mei: add support for mei extended header.

Add an extend header beyond existing 4 bytes of the mei message header.
The extension is of variable length, starting with meta header
that contains the number of headers and the overall size of
the extended headers excluding meta header itself followed by
TLV list of extended headers. Currently only supported extension is
the vtag. From the HW perspective the extended headers is already
part of the payload.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Link: https://lore.kernel.org/r/20200818115147.2567012-5-tomas.winkler@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 89 insertions, 4 deletions

diff --git a/drivers/misc/mei/hw.h b/drivers/misc/mei/hw.h
index ea0a2e459282..c3c628132b50 100644
--- a/drivers/misc/mei/hw.h
+++ b/drivers/misc/mei/hw.h
@@ -197,17 +197,103 @@ enum mei_cl_connect_status {
 /*
  * Client Disconnect Status
  */
-enum  mei_cl_disconnect_status {
+enum mei_cl_disconnect_status {
 	MEI_CL_DISCONN_SUCCESS = MEI_HBMS_SUCCESS
 };
 
 /**
+ * enum mei_ext_hdr_type - extended header type used in
+ *    extended header TLV
+ *
+ * @MEI_EXT_HDR_NONE: sentinel
+ * @MEI_EXT_HDR_VTAG: vtag header
+ */
+enum mei_ext_hdr_type {
+	MEI_EXT_HDR_NONE = 0,
+	MEI_EXT_HDR_VTAG = 1,
+};
+
+/**
+ * struct mei_ext_hdr - extend header descriptor (TLV)
+ * @type: enum mei_ext_hdr_type
+ * @length: length excluding descriptor
+ * @ext_payload: payload of the specific extended header
+ * @hdr: place holder for actual header
+ */
+struct mei_ext_hdr {
+	u8 type;
+	u8 length;
+	u8 ext_payload[2];
+	u8 hdr[0];
+};
+
+/**
+ * struct mei_ext_meta_hdr - extend header meta data
+ * @count: number of headers
+ * @size: total size of the extended header list excluding meta header
+ * @reserved: reserved
+ * @hdrs: extended headers TLV list
+ */
+struct mei_ext_meta_hdr {
+	u8 count;
+	u8 size;
+	u8 reserved[2];
+	struct mei_ext_hdr hdrs[0];
+};
+
+/*
+ * Extended header iterator functions
+ */
+/**
+ * mei_ext_hdr - extended header iterator begin
+ *
+ * @meta: meta header of the extended header list
+ *
+ * Return:
+ *     The first extended header
+ */
+static inline struct mei_ext_hdr *mei_ext_begin(struct mei_ext_meta_hdr *meta)
+{
+	return meta->hdrs;
+}
+
+/**
+ * mei_ext_last - check if the ext is the last one in the TLV list
+ *
+ * @meta: meta header of the extended header list
+ * @ext: a meta header on the list
+ *
+ * Return: true if ext is the last header on the list
+ */
+static inline bool mei_ext_last(struct mei_ext_meta_hdr *meta,
+				struct mei_ext_hdr *ext)
+{
+	return (u8 *)ext >= (u8 *)meta + sizeof(*meta) + (meta->size * 4);
+}
+
+/**
+ *mei_ext_next - following extended header on the TLV list
+ *
+ * @ext: current extend header
+ *
+ * Context: The function does not check for the overflows,
+ *          one should call mei_ext_last before.
+ *
+ * Return: The following extend header after @ext
+ */
+static inline struct mei_ext_hdr *mei_ext_next(struct mei_ext_hdr *ext)
+{
+	return (struct mei_ext_hdr *)(ext->hdr + (ext->length * 4));
+}
+
+/**
  * struct mei_msg_hdr - MEI BUS Interface Section
  *
  * @me_addr: device address
  * @host_addr: host address
  * @length: message length
  * @reserved: reserved
+ * @extended: message has extended header
  * @dma_ring: message is on dma ring
  * @internal: message is internal
  * @msg_complete: last packet of the message
@@ -217,7 +303,8 @@ struct mei_msg_hdr {
 	u32 me_addr:8;
 	u32 host_addr:8;
 	u32 length:9;
-	u32 reserved:4;
+	u32 reserved:3;
+	u32 extended:1;
 	u32 dma_ring:1;
 	u32 internal:1;
 	u32 msg_complete:1;
@@ -227,8 +314,6 @@ struct mei_msg_hdr {
 /* The length is up to 9 bits */
 #define MEI_MSG_MAX_LEN_MASK GENMASK(9, 0)
 
-#define MEI_MSG_HDR_MAX 2
-
 struct mei_bus_message {
 	u8 hbm_cmd;
 	u8 data[];