
-		outb(SB800_PM_WATCHDOG_CONTROL, SB800_IO_PM_INDEX_REG);
-		val = inb(SB800_IO_PM_DATA_REG);
-		val |= SB800_PCI_WATCHDOG_DECODE_EN;
-		val |= SB800_PM_WATCHDOG_DISABLE;
-		outb(val, SB800_IO_PM_DATA_REG);
-	} else {
-		/* 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);
-
-		/* Disable Watchdog timer */
-		outb(SP5100_PM_WATCHDOG_CONTROL, SP5100_IO_PM_INDEX_REG);
-		val = inb(SP5100_IO_PM_DATA_REG);
-		val |= SP5100_PM_WATCHDOG_DISABLE;
 		outb(val, SP5100_IO_PM_DATA_REG);
 	}
 }
···
 {
 	struct pci_dev *dev = NULL;
 	const char *dev_name = NULL;
-	u32 val, tmp_val;
+	u32 val;
 	u32 index_reg, data_reg, base_addr;
 
 	/* Match the PCI device */
···
 	} else
 		pr_debug("SBResource_MMIO is disabled(0x%04x)\n", val);
 
-	/*
-	 * Lastly re-programming the watchdog timer MMIO address,
-	 * This method is a last resort...
-	 *
-	 * Before re-programming, to ensure that the watchdog timer
-	 * is disabled, disable the watchdog timer.
-	 */
-	tco_timer_disable();
-
-	if (force_addr) {
-		/*
-		 * Force the use of watchdog timer MMIO address, and aligned to
-		 * 8byte boundary.
-		 */
-		force_addr &= ~0x7;
-		val = force_addr;
-
-		pr_info("Force the use of 0x%04x as MMIO address\n", val);
-	} else {
-		/*
-		 * Get empty slot into the resource tree for watchdog timer.
-		 */
-		if (allocate_resource(&iomem_resource,
-				      &wdt_res,
-				      SP5100_WDT_MEM_MAP_SIZE,
-				      0xf0000000,
-				      0xfffffff8,
-				      0x8,
-				      NULL,
-				      NULL)) {
-			pr_err("MMIO allocation failed\n");
-			goto unreg_region;
-		}
-
-		val = resbase_phys = wdt_res.start;
-		pr_debug("Got 0x%04x from resource tree\n", val);
-	}
-
-	/* Restore to the low three bits */
-	outb(base_addr+0, index_reg);
-	tmp_val = val | (inb(data_reg) & 0x7);
-
-	/* Re-programming the watchdog timer base address */
-	outb(base_addr+0, index_reg);
-	outb((tmp_val >>  0) & 0xff, data_reg);
-	outb(base_addr+1, index_reg);
-	outb((tmp_val >>  8) & 0xff, data_reg);
-	outb(base_addr+2, index_reg);
-	outb((tmp_val >> 16) & 0xff, data_reg);
-	outb(base_addr+3, index_reg);
-	outb((tmp_val >> 24) & 0xff, data_reg);
-
-	if (!request_mem_region_exclusive(val, SP5100_WDT_MEM_MAP_SIZE,
-								   dev_name)) {
-		pr_err("MMIO address 0x%04x already in use\n", val);
-		goto unreg_resource;
-	}
+	pr_notice("failed to find MMIO address, giving up.\n");
+	goto  unreg_region;
 
 setup_wdt:
 	tcobase_phys = val;
···
 
 unreg_mem_region:
 	release_mem_region(tcobase_phys, SP5100_WDT_MEM_MAP_SIZE);
-unreg_resource:
-	if (resbase_phys)
-		release_resource(&wdt_res);
 unreg_region:
 	release_region(pm_iobase, SP5100_PM_IOPORTS_SIZE);
 exit:
···
 static int sp5100_tco_init(struct platform_device *dev)
 {
 	int ret;
-	char addr_str[16];
 
 	/*
 	 * Check whether or not the hardware watchdog is there. If found, then
···
 	clear_bit(0, &timer_alive);
 
 	/* Show module parameters */
-	if (force_addr == tcobase_phys)
-		/* The force_addr is vaild */
-		sprintf(addr_str, "0x%04x", force_addr);
-	else
-		strcpy(addr_str, "none");
-
-	pr_info("initialized (0x%p). heartbeat=%d sec (nowayout=%d, "
-		"force_addr=%s)\n",
-		tcobase, heartbeat, nowayout, addr_str);
+	pr_info("initialized (0x%p). heartbeat=%d sec (nowayout=%d)\n",
+		tcobase, heartbeat, nowayout);
 
 	return 0;
 
 exit:
 	iounmap(tcobase);
 	release_mem_region(tcobase_phys, SP5100_WDT_MEM_MAP_SIZE);
-	if (resbase_phys)
-		release_resource(&wdt_res);
 	release_region(pm_iobase, SP5100_PM_IOPORTS_SIZE);
 	return ret;
 }
···
 	misc_deregister(&sp5100_tco_miscdev);
 	iounmap(tcobase);
 	release_mem_region(tcobase_phys, SP5100_WDT_MEM_MAP_SIZE);
-	if (resbase_phys)
-		release_resource(&wdt_res);
 	release_region(pm_iobase, SP5100_PM_IOPORTS_SIZE);
 }