| /* |
| * Copyright (c) 2022 Nordic Semiconductor ASA |
| * |
| * SPDX-License-Identifier: Apache-2.0 |
| */ |
| |
| #ifndef ZEPHYR_INCLUDE_SYS_SPSC_PBUF_H_ |
| #define ZEPHYR_INCLUDE_SYS_SPSC_PBUF_H_ |
| |
| #ifdef __cplusplus |
| extern "C" { |
| #endif |
| |
| /** |
| * @brief Single producer, single consumer packet buffer API |
| * @ingroup kernel_apis |
| * @{ |
| */ |
| |
| /**@defgroup SPSC_PBUF_FLAGS MPSC packet buffer flags |
| * @{ |
| */ |
| |
| /** @brief Flag indicating that cache shall be handled. */ |
| #define SPSC_PBUF_CACHE BIT(0) |
| |
| /** @brief Size of the field which stores maximum utilization. */ |
| #define SPSC_PBUF_UTILIZATION_BITS 24 |
| |
| /** @brief Offset of the field which stores maximum utilization. */ |
| #define SPSC_PBUF_UTILIZATION_OFFSET 8 |
| |
| /**@} */ |
| |
| #ifndef CONFIG_SPSC_PBUF_CACHE_LINE |
| #define CONFIG_SPSC_PBUF_CACHE_LINE 0 |
| #endif |
| |
| /** @brief Maximum packet length. */ |
| #define SPSC_PBUF_MAX_LEN 0xFF00 |
| |
| /** @brief First part of packet buffer control block. |
| * |
| * This part contains only data set during the initialization and data touched |
| * by the reader. If packet is shared between to cores then data changed by |
| * the reader should be on different cache line than the data changed by the |
| * writer. |
| */ |
| struct spsc_pbuf_common { |
| uint32_t len; /* Length of data[] in bytes. */ |
| uint32_t flags; /* Flags. See @ref SPSC_PBUF_FLAGS */ |
| uint32_t rd_idx; /* Index of the first valid byte in data[] */ |
| }; |
| |
| /* Padding to fill cache line. */ |
| #define Z_SPSC_PBUF_PADDING \ |
| MAX(0, CONFIG_SPSC_PBUF_CACHE_LINE - (int)sizeof(struct spsc_pbuf_common)) |
| |
| /** @brief Remaining part of a packet buffer when cache is used. |
| * |
| * It contains data that is only changed by the writer. A gap is added to ensure |
| * that it is in different cache line than the data changed by the reader. |
| */ |
| struct spsc_pbuf_ext_cache { |
| uint8_t reserved[Z_SPSC_PBUF_PADDING]; |
| uint32_t wr_idx; /* Index of the first free byte in data[] */ |
| uint8_t data[]; /* Buffer data. */ |
| }; |
| |
| /** @brief Remaining part of a packet buffer when cache is not used. */ |
| struct spsc_pbuf_ext_nocache { |
| uint32_t wr_idx; /* Index of the first free byte in data[] */ |
| uint8_t data[]; /* Buffer data. */ |
| }; |
| |
| /** |
| * @brief Single producer, single consumer packet buffer |
| * |
| * The SPSC packet buffer implements lightweight unidirectional packet buffer |
| * with read/write semantics on top of a memory region shared |
| * by the reader and writer. It optionally embeds cache and memory barier |
| * management to ensure correct data access. |
| * |
| * This structure supports single writer and reader. Data stored in the buffer |
| * is encapsulated to a message (with length header). |
| * |
| */ |
| struct spsc_pbuf { |
| struct spsc_pbuf_common common; |
| union { |
| struct spsc_pbuf_ext_cache cache; |
| struct spsc_pbuf_ext_nocache nocache; |
| } ext; |
| }; |
| |
| /** @brief Get buffer capacity. |
| * |
| * This value is the amount of data that is dedicated for storing packets. Since |
| * each packet is prefixed with 2 byte length header, longest possible packet is |
| * less than that. |
| * |
| * @param pb A buffer. |
| * |
| * @return Packet buffer capacity. |
| */ |
| static inline uint32_t spsc_pbuf_capacity(struct spsc_pbuf *pb) |
| { |
| return pb->common.len - sizeof(uint32_t); |
| } |
| |
| /** |
| * @brief Initialize the packet buffer. |
| * |
| * This function initializes the packet buffer on top of a dedicated |
| * memory region. |
| * |
| * @param buf Pointer to a memory region on which buffer is |
| * created. When cache is used it must be aligned to |
| * CONFIG_SPSC_PBUF_CACHE_LINE, otherwise it must |
| * be 32 bit word aligned. |
| * @param blen Length of the buffer. Must be large enough to |
| * contain the internal structure and at least two |
| * bytes of data (one is reserved for written |
| * messages length). |
| * @param flags Option flags. See @ref SPSC_PBUF_FLAGS. |
| * @retval struct spsc_pbuf* Pointer to the created buffer. The pointer |
| * points to the same address as buf. |
| * @retval NULL Invalid buffer alignment. |
| */ |
| struct spsc_pbuf *spsc_pbuf_init(void *buf, size_t blen, uint32_t flags); |
| |
| /** |
| * @brief Write specified amount of data to the packet buffer. |
| * |
| * It combines @ref spsc_pbuf_alloc and @ref spsc_pbuf_commit into a single call. |
| * |
| * @param pb A buffer to which to write. |
