/* * Copyright 2024 Google LLC * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include "kernel/pbl_malloc.h" #include "drivers/rtc.h" #include "drivers/qemu/qemu_serial.h" #include "drivers/qemu/qemu_serial_private.h" #include "system/passert.h" #include "system/logging.h" #include "util/math.h" #include "util/net.h" #include "system/hexdump.h" // ----------------------------------------------------------------------------------------- void qemu_serial_private_init_state(QemuSerialGlobals *state) { // Create our mutex state->qemu_comm_lock = mutex_create(); state->initialized = true; // Allocate buffer for received characters from the ISR uint32_t buffer_size = QEMU_ISR_RECV_BUFFER_SIZE; uint8_t *buffer_data = kernel_malloc_check(buffer_size); shared_circular_buffer_init(&state->isr_buffer, buffer_data, buffer_size); shared_circular_buffer_add_client(&state->isr_buffer, &state->isr_buffer_client); // Allocate buffer for the received message state->msg_buffer = kernel_malloc_check(QEMU_MAX_DATA_LEN); state->msg_buffer_bytes = 0; } // ----------------------------------------------------------------------------------------- // Helper function triggred by our ISR handler when we detect a high water mark on our receive // buffer or a footer signature. // // Parses the ISR's circular buffer and collects assembled message into a message buffer. If // a complete packets has been assembled, it returns a pointer to the message buffer, // the size of the packet (in *msg_bytes), and the protocol (in *protocol). If a complete packet // is not ready yet, it returns a NULL. // // @param[in] state pointer to our state variables // @param[out] *msg_bytes number of bytes in assembled message // @param[out] *protocol protocol for the message // @return pointer to message, or NULL if no message available yet uint8_t *qemu_serial_private_assemble_message(QemuSerialGlobals *state, uint32_t *msg_bytes, uint16_t *protocol) { uint16_t bytes_read; uint8_t byte; bool exit = false; bool got_msg = false; time_t cur_time = rtc_get_time(); // Reset our state if too much time has passed since we detected start of a packet if (state->recv_state != QemuRecvState_WaitingHdrSignatureMSB && cur_time > state->start_recv_packet_time + QEMU_RECV_PACKET_TIMEOUT_SEC) { state->recv_state = QemuRecvState_WaitingHdrSignatureMSB; PBL_LOG(LOG_LEVEL_WARNING, "Resetting receive state - max packet time expired"); } state->callback_pending = false; uint16_t bytes_avail = shared_circular_buffer_get_read_space_remaining(&state->isr_buffer, &state->isr_buffer_client); QEMU_LOG_DEBUG("prv_assemble_packet, state:%d, bytes:%d", state->recv_state, bytes_avail); // Log message if we detected any receive errors if (state->recv_error_count) { PBL_LOG(LOG_LEVEL_ERROR, "%"PRIu32" receive errors detected", state->recv_error_count); state->recv_error_count = 0; } while (!exit && bytes_avail) { switch (state->recv_state) { case QemuRecvState_WaitingHdrSignatureMSB: { state->msg_buffer_bytes = 0; shared_circular_buffer_read_consume(&state->isr_buffer, &state->isr_buffer_client, 1, &byte, &bytes_read); bytes_avail -= bytes_read; if (byte == QEMU_HEADER_MSB) { QEMU_LOG_DEBUG("got header signature MSB"); state->recv_state = QemuRecvState_WaitingHdrSignatureLSB; state->start_recv_packet_time = cur_time; } } break; case QemuRecvState_WaitingHdrSignatureLSB: { shared_circular_buffer_read_consume(&state->isr_buffer, &state->isr_buffer_client, 1, &byte, &bytes_read); bytes_avail -= bytes_read; if (byte == QEMU_HEADER_LSB) { state->recv_state = QemuRecvState_WaitingHdr; QEMU_LOG_DEBUG("got header signature LSB"); } else { state->recv_state = QemuRecvState_WaitingHdr; } } break; case QemuRecvState_WaitingHdr: { // We already read in the header signature uint16_t req_bytes = sizeof(state->hdr) - sizeof(state->hdr.signature); if (bytes_avail < req_bytes) { exit = true; break; } shared_circular_buffer_read_consume(&state->isr_buffer, &state->isr_buffer_client, req_bytes, (uint8_t *)&state->hdr.protocol, &bytes_read); bytes_avail -= bytes_read; // Do byte swapping state->hdr.signature = QEMU_HEADER_SIGNATURE; state->hdr.protocol = ntohs(state->hdr.protocol); state->hdr.len = ntohs(state->hdr.len); // Validity checking if (state->hdr.len > QEMU_MAX_DATA_LEN) { PBL_LOG(LOG_LEVEL_ERROR, "Invalid header data size %d", state->hdr.len); state->recv_state = QemuRecvState_WaitingHdrSignatureMSB; } else { QEMU_LOG_DEBUG("got header: protocol: %d, len: %d", state->hdr.protocol, state->hdr.len); state->recv_state = QemuRecvState_WaitingData; } } break; case QemuRecvState_WaitingData: { uint16_t bytes_needed = state->hdr.len - state->msg_buffer_bytes; shared_circular_buffer_read_consume(&state->isr_buffer, &state->isr_buffer_client, MIN(bytes_avail, bytes_needed), state->msg_buffer + state->msg_buffer_bytes, &bytes_read); state->msg_buffer_bytes += bytes_read; bytes_avail -= bytes_read; QEMU_LOG_DEBUG("received %d bytes of msg data, need %d more", bytes_read, state->hdr.len - state->msg_buffer_bytes); // Got the complete message? if (state->msg_buffer_bytes >= state->hdr.len) { state->recv_state = QemuRecvState_WaitingFooter; got_msg = true; exit = true; } } break; case QemuRecvState_WaitingFooter: { QemuCommChannelFooter footer; if (bytes_avail < sizeof(QemuCommChannelFooter)) { exit = true; } else { shared_circular_buffer_read_consume(&state->isr_buffer, &state->isr_buffer_client, sizeof(footer), (uint8_t *)&footer, &bytes_read); bytes_avail -= bytes_read; footer.signature = ntohs(footer.signature); if (footer.signature != QEMU_FOOTER_SIGNATURE) { PBL_LOG(LOG_LEVEL_WARNING, "Invalid footer signature"); } state->recv_state = QemuRecvState_WaitingHdrSignatureMSB; } } break; } // switch() } // while (!exit && bytes_avail) // Return pointer if we got a complete message if (got_msg) { *msg_bytes= state->msg_buffer_bytes; *protocol = state->hdr.protocol; return state->msg_buffer; } else { return NULL; } } // ------------------------------------------------------------------------------------------ // Unit test support // @return true if successful (buffer not full) bool qemu_test_add_byte_from_isr(QemuSerialGlobals *state, uint8_t byte) { return shared_circular_buffer_write(&state->isr_buffer, &byte, 1, false /*advance_slackers*/); }