jtag: drivers: usb_blaster: clarify lowlevel driver selection code

[openocd.git] / src / jtag / drivers / usb_blaster / usb_blaster.c

diff --git a/src/jtag/drivers/usb_blaster/usb_blaster.c b/src/jtag/drivers/usb_blaster/usb_blaster.c
index d64a7ea827a3cbe3adff2f09897bc9c13c99022f..df9f2a174797d886ed245921526853255d2c5695 100644 (file)
--- a/src/jtag/drivers/usb_blaster/usb_blaster.c
+++ b/src/jtag/drivers/usb_blaster/usb_blaster.c
@@ -20,6 +20,9 @@
  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *   GNU General Public License for more details.
  *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
  */
 
 /*
@@ -144,12 +147,9 @@ struct drvs_map {
 };
 
 static struct drvs_map lowlevel_drivers_map[] = {
-#if BUILD_USB_BLASTER_LIBFTDI
+#if BUILD_USB_BLASTER
        { .name = "ftdi", .drv_register = ublast_register_ftdi },
 #endif
-#if BUILD_USB_BLASTER_FTD2XX
-       { .name = "ftd2xx", .drv_register = ublast_register_ftd2xx },
-#endif
 #if BUILD_USB_BLASTER_2
        { .name = "ublast2", .drv_register = ublast2_register_libusb },
 #endif
@@ -756,11 +756,41 @@ static void ublast_usleep(int us)
        jtag_sleep(us);
 }
 
+static void ublast_initial_wipeout(void)
+{
+       static uint8_t tms_reset = 0xff;
+       uint8_t out_value;
+       uint32_t retlen;
+       int i;
+
+       out_value = ublast_build_out(SCAN_OUT);
+       for (i = 0; i < BUF_LEN; i++)
+               info.buf[i] = out_value | ((i % 2) ? TCK : 0);
+
+       /*
+        * Flush USB-Blaster queue fifos
+        *  - empty the write FIFO (128 bytes)
+        *  - empty the read FIFO (384 bytes)
+        */
+       ublast_buf_write(info.buf, BUF_LEN, &retlen);
+       /*
+        * Put JTAG in RESET state (five 1 on TMS)
+        */
+       ublast_tms_seq(&tms_reset, 5);
+       tap_set_state(TAP_RESET);
+}
+
 static int ublast_execute_queue(void)
 {
        struct jtag_command *cmd;
+       static int first_call = 1;
        int ret = ERROR_OK;
 
+       if (first_call) {
+               first_call--;
+               ublast_initial_wipeout();
+       }
+
        for (cmd = jtag_command_queue; ret == ERROR_OK && cmd != NULL;
             cmd = cmd->next) {
                switch (cmd->type) {
@@ -801,36 +831,38 @@ static int ublast_execute_queue(void)
  *
  * Initialize the device :
  *  - open the USB device
- *  - empty the write FIFO (128 bytes)
- *  - empty the read FIFO (384 bytes)
+ *  - pretend it's initialized while actual init is delayed until first jtag command
  *
  * Returns ERROR_OK if USB device found, error if not.
  */
 static int ublast_init(void)
 {
-       static uint8_t tms_reset = 0xff;
        int ret, i;
 
-       if (info.lowlevel_name) {
-               for (i = 0; lowlevel_drivers_map[i].name; i++)
-                       if (!strcmp(lowlevel_drivers_map[i].name, info.lowlevel_name))
+       for (i = 0; lowlevel_drivers_map[i].name; i++) {
+               if (info.lowlevel_name) {
+                       if (!strcmp(lowlevel_drivers_map[i].name, info.lowlevel_name)) {
+                               info.drv = lowlevel_drivers_map[i].drv_register();
+                               if (!info.drv) {
+                                       LOG_ERROR("Error registering lowlevel driver \"%s\"",
+                                                 info.lowlevel_name);
+                                       return ERROR_JTAG_DEVICE_ERROR;
+                               }
                                break;
-               if (lowlevel_drivers_map[i].name)
-                       info.drv = lowlevel_drivers_map[i].drv_register();
-               if (!info.drv) {
-                       LOG_ERROR("no lowlevel driver found for %s or lowlevel driver opening error",
-                                 info.lowlevel_name);
-                       return ERROR_JTAG_DEVICE_ERROR;
-               }
-       } else {
-               LOG_INFO("No lowlevel driver configured, will try them all");
-               for (i = 0; !info.drv && lowlevel_drivers_map[i].name; i++)
+                       }
+               } else {
                        info.drv = lowlevel_drivers_map[i].drv_register();
-               if (!info.drv) {
-                       LOG_ERROR("no lowlevel driver found");
-                       return ERROR_JTAG_DEVICE_ERROR;
+                       if (info.drv) {
+                               info.lowlevel_name = strdup(lowlevel_drivers_map[i].name);
+                               LOG_INFO("No lowlevel driver configured, using %s", info.lowlevel_name);
+                               break;
+                       }
                }
-               info.lowlevel_name = strdup(lowlevel_drivers_map[i-1].name);
+       }
+
+       if (!info.drv) {
+               LOG_ERROR("No lowlevel driver available");
+               return ERROR_JTAG_DEVICE_ERROR;
        }
 
        /*
@@ -846,18 +878,13 @@ static int ublast_init(void)
        info.flags |= info.drv->flags;
 
        ret = info.drv->open(info.drv);
-       if (ret == ERROR_OK) {
-               /*
-                * Flush USB-Blaster queue fifos
-                */
-               uint32_t retlen;
-               ublast_buf_write(info.buf, BUF_LEN, &retlen);
-               /*
-                * Put JTAG in RESET state (five 1 on TMS)
-                */
-               ublast_tms_seq(&tms_reset, 5);
-               tap_set_state(TAP_RESET);
-       }
+
+       /*
+        * Let lie here : the TAP is in an unknown state, but the first
+        * execute_queue() will trigger a ublast_initial_wipeout(), which will
+        * put the TAP in RESET.
+        */
+       tap_set_state(TAP_RESET);
        return ret;
 }
 
@@ -1022,8 +1049,8 @@ static const struct command_registration ublast_command_handlers[] = {
                .name = "usb_blaster_lowlevel_driver",
                .handler = ublast_handle_lowlevel_drv_command,
                .mode = COMMAND_CONFIG,
-               .help = "set the lowlevel access for the USB Blaster (ftdi, ftd2xx, ublast2)",
-               .usage = "(ftdi|ftd2xx|ublast2)",
+               .help = "set the lowlevel access for the USB Blaster (ftdi, ublast2)",
+               .usage = "(ftdi|ublast2)",
        },
        {
                .name = "usb_blaster_pin",