ppp.h

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/*
 * Copyright (c) 2022 Trackunit Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */
 
#include <zephyr/kernel.h>
#include <zephyr/types.h>
#include <zephyr/net/net_if.h>
#include <zephyr/net/net_pkt.h>
#include <zephyr/sys/ring_buffer.h>
#include <zephyr/sys/atomic.h>
 
#include <zephyr/modem/pipe.h>
#include <zephyr/modem/stats.h>
 
#ifndef ZEPHYR_MODEM_PPP_
#define ZEPHYR_MODEM_PPP_
 
#ifdef __cplusplus
extern "C" {
#endif
 
typedef void (*modem_ppp_init_iface)(struct net_if *iface);
 
enum modem_ppp_receive_state {
        /* Searching for start of frame and header */
        MODEM_PPP_RECEIVE_STATE_HDR_SOF = 0,
        MODEM_PPP_RECEIVE_STATE_HDR_FF,
        MODEM_PPP_RECEIVE_STATE_HDR_7D,
        MODEM_PPP_RECEIVE_STATE_HDR_23,
        /* Writing bytes to network packet */
        MODEM_PPP_RECEIVE_STATE_WRITING,
        /* Unescaping next byte before writing to network packet */
        MODEM_PPP_RECEIVE_STATE_UNESCAPING,
};
 
enum modem_ppp_transmit_state {
        /* Idle */
        MODEM_PPP_TRANSMIT_STATE_IDLE = 0,
        /* Writing header */
        MODEM_PPP_TRANSMIT_STATE_SOF,
        MODEM_PPP_TRANSMIT_STATE_HDR_FF,
        MODEM_PPP_TRANSMIT_STATE_HDR_7D,
        MODEM_PPP_TRANSMIT_STATE_HDR_23,
        /* Writing protocol */
        MODEM_PPP_TRANSMIT_STATE_PROTOCOL_HIGH,
        MODEM_PPP_TRANSMIT_STATE_ESCAPING_PROTOCOL_HIGH,
        MODEM_PPP_TRANSMIT_STATE_PROTOCOL_LOW,
        MODEM_PPP_TRANSMIT_STATE_ESCAPING_PROTOCOL_LOW,
        /* Writing data */
        MODEM_PPP_TRANSMIT_STATE_DATA,
        MODEM_PPP_TRANSMIT_STATE_ESCAPING_DATA,
        /* Writing FCS */
        MODEM_PPP_TRANSMIT_STATE_FCS_LOW,
        MODEM_PPP_TRANSMIT_STATE_ESCAPING_FCS_LOW,
        MODEM_PPP_TRANSMIT_STATE_FCS_HIGH,
        MODEM_PPP_TRANSMIT_STATE_ESCAPING_FCS_HIGH,
        /* Writing end of frame */
        MODEM_PPP_TRANSMIT_STATE_EOF,
};
 
struct modem_ppp {
        /* Network interface instance is bound to */
        struct net_if *iface;
 
        /* Hook for PPP L2 network interface initialization */
        modem_ppp_init_iface init_iface;
 
        atomic_t state;
 
        /* Buffers used for processing partial frames */
        uint8_t *receive_buf;
        uint8_t *transmit_buf;
        uint16_t buf_size;
 
        /* Wrapped PPP frames are sent and received through this pipe */
        struct modem_pipe *pipe;
 
        /* Receive PPP frame state */
        enum modem_ppp_receive_state receive_state;
 
        /* Allocated network packet being created */
        struct net_pkt *rx_pkt;
 
        /* Packet being sent */
        enum modem_ppp_transmit_state transmit_state;
        struct net_pkt *tx_pkt;
        uint8_t tx_pkt_escaped;
        uint16_t tx_pkt_protocol;
        uint16_t tx_pkt_fcs;
 
        /* Ring buffer used for transmitting partial PPP frame */
        struct ring_buf transmit_rb;
 
        struct k_fifo tx_pkt_fifo;
 
        /* Work */
        struct k_work send_work;
        struct k_work process_work;
 
#if defined(CONFIG_NET_STATISTICS_PPP)
        struct net_stats_ppp stats;
#endif
 
#if CONFIG_MODEM_STATS
        struct modem_stats_buffer receive_buf_stats;
        struct modem_stats_buffer transmit_buf_stats;
#endif
};
 
int modem_ppp_attach(struct modem_ppp *ppp, struct modem_pipe *pipe);
 
struct net_if *modem_ppp_get_iface(struct modem_ppp *ppp);
 
void modem_ppp_release(struct modem_ppp *ppp);
 
int modem_ppp_init_internal(const struct device *dev);
 
#define MODEM_PPP_DEFINE(_name, _init_iface, _prio, _mtu, _buf_size)                               \
        extern const struct ppp_api modem_ppp_ppp_api;                                             \
                                                                                                   \
        static uint8_t _CONCAT(_name, _receive_buf)[_buf_size];                                    \
        static uint8_t _CONCAT(_name, _transmit_buf)[_buf_size];                                   \
                                                                                                   \
        static struct modem_ppp _name = {                                                          \
                .init_iface = _init_iface,                                                         \
                .receive_buf = _CONCAT(_name, _receive_buf),                                       \
                .transmit_buf = _CONCAT(_name, _transmit_buf),                                     \
                .buf_size = _buf_size,                                                             \
        };                                                                                         \
                                                                                                   \
        NET_DEVICE_INIT(_CONCAT(ppp_net_dev_, _name), "modem_ppp_" # _name,                        \
                        modem_ppp_init_internal, NULL, &_name, NULL, _prio, &modem_ppp_ppp_api,    \
                        PPP_L2, NET_L2_GET_CTX_TYPE(PPP_L2), _mtu)
 
#ifdef __cplusplus
}
#endif
 
#endif /* ZEPHYR_MODEM_PPP_ */