pbuf.h

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/*
 * Copyright (c) 2023 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: Apache-2.0
 */
 
#ifndef ZEPHYR_INCLUDE_IPC_PBUF_H_
#define ZEPHYR_INCLUDE_IPC_PBUF_H_
 
#include <zephyr/cache.h>
#include <zephyr/devicetree.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
#define PBUF_PACKET_LEN_SZ sizeof(uint32_t)
 
/* Amount of data that is left unused to distinguish between empty and full. */
#define _PBUF_IDX_SIZE sizeof(uint32_t)
 
/* Minimal length of the data field in the buffer to store the smalest packet
 * possible.
 * (+1) for at least one byte of data.
 * (+_PBUF_IDX_SIZE) to distinguish buffer full and buffer empty.
 * Rounded up to keep wr/rd indexes pointing to aligned address.
 */
#define _PBUF_MIN_DATA_LEN ROUND_UP(PBUF_PACKET_LEN_SZ + 1 + _PBUF_IDX_SIZE, _PBUF_IDX_SIZE)
 
struct pbuf_cfg {
 volatile uint32_t *rd_idx_loc; /* Address of the variable holding
 * index value of the first valid byte
 * in data[].
 */
 volatile uint32_t *wr_idx_loc; /* Address of the variable holding
 * index value of the first free byte
 * in data[].
 */
 uint32_t dcache_alignment; /* CPU data cache line size in bytes.
 * Used for validation - TODO: To be
 * replaced by flags.
 */
 uint32_t len; /* Length of data[] in bytes. */
 uint8_t *data_loc; /* Location of the data[]. */
};
 
struct pbuf_data {
 volatile uint32_t wr_idx; /* Index of the first holding first
 * free byte in data[]. Used for
 * writing.
 */
 volatile uint32_t rd_idx; /* Index of the first holding first
 * valid byte in data[]. Used for
 * reading.
 */
};
 
 
struct pbuf {
 const struct pbuf_cfg *const cfg; /* Configuration of the
 * buffer.
 */
 struct pbuf_data data; /* Data used to read and write
 * to the buffer
 */
};
 
#define PBUF_CFG_INIT(mem_addr, size, dcache_align) \
{ \
 .rd_idx_loc = (uint32_t *)(mem_addr), \
 .wr_idx_loc = (uint32_t *)((uint8_t *)(mem_addr) + \
 MAX(dcache_align, _PBUF_IDX_SIZE)), \
 .data_loc = (uint8_t *)((uint8_t *)(mem_addr) + \
 MAX(dcache_align, _PBUF_IDX_SIZE) + _PBUF_IDX_SIZE), \
 .len = (uint32_t)((uint32_t)(size) - MAX(dcache_align, _PBUF_IDX_SIZE) - \
 _PBUF_IDX_SIZE), \
 .dcache_alignment = (dcache_align), \
}
 
#define PBUF_HEADER_OVERHEAD(dcache_align) \
 (MAX(dcache_align, _PBUF_IDX_SIZE) + _PBUF_IDX_SIZE)
 
#define PBUF_DEFINE(name, mem_addr, size, dcache_align) \
 BUILD_ASSERT(dcache_align >= 0, \
 "Cache line size must be non negative."); \
 BUILD_ASSERT((size) > 0 && IS_PTR_ALIGNED_BYTES(size, _PBUF_IDX_SIZE), \
 "Incorrect size."); \
 BUILD_ASSERT(IS_PTR_ALIGNED_BYTES(mem_addr, MAX(dcache_align, _PBUF_IDX_SIZE)), \
 "Misaligned memory."); \
 BUILD_ASSERT(size >= (MAX(dcache_align, _PBUF_IDX_SIZE) + _PBUF_IDX_SIZE + \
 _PBUF_MIN_DATA_LEN), "Insufficient size."); \
 \
 static const struct pbuf_cfg cfg_##name = \
 PBUF_CFG_INIT(mem_addr, size, dcache_align); \
 static struct pbuf name = { \
 .cfg = &cfg_##name, \
 }
 
int pbuf_init(struct pbuf *pb);
 
int pbuf_write(struct pbuf *pb, const char *buf, uint16_t len);
 
int pbuf_read(struct pbuf *pb, char *buf, uint16_t len);
 
#ifdef __cplusplus
}
#endif
 
#endif /* ZEPHYR_INCLUDE_IPC_PBUF_H_ */