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-rw-r--r--platforms/chibios/drivers/serial_protocol.c164
1 files changed, 164 insertions, 0 deletions
diff --git a/platforms/chibios/drivers/serial_protocol.c b/platforms/chibios/drivers/serial_protocol.c
new file mode 100644
index 0000000000..c95aed9885
--- /dev/null
+++ b/platforms/chibios/drivers/serial_protocol.c
@@ -0,0 +1,164 @@
+// Copyright 2022 Stefan Kerkmann
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <ch.h>
+
+#include "quantum.h"
+#include "serial.h"
+#include "serial_protocol.h"
+#include "printf.h"
+#include "synchronization_util.h"
+
+static inline bool initiate_transaction(uint8_t transaction_id);
+static inline bool react_to_transaction(void);
+
+/**
+ * @brief This thread runs on the slave and responds to transactions initiated
+ * by the master.
+ */
+static THD_WORKING_AREA(waSlaveThread, 1024);
+static THD_FUNCTION(SlaveThread, arg) {
+ (void)arg;
+ chRegSetThreadName("split_protocol_tx_rx");
+
+ while (true) {
+ if (unlikely(!react_to_transaction())) {
+ /* Clear the receive queue, to start with a clean slate.
+ * Parts of failed transactions or spurious bytes could still be in it. */
+ serial_transport_driver_clear();
+ }
+ }
+}
+
+/**
+ * @brief Slave specific initializations.
+ */
+void soft_serial_target_init(void) {
+ serial_transport_driver_slave_init();
+
+ /* Start transport thread. */
+ chThdCreateStatic(waSlaveThread, sizeof(waSlaveThread), HIGHPRIO, SlaveThread, NULL);
+}
+
+/**
+ * @brief Master specific initializations.
+ */
+void soft_serial_initiator_init(void) {
+ serial_transport_driver_master_init();
+}
+
+/**
+ * @brief React to transactions started by the master.
+ */
+static inline bool react_to_transaction(void) {
+ uint8_t transaction_id = 0;
+ /* Wait until there is a transaction for us. */
+ if (unlikely(!serial_transport_receive_blocking(&transaction_id, sizeof(transaction_id)))) {
+ return false;
+ }
+
+ /* Sanity check that we are actually responding to a valid transaction. */
+ if (unlikely(transaction_id >= NUM_TOTAL_TRANSACTIONS)) {
+ return false;
+ }
+
+ split_shared_memory_lock_autounlock();
+
+ split_transaction_desc_t* transaction = &split_transaction_table[transaction_id];
+
+ /* Send back the handshake which is XORed as a simple checksum,
+ to signal that the slave is ready to receive possible transaction buffers */
+ transaction_id ^= NUM_TOTAL_TRANSACTIONS;
+ if (unlikely(!serial_transport_send(&transaction_id, sizeof(transaction_id)))) {
+ return false;
+ }
+
+ /* Receive transaction buffer from the master. If this transaction requires it.*/
+ if (transaction->initiator2target_buffer_size) {
+ if (unlikely(!serial_transport_receive(split_trans_initiator2target_buffer(transaction), transaction->initiator2target_buffer_size))) {
+ return false;
+ }
+ }
+
+ /* Allow any slave processing to occur. */
+ if (transaction->slave_callback) {
+ transaction->slave_callback(transaction->initiator2target_buffer_size, split_trans_initiator2target_buffer(transaction), transaction->initiator2target_buffer_size, split_trans_target2initiator_buffer(transaction));
+ }
+
+ /* Send transaction buffer to the master. If this transaction requires it. */
+ if (transaction->target2initiator_buffer_size) {
+ if (unlikely(!serial_transport_send(split_trans_target2initiator_buffer(transaction), transaction->target2initiator_buffer_size))) {
+ return false;
+ }
+ }
+
+ return true;
+}
+
+/**
+ * @brief Start transaction from the master half to the slave half.
+ *
+ * @param index Transaction Table index of the transaction to start.
+ * @return bool Indicates success of transaction.
+ */
+bool soft_serial_transaction(int index) {
+ bool result = initiate_transaction((uint8_t)index);
+
+ if (unlikely(!result)) {
+ /* Clear the receive queue, to start with a clean slate.
+ * Parts of failed transactions or spurious bytes could still be in it. */
+ serial_transport_driver_clear();
+ }
+
+ return result;
+}
+
+/**
+ * @brief Initiate transaction to slave half.
+ */
+static inline bool initiate_transaction(uint8_t transaction_id) {
+ /* Sanity check that we are actually starting a valid transaction. */
+ if (unlikely(transaction_id >= NUM_TOTAL_TRANSACTIONS)) {
+ serial_dprintf("SPLIT: illegal transaction id\n");
+ return false;
+ }
+
+ split_shared_memory_lock_autounlock();
+
+ split_transaction_desc_t* transaction = &split_transaction_table[transaction_id];
+
+ /* Send transaction table index to the slave, which doubles as basic handshake token. */
+ if (unlikely(!serial_transport_send(&transaction_id, sizeof(transaction_id)))) {
+ serial_dprintf("SPLIT: sending handshake failed\n");
+ return false;
+ }
+
+ uint8_t transaction_id_shake = 0xFF;
+
+ /* Which we always read back first so that we can error out correctly.
+ * - due to the half duplex limitations on return codes, we always have to read *something*.
+ * - without the read, write only transactions *always* succeed, even during the boot process where the slave is not ready.
+ */
+ if (unlikely(!serial_transport_receive(&transaction_id_shake, sizeof(transaction_id_shake)) || (transaction_id_shake != (transaction_id ^ NUM_TOTAL_TRANSACTIONS)))) {
+ serial_dprintf("SPLIT: receiving handshake failed\n");
+ return false;
+ }
+
+ /* Send transaction buffer to the slave. If this transaction requires it. */
+ if (transaction->initiator2target_buffer_size) {
+ if (unlikely(!serial_transport_send(split_trans_initiator2target_buffer(transaction), transaction->initiator2target_buffer_size))) {
+ serial_dprintf("SPLIT: sending buffer failed\n");
+ return false;
+ }
+ }
+
+ /* Receive transaction buffer from the slave. If this transaction requires it. */
+ if (transaction->target2initiator_buffer_size) {
+ if (unlikely(!serial_transport_receive(split_trans_target2initiator_buffer(transaction), transaction->target2initiator_buffer_size))) {
+ serial_dprintf("SPLIT: receiving buffer failed\n");
+ return false;
+ }
+ }
+
+ return true;
+}