Add support for memory mapped UARTs to coreboot and add the OXPCIe952 as an

example.

This newer version reflects the recent changes to further simplify the console
code and partly gets rid of some hacks in the previous version.

Signed-off-by: Stefan Reinauer <reinauer@google.com>
Acked-by: Peter Stuge <peter@stuge.se>                                                                                                                                          



git-svn-id: svn://svn.coreboot.org/coreboot/trunk@6544 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1

src/Kconfig

@@ -159,6 +159,15 @@ config MMCONF_SUPPORT
 
 source src/console/Kconfig
 
+# This should default to N and be set by SuperI/O drivers that have an UART
+config HAVE_UART_IO_MAPPED
+	bool
+	default y
+
+config HAVE_UART_MEMORY_MAPPED
+	bool
+	default n
+
 config HAVE_ACPI_RESUME
 	bool
 	default n

src/arch/x86/boot/coreboot_table.c

@@ -135,6 +135,9 @@ static void lb_console(struct lb_header *header)
 #if CONFIG_CONSOLE_SERIAL8250
 	add_console(header, LB_TAG_CONSOLE_SERIAL8250);
 #endif
+#if CONFIG_CONSOLE_SERIAL8250MEM
+	add_console(header, LB_TAG_CONSOLE_SERIAL8250MEM);
+#endif
 #if CONFIG_CONSOLE_LOGBUF
 	add_console(header, LB_TAG_CONSOLE_LOGBUF);
 #endif

src/arch/x86/lib/romstage_console.c

@@ -19,7 +19,7 @@
 
 #include <console/console.h>
 #include <console/vtxprintf.h>
-#if CONFIG_CONSOLE_SERIAL8250
+#if CONFIG_CONSOLE_SERIAL8250 || CONFIG_CONSOLE_SERIAL8250MEM
 #include <uart8250.h>
 #endif
 #if CONFIG_USBDEBUG
@@ -34,6 +34,9 @@ static void console_tx_byte(unsigned char byte)
 	if (byte == '\n')
 		console_tx_byte('\r');
 
+#if CONFIG_CONSOLE_SERIAL8250MEM
+	uart8250_mem_tx_byte(CONFIG_OXFORD_OXPCIE_BASE_ADDRESS + 0x1000, byte);
+#endif
 #if CONFIG_CONSOLE_SERIAL8250
 	uart8250_tx_byte(CONFIG_TTYS0_BASE, byte);
 #endif

src/console/Kconfig

@@ -2,9 +2,16 @@ menu "Console"
 # TODO: Rename to SERIAL_CONSOLE once Kconfig transition is complete.
 config CONSOLE_SERIAL8250
 	bool "Serial port console output"
+	depends on HAVE_UART_IO_MAPPED
 	default y
 	help
-	  Send coreboot debug output to a serial port console.
+	  Send coreboot debug output to an I/O mapped serial port console.
+
+config CONSOLE_SERIAL8250MEM
+	bool "Serial port console output (memory mapped)"
+	depends on HAVE_UART_MEMORY_MAPPED
+	help
+	  Send coreboot debug output to a memory mapped serial port console.
 
 choice
 	prompt "Serial port"
@@ -43,7 +50,7 @@ config TTYS0_BASE
 choice
 	prompt "Baud rate"
 	default CONSOLE_SERIAL_115200
-	depends on CONSOLE_SERIAL8250
+	depends on CONSOLE_SERIAL8250 || CONSOLE_SERIAL8250MEM
 
 config CONSOLE_SERIAL_115200
 	bool "115200"
@@ -82,7 +89,7 @@ config TTYS0_BAUD
 config TTYS0_LCS
 	int
 	default 3
-	depends on CONSOLE_SERIAL8250
+	depends on CONSOLE_SERIAL8250 || CONSOLE_SERIAL8250MEM
 
 # Use "select HAVE_USBDEBUG" on southbridges which have Debug Port code.
 config HAVE_USBDEBUG

src/console/Makefile.inc

@@ -14,6 +14,7 @@ romstage-y += post.c
 romstage-y += die.c
 
 driver-$(CONFIG_CONSOLE_SERIAL8250) += uart8250_console.c
+driver-$(CONFIG_CONSOLE_SERIAL8250MEM) += uart8250mem_console.c
 driver-$(CONFIG_USBDEBUG) += usbdebug_console.c
 driver-$(CONFIG_CONSOLE_LOGBUF) += logbuf_console.c
 driver-$(CONFIG_CONSOLE_NE2K) += ne2k_console.c

src/console/console.c

@@ -22,7 +22,7 @@
 #include <arch/hlt.h>
 #include <arch/io.h>
 
-#if CONFIG_CONSOLE_SERIAL8250
+#if CONFIG_CONSOLE_SERIAL8250 || CONFIG_CONSOLE_SERIAL8250MEM
 #include <uart8250.h>
 #endif
 
