Watchdog: sp5100_tco: Enable Family 17h+ CPUs

The driver currently uses a CPU family match of 17h to determine
EFCH_PM_DECODEEN_WDT_TMREN register support. This family check will not
support future AMD CPUs and instead will require driver updates to add
support.

Remove the family 17h family check and add a check for SMBus PCI
revision ID 0x51 or greater. The MMIO access method has been available
since at least SMBus controllers using PCI revision 0x51. This revision
check will support family 17h and future AMD processors including EFCH
functionality without requiring driver changes.
Co-developed-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Terry Bowman <terry.bowman@amd.com>
Tested-by: Jean Delvare <jdelvare@suse.de>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220202153525.1693378-5-terry.bowman@amd.comSigned-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/sp5100_tco.c

@@ -86,6 +86,10 @@ static enum tco_reg_layout tco_reg_layout(struct pci_dev *dev)
 	    dev->device == PCI_DEVICE_ID_ATI_SBX00_SMBUS &&
 	    dev->revision < 0x40) {
 		return sp5100;
+	} else if (dev->vendor == PCI_VENDOR_ID_AMD &&
+	    sp5100_tco_pci->device == PCI_DEVICE_ID_AMD_KERNCZ_SMBUS &&
+	    sp5100_tco_pci->revision >= AMD_ZEN_SMBUS_PCI_REV) {
+		return efch_mmio;
 	} else if (dev->vendor == PCI_VENDOR_ID_AMD &&
 	    ((dev->device == PCI_DEVICE_ID_AMD_HUDSON2_SMBUS &&
 	     dev->revision >= 0x41) ||
@@ -459,18 +463,6 @@ static int sp5100_tco_setupdevice(struct device *dev,
 		break;
 	case efch:
 		dev_name = SB800_DEVNAME;
-		/*
-		 * On Family 17h devices, the EFCH_PM_DECODEEN_WDT_TMREN bit of
-		 * EFCH_PM_DECODEEN not only enables the EFCH_PM_WDT_ADDR memory
-		 * region, it also enables the watchdog itself.
-		 */
-		if (boot_cpu_data.x86 == 0x17) {
-			val = sp5100_tco_read_pm_reg8(EFCH_PM_DECODEEN);
-			if (!(val & EFCH_PM_DECODEEN_WDT_TMREN)) {
-				sp5100_tco_update_pm_reg8(EFCH_PM_DECODEEN, 0xff,
-							  EFCH_PM_DECODEEN_WDT_TMREN);
-			}
-		}
 		val = sp5100_tco_read_pm_reg8(EFCH_PM_DECODEEN);
 		if (val & EFCH_PM_DECODEEN_WDT_TMREN)
 			mmio_addr = EFCH_PM_WDT_ADDR;

drivers/watchdog/sp5100_tco.h

@@ -89,3 +89,4 @@
 #define EFCH_PM_ACPI_MMIO_PM_ADDR	(EFCH_PM_ACPI_MMIO_ADDR +	\
 					 EFCH_PM_ACPI_MMIO_PM_OFFSET)
 #define EFCH_PM_ACPI_MMIO_PM_SIZE	8
+#define AMD_ZEN_SMBUS_PCI_REV		0x51