usb: Add support for new GPSDO status field "Accumulated error"

Because we want to handle older firmwares too, we need to excepect
we might get a smaller structure !

(We can't get a larger one since the wLength we send is limited to
the structure we know)

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Change-Id: I4222bf22267f8343abf1e97546111ceb1c299846

4 files changed, 23 insertions, 4 deletions

diff --git a/src/e1d.h b/src/e1d.h
index 42be1b4..ff34800 100644
--- a/src/e1d.h
+++ b/src/e1d.h
@@ -67,6 +67,7 @@ enum e1d_line_stat_item {
 	LINE_GPSDO_TUNE_COARSE,
 	LINE_GPSDO_TUNE_FINE,
 	LINE_GPSDO_FREQ_EST,
+	LINE_GPSDO_ERR_ACC,
 };
 
 enum e1_ts_mode {
diff --git a/src/ice1usb_proto.h b/src/ice1usb_proto.h
index 3170d55..54b91ab 100644
--- a/src/ice1usb_proto.h
+++ b/src/ice1usb_proto.h
@@ -65,6 +65,7 @@ struct e1usb_gpsdo_status {
 	uint8_t mode;			/*!< Current configured operating mode */
 	struct e1usb_gpsdo_tune tune;	/*!< Current VCXO tuning values */
 	uint32_t freq_est;		/*!< Latest frequency estimate measurement */
+	int16_t  err_acc;		/*!< Accumulated error (since fw icE1usb-fw-0.3 commit cfb8b0b7) */
 } __attribute__((packed));
 
 
diff --git a/src/intf_line.c b/src/intf_line.c
index a645cd3..811b8fe 100644
--- a/src/intf_line.c
+++ b/src/intf_line.c
@@ -75,6 +75,7 @@ static const struct osmo_stat_item_desc line_stat_description[] = {
 	[LINE_GPSDO_TUNE_COARSE]= { "gpsdo:tune:coarse", "GSPDO Coarse Tuning" },
 	[LINE_GPSDO_TUNE_FINE]	= { "gpsdo:tune:fine", "GSPDO Fine Tuning" },
 	[LINE_GPSDO_FREQ_EST]	= { "gpsdo:freq_est", "GSPDO Frequency Estimate" },
+	[LINE_GPSDO_ERR_ACC]    = { "gpsdo:err_acc", "GPSDO Accumulated Error" },
 };
 
 static const struct osmo_stat_item_group_desc line_stats_desc = {
diff --git a/src/usb.c b/src/usb.c
index fa6ddee..a60ea99 100644
--- a/src/usb.c
+++ b/src/usb.c
@@ -706,14 +706,29 @@ _e1_usb_intf_gpsdo_status_cb(struct e1_intf *intf, const uint8_t *data, size_t l
 {
 	struct e1_usb_intf_data *id = intf->drv_data;
 	struct e1usb_gpsdo_status *last_st = &id->gpsdo.last_status;
-	const struct e1usb_gpsdo_status *st;
+	struct e1usb_gpsdo_status _st, *st = &_st;
 	struct e1_line *line;
 
 	if (len < sizeof(*st)) {
-		LOGPIF(intf, DE1D, LOGL_ERROR, "GPSDO status %zu < %zu!\n", len, sizeof(*st));
-		return;
+		/*
+		 * Because some fields can be added to the structure by newer
+		 * firmware revisions, this means we can potentially get a shorter
+		 * struct than what we asked for. We simply set those fields to
+		 * zero.
+		 *
+		 * The opposite case (newer firmware than e1d) means the structure
+		 * could be larger, but because we limit the wLength to the struct
+		 * we know, we can't receive a larger one and the new fields are
+		 * just ignored by this e1d version
+		 */
+		LOGPIF(intf, DE1D, LOGL_DEBUG,
+			"GPSDO status %zu < %zu ! Firmware probably outdated. "
+			"Some values will be zeroed\n",
+			len, sizeof(*st));
 	}
-	st = (const struct e1usb_gpsdo_status *) data;
+
+	memset(st, 0x00, sizeof(*st));
+	memcpy(st, data, len);
 
 	if (st->state != last_st->state) {
 		LOGPIF(intf, DE1D, LOGL_NOTICE, "GPSDO state change: %s -> %s\n",
@@ -750,6 +765,7 @@ _e1_usb_intf_gpsdo_status_cb(struct e1_intf *intf, const uint8_t *data, size_t l
 		line_stat_set(line, LINE_GPSDO_TUNE_COARSE, libusb_le16_to_cpu(st->tune.coarse));
 		line_stat_set(line, LINE_GPSDO_TUNE_FINE, libusb_le16_to_cpu(st->tune.fine));
 		line_stat_set(line, LINE_GPSDO_FREQ_EST, osmo_load32le(&st->freq_est));
+		line_stat_set(line, LINE_GPSDO_ERR_ACC, (int16_t)libusb_le16_to_cpu(st->err_acc));
 	}
 
 	/* update our state */