Fix implementation of Tx IRQ for serial ports. BufferedSerial works now!

Author: multiplemonomials

hal/include/hal/serial_api.h

@@ -255,8 +255,10 @@ void serial_format(serial_t *obj, int data_bits, SerialParity parity, int stop_b
 /** The serial interrupt handler registration
  *
  * @param obj     The serial object
- * @param handler The interrupt handler which will be invoked when the interrupt fires
- * @param id      The SerialBase object
+ * @param handler The interrupt handler function which will be invoked when the interrupt fires.  The handler
+ *     function pointer must be common among all serial instances.
+ * @param id      The SerialBase object.  This shall be passed to \c handler when it's
+ *     invoked for this serial instance.
  */
 void serial_irq_handler(serial_t *obj, uart_irq_handler handler, uint32_t id);
 

targets/TARGET_RASPBERRYPI/TARGET_RP2040/objects.h

@@ -51,6 +51,8 @@ extern "C" {
 
 #include "cmsis.h"
 
+#include <stdbool.h>
+
 #include "PortNames.h"
 #include "PeripheralNames.h"
 #include "PinNames.h"
@@ -91,6 +93,10 @@ struct serial_s {
     PinName pin_rts;
     PinName pin_cts;
     uint32_t baud;
+
+    // Current states of the IRQ enables for Tx and Rx
+    bool txIrqEnabled;
+    bool rxIrqEnabled;
 };
 
 struct i2c_s {

targets/TARGET_RASPBERRYPI/TARGET_RP2040/serial_api.c

@@ -30,6 +30,9 @@ extern "C" {
 int stdio_uart_inited = 0;
 serial_t stdio_uart;
 
+static inline void uart0_irq(void);
+static inline void uart1_irq(void);
+
 void serial_init(serial_t *obj, PinName tx, PinName rx)
 {
     if (tx == STDIO_UART_TX && stdio_uart_inited != 0) {
@@ -62,8 +65,15 @@ void serial_init(serial_t *obj, PinName tx, PinName rx)
     //uart_set_translate_crlf(obj->dev, false);
     uart_set_fifo_enabled(obj->dev, false);
 
+    // Prepare interrupt.  Note that we set it to enabled here, but the interrupt
+    // won't fire yet because we haven't enabled any interrupt sources.
+    int UART_IRQ = obj->dev == uart0 ? UART0_IRQ : UART1_IRQ;
+    irq_set_exclusive_handler(UART_IRQ, obj->dev == uart0 ? uart0_irq : uart1_irq);
+    irq_clear(UART_IRQ);
+    irq_set_enabled(UART_IRQ, true);
+
     if (tx == STDIO_UART_TX) {
-        memmove(&stdio_uart, obj, sizeof(serial_t));
+        memcpy(&stdio_uart, obj, sizeof(serial_t));
         stdio_uart_inited = 1;
     }
 }
@@ -102,14 +112,23 @@ void serial_format(serial_t *obj, int data_bits, SerialParity parity, int stop_b
 static volatile uart_irq_handler irq_handler;
 static volatile uint32_t serial_irq_ids[2] = {0};
 
-static inline void uart0_irq(void)
-{
-    irq_handler(serial_irq_ids[0], RxIrq);
+static inline void uart0_irq(void) {
+    if(uart_is_writable(uart0)) {
+        irq_handler(serial_irq_ids[0], TxIrq);
+    }
+    if(uart_is_readable(uart0)) {
+        irq_handler(serial_irq_ids[0], RxIrq);
+    }
 }
 
 static inline void uart1_irq(void)
 {
-    irq_handler(serial_irq_ids[1], RxIrq);
+    if(uart_is_writable(uart1)) {
+        irq_handler(serial_irq_ids[1], TxIrq);
+    }
+    if(uart_is_readable(uart1)) {
+        irq_handler(serial_irq_ids[1], RxIrq);
+    }
 }
 
 void serial_irq_handler(serial_t *obj, uart_irq_handler handler, uint32_t id)
@@ -124,12 +143,14 @@ void serial_irq_handler(serial_t *obj, uart_irq_handler handler, uint32_t id)
 
 void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable)
 {
-    int UART_IRQ = obj->dev == uart0 ? UART0_IRQ : UART1_IRQ;
-
-    irq_set_exclusive_handler(UART_IRQ, obj->dev == uart0 ? uart0_irq : uart1_irq);
-    irq_set_enabled(UART_IRQ, enable);
+    if(irq == RxIrq) {
+        obj->rxIrqEnabled = enable;
+    }
+    else if(irq == TxIrq) {
+        obj->txIrqEnabled = enable;
+    }
 
-    uart_set_irq_enables(obj->dev, irq == RxIrq, irq == TxIrq);
+    uart_set_irq_enables(obj->dev, obj->rxIrqEnabled, obj->txIrqEnabled);
 }
 
 int serial_getc(serial_t *obj)