libbase: blocking UART write if IRQs are enabled

diff --git a/software/libbase/uart.c b/software/libbase/uart.c
index 248e5f527020c5e6e774de0e97188e5689ddf9c0..e4e87ad683ca69d98a3f830eaa40eec2cf199707 100644 (file)
--- a/software/libbase/uart.c
+++ b/software/libbase/uart.c
@@ -23,8 +23,6 @@
 /*
  * Buffer sizes must be a power of 2 so that modulos can be computed
  * with logical AND.
- * RX functions are written in such a way that they do not require locking.
- * TX functions already implement locking.
  */
 
 #define UART_RINGBUFFER_SIZE_RX 128
@@ -41,6 +39,7 @@ static char tx_buf[UART_RINGBUFFER_SIZE_TX];
 static unsigned int tx_produce;
 static unsigned int tx_consume;
 static volatile int tx_cts;
+static volatile int tx_level;
 
 void uart_isr(void)
 {
@@ -54,9 +53,10 @@ void uart_isr(void)
        }
 
        if(stat & UART_EV_TX) {
-               if(tx_produce != tx_consume) {
+               if(tx_level > 0) {
                        CSR_UART_RXTX = tx_buf[tx_consume];
                        tx_consume = (tx_consume + 1) & UART_RINGBUFFER_MASK_TX;
+                       tx_level--;
                } else
                        tx_cts = 1;
        }
@@ -84,6 +84,10 @@ void uart_write(char c)
 {
        unsigned int oldmask;
        
+       if(irq_getie()) {
+               while(tx_level == UART_RINGBUFFER_SIZE_TX);
+       }
+       
        oldmask = irq_getmask();
        irq_setmask(0);
 
@@ -93,6 +97,7 @@ void uart_write(char c)
        } else {
                tx_buf[tx_produce] = c;
                tx_produce = (tx_produce + 1) & UART_RINGBUFFER_MASK_TX;
+               tx_level++;
        }
        irq_setmask(oldmask);
 }
@@ -103,9 +108,11 @@ void uart_init(void)
        
        rx_produce = 0;
        rx_consume = 0;
+       
        tx_produce = 0;
        tx_consume = 0;
        tx_cts = 1;
+       tx_level = 0;
 
        /* ack any events */
        CSR_UART_EV_PENDING = CSR_UART_EV_PENDING;