UEFI: serial debugging support.

Signed-off-by: Jessica Hamilton <jessica.l.hamilton@gmail.com>

src/system/boot/platform/efi/Jamfile

@@ -33,6 +33,7 @@ local platform_src =
 	hpet.cpp
 	cpu.cpp
 	smp.cpp
+	serial.cpp
 	smp_trampoline.S
 	support.S
 	;

src/system/boot/platform/efi/debug.cpp

@@ -11,11 +11,29 @@
 #include <boot/stdio.h>
 
 #include "efi_platform.h"
+#include "serial.h"
+
+
+static void
+dprintf_args(const char *format, va_list args)
+{
+	char buffer[512];
+	int length = vsnprintf(buffer, sizeof(buffer), format, args);
+	if (length == 0)
+		return;
+
+	serial_puts(buffer, length);
+}
 
 
 extern "C" void
 dprintf(const char *format, ...)
 {
+	va_list args;
+
+	va_start(args, format);
+	dprintf_args(format, args);
+	va_end(args);
 }
 
 

src/system/boot/platform/efi/serial.cpp

@@ -0,0 +1,137 @@
+/*
+ * Copyright 2004-2008, Axel Dörfler, axeld@pinc-software.de.
+ * Copyright 2013-2014, Fredrik Holmqvist, fredrik.holmqvist@gmail.com.
+ * Copyright 2016, Jessica Hamilton, jessica.l.hamilton@gmail.com.
+ * Distributed under the terms of the MIT License.
+ */
+
+
+#include "efi_platform.h"
+#include "efiser.h"
+#include "serial.h"
+
+#include <boot/platform.h>
+#include <arch/cpu.h>
+#include <boot/stage2.h>
+#include <boot/stdio.h>
+
+#include <string.h>
+
+
+static EFI_GUID sSerialIOProtocolGUID = SERIAL_IO_PROTOCOL;
+static const uint32 kSerialBaudRate = 115200;
+
+static SERIAL_IO_INTERFACE *sSerial = NULL;
+static bool sSerialEnabled = false;
+static bool sSerialUsesEFI = true;
+
+
+enum serial_register_offsets {
+	SERIAL_TRANSMIT_BUFFER		= 0,
+	SERIAL_RECEIVE_BUFFER		= 0,
+	SERIAL_DIVISOR_LATCH_LOW	= 0,
+	SERIAL_DIVISOR_LATCH_HIGH	= 1,
+	SERIAL_FIFO_CONTROL			= 2,
+	SERIAL_LINE_CONTROL			= 3,
+	SERIAL_MODEM_CONTROL		= 4,
+	SERIAL_LINE_STATUS			= 5,
+	SERIAL_MODEM_STATUS			= 6,
+};
+
+static uint16 sSerialBasePort = 0x3f8;
+
+
+static void
+serial_putc(char ch)
+{
+	if (!sSerialEnabled)
+		return;
+
+	if (sSerialUsesEFI) {
+		UINTN bufSize = 1;
+		sSerial->Write(sSerial, &bufSize, &ch);
+	} else {
+		while ((in8(sSerialBasePort + SERIAL_LINE_STATUS) & 0x20) == 0)
+			asm volatile ("pause;");
+
+		out8(ch, sSerialBasePort + SERIAL_TRANSMIT_BUFFER);
+	}
+}
+
+
+extern "C" void
+serial_puts(const char* string, size_t size)
+{
+	if (!sSerialEnabled || (sSerial == NULL && sSerialUsesEFI))
+		return;
+
+	while (size-- != 0) {
+		char ch = string[0];
+
+		if (ch == '\n') {
+			serial_putc('\r');
+			serial_putc('\n');
+		} else if (ch != '\r')
+			serial_putc(ch);
+
+		string++;
+	}
+}
+
+
+extern "C" void
+serial_disable(void)
+{
+	sSerialEnabled = false;
+}
+
+
+extern "C" void
+serial_enable(void)
+{
+	sSerialEnabled = true;
+}
+
+
+extern "C" void
+serial_init(void)
+{
+	EFI_STATUS status = kSystemTable->BootServices->LocateProtocol(
+		&sSerialIOProtocolGUID, NULL, (void**)&sSerial);
+
+	if (status != EFI_SUCCESS || sSerial == NULL) {
+		sSerial = NULL;
+		return;
+	}
+
+	// Setup serial, 0, 0 = Default Receive FIFO queue and default timeout
+	status = sSerial->SetAttributes(sSerial, kSerialBaudRate, 0, 0, NoParity, 8,
+		OneStopBit);
+
+	if (status != EFI_SUCCESS) {
+		sSerial = NULL;
+		return;
+	}
+}
+
+
+extern "C" void
+serial_switch_to_legacy(void)
+{
+	sSerial = NULL;
+	sSerialUsesEFI = false;
+
+	memset(gKernelArgs.platform_args.serial_base_ports, 0,
+		sizeof(uint16) * MAX_SERIAL_PORTS);
+
+	gKernelArgs.platform_args.serial_base_ports[0] = sSerialBasePort;
+
+	uint16 divisor = uint16(115200 / kSerialBaudRate);
+
+	out8(0x80, sSerialBasePort + SERIAL_LINE_CONTROL);
+		// set divisor latch access bit
+	out8(divisor & 0xf, sSerialBasePort + SERIAL_DIVISOR_LATCH_LOW);
+	out8(divisor >> 8, sSerialBasePort + SERIAL_DIVISOR_LATCH_HIGH);
+	out8(3, sSerialBasePort + SERIAL_LINE_CONTROL);
+		// 8N1
+}

src/system/boot/platform/efi/serial.h

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2004-2007, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef SERIAL_H
+#define SERIAL_H
+
+
+#include <SupportDefs.h>
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern void serial_init(void);
+extern void serial_init_post_mmu(void);
+extern void serial_cleanup(void);
+
+extern void serial_puts(const char *string, size_t size);
+
+extern void serial_disable(void);
+extern void serial_enable(void);
+
+extern void serial_switch_to_legacy(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif	/* SERIAL_H */

src/system/boot/platform/efi/start.cpp

@@ -25,6 +25,7 @@
 #include "hpet.h"
 #include "cpu.h"
 #include "mmu.h"
+#include "serial.h"
 #include "smp.h"
 
 
@@ -223,6 +224,12 @@ platform_start_kernel(void)
 	dprintf("Calling ExitBootServices. So long, EFI!\n");
 	while (true) {
 		if (kBootServices->ExitBootServices(kImage, map_key) == EFI_SUCCESS) {
+			// The console was provided by boot services, disable it.
+			stdout = NULL;
+			stderr = NULL;
+			// Also switch to legacy serial output (may not work on all systems)
+			serial_switch_to_legacy();
+			dprintf("Switched to legacy serial output\n");
 			break;
 		}
 
@@ -231,10 +238,6 @@ platform_start_kernel(void)
 			panic("Unable to fetch system memory map.");
 		}
 	}
-	// We're on our own now...
-
-	// The console was provided by boot services, disable it.
-	stdout = NULL;
 
 	// Update EFI, generate final kernel physical memory map, etc.
 	mmu_post_efi_setup(memory_map_size, memory_map, descriptor_size, descriptor_version);
@@ -279,6 +282,8 @@ efi_main(EFI_HANDLE image, EFI_SYSTEM_TABLE *systemTable)
 	call_ctors();
 
 	console_init();
+	serial_init();
+	serial_enable();
 
 	sBootOptions = console_check_boot_keys();