flash/nor/bluenrg-x: clarify target algo stack usage

While on it rename misleading write_algorithm_sp to write_algorithm_stack
and change messages referring 'stack pointer' instead of stack.

No functional change.

Change-Id: Ibb9897d3f01734812ed0f8bc8cd43b935a573f8a
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: https://review.openocd.org/c/openocd/+/7132
Tested-by: jenkins
Reviewed-by: Salvatore Giorgio Pecorino <salvatore-giorgio.pecorino@st.com>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

1 files changed, 19 insertions, 10 deletions

diff --git a/src/flash/nor/bluenrg-x.c b/src/flash/nor/bluenrg-x.c
index d4fb5e9..ec5cae7 100644
--- a/src/flash/nor/bluenrg-x.c
+++ b/src/flash/nor/bluenrg-x.c
@@ -236,7 +236,7 @@ static int bluenrgx_write(struct flash_bank *bank, const uint8_t *buffer,
 	struct target *target = bank->target;
 	uint32_t buffer_size = 16384 + 8;
 	struct working_area *write_algorithm;
-	struct working_area *write_algorithm_sp;
+	struct working_area *write_algorithm_stack;
 	struct working_area *source;
 	uint32_t address = bank->base + offset;
 	struct reg_param reg_params[5];
@@ -285,10 +285,10 @@ static int bluenrgx_write(struct flash_bank *bank, const uint8_t *buffer,
 		return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;
 	}
 
-	/* Stack pointer area */
+	/* Stack area */
 	if (target_alloc_working_area(target, 128,
-					  &write_algorithm_sp) != ERROR_OK) {
-		LOG_DEBUG("no working area for write code stack pointer");
+					  &write_algorithm_stack) != ERROR_OK) {
+		LOG_DEBUG("no working area for target algorithm stack");
 		return ERROR_TARGET_RESOURCE_NOT_AVAILABLE;
 	}
 
@@ -300,8 +300,19 @@ static int bluenrgx_write(struct flash_bank *bank, const uint8_t *buffer,
 	init_reg_param(&reg_params[2], "r2", 32, PARAM_OUT);
 	init_reg_param(&reg_params[3], "r3", 32, PARAM_OUT);
 	init_reg_param(&reg_params[4], "sp", 32, PARAM_OUT);
-	/* Put the parameter at the first available stack location */
-	init_mem_param(&mem_params[0], write_algorithm_sp->address + 80, 32, PARAM_OUT);
+	/* Put the 4th parameter at the location in the stack frame of target write() function.
+	 * See contrib/loaders/flash/bluenrg-x/bluenrg-x_write.lst
+	 * 34 ldr     r6, [sp, #80]
+	 *                     ^^^ offset
+	 */
+	init_mem_param(&mem_params[0], write_algorithm_stack->address + 80, 32, PARAM_OUT);
+	/* Stack for target write algorithm - target write() function has
+	 * __attribute__((naked)) so it does not setup the new stack frame.
+	 * Therefore the stack frame uses the area from SP upwards!
+	 * Interrupts are disabled and no subroutines are called from write()
+	 * so no need to allocate stack below SP.
+	 * TODO: remove __attribute__((naked)) and use similar parameter passing as stm32l4x */
+	buf_set_u32(reg_params[4].value, 0, 32, write_algorithm_stack->address);
 
 	/* FIFO start address (first two words used for write and read pointers) */
 	buf_set_u32(reg_params[0].value, 0, 32, source->address);
@@ -311,14 +322,12 @@ static int bluenrgx_write(struct flash_bank *bank, const uint8_t *buffer,
 	buf_set_u32(reg_params[2].value, 0, 32, address);
 	/* Number of bytes */
 	buf_set_u32(reg_params[3].value, 0, 32, count);
-	/* Stack pointer for program working area */
-	buf_set_u32(reg_params[4].value, 0, 32, write_algorithm_sp->address);
 	/* Flash register base address */
 	buf_set_u32(mem_params[0].value, 0, 32, bluenrgx_info->flash_ptr->flash_regs_base);
 
 	LOG_DEBUG("source->address = " TARGET_ADDR_FMT, source->address);
 	LOG_DEBUG("source->address+ source->size = " TARGET_ADDR_FMT, source->address+source->size);
-	LOG_DEBUG("write_algorithm_sp->address = " TARGET_ADDR_FMT, write_algorithm_sp->address);
+	LOG_DEBUG("write_algorithm_stack->address = " TARGET_ADDR_FMT, write_algorithm_stack->address);
 	LOG_DEBUG("address = %08" PRIx32, address);
 	LOG_DEBUG("count = %08" PRIx32, count);
 
@@ -357,7 +366,7 @@ static int bluenrgx_write(struct flash_bank *bank, const uint8_t *buffer,
 	}
 	target_free_working_area(target, source);
 	target_free_working_area(target, write_algorithm);
-	target_free_working_area(target, write_algorithm_sp);
+	target_free_working_area(target, write_algorithm_stack);
 
 	destroy_reg_param(&reg_params[0]);
 	destroy_reg_param(&reg_params[1]);