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

src/flash/arm_nandio.c

@@ -33,7 +33,6 @@
  * For now this only supports ARMv4 and ARMv5 cores.
  *
  * Enhancements to target_run_algorithm() could enable:
- *   - faster writes: on ARMv5+ don't setup/teardown hardware breakpoint
  *   - ARMv6 and ARMv7 cores in ARM mode
  *
  * Different code fragments could handle:
@@ -44,8 +43,10 @@ int arm_nandwrite(struct arm_nand_data *nand, uint8_t *data, int size)
 {
 	target_t		*target = nand->target;
 	armv4_5_algorithm_t	algo;
+	armv4_5_common_t	*armv4_5 = target->arch_info;
 	reg_param_t		reg_params[3];
 	uint32_t		target_buf;
+	uint32_t		exit = 0;
 	int			retval;
 
 	/* Inputs:
@@ -112,11 +113,13 @@ int arm_nandwrite(struct arm_nand_data *nand, uint8_t *data, int size)
 	buf_set_u32(reg_params[1].value, 0, 32, target_buf);
 	buf_set_u32(reg_params[2].value, 0, 32, size);
 
+	/* armv4 must exit using a hardware breakpoint */
+	if (armv4_5->is_armv4)
+		exit = nand->copy_area->address + sizeof(code) - 4;
+
 	/* use alg to write data from work area to NAND chip */
 	retval = target_run_algorithm(target, 0, NULL, 3, reg_params,
-			nand->copy_area->address,
-			nand->copy_area->address + sizeof(code) - 4,
-			1000, &algo);
+			nand->copy_area->address, exit, 1000, &algo);
 	if (retval != ERROR_OK)
 		LOG_ERROR("error executing hosted NAND write");
 

src/target/arm7tdmi.c

@@ -828,6 +828,7 @@ int arm7tdmi_target_create(struct target_s *target, Jim_Interp *interp)
 
 	arm7tdmi = calloc(1,sizeof(arm7tdmi_common_t));
 	arm7tdmi_init_arch_info(target, arm7tdmi, target->tap);
+	arm7tdmi->arm7_9_common.armv4_5_common.is_armv4 = true;
 
 	return ERROR_OK;
 }

src/target/arm9tdmi.c

@@ -956,6 +956,7 @@ int arm9tdmi_target_create(struct target_s *target, Jim_Interp *interp)
 	arm9tdmi_common_t *arm9tdmi = calloc(1,sizeof(arm9tdmi_common_t));
 
 	arm9tdmi_init_arch_info(target, arm9tdmi, target->tap);
+	arm9tdmi->arm7_9_common.armv4_5_common.is_armv4 = true;
 
 	return ERROR_OK;
 }

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;
 	}
 
@@ -639,6 +651,7 @@ 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);
 
+	if (exit_point)
 		breakpoint_remove(target, exit_point);
 
 	if (retval != ERROR_OK)

src/target/armv4_5.h

@@ -76,6 +76,7 @@ typedef struct armv4_5_common_s
 	reg_cache_t *core_cache;
 	enum armv4_5_mode core_mode;
 	enum armv4_5_state core_state;
+	bool is_armv4;
 	int (*full_context)(struct target_s *target);
 	int (*read_core_reg)(struct target_s *target, int num, enum armv4_5_mode mode);
 	int (*write_core_reg)(struct target_s *target, int num, enum armv4_5_mode mode, uint32_t value);