@@ -106,6 +106,9 @@ void console_init(void)
 #if CONFIG_CONSOLE_SERIAL8250
 	uart_init();
 #endif
+#if CONFIG_DRIVERS_OXFORD_OXPCIE && CONFIG_CONSOLE_SERIAL8250MEM
+	oxford_init();
+#endif
 #if CONFIG_CONSOLE_NE2K
 	ne2k_init(CONFIG_CONSOLE_NE2K_IO_PORT);
 #endif

src/console/uart8250mem_console.c

@@ -0,0 +1,60 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2003 Eric Biederman
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <console/console.h>
+#include <uart8250.h>
+#include <pc80/mc146818rtc.h>
+
+static u32 uart_bar = 0;
+
+static void uartmem_init(void)
+{
+	uart_bar = uart_mem_init();
+}
+
+static void uartmem_tx_byte(unsigned char data)
+{
+	if (!uart_bar)
+		return;
+
+	uart8250_mem_tx_byte(uart_bar, data);
+}
+
+static unsigned char uartmem_rx_byte(void)
+{
+	if (!uart_bar)
+		return 0;
+
+	return uart8250_mem_rx_byte(uart_bar);
+}
+
+static int uartmem_tst_byte(void)
+{
+	if (!uart_bar)
+		return 0;
+
+	return uart8250_mem_can_rx_byte(uart_bar);
+}
+
+static const struct console_driver uart8250mem_console __console = {
+	.init     = uartmem_init,
+	.tx_byte  = uartmem_tx_byte,
+	.rx_byte  = uartmem_rx_byte,
+	.tst_byte = uartmem_tst_byte,
+};

src/cpu/x86/smm/smiutil.c

@@ -26,7 +26,7 @@
 
 #include <console/console.h>
 #include <console/vtxprintf.h>
-#if CONFIG_CONSOLE_SERIAL8250
+#if CONFIG_CONSOLE_SERIAL8250 || CONFIG_CONSOLE_SERIAL8250MEM
 #include <uart8250.h>
 #endif
 #if CONFIG_USBDEBUG
@@ -36,6 +36,10 @@
 #include <console/ne2k.h>
 #endif
 
+#if CONFIG_CONSOLE_SERIAL8250MEM
+static u32 serial8250mem_base_address = 0;
+#endif
+
 void console_tx_flush(void)
 {
 	// the tx_byte functions take care of the flush.
@@ -47,6 +51,10 @@ void console_tx_byte(unsigned char byte)
 	if (byte == '\n')
 		console_tx_byte('\r');
 
+#if CONFIG_CONSOLE_SERIAL8250MEM
+	if (serial8250mem_base_address)
+		uart8250_mem_tx_byte(serial8250mem_base_address, byte);
+#endif
 #if CONFIG_CONSOLE_SERIAL8250
 	uart8250_tx_byte(CONFIG_TTYS0_BASE, byte);
 #endif
@@ -65,6 +73,9 @@ void console_init(void)
 #if CONFIG_CONSOLE_SERIAL8250
 	uart_init();
 #endif
+#if CONFIG_CONSOLE_SERIAL8250MEM
+	serial8250mem_base_address = uart_mem_init();
+#endif
 #else
 	console_loglevel = 1;
 #endif

src/drivers/Kconfig

@@ -22,6 +22,7 @@ source src/drivers/dec/Kconfig
 source src/drivers/emulation/Kconfig
 source src/drivers/generic/Kconfig
 source src/drivers/i2c/Kconfig
+source src/drivers/oxford/Kconfig
 source src/drivers/sil/Kconfig
 source src/drivers/trident/Kconfig
 

src/drivers/Makefile.inc

@@ -22,6 +22,7 @@ subdirs-y += dec
 subdirs-y += emulation
 subdirs-y += generic
 subdirs-y += i2c
+subdirs-y += oxford
 subdirs-y += sil
 subdirs-y += trident
 

