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-rw-r--r--configs/minnowmax_defconfig2
-rw-r--r--drivers/serial/Kconfig46
-rw-r--r--include/debug_uart.h139
3 files changed, 185 insertions, 2 deletions
diff --git a/configs/minnowmax_defconfig b/configs/minnowmax_defconfig
index 7bc9085b32..d12428996d 100644
--- a/configs/minnowmax_defconfig
+++ b/configs/minnowmax_defconfig
@@ -7,7 +7,5 @@ CONFIG_DEFAULT_DEVICE_TREE="minnowmax"
CONFIG_VIDEO_X86=y
CONFIG_FRAMEBUFFER_SET_VESA_MODE=y
CONFIG_FRAMEBUFFER_VESA_MODE_11A=y
-CONFIG_DEBUG_UART_NS16550=y
-CONFIG_DEBUG_UART=y
CONFIG_MMCONF_BASE_ADDRESS=0xe0000000
CONFIG_HAVE_INTEL_ME=y
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index c94353ba6a..6313258eac 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -7,6 +7,52 @@ config DM_SERIAL
implements serial_putc() etc. The uclass interface is
defined in include/serial.h.
+config DEBUG_UART
+ bool "Enable an early debug UART for debugging"
+ help
+ The debug UART is intended for use very early in U-Boot to debug
+ problems when an ICE or other debug mechanism is not available.
+
+ To use it you should:
+ - Make sure your UART supports this interface
+ - Enable CONFIG_DEBUG_UART
+ - Enable the CONFIG for your UART to tell it to provide this interface
+ (e.g. CONFIG_DEBUG_UART_NS16550)
+ - Define the required settings as needed (see below)
+ - Call debug_uart_init() before use
+ - Call debug_uart_putc() to output a character
+
+ Depending on your platform it may be possible to use this UART before
+ a stack is available.
+
+ If your UART does not support this interface you can probably add
+ support quite easily. Remember that you cannot use driver model and
+ it is preferred to use no stack.
+
+ You must not use this UART once driver model is working and the
+ serial drivers are up and running (done in serial_init()). Otherwise
+ the drivers may conflict and you will get strange output.
+
+config DEBUG_UART_BASE
+ hex "Base address of UART"
+ depends on DEBUG_UART
+ help
+ This is the base address of your UART for memory-mapped UARTs.
+
+ A default should be provided by your board, but if not you will need
+ to use the correct value here.
+
+config DEBUG_UART_CLOCK
+ int "UART input clock"
+ depends on DEBUG_UART
+ help
+ The UART input clock determines the speed of the internal UART
+ circuitry. The baud rate is derived from this by dividing the input
+ clock down.
+
+ A default should be provided by your board, but if not you will need
+ to use the correct value here.
+
config UNIPHIER_SERIAL
bool "UniPhier on-chip UART support"
depends on ARCH_UNIPHIER && DM_SERIAL
diff --git a/include/debug_uart.h b/include/debug_uart.h
new file mode 100644
index 0000000000..f56797b72f
--- /dev/null
+++ b/include/debug_uart.h
@@ -0,0 +1,139 @@
+/*
+ * Early debug UART support
+ *
+ * (C) Copyright 2014 Google, Inc
+ * Writte by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#ifndef _DEBUG_UART_H
+#define _DEBUG_UART_H
+
+#include <linux/linkage.h>
+
+/*
+ * The debug UART is intended for use very early in U-Boot to debug problems
+ * when an ICE or other debug mechanism is not available.
+ *
+ * To use it you should:
+ * - Make sure your UART supports this interface
+ * - Enable CONFIG_DEBUG_UART
+ * - Enable the CONFIG for your UART to tell it to provide this interface
+ * (e.g. CONFIG_DEBUG_UART_NS16550)
+ * - Define the required settings as needed (see below)
+ * - Call debug_uart_init() before use
+ * - Call printch() to output a character
+ *
+ * Depending on your platform it may be possible to use this UART before a
+ * stack is available.
+ *
+ * If your UART does not support this interface you can probably add support
+ * quite easily. Remember that you cannot use driver model and it is preferred
+ * to use no stack.
+ *
+ * You must not use this UART once driver model is working and the serial
+ * drivers are up and running (done in serial_init()). Otherwise the drivers
+ * may conflict and you will get strange output.
+ *
+ *
+ * To enable the debug UART in your serial driver:
+ *
+ * - #include <debug_uart.h>
+ * - Define debug_uart_init(), trying to avoid using the stack
+ * - Define _debug_uart_putc() as static inline (avoiding stack usage)
+ * - Immediately afterwards, add DEBUG_UART_FUNCS to define the rest of the
+ * functionality (printch(), etc.)
+ */
+
+/**
+ * debug_uart_init() - Set up the debug UART ready for use
+ *
+ * This sets up the UART with the correct baud rate, etc.
+ *
+ * Available CONFIG is:
+ *
+ * - CONFIG_DEBUG_UART_BASE: Base address of UART
+ * - CONFIG_BAUDRATE: Requested baud rate
+ * - CONFIG_DEBUG_UART_CLOCK: Input clock for UART
+ */
+void debug_uart_init(void);
+
+/**
+ * printch() - Output a character to the debug UART
+ *
+ * @ch: Character to output
+ */
+asmlinkage void printch(int ch);
+
+/**
+ * printascii() - Output an ASCII string to the debug UART
+ *
+ * @str: String to output
+ */
+asmlinkage void printascii(const char *str);
+
+/**
+ * printhex2() - Output a 2-digit hex value
+ *
+ * @value: Value to output
+ */
+asmlinkage void printhex2(uint value);
+
+/**
+ * printhex4() - Output a 4-digit hex value
+ *
+ * @value: Value to output
+ */
+asmlinkage void printhex4(uint value);
+
+/**
+ * printhex8() - Output a 8-digit hex value
+ *
+ * @value: Value to output
+ */
+asmlinkage void printhex8(uint value);
+
+/*
+ * Now define some functions - this should be inserted into the serial driver
+ */
+#define DEBUG_UART_FUNCS \
+ asmlinkage void printch(int ch) \
+ { \
+ _debug_uart_putc(ch); \
+ } \
+\
+ asmlinkage void printascii(const char *str) \
+ { \
+ while (*str) \
+ _debug_uart_putc(*str++); \
+ } \
+\
+ static inline void printhex1(uint digit) \
+ { \
+ digit &= 0xf; \
+ _debug_uart_putc(digit > 9 ? digit - 10 + 'a' : digit + '0'); \
+ } \
+\
+ static inline void printhex(uint value, int digits) \
+ { \
+ while (digits-- > 0) \
+ printhex1(value >> (4 * digits)); \
+ } \
+\
+ asmlinkage void printhex2(uint value) \
+ { \
+ printhex(value, 2); \
+ } \
+\
+ asmlinkage void printhex4(uint value) \
+ { \
+ printhex(value, 4); \
+ } \
+\
+ asmlinkage void printhex8(uint value) \
+ { \
+ printhex(value, 8); \
+ }
+
+#endif