/** * Copyright (c) 2013 - 2020, Nordic Semiconductor ASA * * All rights reserved. * * Redistribution and use in source and binary forms, with or without modification, * are permitted provided that the following conditions are met: * * 1. Redistributions of source code must retain the above copyright notice, this * list of conditions and the following disclaimer. * * 2. Redistributions in binary form, except as embedded into a Nordic * Semiconductor ASA integrated circuit in a product or a software update for * such product, must reproduce the above copyright notice, this list of * conditions and the following disclaimer in the documentation and/or other * materials provided with the distribution. * * 3. Neither the name of Nordic Semiconductor ASA nor the names of its * contributors may be used to endorse or promote products derived from this * software without specific prior written permission. * * 4. This software, with or without modification, must only be used with a * Nordic Semiconductor ASA integrated circuit. * * 5. Any software provided in binary form under this license must not be reverse * engineered, decompiled, modified and/or disassembled. * * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * */ #include "sdk_common.h" #if NRF_MODULE_ENABLED(HCI_SLIP) #include "hci_slip.h" #include #include "app_uart.h" #include "nrf_error.h" #define APP_SLIP_END 0xC0 /**< SLIP code for identifying the beginning and end of a packet frame.. */ #define APP_SLIP_ESC 0xDB /**< SLIP escape code. This code is used to specify that the following character is specially encoded. */ #define APP_SLIP_ESC_END 0xDC /**< SLIP special code. When this code follows 0xDB, this character is interpreted as payload data 0xC0.. */ #define APP_SLIP_ESC_ESC 0xDD /**< SLIP special code. When this code follows 0xDB, this character is interpreted as payload data 0xDB. */ /** @brief States for the SLIP state machine. */ typedef enum { SLIP_OFF, /**< SLIP state OFF. */ SLIP_READY, /**< SLIP state ON. */ SLIP_TRANSMITTING, /**< SLIP state is transmitting indicating write() has been called but data transmission has not completed. */ } slip_states_t; static slip_states_t m_current_state = SLIP_OFF; /** Current state for the SLIP TX state machine. */ static hci_slip_event_handler_t m_slip_event_handler; /** Event callback function for handling of SLIP events, @ref hci_slip_evt_type_t . */ static const uint8_t * mp_tx_buffer; /** Pointer to the current TX buffer that is in transmission. */ static uint32_t m_tx_buffer_length; /** Length of the current TX buffer that is in transmission. */ static volatile uint32_t m_tx_buffer_index; /** Current index for next byte to transmit in the mp_tx_buffer. */ static uint8_t * mp_rx_buffer; /** Pointer to the current RX buffer where the next SLIP decoded packet will be stored. */ static uint32_t m_rx_buffer_length; /** Length of the current RX buffer. */ static uint32_t m_rx_received_count; /** Number of SLIP decoded bytes received and stored in mp_rx_buffer. */ /**@brief Function for parsing bytes received on the UART until a SLIP escape byte is received. * * @param[in] byte Byte received in UART module. */ static void handle_rx_byte_default(uint8_t byte); /**@brief Function for parsing bytes received on the UART until SLIP end byte is received. * * @param[in] byte Byte received in UART module. */ static void handle_rx_byte_wait_start(uint8_t byte); /**@brief Function for decoding a received SLIP escape byte. * It will ensure correct decoding of the byte following the SLIP escape