qmk_firmware/platforms/chibios/drivers/serial_usart.c

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// Copyright 2021 QMK
// Copyright 2022 Stefan Kerkmann
// SPDX-License-Identifier: GPL-2.0-or-later
#include "serial_usart.h"
#include "synchronization_util.h"
#if defined(SERIAL_USART_CONFIG)
static QMKSerialConfig serial_config = SERIAL_USART_CONFIG;
#else
static QMKSerialConfig serial_config = {
# if HAL_USE_SERIAL
.speed = (SERIAL_USART_SPEED), /* baudrate - mandatory */
# else
.baud = (SERIAL_USART_SPEED), /* baudrate - mandatory */
# endif
.cr1 = (SERIAL_USART_CR1),
.cr2 = (SERIAL_USART_CR2),
# if !defined(SERIAL_USART_FULL_DUPLEX)
.cr3 = ((SERIAL_USART_CR3) | USART_CR3_HDSEL) /* activate half-duplex mode */
# else
.cr3 = (SERIAL_USART_CR3)
# endif
};
#endif
static QMKSerialDriver* serial_driver = (QMKSerialDriver*)&SERIAL_USART_DRIVER;
static inline bool react_to_transactions(void);
static inline bool __attribute__((nonnull)) receive(uint8_t* destination, const size_t size);
static inline bool __attribute__((nonnull)) receive_blocking(uint8_t* destination, const size_t size);
static inline bool __attribute__((nonnull)) send(const uint8_t* source, const size_t size);
static inline bool initiate_transaction(uint8_t sstd_index);
static inline void usart_clear(void);
static inline void usart_driver_start(void);
#if HAL_USE_SERIAL
/**
* @brief SERIAL Driver startup routine.
*/
static inline void usart_driver_start(void) {
sdStart(serial_driver, &serial_config);
}
/**
* @brief Clear the receive input queue.
*/
static inline void usart_clear(void) {
osalSysLock();
bool volatile queue_not_empty = !iqIsEmptyI(&serial_driver->iqueue);
osalSysUnlock();
while (queue_not_empty) {
osalSysLock();
/* Hard reset the input queue. */
iqResetI(&serial_driver->iqueue);
osalSysUnlock();
/* Allow pending interrupts to preempt.
* Do not merge the lock/unlock blocks into one
* or the code will not work properly.
* The empty read adds a tiny amount of delay. */
(void)queue_not_empty;
osalSysLock();
queue_not_empty = !iqIsEmptyI(&serial_driver->iqueue);
osalSysUnlock();
}
}
#elif HAL_USE_SIO
void clear_rx_evt_cb(SIODriver* siop) {
osalSysLockFromISR();
/* If errors occured during transactions this callback is invoked. We just
* clear the error sources and move on. We rely on the fact that we check
* for the success of the transaction by comparing the received/send bytes
* with the actual received/send bytes in the send/receive functions. */
sioGetAndClearEventsI(serial_driver);
osalSysUnlockFromISR();
}
static const SIOOperation serial_usart_operation = {.rx_cb = NULL, .rx_idle_cb = NULL, .tx_cb = NULL, .tx_end_cb = NULL, .rx_evt_cb = &clear_rx_evt_cb};
/**
* @brief SIO Driver startup routine.
*/
static inline void usart_driver_start(void) {
sioStart(serial_driver, &serial_config);
sioStartOperation(serial_driver, &serial_usart_operation);
}
/**
* @brief Clear the receive input queue, as some MCUs have built-in hardware FIFOs.
*/
static inline void usart_clear(void) {
osalSysLock();
while (!sioIsRXEmptyX(serial_driver)) {
(void)sioGetX(serial_driver);
}
osalSysUnlock();
}
#else
# error Either the SERIAL or SIO driver has to be activated to use the usart driver for split keyboards.
#endif
/**
* @brief Blocking send of buffer with timeout.
*
* @return true Send success.
* @return false Send failed.
