esp8266/uart: Add support for polling uart device.

3 files changed, 34 insertions, 2 deletions

diff --git a/esp8266/machine_uart.c b/esp8266/machine_uart.c
index 9bc6422cc7..efdfafd1ae 100644
--- a/esp8266/machine_uart.c
+++ b/esp8266/machine_uart.c
@@ -255,8 +255,22 @@ STATIC mp_uint_t pyb_uart_write(mp_obj_t self_in, const void *buf_in, mp_uint_t
 }
 
 STATIC mp_uint_t pyb_uart_ioctl(mp_obj_t self_in, mp_uint_t request, mp_uint_t arg, int *errcode) {
-    *errcode = MP_EINVAL;
-    return MP_STREAM_ERROR;
+    pyb_uart_obj_t *self = self_in;
+    mp_uint_t ret;
+    if (request == MP_STREAM_POLL) {
+        mp_uint_t flags = arg;
+        ret = 0;
+        if ((flags & MP_STREAM_POLL_RD) && uart_rx_any(self->uart_id)) {
+            ret |= MP_STREAM_POLL_RD;
+        }
+        if ((flags & MP_STREAM_POLL_WR) && uart_tx_any_room(self->uart_id)) {
+            ret |= MP_STREAM_POLL_WR;
+        }
+    } else {
+        *errcode = MP_EINVAL;
+        ret = MP_STREAM_ERROR;
+    }
+    return ret;
 }
 
 STATIC const mp_stream_p_t uart_stream_p = {
diff --git a/esp8266/uart.c b/esp8266/uart.c
index 001a9c673c..6c1f9e095d 100644
--- a/esp8266/uart.c
+++ b/esp8266/uart.c
@@ -200,6 +200,21 @@ bool uart_rx_wait(uint32_t timeout_us) {
     }
 }
 
+int uart_rx_any(uint8 uart) {
+    if (input_buf.iget != input_buf.iput) {
+        return true; // have at least 1 char ready for reading
+    }
+    return false;
+}
+
+int uart_tx_any_room(uint8 uart) {
+    uint32_t fifo_cnt = READ_PERI_REG(UART_STATUS(uart)) & (UART_TXFIFO_CNT << UART_TXFIFO_CNT_S);
+    if ((fifo_cnt >> UART_TXFIFO_CNT_S & UART_TXFIFO_CNT) >= 126) {
+        return false;
+    }
+    return true;
+}
+
 // Returns char from the input buffer, else -1 if buffer is empty.
 int uart_rx_char(void) {
     return ringbuf_get(&input_buf);
diff --git a/esp8266/uart.h b/esp8266/uart.h
index 2b97683ff8..f6850c42db 100644
--- a/esp8266/uart.h
+++ b/esp8266/uart.h
@@ -99,5 +99,8 @@ void uart_tx_one_char(uint8 uart, uint8 TxChar);
 void uart_flush(uint8 uart);
 void uart_os_config(int uart);
 void uart_setup(uint8 uart);
+// check status of rx/tx
+int uart_rx_any(uint8 uart);
+int uart_tx_any_room(uint8 uart);
 
 #endif // _INCLUDED_UART_H_