drivers/stlink_usb: fix stlink_usb_read_regs() for API v2

API v2 implementation for command READALLREGS returns the status
in the first two bytes, followed by two bytes of padding.
This makes the reply 4 bytes longer and changes the offset of the
first register value to 4.

Fix it for the case API v2 and clean-up the management of the
return value.

Change-Id: I448c82bcc0baa72d66fdfe7f0c525b94f8a4468b
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/4824
Tested-by: jenkins
Reviewed-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>

diff --git a/src/jtag/drivers/stlink_usb.c b/src/jtag/drivers/stlink_usb.c
index b02f9d01843da99a2ee8304705b050e1ea22b043..9ba4f4af987212360281eac2f0b8b279d94296be 100644 (file)
--- a/src/jtag/drivers/stlink_usb.c
+++ b/src/jtag/drivers/stlink_usb.c
@@ -1895,20 +1895,21 @@ static int stlink_usb_read_regs(void *handle)
 
        assert(handle != NULL);
 
-       stlink_usb_init_buffer(handle, h->rx_ep, 84);
+       stlink_usb_init_buffer(handle, h->rx_ep, 88);
 
        h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
-       if (h->version.jtag_api == STLINK_JTAG_API_V1)
+       if (h->version.jtag_api == STLINK_JTAG_API_V1) {
+
                h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV1_READALLREGS;
-       else
+               res = stlink_usb_xfer(handle, h->databuf, 84);
+               /* regs data from offset 0 */
+       } else {
                h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_READALLREGS;
+               res = stlink_usb_xfer(handle, h->databuf, 88);
+               /* status at offset 0, regs data from offset 4 */
+       }
 
-       res = stlink_usb_xfer(handle, h->databuf, 84);
-
-       if (res != ERROR_OK)
-               return res;
-
-       return ERROR_OK;
+       return res;
 }
 
 /** */