*/
static inline bool send(const uint8_t* source, const size_t size) {
bool success = (size_t)chnWriteTimeout(serial_driver, source, size, TIME_MS2I(SERIAL_USART_TIMEOUT)) == size;
#if !defined(SERIAL_USART_FULL_DUPLEX)
/* Half duplex fills the input queue with the data we wrote - just throw it away. */
if (likely(success)) {
size_t bytes_left = size;
# if HAL_USE_SERIAL
/* The SERIAL driver uses large soft FIFOs that are filled from an IRQ
* context, so there is a delay between receiving the data and it
* becoming actually available, therefore we have to apply a timeout
* mechanism. Under the right circumstances (e.g. bad cables paired with
* high baud rates) less bytes can be present in the input queue as
* well. */
uint8_t dump[64];
while (unlikely(bytes_left >= 64)) {
if (unlikely(!receive(dump, 64))) {
return false;
}
bytes_left -= 64;
}
return receive(dump, bytes_left);
# else
/* The SIO driver directly accesses the hardware FIFOs of the USART
* peripheral. As these are limited in depth, the RX FIFO might have been
* overflowed by a large that we just send. Therefore we attempt to read
* back all the data we send or until the FIFO runs empty in case it
* overflowed and data was truncated. */
if (unlikely(sioSynchronizeTXEnd(serial_driver, TIME_MS2I(SERIAL_USART_TIMEOUT)) < MSG_OK)) {
return false;
}
osalSysLock();
while (bytes_left > 0 && !sioIsRXEmptyX(serial_driver)) {
(void)sioGetX(serial_driver);
bytes_left--;
}
osalSysUnlock();
# endif
}
#endif
return success;
}
/**
* @brief Blocking receive of size * bytes with timeout.
*
* @return true Receive success.
* @return false Receive failed, e.g. by timeout.
*/
static inline bool receive(uint8_t* destination, const size_t size) {
bool success = (size_t)chnReadTimeout(serial_driver, destination, size, TIME_MS2I(SERIAL_USART_TIMEOUT)) == size;
return success;
}
/**
* @brief Blocking receive of size * bytes.
*
* @return true Receive success.
* @return false Receive failed.
*/
static inline bool receive_blocking(uint8_t* destination, const size_t size) {
bool success = (size_t)chnRead(serial_driver, destination, size) == size;
return success;
}
#if !defined(SERIAL_USART_FULL_DUPLEX)
/**
* @brief Initiate pins for USART peripheral. Half-duplex configuration.
*/
__attribute__((weak)) void usart_init(void) {
# if defined(MCU_STM32)
# if defined(USE_GPIOV1)
palSetLineMode(SERIAL_USART_TX_PIN, PAL_MODE_ALTERNATE_OPENDRAIN);
# else
palSetLineMode(SERIAL_USART_TX_PIN, PAL_MODE_ALTERNATE(SERIAL_USART_TX_PAL_MODE) | PAL_OUTPUT_TYPE_OPENDRAIN);
# endif
# if defined(USART_REMAP)
USART_REMAP;
# endif
# else
# pragma message "usart_init: MCU Familiy not supported by default, please supply your own init code by implementing usart_init() in your keyboard files."
# endif
}
#else
/**
* @brief Initiate pins for USART peripheral. Full-duplex configuration.
*/
__attribute__((weak)) void usart_init(void) {
# if defined(MCU_STM32)
# if defined(USE_GPIOV1)
palSetLineMode(SERIAL_USART_TX_PIN, PAL_MODE_ALTERNATE_PUSHPULL);
palSetLineMode(SERIAL_USART_RX_PIN, PAL_MODE_INPUT);
# else
palSetLineMode(SERIAL_USART_TX_PIN, PAL_MODE_ALTERNATE(SERIAL_USART_TX_PAL_MODE) | PAL_OUTPUT_TYPE_PUSHPULL | PAL_OUTPUT_SPEED_HIGHEST);
palSetLineMode(SERIAL_USART_RX_PIN, PAL_MODE_ALTERNATE(SERIAL_USART_RX_PAL_MODE) | PAL_OUTPUT_TYPE_PUSHPULL | PAL_OUTPUT_SPEED_HIGHEST);
# endif
# if defined(USART_REMAP)
USART_REMAP;
# endif
# else
# pragma message "usart_init: MCU Familiy not supported by default, please supply your own init code by implementing usart_init() in your keyboard files."
# endif
}
#endif
/**
* @brief Overridable master specific initializations.
*/
__attribute__((weak, nonnull)) void usart_master_init(QMKSerialDriver** driver) {
(void)driver;
usart_init();
}
/**
* @brief Overridable slave specific initializations.
