From: Thierry Reding <tred...@nvidia.com>
This is mostly useful for debugging the early boot process. Often boards
can provide some low-level code that outputs a character on some debug
port prior to passing the early setup code. Allow boards to implement an
early_putc() function that will be used to redirect printf() and friends
to this debug port until the proper console becomes ready.
Cc: Simon Glass <s...@chromium.org>
Cc: Tom Rini <tr...@konsulko.com>
Signed-off-by: Thierry Reding <tred...@nvidia.com>
---
README | 17 +++++++++++++++++
common/console.c | 21 +++++++++++++++++++--
2 files changed, 36 insertions(+), 2 deletions(-)
diff --git a/README b/README
index b0124d6022e1..a7cb3d86d2d2 100644
--- a/README
+++ b/README
@@ -5014,6 +5014,23 @@ Low Level (hardware related) configuration options:
driver that uses this:
drivers/mtd/nand/davinci_nand.c
+- CONFIG_EARLY_CONSOLE
+ Enables support for an early console. Output from puts() and
+ printf() will be redirected to this early console. A primary
+ use-case for this is early board bring up, where U-Boot does
+ not boot to the proper console yet, but it can also be quite
+ handy to help debug U-Boot's early boot phases.
+
+ Boards that specify this option in their configuration must
+ provide an implementation of the early_putc() function:
+
+ void early_putc(char ch);
+
+ This function should output a single character on a device
+ that is available during early boot. Often this will be a
+ debug UART that has been preconfigured by a bootloader or
+ ROM before executing U-Boot.
+
Freescale QE/FMAN Firmware Support:
-----------------------------------
diff --git a/common/console.c b/common/console.c
index 3f25e76fe79e..d552dff4ee0f 100644
--- a/common/console.c
+++ b/common/console.c
@@ -479,6 +479,16 @@ void putc(const char c)
}
}
+#ifdef CONFIG_EARLY_CONSOLE
+extern void early_putc(char ch);
+
+static void early_puts(const char *s)
+{
+ while (*s)
+ early_putc(*s++);
+}
+#endif
+
void puts(const char *s)
{
#ifdef CONFIG_SANDBOX
@@ -498,6 +508,11 @@ void puts(const char *s)
return;
#endif
+#ifdef CONFIG_EARLY_CONSOLE
+ if (!gd->have_console)
+ early_puts(s);
+#endif
+
if (!gd->have_console)
return pre_console_puts(s);
@@ -517,7 +532,8 @@ int printf(const char *fmt, ...)
uint i;
char printbuffer[CONFIG_SYS_PBSIZE];
-#if !defined(CONFIG_SANDBOX) && !defined(CONFIG_PRE_CONSOLE_BUFFER)
+#if !defined(CONFIG_SANDBOX) && !defined(CONFIG_PRE_CONSOLE_BUFFER) && \
+ !defined(CONFIG_EARLY_CONSOLE)
if (!gd->have_console)
return 0;
#endif
@@ -540,7 +556,8 @@ int vprintf(const char *fmt, va_list args)
uint i;
char printbuffer[CONFIG_SYS_PBSIZE];
-#if defined(CONFIG_PRE_CONSOLE_BUFFER) && !defined(CONFIG_SANDBOX)
+#if !defined(CONFIG_SANDBOX) && !defined(CONFIG_PRE_CONSOLE_BUFFER) && \
+ !defined(CONFIG_EARLY_CONSOLE)
if (!gd->have_console)
return 0;
#endif
--
2.3.2
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