usb: gadget: composite: Report various SSP sublink speeds

If a gadget supports SuperSpeed Plus, then it may operate in different
sublink speeds. For example, if the gadget supports SuperSpeed Plus
gen2x2, then it can support 2 sublink speeds gen1 and gen2. Inform the
host of these speeds in the BOS descriptor.

Use 1 SSID if the gadget supports up to gen2x1, or not specified:
- SSID 0 for symmetric RX/TX sublink speed of 10 Gbps.

Use 1 SSID if the gadget supports up to gen1x2:
- SSID 0 for symmetric RX/TX sublink speed of 5 Gbps.

Use 2 SSIDs if the gadget supports up to gen2x2:
- SSID 0 for symmetric RX/TX sublink speed of 5 Gbps.
- SSID 1 for symmetric RX/TX sublink speed of 10 Gbps.
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/eb0386fdd5d87a858281e8006a72723d3732240f.1610592135.git.Thinh.Nguyen@synopsys.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/composite.c

@@ -735,49 +735,77 @@ static int bos_desc(struct usb_composite_dev *cdev)
 	/* The SuperSpeedPlus USB Device Capability descriptor */
 	if (gadget_is_superspeed_plus(cdev->gadget)) {
 		struct usb_ssp_cap_descriptor *ssp_cap;
+		u8 ssac = 1;
+		u8 ssic;
+		int i;
 
-		ssp_cap = cdev->req->buf + le16_to_cpu(bos->wTotalLength);
-		bos->bNumDeviceCaps++;
+		if (cdev->gadget->max_ssp_rate == USB_SSP_GEN_2x2)
+			ssac = 3;
 
 		/*
-		 * Report typical values.
+		 * Paired RX and TX sublink speed attributes share
+		 * the same SSID.
 		 */
+		ssic = (ssac + 1) / 2 - 1;
 
-		le16_add_cpu(&bos->wTotalLength, USB_DT_USB_SSP_CAP_SIZE(1));
-		ssp_cap->bLength = USB_DT_USB_SSP_CAP_SIZE(1);
+		ssp_cap = cdev->req->buf + le16_to_cpu(bos->wTotalLength);
+		bos->bNumDeviceCaps++;
+
+		le16_add_cpu(&bos->wTotalLength, USB_DT_USB_SSP_CAP_SIZE(ssac));
+		ssp_cap->bLength = USB_DT_USB_SSP_CAP_SIZE(ssac);
 		ssp_cap->bDescriptorType = USB_DT_DEVICE_CAPABILITY;
 		ssp_cap->bDevCapabilityType = USB_SSP_CAP_TYPE;
 		ssp_cap->bReserved = 0;
 		ssp_cap->wReserved = 0;
 
 		ssp_cap->bmAttributes =
-			cpu_to_le32(FIELD_PREP(USB_SSP_SUBLINK_SPEED_ATTRIBS, 1) |
-				    FIELD_PREP(USB_SSP_SUBLINK_SPEED_IDS, 0));
+			cpu_to_le32(FIELD_PREP(USB_SSP_SUBLINK_SPEED_ATTRIBS, ssac) |
+				    FIELD_PREP(USB_SSP_SUBLINK_SPEED_IDS, ssic));
 
 		ssp_cap->wFunctionalitySupport =
 			cpu_to_le16(FIELD_PREP(USB_SSP_MIN_SUBLINK_SPEED_ATTRIBUTE_ID, 0) |
 				    FIELD_PREP(USB_SSP_MIN_RX_LANE_COUNT, 1) |
 				    FIELD_PREP(USB_SSP_MIN_TX_LANE_COUNT, 1));
 
-		ssp_cap->bmSublinkSpeedAttr[0] =
-			cpu_to_le32(FIELD_PREP(USB_SSP_SUBLINK_SPEED_SSID, 0) |
-				    FIELD_PREP(USB_SSP_SUBLINK_SPEED_LSE,
-					       USB_SSP_SUBLINK_SPEED_LSE_GBPS) |
-				    FIELD_PREP(USB_SSP_SUBLINK_SPEED_ST,
-					       USB_SSP_SUBLINK_SPEED_ST_SYM_RX) |
-				    FIELD_PREP(USB_SSP_SUBLINK_SPEED_LP,
-					       USB_SSP_SUBLINK_SPEED_LP_SSP) |
-				    FIELD_PREP(USB_SSP_SUBLINK_SPEED_LSM, 10));
-
-		ssp_cap->bmSublinkSpeedAttr[1] =
-			cpu_to_le32(FIELD_PREP(USB_SSP_SUBLINK_SPEED_SSID, 0) |
-				    FIELD_PREP(USB_SSP_SUBLINK_SPEED_LSE,
-					       USB_SSP_SUBLINK_SPEED_LSE_GBPS) |
-				    FIELD_PREP(USB_SSP_SUBLINK_SPEED_ST,
-					       USB_SSP_SUBLINK_SPEED_ST_SYM_TX) |
-				    FIELD_PREP(USB_SSP_SUBLINK_SPEED_LP,
-					       USB_SSP_SUBLINK_SPEED_LP_SSP) |
-				    FIELD_PREP(USB_SSP_SUBLINK_SPEED_LSM, 10));
+		/*
+		 * Use 1 SSID if the gadget supports up to gen2x1 or not
+		 * specified:
+		 * - SSID 0 for symmetric RX/TX sublink speed of 10 Gbps.
+		 *
+		 * Use 1 SSID if the gadget supports up to gen1x2:
+		 * - SSID 0 for symmetric RX/TX sublink speed of 5 Gbps.
+		 *
+		 * Use 2 SSIDs if the gadget supports up to gen2x2:
+		 * - SSID 0 for symmetric RX/TX sublink speed of 5 Gbps.
+		 * - SSID 1 for symmetric RX/TX sublink speed of 10 Gbps.
+		 */
+		for (i = 0; i < ssac + 1; i++) {
+			u8 ssid;
+			u8 mantissa;
+			u8 type;
+
+			ssid = i >> 1;
+
+			if (cdev->gadget->max_ssp_rate == USB_SSP_GEN_2x1 ||
+			    cdev->gadget->max_ssp_rate == USB_SSP_GEN_UNKNOWN)
+				mantissa = 10;
+			else
+				mantissa = 5 << ssid;
+
+			if (i % 2)
+				type = USB_SSP_SUBLINK_SPEED_ST_SYM_TX;
+			else
+				type = USB_SSP_SUBLINK_SPEED_ST_SYM_RX;
+
+			ssp_cap->bmSublinkSpeedAttr[i] =
+				cpu_to_le32(FIELD_PREP(USB_SSP_SUBLINK_SPEED_SSID, ssid) |
+					    FIELD_PREP(USB_SSP_SUBLINK_SPEED_LSE,
+						       USB_SSP_SUBLINK_SPEED_LSE_GBPS) |
+					    FIELD_PREP(USB_SSP_SUBLINK_SPEED_ST, type) |
+					    FIELD_PREP(USB_SSP_SUBLINK_SPEED_LP,
+						       USB_SSP_SUBLINK_SPEED_LP_SSP) |
+					    FIELD_PREP(USB_SSP_SUBLINK_SPEED_LSM, mantissa));
+		}
 	}
 
 	return le16_to_cpu(bos->wTotalLength);