usb: gadget: f_fs: add capability for dfu functional descriptor

Add the ability for the USB FunctionFS (FFS) gadget driver to be able
to create Device Firmware Upgrade (DFU) functional descriptors. [1]

This patch allows implementation of DFU in userspace using the
FFS gadget. The DFU protocol uses the control pipe (ep0) for all
messaging so only the addition of the DFU functional descriptor
is needed in the kernel driver.

The DFU functional descriptor is written to the ep0 file along with
any other descriptors during FFS setup. DFU requires an interface
descriptor followed by the DFU functional descriptor.

This patch includes documentation of the added descriptor for DFU
and conversion of some existing documentation to kernel-doc format
so that it can be included in the generated docs.

An implementation of DFU 1.1 that implements just the runtime descriptor
using the FunctionFS gadget (with rebooting into u-boot for DFU mode)
has been tested on an i.MX8 Nano.

An implementation of DFU 1.1 that implements both runtime and DFU mode
using the FunctionFS gadget has been tested on Xilinx Zynq UltraScale+.
Note that for the best performance of firmware update file transfers, the
userspace program should respond as quick as possible to the setup packets.

[1] https://www.usb.org/sites/default/files/DFU_1.1.pdf

Signed-off-by: David Sands <david.sands@biamp.com>
Co-developed-by: Chris Wulff <crwulff@gmail.com>
Signed-off-by: Chris Wulff <crwulff@gmail.com>
Link: https://lore.kernel.org/r/20240811000004.1395888-2-crwulff@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 95 insertions, 10 deletions

diff --git a/include/uapi/linux/usb/ch9.h b/include/uapi/linux/usb/ch9.h
index 44d73ba8788d..91f0f7e214a5 100644
--- a/include/uapi/linux/usb/ch9.h
+++ b/include/uapi/linux/usb/ch9.h
@@ -254,6 +254,9 @@ struct usb_ctrlrequest {
 #define USB_DT_DEVICE_CAPABILITY	0x10
 #define USB_DT_WIRELESS_ENDPOINT_COMP	0x11
 #define USB_DT_WIRE_ADAPTER		0x21
+/* From USB Device Firmware Upgrade Specification, Revision 1.1 */
+#define USB_DT_DFU_FUNCTIONAL		0x21
+/* these are from the Wireless USB spec */
 #define USB_DT_RPIPE			0x22
 #define USB_DT_CS_RADIO_CONTROL		0x23
 /* From the T10 UAS specification */
@@ -329,9 +332,10 @@ struct usb_device_descriptor {
 #define USB_CLASS_USB_TYPE_C_BRIDGE	0x12
 #define USB_CLASS_MISC			0xef
 #define USB_CLASS_APP_SPEC		0xfe
-#define USB_CLASS_VENDOR_SPEC		0xff
+#define USB_SUBCLASS_DFU			0x01
 
-#define USB_SUBCLASS_VENDOR_SPEC	0xff
+#define USB_CLASS_VENDOR_SPEC		0xff
+#define USB_SUBCLASS_VENDOR_SPEC		0xff
 
 /*-------------------------------------------------------------------------*/
 
diff --git a/include/uapi/linux/usb/functionfs.h b/include/uapi/linux/usb/functionfs.h
index 9f88de9c3d66..2ebdba111a8f 100644
--- a/include/uapi/linux/usb/functionfs.h
+++ b/include/uapi/linux/usb/functionfs.h
@@ -3,6 +3,7 @@
 #define _UAPI__LINUX_FUNCTIONFS_H__
 
 
+#include <linux/const.h>
 #include <linux/types.h>
 #include <linux/ioctl.h>
 
@@ -37,6 +38,31 @@ struct usb_endpoint_descriptor_no_audio {
 	__u8  bInterval;
 } __attribute__((packed));
 
+/**
+ * struct usb_dfu_functional_descriptor - DFU Functional descriptor
+ * @bLength:		Size of the descriptor (bytes)
+ * @bDescriptorType:	USB_DT_DFU_FUNCTIONAL
+ * @bmAttributes:	DFU attributes
+ * @wDetachTimeOut:	Maximum time to wait after DFU_DETACH (ms, le16)
+ * @wTransferSize:	Maximum number of bytes per control-write (le16)
+ * @bcdDFUVersion:	DFU Spec version (BCD, le16)
+ */
+struct usb_dfu_functional_descriptor {
+	__u8  bLength;
+	__u8  bDescriptorType;
+	__u8  bmAttributes;
+	__le16 wDetachTimeOut;
+	__le16 wTransferSize;
+	__le16 bcdDFUVersion;
+} __attribute__ ((packed));
+
+/* from DFU functional descriptor bmAttributes */
+#define DFU_FUNC_ATT_CAN_DOWNLOAD	_BITUL(0)
+#define DFU_FUNC_ATT_CAN_UPLOAD		_BITUL(1)
+#define DFU_FUNC_ATT_MANIFEST_TOLERANT	_BITUL(2)
+#define DFU_FUNC_ATT_WILL_DETACH	_BITUL(3)
+
+
 struct usb_functionfs_descs_head_v2 {
 	__le32 magic;
 	__le32 length;
@@ -104,23 +130,38 @@ struct usb_ffs_dmabuf_transfer_req {
 