src/drivers/oxford/Kconfig

@@ -0,0 +1 @@
+source src/drivers/oxford/oxpcie/Kconfig

src/drivers/oxford/Makefile.inc

@@ -0,0 +1 @@
+subdirs-$(CONFIG_DRIVERS_OXFORD_OXPCIE) += oxpcie

src/drivers/oxford/oxpcie/Kconfig

@@ -0,0 +1,68 @@
+config DRIVERS_OXFORD_OXPCIE
+	bool "Oxford OXPCIe952"
+	default n
+	select HAVE_UART_MEMORY_MAPPED
+	help
+	  Support for Oxford OXPCIe952 serial port PCIe cards.
+	  Currently only devices with the vendor ID 0x1415 and device ID
+	  0xc158 will work.
+	  NOTE: Right now you have to set the base address of your OXPCIe952
+	  card to exactly the value that the device allocator would set them
+	  later on, or serial console functionality will stop as soon as the
+	  resource allocator assigns a new base address to the device.
+
+config OXFORD_OXPCIE_BRIDGE_BUS
+	hex "OXPCIe's PCIe bridge bus number"
+	default 0x0
+	depends on DRIVERS_OXFORD_OXPCIE
+	help
+	  While coreboot is executing code from ROM, the coreboot resource
+	  allocator has not been running yet. Hence PCI devices living behind
+	  a bridge are not yet visible to the system. In order to use an
+	  OXPCIe952 based PCIe card, coreboot has to set up the PCIe bridge
+	  that controls the OXPCIe952 controller first.
+
+config OXFORD_OXPCIE_BRIDGE_DEVICE
+	hex "OXPCIe's PCIe bridge device number"
+	default 0x1c
+	depends on DRIVERS_OXFORD_OXPCIE
+	help
+	  While coreboot is executing code from ROM, the coreboot resource
+	  allocator has not been running yet. Hence PCI devices living behind
+	  a bridge are not yet visible to the system. In order to use an
+	  OXPCIe952 based PCIe card, coreboot has to set up the PCIe bridge
+	  that controls the OXPCIe952 controller first.
+
+config OXFORD_OXPCIE_BRIDGE_FUNCTION
+	hex "OXPCIe's PCIe bridge function number"
+	default 0x2
+	depends on DRIVERS_OXFORD_OXPCIE
+	help
+	  While coreboot is executing code from ROM, the coreboot resource
+	  allocator has not been running yet. Hence PCI devices living behind
+	  a bridge are not yet visible to the system. In order to use an
+	  OXPCIe952 based PCIe card, coreboot has to set up the PCIe bridge
+	  that controls the OXPCIe952 controller first.
+
+config OXFORD_OXPCIE_BRIDGE_SUBORDINATE
+	hex "OXPCIe's PCIe bridge subordinate bus"
+	default 0x3
+	depends on DRIVERS_OXFORD_OXPCIE
+	help
+	  While coreboot is executing code from ROM, the coreboot resource
+	  allocator has not been running yet. Hence PCI devices living behind
+	  a bridge are not yet visible to the system. In order to use an
+	  OXPCIe952 based PCIe card, coreboot has to set up the PCIe bridge
+	  that controls the OXPCIe952 controller first.
+
+config OXFORD_OXPCIE_BASE_ADDRESS
+	hex "Base address for rom stage console"
+	default 0xe0400000
+	depends on DRIVERS_OXFORD_OXPCIE
+	help
+	  While coreboot is executing code from ROM, the coreboot resource
+	  allocator has not been running yet. Hence PCI devices living behind
+	  a bridge are not yet visible to the system. In order to use an
+	  OXPCIe952 based PCIe card, coreboot has to set up a temporary address
+	  for the OXPCIe952 controller.
+

src/drivers/oxford/oxpcie/Makefile.inc

@@ -0,0 +1,3 @@
+driver-$(CONFIG_DRIVERS_OXFORD_OXPCIE) += oxpcie.c
+
+romstage-$(CONFIG_DRIVERS_OXFORD_OXPCIE) += oxpcie_early.c

