/* SPDX-License-Identifier: GPL-2.0+ *//* * SSH message builder functions. * * Copyright (C) 2019-2022 Maximilian Luz <luzmaximilian@gmail.com> */ #ifndef _SURFACE_AGGREGATOR_SSH_MSGB_H#define _SURFACE_AGGREGATOR_SSH_MSGB_H #include <linux/unaligned.h>#include <linux/types.h> #include <linux/surface_aggregator/controller.h>#include <linux/surface_aggregator/serial_hub.h> /** * struct msgbuf - Buffer struct to construct SSH messages. * @begin: Pointer to the beginning of the allocated buffer space. * @end:   Pointer to the end (one past last element) of the allocated buffer *         space. * @ptr:   Pointer to the first free element in the buffer. */struct msgbuf {	u8 *begin;	u8 *end;	u8 *ptr;}; /** * msgb_init() - Initialize the given message buffer struct. * @msgb: The buffer struct to initialize * @ptr:  Pointer to the underlying memory by which the buffer will be backed. * @cap:  Size of the underlying memory. * * Initialize the given message buffer struct using the provided memory as * backing. */static inline void msgb_init(struct msgbuf *msgb, u8 *ptr, size_t cap){	msgb->begin = ptr;	msgb->end = ptr + cap;	msgb->ptr = ptr;} /** * msgb_bytes_used() - Return the current number of bytes used in the buffer. * @msgb: The message buffer. */static inline size_t msgb_bytes_used(const struct msgbuf *msgb){	return msgb->ptr - msgb->begin;} static inline void __msgb_push_u8(struct msgbuf *msgb, u8 value){	*msgb->ptr = value;	msgb->ptr += sizeof(u8);} static inline void __msgb_push_u16(struct msgbuf *msgb, u16 value){	put_unaligned_le16(value, msgb->ptr);	msgb->ptr += sizeof(u16);} /** * msgb_push_u16() - Push a u16 value to the buffer. * @msgb:  The message buffer. * @value: The value to push to the buffer. */static inline void msgb_push_u16(struct msgbuf *msgb, u16 value){	if (WARN_ON(msgb->ptr + sizeof(u16) > msgb->end))		return; 	__msgb_push_u16(msgb, value);} /** * msgb_push_syn() - Push SSH SYN bytes to the buffer. * @msgb: The message buffer. */static inline void msgb_push_syn(struct msgbuf *msgb){	msgb_push_u16(msgb, SSH_MSG_SYN);} /** * msgb_push_buf() - Push raw data to the buffer. * @msgb: The message buffer. * @buf:  The data to push to the buffer. * @len:  The length of the data to push to the buffer. */static inline void msgb_push_buf(struct msgbuf *msgb, const u8 *buf, size_t len){	msgb->ptr = memcpy(msgb->ptr, buf, len) + len;} /** * msgb_push_crc() - Compute CRC and push it to the buffer. * @msgb: The message buffer. * @buf:  The data for which the CRC should be computed. * @len:  The length of the data for which the CRC should be computed. */static inline void msgb_push_crc(struct msgbuf *msgb, const u8 *buf, size_t len){	msgb_push_u16(msgb, ssh_crc(buf, len));} /** * msgb_push_frame() - Push a SSH message frame header to the buffer. * @msgb: The message buffer * @ty:   The type of the frame. * @len:  The length of the payload of the frame. * @seq:  The sequence ID of the frame/packet. */static inline void msgb_push_frame(struct msgbuf *msgb, u8 ty, u16 len, u8 seq){	u8 *const begin = msgb->ptr; 	if (WARN_ON(msgb->ptr + sizeof(struct ssh_frame) > msgb->end))		return; 	__msgb_push_u8(msgb, ty);	/* Frame type. */	__msgb_push_u16(msgb, len);	/* Frame payload length. */	__msgb_push_u8(msgb, seq);	/* Frame sequence ID. */ 	msgb_push_crc(msgb, begin, msgb->ptr - begin);} /** * msgb_push_ack() - Push a SSH ACK frame to the buffer. * @msgb: The message buffer * @seq:  The sequence ID of the frame/packet to be ACKed. */static inline void msgb_push_ack(struct msgbuf *msgb, u8 seq){	/* SYN. */	msgb_push_syn(msgb); 	/* ACK-type frame + CRC. */	msgb_push_frame(msgb, SSH_FRAME_TYPE_ACK, 0x00, seq); 	/* Payload CRC (ACK-type frames do not have a payload). */	msgb_push_crc(msgb, msgb->ptr, 0);} /** * msgb_push_nak() - Push a SSH NAK frame to the buffer. * @msgb: The message buffer */static inline void msgb_push_nak(struct msgbuf *msgb){	/* SYN. */	msgb_push_syn(msgb); 	/* NAK-type frame + CRC. */	msgb_push_frame(msgb, SSH_FRAME_TYPE_NAK, 0x00, 0x00); 	/* Payload CRC (ACK-type frames do not have a payload). */	msgb_push_crc(msgb, msgb->ptr, 0);} /** * msgb_push_cmd() - Push a SSH command frame with payload to the buffer. * @msgb: The message buffer. * @seq:  The sequence ID (SEQ) of the frame/packet. * @rqid: The request ID (RQID) of the request contained in the frame. * @rqst: The request to wrap in the frame. */static inline void msgb_push_cmd(struct msgbuf *msgb, u8 seq, u16 rqid,				 const struct ssam_request *rqst){	const u8 type = SSH_FRAME_TYPE_DATA_SEQ;	u8 *cmd; 	/* SYN. */	msgb_push_syn(msgb); 	/* Command frame + CRC. */	msgb_push_frame(msgb, type, sizeof(struct ssh_command) + rqst->length, seq); 	/* Frame payload: Command struct + payload. */	if (WARN_ON(msgb->ptr + sizeof(struct ssh_command) > msgb->end))		return; 	cmd = msgb->ptr; 	__msgb_push_u8(msgb, SSH_PLD_TYPE_CMD);		/* Payload type. */	__msgb_push_u8(msgb, rqst->target_category);	/* Target category. */	__msgb_push_u8(msgb, rqst->target_id);		/* Target ID. */	__msgb_push_u8(msgb, SSAM_SSH_TID_HOST);	/* Source ID. */	__msgb_push_u8(msgb, rqst->instance_id);	/* Instance ID. */	__msgb_push_u16(msgb, rqid);			/* Request ID. */	__msgb_push_u8(msgb, rqst->command_id);		/* Command ID. */ 	/* Command payload. */	msgb_push_buf(msgb, rqst->payload, rqst->length); 	/* CRC for command struct + payload. */	msgb_push_crc(msgb, cmd, msgb->ptr - cmd);} #endif /* _SURFACE_AGGREGATOR_SSH_MSGB_H */