stm32: add synchronous debug printf

Allow use of a synchronous debug printf instead of using the
full console task to save space. This can be turned on with
CONFIG_DEBUG_PRINTF, and will provide essentially a one-way
console for debugging. This is essentially expanding upon
the debug_printf work done for zinger.

BUG=chrome-os-partner:41959
BRANCH=none
TEST=tested with following CLs on glados_pd by verifying we
get a one-way console.

Change-Id: If028b5d873261890de5b270bbc00e06bdcaa7431
Signed-off-by: Alec Berg <alecaberg@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/306782
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

12 files changed, 128 insertions, 48 deletions

diff --git a/board/zinger/board.c b/board/zinger/board.c
index ac3b95db20..bf4b51d5c7 100644
--- a/board/zinger/board.c
+++ b/board/zinger/board.c
@@ -5,7 +5,7 @@
 /* Tiny charger configuration */
 
 #include "common.h"
-#include "debug.h"
+#include "debug_printf.h"
 #include "ec_commands.h"
 #include "registers.h"
 #include "rsa.h"
diff --git a/board/zinger/build.mk b/board/zinger/build.mk
index 4e9e2f1f6d..249f8a3e1b 100644
--- a/board/zinger/build.mk
+++ b/board/zinger/build.mk
@@ -11,4 +11,3 @@ CHIP_FAMILY:=stm32f0
 CHIP_VARIANT:=stm32f03x
 
 board-y=board.o hardware.o runtime.o usb_pd_policy.o
-board-$(CONFIG_DEBUG_PRINTF)+=debug.o
diff --git a/board/zinger/debug.c b/board/zinger/debug.c
deleted file mode 100644
index 48c2259083..0000000000
--- a/board/zinger/debug.c
+++ /dev/null
@@ -1,37 +0,0 @@
-/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-/* Synchronous UART debug printf */
-
-#include "common.h"
-#include "printf.h"
-#include "registers.h"
-#include "util.h"
-
-static int debug_txchar(void *context, int c)
-{
-	if (c == '\n') {
-		while (!(STM32_USART_SR(UARTN_BASE) & STM32_USART_SR_TXE))
-			;
-		STM32_USART_TDR(UARTN_BASE) = '\r';
-	}
-
-	/* Wait for space to transmit */
-	while (!(STM32_USART_SR(UARTN_BASE) & STM32_USART_SR_TXE))
-		;
-	STM32_USART_TDR(UARTN_BASE) = c;
-
-	return 0;
-}
-
-
-
-void debug_printf(const char *format, ...)
-{
-	va_list args;
-
-	va_start(args, format);
-	vfnprintf(debug_txchar, NULL, format, args);
-	va_end(args);
-}
diff --git a/board/zinger/runtime.c b/board/zinger/runtime.c
index 8631eea74e..502d6649de 100644
--- a/board/zinger/runtime.c
+++ b/board/zinger/runtime.c
@@ -7,7 +7,7 @@
 #include "clock.h"
 #include "common.h"
 #include "cpu.h"
-#include "debug.h"
+#include "debug_printf.h"
 #include "registers.h"
 #include "system.h"
 #include "task.h"
diff --git a/board/zinger/usb_pd_policy.c b/board/zinger/usb_pd_policy.c
index 477060d17d..fd9cf8be7b 100644
--- a/board/zinger/usb_pd_policy.c
+++ b/board/zinger/usb_pd_policy.c
@@ -6,7 +6,7 @@
 #include "adc.h"
 #include "common.h"
 #include "console.h"
-#include "debug.h"
+#include "debug_printf.h"
 #include "ec_commands.h"
 #include "hooks.h"
 #include "registers.h"
diff --git a/chip/stm32/build.mk b/chip/stm32/build.mk
index 1c1df1a789..53b48b6ab5 100644
--- a/chip/stm32/build.mk
+++ b/chip/stm32/build.mk
@@ -50,6 +50,7 @@ chip-$(CHIP_FAMILY_STM32F0)+=flash-f.o
 chip-$(CHIP_FAMILY_STM32F3)+=flash-f.o
 endif
 chip-$(CONFIG_ADC)+=adc-$(CHIP_FAMILY).o
+chip-$(CONFIG_DEBUG_PRINTF)+=debug_printf.o
 chip-$(CONFIG_PWM)+=pwm.o
 chip-$(CONFIG_USB)+=usb.o usb-$(CHIP_FAMILY).o usb_endpoints.o
 chip-$(CONFIG_USB_CONSOLE)+=usb_console.o
diff --git a/chip/stm32/debug_printf.c b/chip/stm32/debug_printf.c
new file mode 100644
index 0000000000..c4e151692c
--- /dev/null
+++ b/chip/stm32/debug_printf.c
@@ -0,0 +1,115 @@
+/* Copyright 2015 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+/* Synchronous UART debug printf */
+
+#include "common.h"
+#include "console.h"
+#include "gpio.h"
+#include "printf.h"
+#include "registers.h"
+#include "util.h"
+
+static int debug_txchar(void *context, int c)
+{
+	if (c == '\n') {
+		while (!(STM32_USART_SR(UARTN_BASE) & STM32_USART_SR_TXE))
+			;
+		STM32_USART_TDR(UARTN_BASE) = '\r';
+	}
+
+	/* Wait for space to transmit */
+	while (!(STM32_USART_SR(UARTN_BASE) & STM32_USART_SR_TXE))
+		;
+	STM32_USART_TDR(UARTN_BASE) = c;
+
+	return 0;
+}
+
+
+
+void debug_printf(const char *format, ...)
+{
+	va_list args;
+
+	va_start(args, format);
+	vfnprintf(debug_txchar, NULL, format, args);
+	va_end(args);
+}
+
+#ifdef CONFIG_COMMON_RUNTIME
+void cflush(void)
+{
+	/* Wait for transmit complete */
+	while (!(STM32_USART_SR(UARTN_BASE) & STM32_USART_SR_TC))
+		;
+}
+
+int cputs(enum console_channel channel, const char *outstr)
+{
+	debug_printf(outstr);
+
+	return 0;
+}
+
+void panic_puts(const char *outstr)
+{
+	debug_printf(outstr);
+	cflush();
+}
+
+int cprintf(enum console_channel channel, const char *format, ...)
+{
+	va_list args;
+
+	va_start(args, format);
+	vfnprintf(debug_txchar, NULL, format, args);
+	va_end(args);
+
+	return 0;
+}
+
+void panic_printf(const char *format, ...)
+{
+	va_list args;
+
+	va_start(args, format);
+	vfnprintf(debug_txchar, NULL, format, args);
+	va_end(args);
+
+	cflush();
+}
+
+int cprints(enum console_channel channel, const char *format, ...)
+{
+	va_list args;
+
+	va_start(args, format);
+	vfnprintf(debug_txchar, NULL, format, args);
+	va_end(args);
+
+	debug_printf("\n");
+
+	return 0;
+}
+
+void uart_init(void)
+{
+	/* Enable USART1 clock */
+	STM32_RCC_APB2ENR |= STM32_RCC_PB2_USART1;
+	/* set baudrate */
+	STM32_USART_BRR(UARTN_BASE) =
+		DIV_ROUND_NEAREST(CPU_CLOCK, CONFIG_UART_BAUD_RATE);
+	/* UART enabled, 8 Data bits, oversampling x16, no parity */
+	STM32_USART_CR1(UARTN_BASE) =
+		STM32_USART_CR1_UE | STM32_USART_CR1_TE | STM32_USART_CR1_RE;
+	/* 1 stop bit, no fancy stuff */
+	STM32_USART_CR2(UARTN_BASE) = 0x0000;
+	/* DMA disabled, special modes disabled, error interrupt disabled */
+	STM32_USART_CR3(UARTN_BASE) = 0x0000;
+
+	/* Configure GPIOs */
+	gpio_config_module(MODULE_UART, 1);
+}
+#endif
diff --git a/board/zinger/debug.h b/chip/stm32/debug_printf.h
index 38cea6fb28..38cea6fb28 100644
--- a/board/zinger/debug.h
+++ b/chip/stm32/debug_printf.h
diff --git a/common/panic_output.c b/common/panic_output.c
index 144b7a0e19..8d9cf2205d 100644
--- a/common/panic_output.c
+++ b/common/panic_output.c
@@ -26,6 +26,7 @@ static struct panic_data * const pdata_ptr = PANIC_DATA_PTR;
  * @param c		Character to write.
  * @return 0 if the character was transmitted, 1 if it was dropped.
  */
+#ifndef CONFIG_DEBUG_PRINTF
 static int panic_txchar(void *context, int c)
 {
 	if (c == '\n')
@@ -68,6 +69,7 @@ void panic_printf(const char *format, ...)
 	/* Flush the transmit FIFO */
 	uart_tx_flush();
 }
+#endif
 