src/drivers/oxford/oxpcie/oxpcie.c

@@ -0,0 +1,56 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2011 Google Inc
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#include <device/device.h>
+#include <device/pci_def.h>
+#include <device/pci.h>
+#include <device/pci_ids.h>
+#include <console/console.h>
+#include <arch/io.h>
+#include <uart8250.h>
+
+static void oxford_oxpcie_enable(device_t dev)
+{
+	printk(BIOS_DEBUG, "Initializing Oxford OXPCIe952\n");
+
+	struct resource *res = find_resource(dev, 0x10);
+	if (!res) {
+		printk(BIOS_WARNING, "OXPCIe952: No UART resource found.\n");
+		return;
+	}
+
+	printk(BIOS_DEBUG, "OXPCIe952: Class=%x Revision ID=%x\n",
+			(read32(res->base) >> 8), (read32(res->base) & 0xff));
+	printk(BIOS_DEBUG, "OXPCIe952: %d UARTs detected.\n",
+			(read32(res->base + 4) & 3));
+}
+
+static struct device_operations oxford_oxpcie_ops = {
+	.read_resources   = pci_dev_read_resources,
+	.set_resources    = pci_dev_set_resources,
+	.enable_resources = pci_dev_enable_resources,
+	.init             = oxford_oxpcie_enable,
+	.scan_bus         = 0,
+};
+
+static const struct pci_driver oxford_oxpcie_driver __pci_driver = {
+	.ops    = &oxford_oxpcie_ops,
+	.vendor = 0x1415,
+	.device = 0xc158,
+};

src/drivers/oxford/oxpcie/oxpcie_early.c

@@ -0,0 +1,89 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2011 Google Inc
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#include <stdint.h>
+#include <arch/io.h>
+#include <arch/romcc_io.h>
+#include <uart8250.h>
+#include <device/pci_def.h>
+
+#define PCIE_BRIDGE \
+	PCI_DEV(CONFIG_OXFORD_OXPCIE_BRIDGE_BUS, \
+		CONFIG_OXFORD_OXPCIE_BRIDGE_DEVICE, \
+		CONFIG_OXFORD_OXPCIE_BRIDGE_FUNCTION)
+
+#define OXPCIE_DEVICE \
+	PCI_DEV(CONFIG_OXFORD_OXPCIE_BRIDGE_SUBORDINATE, 0, 0) 
+
+void oxford_init(void)
+{
+	u16 reg16;
+
+	/* First we reset the secondary bus */
+	reg16 = pci_read_config16(PCIE_BRIDGE, PCI_BRIDGE_CONTROL);
+	reg16 |= (1 << 6); /* SRESET */
+	pci_write_config16(PCIE_BRIDGE, PCI_BRIDGE_CONTROL, reg16);
+
+	/* Assume we don't have to wait here forever */
+
+	/* Read back and clear reset bit. */
+	reg16 = pci_read_config16(PCIE_BRIDGE, PCI_BRIDGE_CONTROL);
+	reg16 &= ~(1 << 6); /* SRESET */
+	pci_write_config16(PCIE_BRIDGE, PCI_BRIDGE_CONTROL, reg16);
+
+	/* Set up subordinate bus number */
+	pci_write_config8(PCIE_BRIDGE, PCI_SECONDARY_BUS, 0x00);
+	pci_write_config8(PCIE_BRIDGE, PCI_SUBORDINATE_BUS, 0x00);
+	pci_write_config8(PCIE_BRIDGE, PCI_SECONDARY_BUS,
+			CONFIG_OXFORD_OXPCIE_BRIDGE_SUBORDINATE);
+	pci_write_config8(PCIE_BRIDGE, PCI_SUBORDINATE_BUS,
+			CONFIG_OXFORD_OXPCIE_BRIDGE_SUBORDINATE);
+
+	/* Memory window for the OXPCIe952 card */
+	// XXX is the calculation of base and limit corect?
+	pci_write_config32(PCIE_BRIDGE, PCI_MEMORY_BASE, 
+			((CONFIG_OXFORD_OXPCIE_BASE_ADDRESS & 0xffff0000) |
+			((CONFIG_OXFORD_OXPCIE_BASE_ADDRESS >> 16) & 0xff00)));
+
+	/* Enable memory access through bridge */
+	reg16 = pci_read_config16(PCIE_BRIDGE, PCI_COMMAND);
+	reg16 |= PCI_COMMAND_MEMORY;
+	pci_write_config16(PCIE_BRIDGE, PCI_COMMAND, reg16);
+
+	// FIXME Add a timeout or this will hang forever if 
+	// no device is in the slot.
+	u32 id = 0;
+	while ((id == 0) || (id == 0xffffffff))
+		id = pci_read_config32(OXPCIE_DEVICE, PCI_VENDOR_ID);
+
+	/* Setup base address on device */
+	pci_write_config32(OXPCIE_DEVICE, PCI_BASE_ADDRESS_0,
+				CONFIG_OXFORD_OXPCIE_BASE_ADDRESS);
+
+	/* Enable memory on device */
+	reg16 = pci_read_config16(OXPCIE_DEVICE, PCI_COMMAND);
+	reg16 |= PCI_COMMAND_MEMORY;
+	pci_write_config16(OXPCIE_DEVICE, PCI_COMMAND, reg16);
+
+	/* Now the UART initialization */
+	u32 uart0_base = CONFIG_OXFORD_OXPCIE_BASE_ADDRESS + 0x1000;
+
+	uart8250_mem_init(uart0_base, (4000000 / CONFIG_TTYS0_BAUD));
+}
+

