bsp/xilinx-zynq: Add interrupt support to UART

c/src/lib/libbsp/arm/xilinx-zynq/configure.ac

@@ -59,6 +59,9 @@ simulation times.])
 RTEMS_BSPOPTS_SET([BSP_CONSOLE_MINOR],[*],[1])
 RTEMS_BSPOPTS_HELP([BSP_CONSOLE_MINOR],[minor number of console device])
 
+RTEMS_BSPOPTS_SET([ZYNQ_CONSOLE_USE_INTERRUPTS],[*],[1])
+RTEMS_BSPOPTS_HELP([ZYNQ_CONSOLE_USE_INTERRUPTS],[use interrupt driven mode for console devices (used by default)])
+
 ZYNQ_CPUS="1"
 RTEMS_CHECK_SMP
 AM_CONDITIONAL(HAS_SMP,[test "$rtems_cv_HAS_SMP" = "yes"])

c/src/lib/libbsp/arm/xilinx-zynq/console/zynq-uart.c

@@ -14,6 +14,7 @@
 
 #include <bsp/zynq-uart.h>
 #include <bsp/zynq-uart-regs.h>
+#include <bsp/irq.h>
 
 #include <bspopts.h>
 
@@ -128,6 +129,34 @@ void zynq_uart_initialize(rtems_termios_device_context *base)
     | ZYNQ_UART_CONTROL_RSTTO;
 }
 
+#ifdef ZYNQ_CONSOLE_USE_INTERRUPTS
+static void zynq_uart_interrupt(void *arg)
+{
+  rtems_termios_tty *tty = arg;
+  zynq_uart_context *ctx = rtems_termios_get_device_context(tty);
+  volatile zynq_uart *regs = ctx->regs;
+  uint32_t channel_sts;
+
+  if ((regs->irq_sts & (ZYNQ_UART_TIMEOUT | ZYNQ_UART_RTRIG)) != 0) {
+    regs->irq_sts = ZYNQ_UART_TIMEOUT | ZYNQ_UART_RTRIG;
+
+    do {
+      char c = (char) ZYNQ_UART_TX_RX_FIFO_FIFO_GET(regs->tx_rx_fifo);
+
+      rtems_termios_enqueue_raw_characters(tty, &c, 1);
+
+      channel_sts = regs->channel_sts;
+    } while ((channel_sts & ZYNQ_UART_CHANNEL_STS_REMPTY) == 0);
+  } else {
+    channel_sts = regs->channel_sts;
+  }
+
+  if (ctx->transmitting && (channel_sts & ZYNQ_UART_CHANNEL_STS_TEMPTY) != 0) {
+    rtems_termios_dequeue_characters(tty, 1);
+  }
+}
+#endif
+
 static bool zynq_uart_first_open(
   rtems_termios_tty *tty,
   rtems_termios_device_context *base,
@@ -135,12 +164,49 @@ static bool zynq_uart_first_open(
   rtems_libio_open_close_args_t *args
 )
 {
+#ifdef ZYNQ_CONSOLE_USE_INTERRUPTS
+  zynq_uart_context *ctx = (zynq_uart_context *) base;
+  volatile zynq_uart *regs = ctx->regs;
+  rtems_status_code sc;
+#endif
+
   rtems_termios_set_initial_baud(tty, ZYNQ_UART_DEFAULT_BAUD);
   zynq_uart_initialize(base);
 
+#ifdef ZYNQ_CONSOLE_USE_INTERRUPTS
+  regs->rx_timeout = 32;
+  regs->rx_fifo_trg_lvl = ZYNQ_UART_FIFO_DEPTH / 2;
+  regs->irq_dis = 0xffffffff;
+  regs->irq_sts = 0xffffffff;
+  regs->irq_en = ZYNQ_UART_RTRIG | ZYNQ_UART_TIMEOUT;
+  sc = rtems_interrupt_handler_install(
+    ctx->irq,
+    "UART",
+    RTEMS_INTERRUPT_SHARED,
+    zynq_uart_interrupt,
+    tty
+  );
+  if (sc != RTEMS_SUCCESSFUL) {
+    return false;
+  }
+#endif
+
   return true;
 }
 
