David Brownell <david-b@pacbell.net>

Optionally shave time off the armv4_5 run_algorithm() code:  let
them terminate using software breakpoints, avoiding roundtrips
to manage hardware ones.

Enable this by using BKPT to terminate execution instead of "branch
to here" loops.  Then pass zero as the exit address, except when
running on an ARMv4 core.  ARM7TDMI, ARM9TDMI, and derived cores
now set a flag saying they're ARMv4.

Use that mechanism in arm_nandwrite(), for about 3% speedup on a
DaVinci ARM926 core; not huge, but it helps.  Some other algorithms
could use this too (mostly flavors of flash operation).

git-svn-id: svn://svn.berlios.de/openocd/trunk@2680 b42882b7-edfa-0310-969c-e2dbd0fdcd60

1 files changed, 17 insertions, 4 deletions

diff --git a/src/target/armv4_5.c b/src/target/armv4_5.c
index 9f9aa2f5..eedbc702 100644
--- a/src/target/armv4_5.c
+++ b/src/target/armv4_5.c
@@ -532,7 +532,10 @@ static int armv4_5_run_algorithm_completion(struct target_s *target, uint32_t ex
 		}
 		return ERROR_TARGET_TIMEOUT;
 	}
-	if (buf_get_u32(armv4_5->core_cache->reg_list[15].value, 0, 32) != exit_point)
+
+	/* fast exit: ARMv5+ code can use BKPT */
+	if (exit_point && buf_get_u32(armv4_5->core_cache->reg_list[15].value,
+				0, 32) != exit_point)
 	{
 		LOG_WARNING("target reentered debug state, but not at the desired exit point: 0x%4.4" PRIx32 "",
 			buf_get_u32(armv4_5->core_cache->reg_list[15].value, 0, 32));
@@ -570,6 +573,13 @@ int armv4_5_run_algorithm_inner(struct target_s *target, int num_mem_params, mem
 	if (armv4_5_mode_to_number(armv4_5->core_mode)==-1)
 		return ERROR_FAIL;
 
+	/* armv5 and later can terminate with BKPT instruction; less overhead */
+	if (!exit_point && armv4_5->is_armv4)
+	{
+		LOG_ERROR("ARMv4 target needs HW breakpoint location");
+		return ERROR_FAIL;
+	}
+
 	for (i = 0; i <= 16; i++)
 	{
 		if (!ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, armv4_5_algorithm_info->core_mode, i).valid)
@@ -626,9 +636,11 @@ int armv4_5_run_algorithm_inner(struct target_s *target, int num_mem_params, mem
 		armv4_5->core_cache->reg_list[ARMV4_5_CPSR].valid = 1;
 	}
 
-	if ((retval = breakpoint_add(target, exit_point, exit_breakpoint_size, BKPT_HARD)) != ERROR_OK)
+	/* terminate using a hardware or (ARMv5+) software breakpoint */
+	if (exit_point && (retval = breakpoint_add(target, exit_point,
+				exit_breakpoint_size, BKPT_HARD)) != ERROR_OK)
 	{
-		LOG_ERROR("can't add breakpoint to finish algorithm execution");
+		LOG_ERROR("can't add HW breakpoint to terminate algorithm");
 		return ERROR_TARGET_FAILURE;
 	}
 
@@ -639,7 +651,8 @@ int armv4_5_run_algorithm_inner(struct target_s *target, int num_mem_params, mem
 	int retvaltemp;
 	retval = run_it(target, exit_point, timeout_ms, arch_info);
 
-	breakpoint_remove(target, exit_point);
+	if (exit_point)
+		breakpoint_remove(target, exit_point);
 
 	if (retval != ERROR_OK)
 		return retval;