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