 #ifndef __KERNEL__
 
-/*
+/**
+ * DOC: descriptors
+ *
  * Descriptors format:
  *
+ * +-----+-----------+--------------+--------------------------------------+
  * | off | name      | type         | description                          |
- * |-----+-----------+--------------+--------------------------------------|
+ * +-----+-----------+--------------+--------------------------------------+
  * |   0 | magic     | LE32         | FUNCTIONFS_DESCRIPTORS_MAGIC_V2      |
+ * +-----+-----------+--------------+--------------------------------------+
  * |   4 | length    | LE32         | length of the whole data chunk       |
+ * +-----+-----------+--------------+--------------------------------------+
  * |   8 | flags     | LE32         | combination of functionfs_flags      |
+ * +-----+-----------+--------------+--------------------------------------+
  * |     | eventfd   | LE32         | eventfd file descriptor              |
+ * +-----+-----------+--------------+--------------------------------------+
  * |     | fs_count  | LE32         | number of full-speed descriptors     |
+ * +-----+-----------+--------------+--------------------------------------+
  * |     | hs_count  | LE32         | number of high-speed descriptors     |
+ * +-----+-----------+--------------+--------------------------------------+
  * |     | ss_count  | LE32         | number of super-speed descriptors    |
+ * +-----+-----------+--------------+--------------------------------------+
  * |     | os_count  | LE32         | number of MS OS descriptors          |
+ * +-----+-----------+--------------+--------------------------------------+
  * |     | fs_descrs | Descriptor[] | list of full-speed descriptors       |
+ * +-----+-----------+--------------+--------------------------------------+
  * |     | hs_descrs | Descriptor[] | list of high-speed descriptors       |
+ * +-----+-----------+--------------+--------------------------------------+
  * |     | ss_descrs | Descriptor[] | list of super-speed descriptors      |
+ * +-----+-----------+--------------+--------------------------------------+
  * |     | os_descrs | OSDesc[]     | list of MS OS descriptors            |
+ * +-----+-----------+--------------+--------------------------------------+
  *
  * Depending on which flags are set, various fields may be missing in the
  * structure.  Any flags that are not recognised cause the whole block to be
@@ -128,71 +169,111 @@ struct usb_ffs_dmabuf_transfer_req {
  *
  * Legacy descriptors format (deprecated as of 3.14):
  *
+ * +-----+-----------+--------------+--------------------------------------+
  * | off | name      | type         | description                          |
- * |-----+-----------+--------------+--------------------------------------|
+ * +-----+-----------+--------------+--------------------------------------+
  * |   0 | magic     | LE32         | FUNCTIONFS_DESCRIPTORS_MAGIC         |
+ * +-----+-----------+--------------+--------------------------------------+
  * |   4 | length    | LE32         | length of the whole data chunk       |
+ * +-----+-----------+--------------+--------------------------------------+
  * |   8 | fs_count  | LE32         | number of full-speed descriptors     |
+ * +-----+-----------+--------------+--------------------------------------+
  * |  12 | hs_count  | LE32         | number of high-speed descriptors     |
+ * +-----+-----------+--------------+--------------------------------------+
  * |  16 | fs_descrs | Descriptor[] | list of full-speed descriptors       |
+ * +-----+-----------+--------------+--------------------------------------+
  * |     | hs_descrs | Descriptor[] | list of high-speed descriptors       |
+ * +-----+-----------+--------------+--------------------------------------+
  *
  * All numbers must be in little endian order.
  *
  * Descriptor[] is an array of valid USB descriptors which have the following
  * format:
  *
+ * +-----+-----------------+------+--------------------------+
  * | off | name            | type | description              |
- * |-----+-----------------+------+--------------------------|
+ * +-----+-----------------+------+--------------------------+
  * |   0 | bLength         | U8   | length of the descriptor |
+ * +-----+-----------------+------+--------------------------+
  * |   1 | bDescriptorType | U8   | descriptor type          |
+ * +-----+-----------------+------+--------------------------+
  * |   2 | payload         |      | descriptor's payload     |
+ * +-----+-----------------+------+--------------------------+
  *
  * OSDesc[] is an array of valid MS OS Feature Descriptors which have one of
  * the following formats:
  *
+ * +-----+-----------------+------+--------------------------+
  * | off | name            | type | description              |
- * |-----+-----------------+------+--------------------------|
