tests: drivers: uart: uart_async_api: Tweak test_read_abort test

Test was staring a TX transfer and aborting it after 300 us from
the timer handler. Test was assuming that ongoing transfer will
not finish in those 300 us. This might not be true for higher
baudrates. Instead of using fixed timeout, a value is calculated
from the baudrate and targets to abort the transfer after approx.
20 bytes of 95 byte long transfer.

Signed-off-by: Krzysztof Chruściński <[email protected]>

tests/drivers/uart/uart_async_api/src/test_uart_async.c

@@ -589,6 +589,9 @@ static void *read_abort_setup(void)
 
 ZTEST_USER(uart_async_read_abort, test_read_abort)
 {
+	struct uart_config cfg;
+	int err;
+	uint32_t t_us;
 #if NOCACHE_MEM
 	static __aligned(32) uint8_t rx_buf[100] __used __NOCACHE;
 	static __aligned(32) uint8_t tx_buf[100] __used __NOCACHE;
@@ -600,17 +603,26 @@ ZTEST_USER(uart_async_read_abort, test_read_abort)
 	memset(rx_buf, 0, sizeof(rx_buf));
 	memset(tx_buf, 1, sizeof(tx_buf));
 
-	uart_rx_enable(uart_dev, rx_buf, sizeof(rx_buf), 50 * USEC_PER_MSEC);
+	err = uart_config_get(uart_dev, &cfg);
+	zassert_equal(err, 0);
+
+	/* Lets aim to abort after transmitting ~20 bytes (200 bauds) */
+	t_us = (20 * 10 * 1000000) / cfg.baudrate;
+
+	err = uart_rx_enable(uart_dev, rx_buf, sizeof(rx_buf), 50 * USEC_PER_MSEC);
+	zassert_equal(err, 0);
 	k_sem_give(&rx_buf_coherency);
 
-	uart_tx(uart_dev, tx_buf, 5, 100 * USEC_PER_MSEC);
+	err = uart_tx(uart_dev, tx_buf, 5, 100 * USEC_PER_MSEC);
+	zassert_equal(err, 0);
 	zassert_equal(k_sem_take(&tx_done, K_MSEC(100)), 0, "TX_DONE timeout");
 	zassert_equal(k_sem_take(&rx_rdy, K_MSEC(100)), 0, "RX_RDY timeout");
 	zassert_equal(memcmp(tx_buf, rx_buf, 5), 0, "Buffers not equal");
 
-	uart_tx(uart_dev, tx_buf, 95, 100 * USEC_PER_MSEC);
+	err = uart_tx(uart_dev, tx_buf, 95, 100 * USEC_PER_MSEC);
+	zassert_equal(err, 0);
 
-	k_timer_start(&read_abort_timer, K_USEC(300), K_NO_WAIT);
+	k_timer_start(&read_abort_timer, K_USEC(t_us), K_NO_WAIT);
 
 	/* RX will be aborted from k_timer timeout */