byte. * * @param[in] byte Byte received in UART module. */ static void handle_rx_byte_esc(uint8_t byte); /**@brief Function pointer for parsing and decoding SLIP bytes from the UART module. * * @param[in] byte Byte received in UART module. */ static void (*handle_rx_byte) (uint8_t byte) = handle_rx_byte_wait_start; /**@brief Function pointer for sending a byte through the UART module. */ static uint32_t send_tx_byte_default(void); /**@brief Function for transferring a SLIP escape byte (0xDB) when special bytes are transferred, * that is 0xC0 and 0xDB. */ static uint32_t send_tx_byte_esc(void); /**@brief Function for transferring a byte when it collides with SLIP commands and follows the SLIP * escape byte, that is 0xC0 => 0xDC and 0xDB => 0xDD. */ static uint32_t send_tx_byte_encoded(void); /**@brief Function for transferring the SLIP end frame byte, 0xC0. */ static uint32_t send_tx_byte_end(void); /**@brief Function pointer for sending a byte through the UART module. */ uint32_t (*send_tx_byte) (void) = send_tx_byte_default; static uint32_t send_tx_byte_end(void) { uint32_t err_code = app_uart_put(APP_SLIP_END); if ((err_code == NRF_SUCCESS) && (m_tx_buffer_index == 0)) { // Packet transmission started. send_tx_byte = send_tx_byte_default; } return err_code; } static uint32_t send_tx_byte_default(void) { uint32_t err_code = app_uart_put(mp_tx_buffer[m_tx_buffer_index]); if (err_code == NRF_SUCCESS) { m_tx_buffer_index++; } return err_code; } static uint32_t send_tx_byte_encoded(void) { uint32_t err_code; switch (mp_tx_buffer[m_tx_buffer_index]) { case APP_SLIP_END: err_code = app_uart_put(APP_SLIP_ESC_END); break; case APP_SLIP_ESC: err_code = app_uart_put(APP_SLIP_ESC_ESC); break; default: err_code = NRF_ERROR_NO_MEM; break; } if (err_code == NRF_SUCCESS) { m_tx_buffer_index++; send_tx_byte = send_tx_byte_default; } return err_code; } static uint32_t send_tx_byte_esc(void) { uint32_t err_code = app_uart_put(APP_SLIP_ESC); if (err_code == NRF_SUCCESS) { send_tx_byte = send_tx_byte_encoded; } return err_code; } /** @brief Function for transferring the content of the mp_tx_buffer to the UART. * It continues to transfer bytes until the UART buffer is full or the complete buffer is * transferred. */ static void transmit_buffer(void) { uint32_t err_code = NRF_SUCCESS; while (m_tx_buffer_index < m_tx_buffer_length) { if ((mp_tx_buffer[m_tx_buffer_index] == APP_SLIP_END || mp_tx_buffer[m_tx_buffer_index] == APP_SLIP_ESC) && send_tx_byte == send_tx_byte_default) { send_tx_byte = send_tx_byte_esc; } err_code = send_tx_byte(); if (err_code == NRF_ERROR_NO_MEM || err_code == NRF_ERROR_BUSY) { // No memory left in UART TX buffer. Abort and wait for APP_UART_TX_EMPTY to continue. return; } } send_tx_byte = send_tx_byte_end; err_code = send_tx_byte(); if (err_code == NRF_SUCCESS) { // Packet transmission ended. Notify higher level. m_current_state = SLIP_READY; if (m_slip_event_handler != NULL) { hci_slip_evt_t event = {HCI_SLIP_TX_DONE, mp_tx_buffer, m_tx_buffer_index}; m_slip_event_handler(event); } } } /** @brief Function for handling the reception of a SLIP end byte. * If the number of bytes received is greater than zero it will call m_slip_event_handler * with number of bytes received and invalidate the mp_rx_buffer to protect against data * corruption. * No new bytes can be received until a new RX buffer is supplied. */ static void handle_slip_end(void) { if (m_rx_received_count > 0) { // Full packet received, push it up. if (m_slip_event_handler != NULL) { hci_slip_evt_t event = {HCI_SLIP_RX_RDY, mp_rx_buffer, m_rx_received_count}; m_rx_received_count = 0; mp_rx_buffer = NULL; m_slip_event_handler(event); } } } static void handle_rx_byte_esc(uint8_t byte) { switch (byte) { case APP_SLIP_END: handle_slip_end(); break; case APP_SLIP_ESC_END: mp_rx_buffer[m_rx_received_count++] = APP_SLIP_END; break; case APP_SLIP_ESC_ESC: mp_rx_buffer[m_rx_received_count++] = APP_SLIP_ESC; break; default: mp_rx_buffer[m_rx_received_count++] = byte; break; } handle_rx_byte = handle_rx_byte_default; } static void handle_rx_byte_default(uint8_t byte) { switch (byte) { case APP_SLIP_END: handle_slip_end(); break; case APP_SLIP_ESC: handle_rx_byte = handle_rx_byte_esc; break; default: mp_rx_buffer[m_rx_received_count++] = byte; break; } } static void handle_rx_byte_wait_start(uint8_t byte) { if (byte == APP_SLIP_END) { handle_rx_byte = handle_rx_byte_default; } } /** @brief Function for checking the current index and length of the RX buffer to determine if the * buffer is full. If an event handler has been registered, the callback function will * be executed.. * * @retval true If RX buffer has overflowed. * @retval false otherwise. * */ static bool rx_buffer_overflowed(void) { if (mp_rx_buffer == NULL || m_rx_received_count >= m_rx_buffer_length) { if (m_slip_event_handler != NULL) { hci_slip_evt_t event = {HCI_SLIP_RX_OVERFLOW, mp_rx_buffer, m_rx_received_count}; m_slip_event_handler(event); } return true; } return false; } /** @brief Function for handling the UART module event. It parses events from the UART when * bytes are received/transmitted. * * @param[in] uart_event Event received from app_uart module. */ static void slip_uart_eventhandler(app_uart_evt_t * uart_event) { if (uart_event->evt_type == APP_UART_TX_EMPTY && m_current_state == SLIP_TRANSMITTING) { transmit_buffer(); } if ((uart_event->evt_type == APP_UART_DATA) && (!rx_buffer_overflowed())) { handle_rx_byte(uart_event->data.value); } } /** @brief Function for enabling the UART module when the SLIP layer is opened. */ static uint32_t slip_uart_open(void) { uint32_t err_code; app_uart_comm_params_t comm_params = { HCI_UART_RX_PIN, HCI_UART_TX_PIN, HCI_UART_RTS_PIN, HCI_UART_CTS_PIN, (app_uart_flow_control_t)HCI_UART_FLOW_CONTROL, false, HCI_UART_BAUDRATE }; err_code = app_uart_init(&comm_params, NULL, slip_uart_eventhandler, APP_IRQ_PRIORITY_LOWEST); if (err_code == NRF_SUCCESS) { m_current_state = SLIP_READY; } return err_code; } uint32_t hci_slip_evt_handler_register(hci_slip_event_handler_t event_handler) { m_slip_event_handler = event_handler; return NRF_SUCCESS; } uint32_t hci_slip_open() { switch (m_current_state) { case SLIP_OFF: return slip_uart_open(); default: // Do nothing. break; } return NRF_SUCCESS; } uint32_t hci_slip_close() { m_current_state = SLIP_OFF; uint32_t err_code = app_uart_close(); return err_code; } uint32_t hci_slip_write(const uint8_t * p_buffer, uint32_t length) { if (p_buffer == NULL) { return NRF_ERROR_INVALID_ADDR; } switch (m_current_state) { case SLIP_READY: m_tx_buffer_index = 0; m_tx_buffer_length = length; mp_tx_buffer = p_buffer; m_current_state = SLIP_TRANSMITTING; send_tx_byte = send_tx_byte_end; transmit_buffer(); return NRF_SUCCESS; case SLIP_TRANSMITTING: return NRF_ERROR_NO_MEM; case SLIP_OFF: default: return NRF_ERROR_INVALID_STATE; } } uint32_t hci_slip_rx_buffer_register(uint8_t * p_buffer, uint32_t length) { mp_rx_buffer = p_buffer; m_rx_buffer_length = length; m_rx_received_count = 0; handle_rx_byte = handle_rx_byte_wait_start; return NRF_SUCCESS; } #endif //NRF_MODULE_ENABLED(HCI_SLIP)