*/
__attribute__((weak, nonnull)) void usart_slave_init(QMKSerialDriver** driver) {
(void)driver;
usart_init();
}
/**
* @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("usart_tx_rx");
while (true) {
if (unlikely(!react_to_transactions())) {
/* Clear the receive queue, to start with a clean slate.
* Parts of failed transactions or spurious bytes could still be in it. */
usart_clear();
}
split_shared_memory_unlock();
}
}
/**
* @brief Slave specific initializations.
*/
void soft_serial_target_init(void) {
usart_slave_init(&serial_driver);
usart_driver_start();
/* Start transport thread. */
chThdCreateStatic(waSlaveThread, sizeof(waSlaveThread), HIGHPRIO, SlaveThread, NULL);
}
/**
* @brief React to transactions started by the master.
*/
static inline bool react_to_transactions(void) {
/* Wait until there is a transaction for us. */
uint8_t sstd_index = 0;
receive_blocking(&sstd_index, sizeof(sstd_index));
/* Sanity check that we are actually responding to a valid transaction. */
if (unlikely(sstd_index >= NUM_TOTAL_TRANSACTIONS)) {
return false;
}
split_shared_memory_lock();
split_transaction_desc_t* trans = &split_transaction_table[sstd_index];
/* Send back the handshake which is XORed as a simple checksum,
to signal that the slave is ready to receive possible transaction buffers */
sstd_index ^= HANDSHAKE_MAGIC;
if (unlikely(!send(&sstd_index, sizeof(sstd_index)))) {
return false;
}
/* Receive transaction buffer from the master. If this transaction requires it.*/
if (trans->initiator2target_buffer_size) {
if (unlikely(!receive(split_trans_initiator2target_buffer(trans), trans->initiator2target_buffer_size))) {
return false;
}
}
/* Allow any slave processing to occur. */
if (trans->slave_callback) {
trans->slave_callback(trans->initiator2target_buffer_size, split_trans_initiator2target_buffer(trans), trans->initiator2target_buffer_size, split_trans_target2initiator_buffer(trans));
}
/* Send transaction buffer to the master. If this transaction requires it. */
if (trans->target2initiator_buffer_size) {
if (unlikely(!send(split_trans_target2initiator_buffer(trans), trans->target2initiator_buffer_size))) {
return false;
}
}
return true;
}
/**
* @brief Master specific initializations.
*/
void soft_serial_initiator_init(void) {
usart_master_init(&serial_driver);
#if defined(MCU_STM32) && defined(SERIAL_USART_PIN_SWAP)
serial_config.cr2 |= USART_CR2_SWAP; // master has swapped TX/RX pins
#endif
usart_driver_start();
}
/**
* @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) {
/* Clear the receive queue, to start with a clean slate.
* Parts of failed transactions or spurious bytes could still be in it. */
usart_clear();
split_shared_memory_lock();
bool result = initiate_transaction((uint8_t)index);
split_shared_memory_unlock();
return result;
}
/**
* @brief Initiate transaction to slave half.
*/
static inline bool initiate_transaction(uint8_t sstd_index) {
/* Sanity check that we are actually starting a valid transaction. */
if (unlikely(sstd_index >= NUM_TOTAL_TRANSACTIONS)) {
dprintln("USART: Illegal transaction Id.");
return false;
}
split_transaction_desc_t* trans = &split_transaction_table[sstd_index];
/* Send transaction table index to the slave, which doubles as basic handshake token. */
if (unlikely(!send(&sstd_index, sizeof(sstd_index)))) {
dprintln("USART: Send Handshake failed.");
return false;
}
uint8_t sstd_index_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(!receive(&sstd_index_shake, sizeof(sstd_index_shake)) || (sstd_index_shake != (sstd_index ^ HANDSHAKE_MAGIC)))) {
dprintln("USART: Handshake failed.");
return false;
}
/* Send transaction buffer to the slave. If this transaction requires it. */
if (trans->initiator2target_buffer_size) {
if (unlikely(!send(split_trans_initiator2target_buffer(trans), trans->initiator2target_buffer_size))) {
dprintln("USART: Send failed.");
return false;
}
}
/* Receive transaction buffer from the slave. If this transaction requires it. */
if (trans->target2initiator_buffer_size) {
if (unlikely(!receive(split_trans_target2initiator_buffer(trans), trans->target2initiator_buffer_size))) {
dprintln("USART: Receive failed.");
return false;
}
}
return true;
}