+ * +-----+-----------------+------+--------------------------+
  * |   0 | inteface        | U8   | related interface number |
+ * +-----+-----------------+------+--------------------------+
  * |   1 | dwLength        | U32  | length of the descriptor |
+ * +-----+-----------------+------+--------------------------+
  * |   5 | bcdVersion      | U16  | currently supported: 1   |
+ * +-----+-----------------+------+--------------------------+
  * |   7 | wIndex          | U16  | currently supported: 4   |
+ * +-----+-----------------+------+--------------------------+
  * |   9 | bCount          | U8   | number of ext. compat.   |
+ * +-----+-----------------+------+--------------------------+
  * |  10 | Reserved        | U8   | 0                        |
+ * +-----+-----------------+------+--------------------------+
  * |  11 | ExtCompat[]     |      | list of ext. compat. d.  |
+ * +-----+-----------------+------+--------------------------+
  *
+ * +-----+-----------------+------+--------------------------+
  * | off | name            | type | description              |
- * |-----+-----------------+------+--------------------------|
+ * +-----+-----------------+------+--------------------------+
  * |   0 | inteface        | U8   | related interface number |
+ * +-----+-----------------+------+--------------------------+
  * |   1 | dwLength        | U32  | length of the descriptor |
+ * +-----+-----------------+------+--------------------------+
  * |   5 | bcdVersion      | U16  | currently supported: 1   |
+ * +-----+-----------------+------+--------------------------+
  * |   7 | wIndex          | U16  | currently supported: 5   |
+ * +-----+-----------------+------+--------------------------+
  * |   9 | wCount          | U16  | number of ext. compat.   |
+ * +-----+-----------------+------+--------------------------+
  * |  11 | ExtProp[]       |      | list of ext. prop. d.    |
+ * +-----+-----------------+------+--------------------------+
  *
  * ExtCompat[] is an array of valid Extended Compatiblity descriptors
  * which have the following format:
  *
+ * +-----+-----------------------+------+-------------------------------------+
  * | off | name                  | type | description                         |
- * |-----+-----------------------+------+-------------------------------------|
+ * +-----+-----------------------+------+-------------------------------------+
  * |   0 | bFirstInterfaceNumber | U8   | index of the interface or of the 1st|
+ * +-----+-----------------------+------+-------------------------------------+
  * |     |                       |      | interface in an IAD group           |
+ * +-----+-----------------------+------+-------------------------------------+
  * |   1 | Reserved              | U8   | 1                                   |
+ * +-----+-----------------------+------+-------------------------------------+
  * |   2 | CompatibleID          | U8[8]| compatible ID string                |
+ * +-----+-----------------------+------+-------------------------------------+
  * |  10 | SubCompatibleID       | U8[8]| subcompatible ID string             |
+ * +-----+-----------------------+------+-------------------------------------+
  * |  18 | Reserved              | U8[6]| 0                                   |
+ * +-----+-----------------------+------+-------------------------------------+
  *
  * ExtProp[] is an array of valid Extended Properties descriptors
  * which have the following format:
  *
+ * +-----+-----------------------+------+-------------------------------------+
  * | off | name                  | type | description                         |
- * |-----+-----------------------+------+-------------------------------------|
+ * +-----+-----------------------+------+-------------------------------------+
  * |   0 | dwSize                | U32  | length of the descriptor            |
+ * +-----+-----------------------+------+-------------------------------------+
  * |   4 | dwPropertyDataType    | U32  | 1..7                                |
+ * +-----+-----------------------+------+-------------------------------------+
  * |   8 | wPropertyNameLength   | U16  | bPropertyName length (NL)           |
+ * +-----+-----------------------+------+-------------------------------------+
  * |  10 | bPropertyName         |U8[NL]| name of this property               |
+ * +-----+-----------------------+------+-------------------------------------+
  * |10+NL| dwPropertyDataLength  | U32  | bPropertyData length (DL)           |
+ * +-----+-----------------------+------+-------------------------------------+
  * |14+NL| bProperty             |U8[DL]| payload of this property            |
+ * +-----+-----------------------+------+-------------------------------------+
  */
 
 struct usb_functionfs_strings_head {