Introduce crash console APIs for crash reporting

This patch introduces platform APIs to initialise and
print a character on a designated crash console.
For the FVP platform, PL011_UART0 is the designated
crash console. The platform porting guide is also updated
to document the new APIs.

Change-Id: I5e97d8762082e0c88c8c9bbb479353eac8f11a66

1 files changed, 36 insertions, 0 deletions

diff --git a/docs/porting-guide.md b/docs/porting-guide.md
index 813d0be..9002a99 100644
--- a/docs/porting-guide.md
+++ b/docs/porting-guide.md
@@ -15,6 +15,7 @@ Contents
     *   Boot Loader stage 3-1 (BL3-1)
     *   PSCI implementation (in BL3-1)
     *   Interrupt Management framework (in BL3-1)
+    *   Crash Reporting mechanism (in BL3-1)
 4.  C Library
 5.  Storage abstraction layer
 
@@ -1316,6 +1317,41 @@ interrupts as Group1 interrupts. It reads the group value corresponding to the
 interrupt id from the relevant _Interrupt Group Register_ (`GICD_IGROUPRn`). It
 uses the group value to determine the type of interrupt.
 
+3.5  Crash Reporting mechanism (in BL3-1)
+----------------------------------------------
+BL3-1 implements a crash reporting mechanism which prints the various registers
+of the CPU to enable quick crash analysis and debugging. It requires that a console
+is designated as the crash console by the platform which will used to print the
+register dump.
+
+The following functions must be implemented by the platform if it wants crash reporting
+mechanism in BL3-1. The functions are implemented in assembly so that they can be
+invoked without a C Runtime stack.
+
+### Function : plat_crash_console_init
+
+    Argument : void
+    Return   : int
+
+This API is used by the crash reporting mechanism to intialize the crash console.
+It should only use the general purpose registers x0 to x2 to do the initiaization
+and returns 1 on success.
+
+The FVP port designates the PL011_UART0 as the crash console and calls the
+console_core_init() to initialize the console.
+
+### Function : plat_crash_console_putc
+
+    Argument : int
+    Return   : int
+
+This API is used by the crash reporting mechanism to print a character on the
+designated crash console. It should only use general purpose registers x1 and
+x2 to do its work. The parameter and the return value are in general purpose
+register x0.
+
+The FVP port designates the PL011_UART0 as the crash console and calls the
+console_core_putc() to print the character on the console.
 
 4.  C Library
 -------------