firmware: tegra: Use in-band messages for firmware version query

Add support for a new MRQ, that uses in-band messaging instead of IOVA
buffer, to retrieve the firmware version 'tag' during boot. If an
older firmware is used, that does not support the new MRQ, fall back
to the earlier implementation.
Signed-off-by: Timo Alho <talho@nvidia.com>
Acked-by: Sivaram Nair <sivaramn@nvidia.com>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/firmware/tegra/bpmp.c

@@ -547,8 +547,9 @@ static int tegra_bpmp_ping(struct tegra_bpmp *bpmp)
 	return err;
 }
 
-static int tegra_bpmp_get_firmware_tag(struct tegra_bpmp *bpmp, char *tag,
-				       size_t size)
+/* deprecated version of tag query */
+static int tegra_bpmp_get_firmware_tag_old(struct tegra_bpmp *bpmp, char *tag,
+					   size_t size)
 {
 	struct mrq_query_tag_request request;
 	struct tegra_bpmp_message msg;
@@ -585,6 +586,37 @@ static int tegra_bpmp_get_firmware_tag(struct tegra_bpmp *bpmp, char *tag,
 	return err;
 }
 
+static int tegra_bpmp_get_firmware_tag(struct tegra_bpmp *bpmp, char *tag,
+				       size_t size)
+{
+	if (tegra_bpmp_mrq_is_supported(bpmp, MRQ_QUERY_FW_TAG)) {
+		struct mrq_query_fw_tag_response resp;
+		struct tegra_bpmp_message msg = {
+			.mrq = MRQ_QUERY_FW_TAG,
+			.rx = {
+				.data = &resp,
+				.size = sizeof(resp),
+			},
+		};
+		int err;
+
+		if (size != sizeof(resp.tag))
+			return -EINVAL;
+
+		err = tegra_bpmp_transfer(bpmp, &msg);
+
+		if (err)
+			return err;
+		if (msg.rx.ret < 0)
+			return -EINVAL;
+
+		memcpy(tag, resp.tag, sizeof(resp.tag));
+		return 0;
+	}
+
+	return tegra_bpmp_get_firmware_tag_old(bpmp, tag, size);
+}
+
 static void tegra_bpmp_channel_signal(struct tegra_bpmp_channel *channel)
 {
 	unsigned long flags = channel->ob->flags;