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/* SPDX-License-Identifier: GPL-2.0+ */
/*
* SSH message parser.
*
* Copyright (C) 2019-2022 Maximilian Luz <luzmaximilian@gmail.com>
*/
#ifndef _SURFACE_AGGREGATOR_SSH_PARSER_H
#define _SURFACE_AGGREGATOR_SSH_PARSER_H
#include <linux/device.h>
#include <linux/kfifo.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/surface_aggregator/serial_hub.h>
/**
* struct sshp_buf - Parser buffer for SSH messages.
* @ptr: Pointer to the beginning of the buffer.
* @len: Number of bytes used in the buffer.
* @cap: Maximum capacity of the buffer.
*/
struct sshp_buf {
u8 *ptr;
size_t len;
size_t cap;
};
/**
* sshp_buf_init() - Initialize a SSH parser buffer.
* @buf: The buffer to initialize.
* @ptr: The memory backing the buffer.
* @cap: The length of the memory backing the buffer, i.e. its capacity.
*
* Initializes the buffer with the given memory as backing and set its used
* length to zero.
*/
static inline void sshp_buf_init(struct sshp_buf *buf, u8 *ptr, size_t cap)
{
buf->ptr = ptr;
buf->len = 0;
buf->cap = cap;
}
/**
* sshp_buf_alloc() - Allocate and initialize a SSH parser buffer.
* @buf: The buffer to initialize/allocate to.
* @cap: The desired capacity of the buffer.
* @flags: The flags used for allocating the memory.
*
* Allocates @cap bytes and initializes the provided buffer struct with the
* allocated memory.
*
* Return: Returns zero on success and %-ENOMEM if allocation failed.
*/
static inline int sshp_buf_alloc(struct sshp_buf *buf, size_t cap, gfp_t flags)
{
u8 *ptr;
ptr = kzalloc(cap, flags);
if (!ptr)
return -ENOMEM;
sshp_buf_init(buf, ptr, cap);
return 0;
}
/**
* sshp_buf_free() - Free a SSH parser buffer.
* @buf: The buffer to free.
*
* Frees a SSH parser buffer by freeing the memory backing it and then
* resetting its pointer to %NULL and length and capacity to zero. Intended to
* free a buffer previously allocated with sshp_buf_alloc().
*/
static inline void sshp_buf_free(struct sshp_buf *buf)
{
kfree(buf->ptr);
buf->ptr = NULL;
buf->len = 0;
buf->cap = 0;
}
/**
* sshp_buf_drop() - Drop data from the beginning of the buffer.
* @buf: The buffer to drop data from.
* @n: The number of bytes to drop.
*
* Drops the first @n bytes from the buffer. Re-aligns any remaining data to
* the beginning of the buffer.
*/
static inline void sshp_buf_drop(struct sshp_buf *buf, size_t n)
{
memmove(buf->ptr, buf->ptr + n, buf->len - n);
buf->len -= n;
}
/**
* sshp_buf_read_from_fifo() - Transfer data from a fifo to the buffer.
* @buf: The buffer to write the data into.
* @fifo: The fifo to read the data from.
*
* Transfers the data contained in the fifo to the buffer, removing it from
* the fifo. This function will try to transfer as much data as possible,
* limited either by the remaining space in the buffer or by the number of
* bytes available in the fifo.
*
* Return: Returns the number of bytes transferred.
*/
static inline size_t sshp_buf_read_from_fifo(struct sshp_buf *buf,
struct kfifo *fifo)
{
size_t n;
n = kfifo_out(fifo, buf->ptr + buf->len, buf->cap - buf->len);
buf->len += n;
return n;
}
/**
* sshp_buf_span_from() - Initialize a span from the given buffer and offset.
* @buf: The buffer to create the span from.
* @offset: The offset in the buffer at which the span should start.
* @span: The span to initialize (output).
*
* Initializes the provided span to point to the memory at the given offset in
* the buffer, with the length of the span being capped by the number of bytes
* used in the buffer after the offset (i.e. bytes remaining after the
* offset).
*
* Warning: This function does not validate that @offset is less than or equal
* to the number of bytes used in the buffer or the buffer capacity. This must
* be guaranteed by the caller.
*/
static inline void sshp_buf_span_from(struct sshp_buf *buf, size_t offset,
struct ssam_span *span)
{
span->ptr = buf->ptr + offset;
span->len = buf->len - offset;
}
bool sshp_find_syn(const struct ssam_span *src, struct ssam_span *rem);
int sshp_parse_frame(const struct device *dev, const struct ssam_span *source,
struct ssh_frame **frame, struct ssam_span *payload,
size_t maxlen);
int sshp_parse_command(const struct device *dev, const struct ssam_span *source,
struct ssh_command **command,
struct ssam_span *command_data);
#endif /* _SURFACE_AGGREGATOR_SSH_PARSER_h */
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