add USBTMC device search helper

diff --git a/hardware/common/usb.c b/hardware/common/usb.c
index 3da583218ca6ff02921831b80607a6b2af5e8ec2..584a09dc383f4a0014331a82a648effa19de1737 100644 (file)
--- a/hardware/common/usb.c
+++ b/hardware/common/usb.c
@@ -29,6 +29,10 @@
 #define CONN_USB_VIDPID  "^([0-9a-z]{1,4})\\.([0-9a-z]{1,4})$"
 #define CONN_USB_BUSADDR "^(\\d+)\\.(\\d+)$"
 
+/* Some USBTMC-specific enums, as defined in the USBTMC standard. */
+#define SUBCLASS_USBTMC 0x03
+#define USBTMC_USB488   0x01
+
 /* Message logging helpers with driver-specific prefix string. */
 #define DRIVER_LOG_DOMAIN "usb: "
 #define sr_log(l, s, args...) sr_log(l, DRIVER_LOG_DOMAIN s, ## args)
@@ -138,6 +142,62 @@ SR_PRIV GSList *sr_usb_find(libusb_context *usb_ctx, const char *conn)
        return devices;
 }
 
+/**
+ * Find USB devices supporting the USBTMC class
+ *
+ * @param usb_ctx libusb context to use while scanning.
+ *
+ * @return A GSList of struct sr_usb_dev_inst, with bus and address fields
+ * indicating devices with USBTMC support.
+ */
+SR_PRIV GSList *sr_usb_find_usbtmc(libusb_context *usb_ctx)
+{
+       struct sr_usb_dev_inst *usb;
+       struct libusb_device **devlist;
+       struct libusb_device_descriptor des;
+       struct libusb_config_descriptor *confdes;
+       const struct libusb_interface_descriptor *intfdes;
+       GSList *devices;
+       int confidx, intfidx, ret, i;
+
+       devices = NULL;
+       libusb_get_device_list(usb_ctx, &devlist);
+       for (i = 0; devlist[i]; i++) {
+               if ((ret = libusb_get_device_descriptor(devlist[i], &des))) {
+                       sr_err("Failed to get device descriptor: %s.",
+                              libusb_error_name(ret));
+                       continue;
+               }
+
+               for (confidx = 0; confidx < des.bNumConfigurations; confidx++) {
+                       if (libusb_get_config_descriptor(devlist[i], confidx, &confdes) != 0) {
+                               sr_err("Failed to get configuration descriptor.");
+                               break;
+                       }
+                       for (intfidx = 0; intfidx < confdes->bNumInterfaces; intfidx++) {
+                               intfdes = confdes->interface[intfidx].altsetting;
+                               if (intfdes->bInterfaceClass != LIBUSB_CLASS_APPLICATION
+                                               || intfdes->bInterfaceSubClass != SUBCLASS_USBTMC
+                                               || intfdes->bInterfaceProtocol != USBTMC_USB488)
+                                       continue;
+                               sr_dbg("Found USBTMC device (VID:PID = %04x:%04x, bus.address = "
+                                          "%d.%d).", des.idVendor, des.idProduct,
+                                          libusb_get_bus_number(devlist[i]),
+                                          libusb_get_device_address(devlist[i]));
+
+                               usb = sr_usb_dev_inst_new(libusb_get_bus_number(devlist[i]),
+                                               libusb_get_device_address(devlist[i]), NULL);
+                               devices = g_slist_append(devices, usb);
+                       }
+               }
+       }
+       libusb_free_device_list(devlist, 1);
+
+       sr_dbg("Found %d device(s).", g_slist_length(devices));
+
+       return devices;
+}
+
 SR_PRIV int sr_usb_open(libusb_context *usb_ctx, struct sr_usb_dev_inst *usb)
 {
        struct libusb_device **devlist;

diff --git a/libsigrok-internal.h b/libsigrok-internal.h
index e63ea9305bdf3180215423686f02ed5bb370c9d9..f68c746421cdd787985e4536eb67617b14285c2b 100644 (file)
--- a/libsigrok-internal.h
+++ b/libsigrok-internal.h
@@ -103,6 +103,7 @@ SR_PRIV void sr_dev_inst_free(struct sr_dev_inst *sdi);
 /* USB-specific instances */
 SR_PRIV struct sr_usb_dev_inst *sr_usb_dev_inst_new(uint8_t bus,
                uint8_t address, struct libusb_device_handle *hdl);
+SR_PRIV GSList *sr_usb_find_usbtmc(libusb_context *usb_ctx);
 SR_PRIV void sr_usb_dev_inst_free(struct sr_usb_dev_inst *usb);
 #endif