Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/acpi/reboot.c b/drivers/acpi/reboot.c
index 6fa9c2a..ca707f5 100644
--- a/drivers/acpi/reboot.c
+++ b/drivers/acpi/reboot.c
@@ -4,11 +4,35 @@
 #include <linux/acpi.h>
 #include <acpi/reboot.h>
 
+#ifdef CONFIG_PCI
+static void acpi_pci_reboot(struct acpi_generic_address *rr, u8 reset_value)
+{
+	unsigned int devfn;
+	struct pci_bus *bus0;
+
+	/* The reset register can only live on bus 0. */
+	bus0 = pci_find_bus(0, 0);
+	if (!bus0)
+		return;
+	/* Form PCI device/function pair. */
+	devfn = PCI_DEVFN((rr->address >> 32) & 0xffff,
+			  (rr->address >> 16) & 0xffff);
+	pr_debug("Resetting with ACPI PCI RESET_REG.\n");
+	/* Write the value that resets us. */
+	pci_bus_write_config_byte(bus0, devfn,
+			(rr->address & 0xffff), reset_value);
+}
+#else
+static inline void acpi_pci_reboot(struct acpi_generic_address *rr,
+				   u8 reset_value)
+{
+	pr_warn_once("PCI configuration space access is not supported\n");
+}
+#endif
+
 void acpi_reboot(void)
 {
 	struct acpi_generic_address *rr;
-	struct pci_bus *bus0;
-	unsigned int devfn;
 	u8 reset_value;
 
 	if (acpi_disabled)
@@ -33,17 +57,7 @@
 	 * on a device on bus 0. */
 	switch (rr->space_id) {
 	case ACPI_ADR_SPACE_PCI_CONFIG:
-		/* The reset register can only live on bus 0. */
-		bus0 = pci_find_bus(0, 0);
-		if (!bus0)
-			return;
-		/* Form PCI device/function pair. */
-		devfn = PCI_DEVFN((rr->address >> 32) & 0xffff,
-				  (rr->address >> 16) & 0xffff);
-		printk(KERN_DEBUG "Resetting with ACPI PCI RESET_REG.\n");
-		/* Write the value that resets us. */
-		pci_bus_write_config_byte(bus0, devfn,
-				(rr->address & 0xffff), reset_value);
+		acpi_pci_reboot(rr, reset_value);
 		break;
 
 	case ACPI_ADR_SPACE_SYSTEM_MEMORY: