static int jlink_init(void)
{
- int check_cnt;
int i;
jlink_jtag_handle = jlink_usb_open();
return ERROR_JTAG_INIT_FAILED;
}
- jlink_hw_jtag_version = 2;
- check_cnt = 0;
- while (check_cnt < 3)
- {
- if (jlink_get_version_info() == ERROR_OK)
- {
- /* attempt to get status */
- jlink_get_status();
- break;
- }
+ /*
+ * The next three instructions were added after discovering a problem while using an oscilloscope. For the V8
+ * SAM-ICE dongle (and likely other j-link device variants), the reset line to the target microprocessor was found to
+ * cycle only intermittently during emulator startup (even after encountering the downstream reset instruction later
+ * in the code). This was found to create two issues: 1) In general it is a bad practice to not reset a CPU to a known
+ * state when starting an emulator and 2) something critical happens inside the dongle when it does the first read
+ * following a new USB session. Keeping the processor in reset during the first read collecting version information
+ * seems to prevent errant "J-Link command EMU_CMD_VERSION failed" issues.
+ */
+
+ LOG_INFO("J-Link initialization started / target CPU reset initiated");
+ jlink_simple_command(EMU_CMD_HW_TRST0);
+ jlink_simple_command(EMU_CMD_HW_RESET0);
+ usleep(1000);
- check_cnt++;
- }
+ jlink_hw_jtag_version = 2;
- if (check_cnt == 3)
+ if (jlink_get_version_info() == ERROR_OK)
{
- LOG_INFO("J-Link initial read failed, don't worry");
+ /* attempt to get status */
+ jlink_get_status();
}
LOG_INFO("J-Link JTAG Interface ready");
{
jlink_simple_command(EMU_CMD_HW_TRST0);
}
+
if (trst == 0)
{
jlink_simple_command(EMU_CMD_HW_TRST1);
- jtag_sleep(5000);
- jlink_end_state(TAP_RESET);
- jlink_state_move();
}
}
return ERROR_OK;
}
+static struct usb_device* find_jlink_device(void)
+{
+ struct usb_bus *busses;
+ struct usb_bus *bus;
+ struct usb_device *dev;
+
+ usb_find_busses();
+ usb_find_devices();
+
+ busses = usb_get_busses();
+
+ /* find jlink_jtag device in usb bus */
+
+ for (bus = busses; bus; bus = bus->next)
+ {
+ for (dev = bus->devices; dev; dev = dev->next)
+ {
+ if ((dev->descriptor.idVendor == VID) && (dev->descriptor.idProduct == PID)) {
+ return dev;
+ }
+ }
+ }
+
+ return NULL;
+}
+
/*****************************************************************************/
/* JLink USB low-level functions */
static jlink_jtag_t* jlink_usb_open()
{
- struct usb_bus *busses;
- struct usb_bus *bus;
struct usb_device *dev;
jlink_jtag_t *result;
result = (jlink_jtag_t*) malloc(sizeof(jlink_jtag_t));
usb_init();
- usb_find_busses();
- usb_find_devices();
- busses = usb_get_busses();
+ if ((dev = find_jlink_device()) == NULL) {
+ free(result);
+ return NULL;
+ }
- /* find jlink_jtag device in usb bus */
+ result->usb_handle = usb_open(dev);
- for (bus = busses; bus; bus = bus->next)
+ if (result->usb_handle)
{
- for (dev = bus->devices; dev; dev = dev->next)
+
+ /* BE ***VERY CAREFUL*** ABOUT MAKING CHANGES IN THIS AREA!!!!!!!!!!!
+ * The behavior of libusb is not completely consistent across Windows, Linux, and Mac OS X platforms. The actions taken
+ * in the following compiler conditionals may not agree with published documentation for libusb, but were found
+ * to be necessary through trials and tribulations. Even little tweaks can break one or more platforms, so if you do make changes
+ * test them carefully on all platforms before committing them!
+ */
+
+#if IS_WIN32 == 0
+
+ usb_reset(result->usb_handle);
+
+#if IS_DARWIN == 0
+
+ int timeout = 5;
+
+ /* reopen jlink after usb_reset
+ * on win32 this may take a second or two to re-enumerate */
+ while ((dev = find_jlink_device()) == NULL)
{
- if ((dev->descriptor.idVendor == VID) && (dev->descriptor.idProduct == PID))
- {
- result->usb_handle = usb_open(dev);
+ usleep(1000);
+ timeout--;
+ if (!timeout) {
+ break;
+ }
+ }
+
+ if (dev == NULL)
+ {
+ free(result);
+ return NULL;
+ }
- /* usb_set_configuration required under win32 */
- usb_set_configuration(result->usb_handle, dev->config[0].bConfigurationValue);
- usb_claim_interface(result->usb_handle, 0);
+ result->usb_handle = usb_open(dev);
+#endif
+
+#endif
+
+ if (result->usb_handle)
+ {
+ /* usb_set_configuration required under win32 */
+ usb_set_configuration(result->usb_handle, dev->config[0].bConfigurationValue);
+ usb_claim_interface(result->usb_handle, 0);
#if 0
- /*
- * This makes problems under Mac OS X. And is not needed
- * under Windows. Hopefully this will not break a linux build
- */
- usb_set_altinterface(result->usb_handle, 0);
+ /*
+ * This makes problems under Mac OS X. And is not needed
+ * under Windows. Hopefully this will not break a linux build
+ */
+ usb_set_altinterface(result->usb_handle, 0);
#endif
- struct usb_interface *iface = dev->config->interface;
- struct usb_interface_descriptor *desc = iface->altsetting;
- for (int i = 0; i < desc->bNumEndpoints; i++)
- {
- uint8_t epnum = desc->endpoint[i].bEndpointAddress;
- bool is_input = epnum & 0x80;
- LOG_DEBUG("usb ep %s %02x", is_input ? "in" : "out", epnum);
- if (is_input)
- jlink_read_ep = epnum;
- else
- jlink_write_ep = epnum;
- }
-
- return result;
+ struct usb_interface *iface = dev->config->interface;
+ struct usb_interface_descriptor *desc = iface->altsetting;
+ for (int i = 0; i < desc->bNumEndpoints; i++)
+ {
+ uint8_t epnum = desc->endpoint[i].bEndpointAddress;
+ bool is_input = epnum & 0x80;
+ LOG_DEBUG("usb ep %s %02x", is_input ? "in" : "out", epnum);
+ if (is_input)
+ jlink_read_ep = epnum;
+ else
+ jlink_write_ep = epnum;
}
+
+ return result;
}
}
projects / openocd / blobdiff