src/include/boot/coreboot_tables.h

@@ -163,6 +163,7 @@ struct lb_console {
 #define LB_TAG_CONSOLE_LOGBUF		3
 #define LB_TAG_CONSOLE_SROM		4 // OBSOLETE
 #define LB_TAG_CONSOLE_EHCI		5
+#define LB_TAG_CONSOLE_SERIAL8250MEM	6
 
 #define LB_TAG_FORWARD		0x0011
 struct lb_forward {

src/include/uart8250.h

@@ -124,6 +124,7 @@
 #define   UART_MSR_DCTS		0x01 /* Delta CTS */
 
 #define UART_SCR 0x07
+#define UART_SPR 0x07
 
 
 #ifndef __ROMCC__
@@ -136,6 +137,17 @@ void uart8250_tx_byte(unsigned base_port, unsigned char data);
  */
 void uart8250_init(unsigned base_port, unsigned divisor);
 void uart_init(void);
+
+/* and the same for memory mapped uarts */
+unsigned char uart8250_mem_rx_byte(unsigned base_port);
+int uart8250_mem_can_rx_byte(unsigned base_port);
+void uart8250_mem_tx_byte(unsigned base_port, unsigned char data);
+void uart8250_mem_init(unsigned base_port, unsigned divisor);
+u32 uart_mem_init(void);
+
+/* and special init for OXPCIe based cards */
+void oxford_init(void);
+
 #endif
 
 #endif /* UART8250_H */

src/lib/Makefile.inc

@@ -9,6 +9,7 @@ romstage-y += lzma.c
 romstage-$(CONFIG_CACHE_AS_RAM) += ramtest.c
 romstage-$(CONFIG_HAVE_ACPI_RESUME) += cbmem.c
 romstage-$(CONFIG_CONSOLE_SERIAL8250) += uart8250.c
+romstage-$(CONFIG_CONSOLE_SERIAL8250MEM) += uart8250mem.c
 romstage-$(CONFIG_CONSOLE_NE2K) += ne2k.c
 romstage-$(CONFIG_CONSOLE_NE2K) += compute_ip_checksum.c
 romstage-$(CONFIG_USBDEBUG) += usbdebug.c
@@ -29,6 +30,7 @@ ramstage-y += gcc.c
 ramstage-y += clog2.c
 ramstage-y += cbmem.c
 ramstage-$(CONFIG_CONSOLE_SERIAL8250) += uart8250.c
+ramstage-$(CONFIG_CONSOLE_SERIAL8250MEM) += uart8250mem.c
 ramstage-$(CONFIG_USBDEBUG) += usbdebug.c
 ramstage-$(CONFIG_BOOTSPLASH) += jpeg.c
 
@@ -36,5 +38,6 @@ driver-$(CONFIG_CONSOLE_NE2K) += ne2k.c
 
 smm-y += memcpy.c
 smm-$(CONFIG_CONSOLE_SERIAL8250) += uart8250.c
+smm-$(CONFIG_CONSOLE_SERIAL8250MEM) += uart8250mem.c
 