| * @param buf Pointer to the data to be written to the buffer. |
| * @param len Number of bytes to be written to the buffer. Must be positive |
| * but less than @ref SPSC_PBUF_MAX_LEN. |
| * @retval int Number of bytes written, negative error code on fail. |
| * -EINVAL, if len == 0. |
| * -ENOMEM, if len is bigger than the buffer can fit. |
| */ |
| int spsc_pbuf_write(struct spsc_pbuf *pb, const char *buf, uint16_t len); |
| |
| /** |
| * @brief Allocate space in the packet buffer. |
| * |
| * This function attempts to allocate @p len bytes of continuous memory within |
| * the packet buffer. An internal padding is added at the end of the buffer, if |
| * wrapping occurred during allocation. Apart from padding, allocation does not |
| * change the state of the buffer so if after allocation packet is not needed |
| * a commit is not needed. |
| * |
| * Allocated buffer must be committed (@ref spsc_pbuf_commit) to make the packet |
| * available for reading. |
| * |
| * Packet buffer ensures that allocated buffers are 32 bit word aligned. |
| * |
| * @note If data cache is used, it is the user responsibility to write back the |
| * new data. |
| * |
| * @param[in] pb A buffer to which to write. |
| * @param[in] len Allocation length. Must be positive. If less than @ref SPSC_PBUF_MAX_LEN |
| * then if requested length cannot be allocated, an attempt to allocate |
| * largest possible is performed (which may include adding wrap padding). |
| * If @ref SPSC_PBUF_MAX_LEN is used then an attempt to allocate largest |
| * buffer without applying wrap padding is performed. |
| * @param[out] buf Location where buffer address is written on successful allocation. |
| * |
| * @retval non-negative Amount of space that got allocated. Can be equal or smaller than %p len. |
| * @retval -EINVAL if @p len is forbidden. |
| */ |
| int spsc_pbuf_alloc(struct spsc_pbuf *pb, uint16_t len, char **buf); |
| |
| /** |
| * @brief Commit packet to the buffer. |
| * |
| * Commit a packet which was previously allocated (@ref spsc_pbuf_alloc). |
| * If cache is used, cache writeback is perfromed on the written data. |
| * |
| * @param pb A buffer to which to write. |
| * @param len Packet length. Must be equal or less than the length used for allocation. |
| */ |
| void spsc_pbuf_commit(struct spsc_pbuf *pb, uint16_t len); |
| |
| /** |
| * @brief Read specified amount of data from the packet buffer. |
| * |
| * Single read allows to read the message send by the single write. |
| * The provided %p buf must be big enough to store the whole message. |
| * |
| * It combines @ref spsc_pbuf_claim and @ref spsc_pbuf_free into a single call. |
| * |
| * @param pb A buffer from which data will be read. |
| * @param buf Data pointer to which read data will be written. |
| * If NULL, len of stored message is returned. |
| * @param len Number of bytes to be read from the buffer. |
| * @retval int Bytes read, negative error code on fail. |
| * Bytes to be read, if buf == NULL. |
| * -ENOMEM, if message can not fit in provided buf. |
| * -EAGAIN, if not whole message is ready yet. |
| */ |
| int spsc_pbuf_read(struct spsc_pbuf *pb, char *buf, uint16_t len); |
| |
| /** |
| * @brief Claim packet from the buffer. |
| * |
| * Claimed packet must be freed using @ref spsc_pbuf_free. |
| * |
| * @note If data cache is used, cache is invalidate on the packet. |
| * |
| * @param[in] pb A buffer from which packet will be claimed. |
| * @param[in,out] buf A location where claimed packet address is written. |
| * |
| * @retval 0 No packets in the buffer. |
| * @retval positive packet length. |
| */ |
| uint16_t spsc_pbuf_claim(struct spsc_pbuf *pb, char **buf); |
| |
| /** |
| * @brief Free the packet to the buffer. |
| * |
| * Packet must be claimed (@ref spsc_pbuf_claim) before it can be freed. |
| * |
| * @param pb A packet buffer from which packet was claimed. |
| * @param len Claimed packet length. |
| */ |
| void spsc_pbuf_free(struct spsc_pbuf *pb, uint16_t len); |
| |
| /** |
| * @brief Get maximum utilization of the packet buffer. |
| * |
| * Function can be used to tune the buffer size. Feature is enabled by |
| * CONFIG_SPSC_PBUF_UTILIZATION. Utilization is updated by the consumer. |
| * |
| * @param pb A packet buffer. |
| * |
| * @retval -ENOTSUP Feature not enabled. |
| * @retval non-negative Maximum utilization. |
| */ |
| int spsc_pbuf_get_utilization(struct spsc_pbuf *pb); |
| /** |
| * @} |
| */ |
| |
| #ifdef __cplusplus |
| } |
| #endif |
| |
| #endif /* ZEPHYR_INCLUDE_SYS_SPSC_PBUF_H_ */ |