target/adi_v5_swd: improve error check while updating DP_SELECT

Write to register DP_SELECT can fail, but both functions
swd_queue_dp_bankselect() and swd_queue_ap_bankselect() return
void and do not propagate the error.

Change the return type of the two functions to int and check the
returned value.
Invalidate the cached value of DP_SELECT if the write fails.

Change-Id: Iba6ef8b0c2332e7f7efb66337d558fb7a4a0d39c
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/4980
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>

1 files changed, 42 insertions, 13 deletions

diff --git a/src/target/adi_v5_swd.c b/src/target/adi_v5_swd.c
index d099f4e7..d92e2961 100644
--- a/src/target/adi_v5_swd.c
+++ b/src/target/adi_v5_swd.c
@@ -166,22 +166,26 @@ static int swd_queue_ap_abort(struct adiv5_dap *dap, uint8_t *ack)
 }
 
 /** Select the DP register bank matching bits 7:4 of reg. */
-static void swd_queue_dp_bankselect(struct adiv5_dap *dap, unsigned reg)
+static int swd_queue_dp_bankselect(struct adiv5_dap *dap, unsigned reg)
 {
 	/* Only register address 4 is banked. */
 	if ((reg & 0xf) != 4)
-		return;
+		return ERROR_OK;
 
 	uint32_t select_dp_bank = (reg & 0x000000F0) >> 4;
 	uint32_t sel = select_dp_bank
 			| (dap->select & (DP_SELECT_APSEL | DP_SELECT_APBANK));
 
 	if (sel == dap->select)
-		return;
+		return ERROR_OK;
 
 	dap->select = sel;
 
-	swd_queue_dp_write(dap, DP_SELECT, sel);
+	int retval = swd_queue_dp_write(dap, DP_SELECT, sel);
+	if (retval != ERROR_OK)
+		dap->select = DP_SELECT_INVALID;
+
+	return retval;
 }
 
 static int swd_queue_dp_read(struct adiv5_dap *dap, unsigned reg,
@@ -194,7 +198,10 @@ static int swd_queue_dp_read(struct adiv5_dap *dap, unsigned reg,
 	if (retval != ERROR_OK)
 		return retval;
 
-	swd_queue_dp_bankselect(dap, reg);
+	retval = swd_queue_dp_bankselect(dap, reg);
+	if (retval != ERROR_OK)
+		return retval;
+
 	swd->read_reg(swd_cmd(true,  false, reg), data, 0);
 
 	return check_sync(dap);
@@ -211,17 +218,29 @@ static int swd_queue_dp_write(struct adiv5_dap *dap, unsigned reg,
 		return retval;
 
 	swd_finish_read(dap);
-	if (reg == DP_SELECT)
+	if (reg == DP_SELECT) {
 		dap->select = data & (DP_SELECT_APSEL | DP_SELECT_APBANK | DP_SELECT_DPBANK);
-	else
-		swd_queue_dp_bankselect(dap, reg);
+
+		swd->write_reg(swd_cmd(false,  false, reg), data, 0);
+
+		retval = check_sync(dap);
+		if (retval != ERROR_OK)
+			dap->select = DP_SELECT_INVALID;
+
+		return retval;
+	}
+
+	retval = swd_queue_dp_bankselect(dap, reg);
+	if (retval != ERROR_OK)
+		return retval;
+
 	swd->write_reg(swd_cmd(false,  false, reg), data, 0);
 
 	return check_sync(dap);
 }
 
 /** Select the AP register bank matching bits 7:4 of reg. */
-static void swd_queue_ap_bankselect(struct adiv5_ap *ap, unsigned reg)
+static int swd_queue_ap_bankselect(struct adiv5_ap *ap, unsigned reg)
 {
 	struct adiv5_dap *dap = ap->dap;
 	uint32_t sel = ((uint32_t)ap->ap_num << 24)
@@ -229,11 +248,15 @@ static void swd_queue_ap_bankselect(struct adiv5_ap *ap, unsigned reg)
 			| (dap->select & DP_SELECT_DPBANK);
 
 	if (sel == dap->select)
-		return;
+		return ERROR_OK;
 
 	dap->select = sel;
 
-	swd_queue_dp_write(dap, DP_SELECT, sel);
+	int retval = swd_queue_dp_write(dap, DP_SELECT, sel);
+	if (retval != ERROR_OK)
+		dap->select = DP_SELECT_INVALID;
+
+	return retval;
 }
 
 static int swd_queue_ap_read(struct adiv5_ap *ap, unsigned reg,
@@ -247,7 +270,10 @@ static int swd_queue_ap_read(struct adiv5_ap *ap, unsigned reg,
 	if (retval != ERROR_OK)
 		return retval;
 
-	swd_queue_ap_bankselect(ap, reg);
+	retval = swd_queue_ap_bankselect(ap, reg);
+	if (retval != ERROR_OK)
+		return retval;
+
 	swd->read_reg(swd_cmd(true,  true, reg), dap->last_read, ap->memaccess_tck);
 	dap->last_read = data;
 
@@ -266,7 +292,10 @@ static int swd_queue_ap_write(struct adiv5_ap *ap, unsigned reg,
 		return retval;
 
 	swd_finish_read(dap);
-	swd_queue_ap_bankselect(ap, reg);
+	retval = swd_queue_ap_bankselect(ap, reg);
+	if (retval != ERROR_OK)
+		return retval;
+
 	swd->write_reg(swd_cmd(false,  true, reg), data, ap->memaccess_tck);
 
 	return check_sync(dap);