cdc_ncm: Implement the 32-bit version of NCM Transfer Block

The NCM specification defines two formats of transfer blocks: with 16-bit
fields (NTB-16) and with 32-bit fields (NTB-32). Currently only NTB-16 is
implemented.

This patch adds the support of NTB-32. The motivation behind this is that
some devices such as E5785 or E5885 from the current generation of Huawei
LTE routers do not support NTB-16. The previous generations of Huawei
devices are also use NTB-32 by default.

Also this patch enables NTB-32 by default for Huawei devices.

During the 2019 ValdikSS made five attempts to contact Huawei to add the
NTB-16 support to their router firmware, but they were unsuccessful.
Signed-off-by: Alexander Bersenev <bay@hackerdom.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/huawei_cdc_ncm.c

@@ -77,11 +77,11 @@ static int huawei_cdc_ncm_bind(struct usbnet *usbnet_dev,
 	 */
 	drvflags |= CDC_NCM_FLAG_NDP_TO_END;
 
-	/* Additionally, it has been reported that some Huawei E3372H devices, with
-	 * firmware version 21.318.01.00.541, come out of reset in NTB32 format mode, hence
-	 * needing to be set to the NTB16 one again.
+	/* For many Huawei devices the NTB32 mode is the default and the best mode
+	 * they work with. Huawei E5785 and E5885 devices refuse to work in NTB16 mode at all.
 	 */
-	drvflags |= CDC_NCM_FLAG_RESET_NTB16;
+	drvflags |= CDC_NCM_FLAG_PREFER_NTB32;
+
 	ret = cdc_ncm_bind_common(usbnet_dev, intf, 1, drvflags);
 	if (ret)
 		goto err;

include/linux/usb/cdc_ncm.h

@@ -46,9 +46,12 @@
 #define CDC_NCM_DATA_ALTSETTING_NCM		1
 #define CDC_NCM_DATA_ALTSETTING_MBIM		2
 
-/* CDC NCM subclass 3.2.1 */
+/* CDC NCM subclass 3.3.1 */
 #define USB_CDC_NCM_NDP16_LENGTH_MIN		0x10
 
+/* CDC NCM subclass 3.3.2 */
+#define USB_CDC_NCM_NDP32_LENGTH_MIN		0x20
+
 /* Maximum NTB length */
 #define	CDC_NCM_NTB_MAX_SIZE_TX			32768	/* bytes */
 #define	CDC_NCM_NTB_MAX_SIZE_RX			32768	/* bytes */
@@ -84,7 +87,7 @@
 /* Driver flags */
 #define CDC_NCM_FLAG_NDP_TO_END			0x02	/* NDP is placed at end of frame */
 #define CDC_MBIM_FLAG_AVOID_ALTSETTING_TOGGLE	0x04	/* Avoid altsetting toggle during init */
-#define CDC_NCM_FLAG_RESET_NTB16 0x08	/* set NDP16 one more time after altsetting switch */
+#define CDC_NCM_FLAG_PREFER_NTB32 0x08	/* prefer NDP32 over NDP16 */
 
 #define cdc_ncm_comm_intf_is_mbim(x)  ((x)->desc.bInterfaceSubClass == USB_CDC_SUBCLASS_MBIM && \
 				       (x)->desc.bInterfaceProtocol == USB_CDC_PROTO_NONE)
@@ -113,7 +116,11 @@ struct cdc_ncm_ctx {
 
 	u32 timer_interval;
 	u32 max_ndp_size;
-	struct usb_cdc_ncm_ndp16 *delayed_ndp16;
+	u8 is_ndp16;
+	union {
+		struct usb_cdc_ncm_ndp16 *delayed_ndp16;
+		struct usb_cdc_ncm_ndp32 *delayed_ndp32;
+	};
 
 	u32 tx_timer_pending;
 	u32 tx_curr_frame_num;
@@ -150,6 +157,8 @@ void cdc_ncm_unbind(struct usbnet *dev, struct usb_interface *intf);
 struct sk_buff *cdc_ncm_fill_tx_frame(struct usbnet *dev, struct sk_buff *skb, __le32 sign);
 int cdc_ncm_rx_verify_nth16(struct cdc_ncm_ctx *ctx, struct sk_buff *skb_in);
 int cdc_ncm_rx_verify_ndp16(struct sk_buff *skb_in, int ndpoffset);
+int cdc_ncm_rx_verify_nth32(struct cdc_ncm_ctx *ctx, struct sk_buff *skb_in);
+int cdc_ncm_rx_verify_ndp32(struct sk_buff *skb_in, int ndpoffset);
 struct sk_buff *
 cdc_ncm_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags);
 int cdc_ncm_rx_fixup(struct usbnet *dev, struct sk_buff *skb_in);