diff --git a/drivers/watchdog/sp5100_tco.c b/drivers/watchdog/sp5100_tco.c
index b365bbc9ac36..16e122d5045e 100644
--- a/drivers/watchdog/sp5100_tco.c
+++ b/drivers/watchdog/sp5100_tco.c
@@ -223,6 +223,55 @@ static u32 sp5100_tco_read_pm_reg32(u8 index)
 	return val;
 }
 
+static u32 sp5100_tco_request_region(struct device *dev,
+				     u32 mmio_addr,
+				     const char *dev_name)
+{
+	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);
+		return 0;
+	}
+
+	return mmio_addr;
+}
+
+static u32 sp5100_tco_prepare_base(struct sp5100_tco *tco,
+				   u32 mmio_addr,
+				   u32 alt_mmio_addr,
+				   const char *dev_name)
+{
+	struct device *dev = tco->wdd.parent;
+
+	dev_dbg(dev, "Got 0x%08x from SBResource_MMIO register\n", mmio_addr);
+
+	if (!mmio_addr && !alt_mmio_addr)
+		return -ENODEV;
+
+	/* Check for MMIO address and alternate MMIO address conflicts */
+	if (mmio_addr)
+		mmio_addr = sp5100_tco_request_region(dev, mmio_addr, dev_name);
+
+	if (!mmio_addr && alt_mmio_addr)
+		mmio_addr = sp5100_tco_request_region(dev, alt_mmio_addr, dev_name);
+
+	if (!mmio_addr) {
+		dev_err(dev, "Failed to reserve MMIO or alternate MMIO region\n");
+		return -EBUSY;
+	}
+
+	tco->tcobase = devm_ioremap(dev, mmio_addr, SP5100_WDT_MEM_MAP_SIZE);
+	if (!tco->tcobase) {
+		dev_err(dev, "MMIO address 0x%08x failed mapping\n", mmio_addr);
+		devm_release_mem_region(dev, mmio_addr, SP5100_WDT_MEM_MAP_SIZE);
+		return -ENOMEM;
+	}
+
+	dev_info(dev, "Using 0x%08x for watchdog MMIO address\n", tco->tcobase);
+
+	return 0;
+}
+
 static int sp5100_tco_timer_init(struct sp5100_tco *tco)
 {
 	struct watchdog_device *wdd = &tco->wdd;
@@ -264,6 +313,7 @@ static int sp5100_tco_setupdevice(struct device *dev,
 	struct sp5100_tco *tco = watchdog_get_drvdata(wdd);
 	const char *dev_name;
 	u32 mmio_addr = 0, val;
+	u32 alt_mmio_addr = 0;
 	int ret;
 
 	/* Request the IO ports used by this driver */
@@ -282,11 +332,32 @@ static int sp5100_tco_setupdevice(struct device *dev,
 		dev_name = SP5100_DEVNAME;
 		mmio_addr = sp5100_tco_read_pm_reg32(SP5100_PM_WATCHDOG_BASE) &
 								0xfffffff8;
+
+		/*
+		 * 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,
+				      &val);
+
+		/* Verify MMIO is enabled and using bar0 */
+		if ((val & SB800_ACPI_MMIO_MASK) == SB800_ACPI_MMIO_DECODE_EN)
+			alt_mmio_addr = (val & ~0xfff) + SB800_PM_WDT_MMIO_OFFSET;
 		break;
 	case sb800:
 		dev_name = SB800_DEVNAME;
 		mmio_addr = sp5100_tco_read_pm_reg32(SB800_PM_WATCHDOG_BASE) &
 								0xfffffff8;
+
+		/* Read SBResource_MMIO from AcpiMmioEn(PM_Reg: 24h) */
+		val = sp5100_tco_read_pm_reg32(SB800_PM_ACPI_MMIO_EN);
+
+		/* Verify MMIO is enabled and using bar0 */
+		if ((val & SB800_ACPI_MMIO_MASK) == SB800_ACPI_MMIO_DECODE_EN)
+			alt_mmio_addr = (val & ~0xfff) + SB800_PM_WDT_MMIO_OFFSET;
 		break;
 	case efch:
 		dev_name = SB800_DEVNAME;
@@ -305,87 +376,23 @@ static int sp5100_tco_setupdevice(struct device *dev,
 		val = sp5100_tco_read_pm_reg8(EFCH_PM_DECODEEN);
 		if (val & EFCH_PM_DECODEEN_WDT_TMREN)
 			mmio_addr = EFCH_PM_WDT_ADDR;
+
+		val = sp5100_tco_read_pm_reg8(EFCH_PM_ISACONTROL);
+		if (val & EFCH_PM_ISACONTROL_MMIOEN)
+			alt_mmio_addr = EFCH_PM_ACPI_MMIO_ADDR +
+				EFCH_PM_ACPI_MMIO_WDT_OFFSET;
 		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;
+	ret = sp5100_tco_prepare_base(tco, mmio_addr, alt_mmio_addr, dev_name);
+	if (!ret) {
+		/* Setup the watchdog timer */
+		tco_timer_enable(tco);
+		ret = sp5100_tco_timer_init(tco);
 	}
 
-	dev_info(dev, "Using 0x%08x for watchdog MMIO address\n", mmio_addr);
-
-	/* Setup the watchdog timer */
-	tco_timer_enable(tco);
-
-	ret = sp5100_tco_timer_init(tco);
-
-unreg_region:
 	release_region(SP5100_IO_PM_INDEX_REG, SP5100_PM_IOPORTS_SIZE);
 	return ret;
 }
diff --git a/drivers/watchdog/sp5100_tco.h b/drivers/watchdog/sp5100_tco.h
index adf015aa4126..daee872f9b71 100644
--- a/drivers/watchdog/sp5100_tco.h
+++ b/drivers/watchdog/sp5100_tco.h
@@ -58,6 +58,7 @@
 #define SB800_PM_WATCHDOG_SECOND_RES	GENMASK(1, 0)
 #define SB800_ACPI_MMIO_DECODE_EN	BIT(0)
 #define SB800_ACPI_MMIO_SEL		BIT(1)
+#define SB800_ACPI_MMIO_MASK		GENMASK(1, 0)
 
 #define SB800_PM_WDT_MMIO_OFFSET	0xB00
 
