usb: ch9: Add size macro for SSP dev cap descriptor

commit 446fa3a95df1e8b78f25e1babc41e46edd200821 upstream.

The SuperspeedPlus Device Capability Descriptor has a variable size
depending on the number of sublink speed attributes.

This patch adds a macro to calculate that size. The macro takes one
argument, the Sublink Speed Attribute Count (SSAC) as reported by the
descriptor in bmAttributes[4:0].

See USB 3.1 9.6.2.5, Table 9-19.

Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/uapi/linux/usb/ch9.h b/include/uapi/linux/usb/ch9.h
index 0ae800f600210b3d0322c98cb326a5e457867034..3e4f8af546118227cc9523a2f6920734e692b73d 100644 (file)
--- a/include/uapi/linux/usb/ch9.h
+++ b/include/uapi/linux/usb/ch9.h
@@ -906,6 +906,12 @@ struct usb_ptm_cap_descriptor {
        __u8  bDevCapabilityType;
 } __attribute__((packed));
 
+/*
+ * The size of the descriptor for the Sublink Speed Attribute Count
+ * (SSAC) specified in bmAttributes[4:0].
+ */
+#define USB_DT_USB_SSP_CAP_SIZE(ssac)  (16 + ssac * 4)
+
 /*-------------------------------------------------------------------------*/
 
 /* USB_DT_WIRELESS_ENDPOINT_COMP:  companion descriptor associated with