+#ifdef ZYNQ_CONSOLE_USE_INTERRUPTS
+static void zynq_uart_last_close(
+  rtems_termios_tty *tty,
+  rtems_termios_device_context *base,
+  rtems_libio_open_close_args_t *args
+)
+{
+  zynq_uart_context *ctx = (zynq_uart_context *) base;
+
+  rtems_interrupt_handler_remove(ctx->irq, zynq_uart_interrupt, tty);
+}
+#endif
+
 int zynq_uart_read_polled(rtems_termios_device_context *base)
 {
   zynq_uart_context *ctx = (zynq_uart_context *) base;
@@ -168,17 +234,32 @@ void zynq_uart_write_polled(
   regs->tx_rx_fifo = ZYNQ_UART_TX_RX_FIFO_FIFO(c);
 }
 
-static void zynq_uart_write_support_polled(
+static void zynq_uart_write_support(
   rtems_termios_device_context *base,
-  const char *s,
-  size_t n
+  const char *buf,
+  size_t len
 )
 {
-  ssize_t i = 0;
+#ifdef ZYNQ_CONSOLE_USE_INTERRUPTS
+  zynq_uart_context *ctx = (zynq_uart_context *) base;
+  volatile zynq_uart *regs = ctx->regs;
 
-  for (i = 0; i < n; ++i) {
-    zynq_uart_write_polled(base, s[i]);
+  if (len > 0) {
+    ctx->transmitting = true;
+    regs->irq_sts = ZYNQ_UART_TEMPTY;
+    regs->irq_en = ZYNQ_UART_TEMPTY;
+    regs->tx_rx_fifo = ZYNQ_UART_TX_RX_FIFO_FIFO(buf[0]);
+  } else {
+    ctx->transmitting = false;
+    regs->irq_dis = ZYNQ_UART_TEMPTY;
   }
+#else
+  ssize_t i;
+
+  for (i = 0; i < len; ++i) {
+    zynq_uart_write_polled(base, buf[i]);
+  }
+#endif
 }
 
 static bool zynq_uart_set_attributes(
@@ -209,10 +290,15 @@ static bool zynq_uart_set_attributes(
 
 const rtems_termios_device_handler zynq_uart_handler = {
   .first_open = zynq_uart_first_open,
-  .write = zynq_uart_write_support_polled,
-  .poll_read = zynq_uart_read_polled,
   .set_attributes = zynq_uart_set_attributes,
+  .write = zynq_uart_write_support,
+#ifdef ZYNQ_CONSOLE_USE_INTERRUPTS
+  .last_close = zynq_uart_last_close,
+  .mode = TERMIOS_IRQ_DRIVEN
+#else
+  .poll_read = zynq_uart_read_polled,
   .mode = TERMIOS_POLLED
+#endif
 };
 
 void zynq_uart_reset_tx_flush(zynq_uart_context *ctx)

c/src/lib/libbsp/arm/xilinx-zynq/include/zynq-uart-regs.h

@@ -30,6 +30,8 @@
 
 #include <bsp/utility.h>
 
+#define ZYNQ_UART_FIFO_DEPTH 64
+
 typedef struct zynq_uart {
 	uint32_t control;
 #define ZYNQ_UART_CONTROL_STPBRK BSP_BIT32(8)

c/src/lib/libbsp/arm/xilinx-zynq/include/zynq-uart.h

@@ -36,6 +36,7 @@ extern "C" {
 typedef struct {
   rtems_termios_device_context base;
   volatile struct zynq_uart *regs;
+  bool transmitting;
   rtems_vector_number irq;
 } zynq_uart_context;