 $(obj)/lib/version.ramstage.o : $(obj)/build.h

src/lib/uart8250mem.c

@@ -0,0 +1,139 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2003 Eric Biederman
+ * Copyright (C) 2006-2010 coresystems GmbH
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <arch/io.h>
+#include <uart8250.h>
+#include <pc80/mc146818rtc.h>
+#if CONFIG_USE_OPTION_TABLE
+#include "option_table.h"
+#endif
+#if !defined(__SMM__) && !defined(__PRE_RAM__)
+#include <device/device.h>
+#endif
+
+/* Should support 8250, 16450, 16550, 16550A type UARTs */
+
+static inline int uart8250_mem_can_tx_byte(unsigned base_port)
+{
+	return read8(base_port + UART_LSR) & UART_MSR_DSR;
+}
+
+static inline void uart8250_mem_wait_to_tx_byte(unsigned base_port)
+{
+	while(!uart8250_mem_can_tx_byte(base_port))
+		;
+}
+
+static inline void uart8250_mem_wait_until_sent(unsigned base_port)
+{
+	while(!(read8(base_port + UART_LSR) & UART_LSR_TEMT))
+		;
+}
+
+void uart8250_mem_tx_byte(unsigned base_port, unsigned char data)
+{
+	uart8250_mem_wait_to_tx_byte(base_port);
+	write8(base_port + UART_TBR, data);
+	/* Make certain the data clears the FIFOs */
+	uart8250_mem_wait_until_sent(base_port);
+}
+
+int uart8250_mem_can_rx_byte(unsigned base_port)
+{
+	return read8(base_port + UART_LSR) & UART_LSR_DR;
+}
+
+unsigned char uart8250_mem_rx_byte(unsigned base_port)
+{
+	while(!uart8250_mem_can_rx_byte(base_port))
+		;
+	return read8(base_port + UART_RBR);
+}
+
+void uart8250_mem_init(unsigned base_port, unsigned divisor)
+{
+	/* Disable interrupts */
+	write8(base_port + UART_IER, 0x0);
+	/* Enable FIFOs */
+	write8(base_port + UART_FCR, UART_FCR_FIFO_EN);
+
+	/* Assert DTR and RTS so the other end is happy */
+	write8(base_port + UART_MCR, UART_MCR_DTR | UART_MCR_RTS);
+
+	/* DLAB on */
+	write8(base_port + UART_LCR, UART_LCR_DLAB | CONFIG_TTYS0_LCS);
+
+	/* Set Baud Rate Divisor. 12 ==> 115200 Baud */
+	write8(base_port + UART_DLL, divisor & 0xFF);
+	write8(base_port + UART_DLM, (divisor >> 8) & 0xFF);
+
+	/* Set to 3 for 8N1 */
+	write8(base_port + UART_LCR, CONFIG_TTYS0_LCS);
+}
+
+u32 uart_mem_init(void)
+{
+	unsigned uart_baud = CONFIG_TTYS0_BAUD;
+	u32 uart_bar = 0;
+	unsigned div;
+
+	/* find out the correct baud rate */
+#if !defined(__SMM__) && CONFIG_USE_OPTION_TABLE
+	static const unsigned baud[8] = { 115200, 57600, 38400, 19200, 9600, 4800, 2400, 1200 };
+	unsigned b_index = 0;
+#if defined(__PRE_RAM__)
+	b_index = read_option(CMOS_VSTART_baud_rate, CMOS_VLEN_baud_rate, 0);
+	b_index &= 7;
+	uart_baud = baud[b_index];
+#else
+	if (get_option(&b_index, "baud_rate") == 0) {
+		uart_baud = baud[b_index];
+	}
+#endif
+#endif
+
+	/* Now find the UART base address and calculate the divisor */
+#if CONFIG_DRIVERS_OXFORD_OXPCIE
+
+#if defined(MORE_TESTING) && !defined(__SMM__) && !defined(__PRE_RAM__)
+	device_t dev = dev_find_device(0x1415, 0xc158, NULL);
+
+	if (dev) {
+		struct resource *res = find_resource(dev, 0x10);
+	
+		if (res) {
+			uart_bar = res->base + 0x1000; // for 1st UART
+			// uart_bar = res->base + 0x2000; // for 2nd UART
+		}
+	}
+
+	if (!uart_bar)
+#endif
+	uart_bar = CONFIG_OXFORD_OXPCIE_BASE_ADDRESS + 0x1000; // 1st UART
+	// uart_bar = CONFIG_OXFORD_OXPCIE_BASE_ADDRESS + 0x2000; // 2nd UART
+	
+	div = 4000000 / uart_baud;
+#endif
+
+	if (uart_bar)
+		uart8250_mem_init(uart_bar, div);
+
+	return uart_bar;
+}