 /**
  * Display a message and reboot
diff --git a/common/printf.c b/common/printf.c
index 6e1a7401e9..987f7415ca 100644
--- a/common/printf.c
+++ b/common/printf.c
@@ -13,12 +13,12 @@ static const char error_str[] = "ERROR";
 
 #define MAX_FORMAT 1024  /* Maximum chars in a single format field */
 
-#ifdef CONFIG_COMMON_RUNTIME
+#ifndef CONFIG_DEBUG_PRINTF
 static inline int divmod(uint64_t *n, int d)
 {
 	return uint64divmod(n, d);
 }
-#else /* !CONFIG_COMMON_RUNTIME */
+#else /* CONFIG_DEBUG_PRINTF */
 /* if we are optimizing for size, remove the 64-bit support */
 #define NO_UINT64_SUPPORT
 static inline int divmod(uint32_t *n, int d)
diff --git a/common/system.c b/common/system.c
index 224ae7d78e..7f5a5ee5b4 100644
--- a/common/system.c
+++ b/common/system.c
@@ -448,9 +448,9 @@ static void jump_to_image(uintptr_t init_addr)
 	/* Prepare I2C module for sysjump */
 	i2c_prepare_sysjump();
 #endif
-	/* Flush UART output unless the UART hasn't been initialized yet */
-	if (uart_init_done())
-		uart_flush_output();
+
+	/* Flush UART output */
+	cflush();
 
 	/* Disable interrupts before jump */
 	interrupt_disable();
diff --git a/common/uart_buffering.c b/common/uart_buffering.c
index 86a3482951..949c3968d6 100644
--- a/common/uart_buffering.c
+++ b/common/uart_buffering.c
@@ -301,8 +301,8 @@ int uart_printf(const char *format, ...)
 
 void uart_flush_output(void)
 {
-	/* If UART is suspended, ignore flush request. */
-	if (uart_suspended)
+	/* If UART not initialized or is suspended, ignore flush request. */
+	if (!uart_init_done() || uart_suspended)
 		return;
 
 	/* Loop until buffer is empty */