target: add API to temporarily mask target polling

The same flag 'jtag_poll' is currently used as local data for the
command 'poll' and to temporarily mask the target polling.
This can cause unexpected behavior if the command 'poll' is
executed while polling is temporarily masked.

Add a new flag 'jtag_poll_en' to hold the temporarily mask
condition and keep 'jtag_poll' for the 'poll' command only.

While there, change the initial assignment of 'jtag_poll' using
the proper boolean value.

Change-Id: I18dcf7c65b07aefadf046caaa2fcd2d74fa6fbae
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/7009
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Tested-by: jenkins

src/flash/nor/psoc4.c

@@ -651,8 +651,8 @@ static int psoc4_write(struct flash_bank *bank, const uint8_t *buffer,
 	if (row_offset)
 		memset(row_buffer, bank->default_padded_value, row_offset);
 
-	bool save_poll = jtag_poll_get_enabled();
-	jtag_poll_set_enabled(false);
+	/* Mask automatic polling triggered by execution of halted events */
+	bool save_poll_mask = jtag_poll_mask();
 
 	while (count) {
 		uint32_t chunk_size = psoc4_info->row_size - row_offset;
@@ -693,7 +693,7 @@ static int psoc4_write(struct flash_bank *bank, const uint8_t *buffer,
 	}
 
 cleanup:
-	jtag_poll_set_enabled(save_poll);
+	jtag_poll_unmask(save_poll_mask);
 
 	free(sysrq_buffer);
 	return retval;

src/helper/command.c

@@ -702,14 +702,12 @@ static int jim_capture(Jim_Interp *interp, int argc, Jim_Obj *const *argv)
 	 * This is necessary in order to avoid accidentally getting a non-empty
 	 * string for tcl fn's.
 	 */
-	bool save_poll = jtag_poll_get_enabled();
-
-	jtag_poll_set_enabled(false);
+	bool save_poll_mask = jtag_poll_mask();
 
 	const char *str = Jim_GetString(argv[1], NULL);
 	int retcode = Jim_Eval_Named(interp, str, __THIS__FILE__, __LINE__);
 
-	jtag_poll_set_enabled(save_poll);
+	jtag_poll_unmask(save_poll_mask);
 
 	command_log_capture_finish(state);
 

src/jtag/core.c

@@ -136,14 +136,19 @@ int jtag_error_clear(void)
 
 /************/
 
-static bool jtag_poll = 1;
+static bool jtag_poll = true;
+static bool jtag_poll_en = true;
 
 bool is_jtag_poll_safe(void)
 {
 	/* Polling can be disabled explicitly with set_enabled(false).
+	 * It can also be masked with mask().
 	 * It is also implicitly disabled while TRST is active and
 	 * while SRST is gating the JTAG clock.
 	 */
+	if (!jtag_poll_en)
+		return false;
+
 	if (!transport_is_jtag())
 		return jtag_poll;
 
@@ -162,6 +167,18 @@ void jtag_poll_set_enabled(bool value)
 	jtag_poll = value;
 }
 
+bool jtag_poll_mask(void)
+{
+	bool retval = jtag_poll_en;
+	jtag_poll_en = false;
+	return retval;
+}
+
+void jtag_poll_unmask(bool saved)
+{
+	jtag_poll_en = saved;
+}
+
 /************/
 
 struct jtag_tap *jtag_all_taps(void)

src/jtag/jtag.h

@@ -587,6 +587,19 @@ bool jtag_poll_get_enabled(void);
  */
 void jtag_poll_set_enabled(bool value);
 
+/**
+ * Mask (disable) polling and return the current mask status that should be
+ * feed to jtag_poll_unmask() to restore it.
+ * Multiple nested calls to jtag_poll_mask() are allowed, each balanced with
+ * its call to jtag_poll_unmask().
+ */
+bool jtag_poll_mask(void);
+
+/**
+ * Restore saved mask for polling.
+ */
+void jtag_poll_unmask(bool saved);
+
 #include <jtag/minidriver.h>
 
 int jim_jtag_newtap(Jim_Interp *interp, int argc, Jim_Obj *const *argv);

src/target/target.c

@@ -654,10 +654,10 @@ int target_resume(struct target *target, int current, target_addr_t address,
 	 * Disable polling during resume() to guarantee the execution of handlers
 	 * in the correct order.
 	 */
-	bool save_poll = jtag_poll_get_enabled();
-	jtag_poll_set_enabled(false);
+	bool save_poll_mask = jtag_poll_mask();
 	retval = target->type->resume(target, current, address, handle_breakpoints, debug_execution);
-	jtag_poll_set_enabled(save_poll);
+	jtag_poll_unmask(save_poll_mask);
+
 	if (retval != ERROR_OK)
 		return retval;
 
@@ -685,14 +685,12 @@ static int target_process_reset(struct command_invocation *cmd, enum target_rese
 	 * more predictable, i.e. dr/irscan & pathmove in events will
 	 * not have JTAG operations injected into the middle of a sequence.
 	 */
-	bool save_poll = jtag_poll_get_enabled();
-
-	jtag_poll_set_enabled(false);
+	bool save_poll_mask = jtag_poll_mask();
 
 	sprintf(buf, "ocd_process_reset %s", n->name);
 	retval = Jim_Eval(cmd->ctx->interp, buf);
 
-	jtag_poll_set_enabled(save_poll);
+	jtag_poll_unmask(save_poll_mask);
 
 	if (retval != JIM_OK) {
 		Jim_MakeErrorMessage(cmd->ctx->interp);