Index: sys/dev/uart/uart_bus_pci.c
===================================================================
--- sys/dev/uart/uart_bus_pci.c
+++ sys/dev/uart/uart_bus_pci.c
@@ -43,6 +43,7 @@
 
 #include <dev/uart/uart.h>
 #include <dev/uart/uart_bus.h>
+#include <dev/uart/uart_cpu.h>
 
 #define	DEFAULT_RCLK	1843200
 
@@ -125,7 +126,7 @@
 	128 * DEFAULT_RCLK, 2},
 { 0x14e4, 0x4344, 0xffff, 0, "Sony Ericsson GC89 PC Card", 0x10},
 { 0x151f, 0x0000, 0xffff, 0, "TOPIC Semiconductor TP560 56k modem", 0x10 },
-{ 0x1d0f, 0x8250, 0x1d0f, 0, "Amazon PCI serial device", 0x10 },
+{ 0x1d0f, 0x8250, 0, 0, "Amazon EC2 PCI serial console", 0x10 },
 { 0x1fd4, 0x1999, 0x1fd4, 0x0001, "Sunix SER5xxxx Serial Port", 0x10,
 	8 * DEFAULT_RCLK },
 { 0x8086, 0x0f0a, 0xffff, 0, "Intel ValleyView LPIO1 HSUART#1", 0x10,
@@ -189,10 +190,13 @@
 	return ((id->vendor == vendor && id->device == device) ? id : NULL);
 }
 
+extern SLIST_HEAD(uart_devinfo_list, uart_devinfo) uart_sysdevs;
+
 static int
 uart_pci_probe(device_t dev)
 {
 	struct uart_softc *sc;
+	struct uart_devinfo *sysdev;
 	const struct pci_id *id;
 	int result;
 
@@ -207,6 +211,16 @@
 	return (ENXIO);
 
  match:
+	SLIST_FOREACH(sysdev, &uart_sysdevs, next) {
+		if (sysdev->pci_info.vendor == pci_get_vendor(dev)
+			&& sysdev->pci_info.device == pci_get_device(dev)
+			&& sysdev->pci_info.bus == pci_get_bus(dev)
+			&& sysdev->pci_info.slot == pci_get_slot(dev)) {
+			sc->sc_sysdev = sysdev;
+			sysdev->bas.rclk = sc->sc_bas.rclk;
+		}
+	}
+
 	result = uart_bus_probe(dev, id->regshft, 0, id->rclk, id->rid, 0, 0);
 	/* Bail out on error. */
 	if (result > 0)
Index: sys/dev/uart/uart_cpu.h
===================================================================
--- sys/dev/uart/uart_cpu.h
+++ sys/dev/uart/uart_cpu.h
@@ -52,6 +52,16 @@
 extern bus_space_tag_t uart_bus_space_io;
 extern bus_space_tag_t uart_bus_space_mem;
 
+/*
+ * PCI bus address from the ACPI SPCR table.
+ */
+struct uart_pci_info {
+	uint16_t	vendor;
+	uint16_t	device;
+	uint8_t		bus;
+	uint8_t		slot;
+};
+
 /*
  * Console and debug port device info.
  */
@@ -72,6 +82,7 @@
 	void	*cookie;		/* Type dependent use. */
 	struct mtx *hwmtx;
 	struct uart_softc *sc;		/* valid only from start of attach */
+	struct uart_pci_info pci_info;
 };
 
 int uart_cpu_eqres(struct uart_bas *, struct uart_bas *);
Index: sys/dev/uart/uart_cpu_arm64.c
===================================================================
--- sys/dev/uart/uart_cpu_arm64.c
+++ sys/dev/uart/uart_cpu_arm64.c
@@ -65,8 +65,9 @@
 /*
  * UART console routines.
  */
+extern struct bus_space memmap_bus;
 bus_space_tag_t uart_bus_space_io;
-bus_space_tag_t uart_bus_space_mem;
+bus_space_tag_t uart_bus_space_mem = &memmap_bus;
 
 int
 uart_cpu_eqres(struct uart_bas *b1, struct uart_bas *b2)
@@ -108,7 +109,7 @@
 static int
 uart_cpu_acpi_probe(struct uart_class **classp, bus_space_tag_t *bst,
     bus_space_handle_t *bsh, int *baud, u_int *rclk, u_int *shiftp,
-    u_int *iowidthp)
+    u_int *iowidthp, struct uart_pci_info *pcip)
 {
 	struct acpi_uart_compat_data *cd;
 	ACPI_TABLE_SPCR *spcr;
@@ -148,10 +149,15 @@
 		goto out;
 
 	*classp = cd->cd_class;
+	*shiftp = spcr->SerialPort.AccessWidth - 1;
 	*rclk = 0;
-	*shiftp = 2;
 	*iowidthp = spcr->SerialPort.BitWidth / 8;
 
+	pcip->vendor = spcr->PciVendorId;
+	pcip->device = spcr->PciDeviceId;
+	pcip->bus = spcr->PciBus;
+	pcip->slot = spcr->PciDevice;
+
 out:
 	acpi_unmap_table(spcr);
 	return (err);
@@ -179,7 +185,7 @@
 	err = ENXIO;
 #ifdef DEV_ACPI
 	err = uart_cpu_acpi_probe(&class, &bst, &bsh, &br, &rclk, &shift,
-	    &iowidth);
+	    &iowidth, &di->pci_info);
 #endif
 #ifdef FDT
 	if (err != 0) {