Blackfin arch: Add ability to expend the hardware trace buffer

Add ability to expend the hardware trace buffer via a configurable
software buffer - so you can have lots of history when a crash occurs.

The interesting way we do printk in the traps.c confusese the checking
script

Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

1 files changed, 81 insertions, 0 deletions

diff --git a/arch/blackfin/Kconfig b/arch/blackfin/Kconfig
index 9ce675e80260..a7a6e0c5827d 100644
--- a/arch/blackfin/Kconfig
+++ b/arch/blackfin/Kconfig
@@ -1024,8 +1024,89 @@ config DEBUG_HUNT_FOR_ZERO
 	  Enabling this option will take up an extra entry in CPLB table.
 	  Otherwise, there is no extra overhead.
 
+config DEBUG_BFIN_HWTRACE_ON
+	bool "Turn on Blackfin's Hardware Trace"
+	default y
+	help
+	  All Blackfins include a Trace Unit which stores a history of the last
+	  16 changes in program flow taken by the program sequencer. The history
+	  allows the user to recreate the program sequencer’s recent path. This
+	  can be handy when an application dies - we print out the execution
+	  path of how it got to the offending instruction.
+
+	  By turning this off, you may save a tiny amount of power.
+
+choice
+	prompt "Omit loop Tracing"
+	default DEBUG_BFIN_HWTRACE_COMPRESSION_OFF
+	depends on DEBUG_BFIN_HWTRACE_ON
+	help
+	  The trace buffer can be configured to omit recording of changes in
+	  program flow that match either the last entry or one of the last
+	  two entries. Omitting one of these entries from the record prevents
+	  the trace buffer from overflowing because of any sort of loop (for, do
+	  while, etc) in the program.
+
+	  Because zero-overhead Hardware loops are not recorded in the trace buffer,
+	  this feature can be used to prevent trace overflow from loops that
+	  are nested four deep.
+
+config DEBUG_BFIN_HWTRACE_COMPRESSION_OFF
+	bool "Trace all Loops"
+	help
+	  The trace buffer records all changes of flow 
+
+config DEBUG_BFIN_HWTRACE_COMPRESSION_ONE
+	bool "Compress single-level loops"
+	help
+	  The trace buffer does not record single loops - helpful if trace 
+	  is spinning on a while or do loop.
+
+config DEBUG_BFIN_HWTRACE_COMPRESSION_TWO
+	bool "Compress two-level loops"
+	help
+	  The trace buffer does not record loops two levels deep. Helpful if
+	  the trace is spinning in a nested loop
+
+endchoice
+
+config DEBUG_BFIN_HWTRACE_COMPRESSION
+	int
+	depends on DEBUG_BFIN_HWTRACE_ON
+	default 0 if DEBUG_BFIN_HWTRACE_COMPRESSION_OFF
+	default 1 if DEBUG_BFIN_HWTRACE_COMPRESSION_ONE
+	default 2 if DEBUG_BFIN_HWTRACE_COMPRESSION_TWO
+
+
+config DEBUG_BFIN_HWTRACE_EXPAND
+	bool "Expand Trace Buffer greater than 16 entries"
+	depends on DEBUG_BFIN_HWTRACE_ON
+	default n
+	help
+	  By selecting this option, every time the 16 hardware entries in
+	  the Blackfin's HW Trace buffer are full, the kernel will move them
+	  into a software buffer, for dumping when there is an issue. This 
+	  has a great impact on performance, (an interrupt every 16 change of 
+	  flows) and should normally be turned off, except in those nasty
+	  debugging sessions
+
+config DEBUG_BFIN_HWTRACE_EXPAND_LEN
+	int "Size of Trace buffer (in power of 2k)"
+	range 0 4
+	depends on DEBUG_BFIN_HWTRACE_EXPAND
+	default 1
+	help
+	  This sets the size of the software buffer that the trace information
+	  is kept in.
+	  0 for (2^0)  1k, or 256 entries,
+	  1 for (2^1)  2k, or 512 entries,
+	  2 for (2^2)  4k, or 1024 entries,
+	  3 for (2^3)  8k, or 2048 entries,
+	  4 for (2^4) 16k, or 4096 entries
+
 config DEBUG_BFIN_NO_KERN_HWTRACE
 	bool "Trace user apps (turn off hwtrace in kernel)"
+	depends on DEBUG_BFIN_HWTRACE_ON
 	default n
 	help
 	  Some pieces of the kernel contain a lot of flow changes which can