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1/* SPDX-License-Identifier: GPL-2.0+ */2/*3 * SSH message parser.4 *5 * Copyright (C) 2019-2022 Maximilian Luz <luzmaximilian@gmail.com>6 */7 8#ifndef _SURFACE_AGGREGATOR_SSH_PARSER_H9#define _SURFACE_AGGREGATOR_SSH_PARSER_H10 11#include <linux/device.h>12#include <linux/kfifo.h>13#include <linux/slab.h>14#include <linux/types.h>15 16#include <linux/surface_aggregator/serial_hub.h>17 18/**19 * struct sshp_buf - Parser buffer for SSH messages.20 * @ptr: Pointer to the beginning of the buffer.21 * @len: Number of bytes used in the buffer.22 * @cap: Maximum capacity of the buffer.23 */24struct sshp_buf {25 u8 *ptr;26 size_t len;27 size_t cap;28};29 30/**31 * sshp_buf_init() - Initialize a SSH parser buffer.32 * @buf: The buffer to initialize.33 * @ptr: The memory backing the buffer.34 * @cap: The length of the memory backing the buffer, i.e. its capacity.35 *36 * Initializes the buffer with the given memory as backing and set its used37 * length to zero.38 */39static inline void sshp_buf_init(struct sshp_buf *buf, u8 *ptr, size_t cap)40{41 buf->ptr = ptr;42 buf->len = 0;43 buf->cap = cap;44}45 46/**47 * sshp_buf_alloc() - Allocate and initialize a SSH parser buffer.48 * @buf: The buffer to initialize/allocate to.49 * @cap: The desired capacity of the buffer.50 * @flags: The flags used for allocating the memory.51 *52 * Allocates @cap bytes and initializes the provided buffer struct with the53 * allocated memory.54 *55 * Return: Returns zero on success and %-ENOMEM if allocation failed.56 */57static inline int sshp_buf_alloc(struct sshp_buf *buf, size_t cap, gfp_t flags)58{59 u8 *ptr;60 61 ptr = kzalloc(cap, flags);62 if (!ptr)63 return -ENOMEM;64 65 sshp_buf_init(buf, ptr, cap);66 return 0;67}68 69/**70 * sshp_buf_free() - Free a SSH parser buffer.71 * @buf: The buffer to free.72 *73 * Frees a SSH parser buffer by freeing the memory backing it and then74 * resetting its pointer to %NULL and length and capacity to zero. Intended to75 * free a buffer previously allocated with sshp_buf_alloc().76 */77static inline void sshp_buf_free(struct sshp_buf *buf)78{79 kfree(buf->ptr);80 buf->ptr = NULL;81 buf->len = 0;82 buf->cap = 0;83}84 85/**86 * sshp_buf_drop() - Drop data from the beginning of the buffer.87 * @buf: The buffer to drop data from.88 * @n: The number of bytes to drop.89 *90 * Drops the first @n bytes from the buffer. Re-aligns any remaining data to91 * the beginning of the buffer.92 */93static inline void sshp_buf_drop(struct sshp_buf *buf, size_t n)94{95 memmove(buf->ptr, buf->ptr + n, buf->len - n);96 buf->len -= n;97}98 99/**100 * sshp_buf_read_from_fifo() - Transfer data from a fifo to the buffer.101 * @buf: The buffer to write the data into.102 * @fifo: The fifo to read the data from.103 *104 * Transfers the data contained in the fifo to the buffer, removing it from105 * the fifo. This function will try to transfer as much data as possible,106 * limited either by the remaining space in the buffer or by the number of107 * bytes available in the fifo.108 *109 * Return: Returns the number of bytes transferred.110 */111static inline size_t sshp_buf_read_from_fifo(struct sshp_buf *buf,112 struct kfifo *fifo)113{114 size_t n;115 116 n = kfifo_out(fifo, buf->ptr + buf->len, buf->cap - buf->len);117 buf->len += n;118 119 return n;120}121 122/**123 * sshp_buf_span_from() - Initialize a span from the given buffer and offset.124 * @buf: The buffer to create the span from.125 * @offset: The offset in the buffer at which the span should start.126 * @span: The span to initialize (output).127 *128 * Initializes the provided span to point to the memory at the given offset in129 * the buffer, with the length of the span being capped by the number of bytes130 * used in the buffer after the offset (i.e. bytes remaining after the131 * offset).132 *133 * Warning: This function does not validate that @offset is less than or equal134 * to the number of bytes used in the buffer or the buffer capacity. This must135 * be guaranteed by the caller.136 */137static inline void sshp_buf_span_from(struct sshp_buf *buf, size_t offset,138 struct ssam_span *span)139{140 span->ptr = buf->ptr + offset;141 span->len = buf->len - offset;142}143 144bool sshp_find_syn(const struct ssam_span *src, struct ssam_span *rem);145 146int sshp_parse_frame(const struct device *dev, const struct ssam_span *source,147 struct ssh_frame **frame, struct ssam_span *payload,148 size_t maxlen);149 150int sshp_parse_command(const struct device *dev, const struct ssam_span *source,151 struct ssh_command **command,152 struct ssam_span *command_data);153 154#endif /* _SURFACE_AGGREGATOR_SSH_PARSER_h */155