dcttech-usbrelay: rework scan (enumeration) and probe (identification)

[libsigrok.git] / src / hardware / dcttech-usbrelay / api.c

diff --git a/src/hardware/dcttech-usbrelay/api.c b/src/hardware/dcttech-usbrelay/api.c
index 583a12c4117abe03d8dc82a230154cb2e8462789..2f35d436d68aa7790716156449aa832f33cf9e2f 100644 (file)
--- a/src/hardware/dcttech-usbrelay/api.c
+++ b/src/hardware/dcttech-usbrelay/api.c
@@ -43,7 +43,8 @@ static const uint32_t devopts_cg[] = {
 
 static struct sr_dev_driver dcttech_usbrelay_driver_info;
 
-static struct sr_dev_inst *probe_device(const char *path, size_t relay_count)
+static struct sr_dev_inst *probe_device(struct hid_device_info *dev,
+       size_t relay_count)
 {
        hid_device *hid;
        int ret;
@@ -60,9 +61,11 @@ static struct sr_dev_inst *probe_device(const char *path, size_t relay_count)
        struct sr_channel_group *cg;
 
        /* Open device, need to communicate to identify. */
-       hid = hid_open_path(path);
-       if (!hid)
+       hid = hid_open_path(dev->path);
+       if (!hid) {
+               sr_err("Cannot open %s: %ls.", dev->path, hid_error(NULL));
                return NULL;
+       }
 
        /* Get an HID report. */
        hid_set_nonblocking(hid, 0);
@@ -75,8 +78,14 @@ static struct sr_dev_inst *probe_device(const char *path, size_t relay_count)
                sr_spew("raw report, rc %d, bytes %s", ret, txt->str);
                sr_hexdump_free(txt);
        }
-       if (ret != sizeof(report))
+       if (ret < 0) {
+               sr_err("Cannot read %s: %ls.", dev->path, hid_error(NULL));
+               return NULL;
+       }
+       if (ret != sizeof(report)) {
+               sr_err("Unexpected HID report length: %s.", dev->path);
                return NULL;
+       }
 
        /*
         * Serial number must be all printable characters. Relay state
@@ -87,22 +96,27 @@ static struct sr_dev_inst *probe_device(const char *path, size_t relay_count)
        for (snr_pos = 0; snr_pos < SERNO_LENGTH; snr_pos++) {
                c = report[1 + snr_pos];
                serno[snr_pos] = c;
-               if (c < 0x20 || c > 0x7e)
+               if (c < 0x20 || c > 0x7e) {
+                       sr_dbg("non-printable serno");
                        return NULL;
+               }
        }
        curr_state = report[1 + STATE_INDEX];
        sr_spew("report data, serno[%s], relays 0x%02x.", serno, curr_state);
 
-       /*
-        * Create a device instance, create channels (groups). The
-        * caller fills in vendor, model, conn from USB enum details.
-        */
+       /* Create a device instance. */
        sdi = g_malloc0(sizeof(*sdi));
+       sdi->vendor = g_strdup_printf("%ls", dev->manufacturer_string);
+       sdi->model = g_strdup_printf("%ls", dev->product_string);
        sdi->serial_num = g_strdup(serno);
-       sdi->connection_id = g_strdup(path);
+       sdi->connection_id = g_strdup(dev->path);
+       sdi->driver = &dcttech_usbrelay_driver_info;
+       sdi->inst_type = SR_INST_USB;
+
+       /* Create channels (groups). */
        devc = g_malloc0(sizeof(*devc));
        sdi->priv = devc;
-       devc->hid_path = g_strdup(path);
+       devc->hid_path = g_strdup(dev->path);
        devc->relay_count = relay_count;
        devc->relay_mask = (1U << relay_count) - 1;
        for (idx = 0; idx < devc->relay_count; idx++) {
@@ -195,18 +209,11 @@ static GSList *scan(struct sr_dev_driver *di, GSList *options)
                        curdev->path, relay_count);
 
                /* Identify device by communicating to it. */
-               sdi = probe_device(curdev->path, relay_count);
+               sdi = probe_device(curdev, relay_count);
                if (!sdi) {
                        sr_warn("Failed to communicate to %s.", curdev->path);
                        continue;
                }
-
-               /* Amend driver instance from USB enumeration details. */
-               sdi->vendor = g_strdup_printf("%ls", curdev->manufacturer_string);
-               sdi->model = g_strdup_printf("%ls", curdev->product_string);
-               sdi->driver = &dcttech_usbrelay_driver_info;
-               sdi->inst_type = SR_INST_USB;
-
                devices = g_slist_append(devices, sdi);
        }
        hid_free_enumeration(devs);