static void usart_tx_interrupt_handler(struct usart_config const *config)
{
intptr_t base = config->hw->base;
uint8_t byte;
if (!(STM32_USART_SR(base) & STM32_USART_SR_TXE))
return;
if (queue_remove_unit(config->consumer.queue, &byte)) {
STM32_USART_TDR(base) = byte;
/*
* Make sure the TXE interrupt is enabled and that we won't go
* into deep sleep. This invocation of the USART interrupt
* handler may have been manually triggered to start
* transmission.
*/
disable_sleep(SLEEP_MASK_UART);
STM32_USART_CR1(base) |= STM32_USART_CR1_TXEIE;
} else {
/*
* The TX queue is empty, disable the TXE interrupt and enable
* deep sleep mode. The TXE interrupt will remain disabled
* until a write call happens.
*/
enable_sleep(SLEEP_MASK_UART);
STM32_USART_CR1(base) &= ~STM32_USART_CR1_TXEIE;
}
}
static void usart_rx_init(struct usart_config const *config)
{
intptr_t base = config->hw->base;
STM32_USART_CR1(base) |= STM32_USART_CR1_RXNEIE;
STM32_USART_CR1(base) |= STM32_USART_CR1_RE;
}
static void usart_written(struct consumer const *consumer, size_t count)
{
struct usart_config const *config =
DOWNCAST(consumer, struct usart_config, consumer);
/*
* Enable USART interrupt. This causes the USART interrupt handler to
* start fetching from the TX queue if it wasn't already.
*/
if (count)
STM32_USART_CR1(config->hw->base) |= STM32_USART_CR1_TXEIE;
}
static void uart_init(void)
{
/* set baudrate */
STM32_USART_BRR(UARTN) =
DIV_ROUND_NEAREST(CPU_CLOCK, CONFIG_UART_BAUD_RATE);
/* UART enabled, 8 Data bits, oversampling x16, no parity */
STM32_USART_CR1(UARTN) =
STM32_USART_CR1_UE | STM32_USART_CR1_TE | STM32_USART_CR1_RE;
/* 1 stop bit, no fancy stuff */
STM32_USART_CR2(UARTN) = 0x0000;
/* DMA disabled, special modes disabled, error interrupt disabled */
STM32_USART_CR3(UARTN) = 0x0000;
}
static void usart_flush(struct consumer const *consumer)
{
struct usart_config const *config =
DOWNCAST(consumer, struct usart_config, consumer);
/*
* Enable USART interrupt. This causes the USART interrupt handler to
* start fetching from the TX queue if it wasn't already.
*/
STM32_USART_CR1(config->hw->base) |= STM32_USART_CR1_TXEIE;
while (queue_count(consumer->queue))
;
}
