backport a serial console fix from the sam4e to the sama5d3

arch/arm/src/sam34/sam_lowputc.c

@@ -285,14 +285,16 @@ void up_lowputc(char ch)
     {
       /* Wait for the transmitter to be available */
 
-      while ((getreg32(SAM_CONSOLE_BASE + SAM_UART_SR_OFFSET) & UART_INT_TXEMPTY) == 0);
+      while ((getreg32(SAM_CONSOLE_BASE + SAM_UART_SR_OFFSET) &
+        UART_INT_TXEMPTY) == 0);
 
       /* Disable interrupts so that the test and the transmission are
        * atomic.
        */
 
       flags = irqsave();
-      if ((getreg32(SAM_CONSOLE_BASE + SAM_UART_SR_OFFSET) & UART_INT_TXEMPTY) != 0)
+      if ((getreg32(SAM_CONSOLE_BASE + SAM_UART_SR_OFFSET) &
+        UART_INT_TXEMPTY) != 0)
         {
           /* Send the character */
 

arch/arm/src/sama5/sam_lowputc.c

@@ -247,13 +247,59 @@
 
 void up_lowputc(char ch)
 {
-  /* Wait for the transmitter to be available */
+#ifdef HAVE_CONSOLE
+  irqstate_t flags;
 
-  while ((getreg32(SAM_CONSOLE_VBASE + SAM_UART_SR_OFFSET) & UART_INT_TXEMPTY) == 0);
+  for (;;)
+    {
+      /* Wait for the transmitter to be available */
 
-  /* Send the character */
+      while (((getreg32(SAM_CONSOLE_VBASE + SAM_UART_SR_OFFSET) &
+        UART_INT_TXEMPTY) == 0);
 
-  putreg32((uint32_t)ch, SAM_CONSOLE_VBASE + SAM_UART_THR_OFFSET);
+      /* Disable interrupts so that the test and the transmission are
+       * atomic.
+       */
+
+      flags = irqsave();
+      if ((getreg32(SAM_CONSOLE_VBASE + SAM_UART_SR_OFFSET) &
+        UART_INT_TXEMPTY) != 0)
+        {
+          /* Send the character */
+
+          putreg32((uint32_t)ch, SAM_CONSOLE_VBASE + SAM_UART_THR_OFFSET);
+          irqrestore(flags);
+          return;
+        }
+
+      irqrestore(flags);
+    }
+#endif
+}
+
+/****************************************************************************
+ * Name: up_putc
+ *
+ * Description:
+ *   Provide priority, low-level access to support OS debug writes
+ *
+ ****************************************************************************/
+
+int up_putc(int ch)
+{
+#ifdef HAVE_CONSOLE
+  /* Check for LF */
+
+  if (ch == '\n')
+    {
+      /* Add CR */
+
+      up_lowputc('\r');
+    }
+
+  up_lowputc(ch);
+#endif
+  return ch;
 }
 
 /**************************************************************************
@@ -373,5 +419,3 @@ void sam_lowsetup(void)
            SAM_CONSOLE_VBASE + SAM_UART_CR_OFFSET);
 #endif
 }
-
-

arch/arm/src/sama5/sam_serial.c

@@ -1189,90 +1189,4 @@ void up_serialinit(void)
 #endif
 }
 
-/****************************************************************************
- * Name: up_putc
- *
- * Description:
- *   Provide priority, low-level access to support OS debug writes.  This
- *   function is intended only to support early boot-up logic and serial
- *   debug output from interrupt handlers.  It is invasive and will effect
- *   your realtime performance!
- *
- ****************************************************************************/
-
-int up_putc(int ch)
-{
-#ifdef HAVE_CONSOLE
-  /* This logic does not work.  Apparently re-entrancy problems cause the
-   * loss of serial interrupts (a bad, zero IMR gets set).  My attempts to
-   * make this function fully re-entrant have not been successful but the
-   * following brute force approach works just fine.
-   */
-
-#if 0
-  struct up_dev_s *priv = (struct up_dev_s*)CONSOLE_DEV.priv;
-  uint32_t imr;
-
-  /* Disable serial interrupts */
-
-  up_disableallints(priv, &imr);
-#else
-  irqstate_t flags;
-
-  /* Disable all interrupts */
-
-  flags = irqsave();
-#endif
-
-  /* Check for LF */
-
-  if (ch == '\n')
-    {
-      /* Add CR */
-
-      up_lowputc('\r');
-    }
-
-  up_lowputc(ch);
-
-#if 0 /* See comments above */
-  /* Restore serial interrupts */
-
-  up_restoreusartint(priv, imr);
-#else
-  /* Restore all interrupts */
-
-  irqrestore(flags);
-#endif
-#endif
-  return ch;
-}
-
-#else /* USE_SERIALDRIVER */
-
-/****************************************************************************
- * Name: up_putc
- *
- * Description:
- *   Provide priority, low-level access to support OS debug writes
- *
- ****************************************************************************/
-
-int up_putc(int ch)
-{
-#ifdef HAVE_CONSOLE
-  /* Check for LF */
-
-  if (ch == '\n')
-    {
-      /* Add CR */
-
-      up_lowputc('\r');
-    }
-
-  up_lowputc(ch);
-#endif
-  return ch;
-}
-
 #endif /* USE_SERIALDRIVER */

configs/sam4e-ek/README.txt

@@ -660,7 +660,8 @@ USB Full-Speed Device
     b. If you change the value CONFIG_SYSTEM_USBMSC_DEVPATH1, then you
        can export other file systems:
 
-        "/dev/mmcsd0" would export the HSMCI SD slot
+        "/dev/mmcsd0" would export the HSMCI SD slot (not currently available,
+        see the "HSMCI" section).
 
         "/dev/ram0" could even be used to export a RAM disk.  But you would
          first have to use mkrd to create the RAM disk and mkfatfs to put
@@ -781,6 +782,14 @@ HSMCI
 
   The SD card contents will then be available under /mnt/sdcard.
 
+  NOTES:
+
+  1. DMA is not currently functional and without DMA, there may not be
+     reliable data transfers at high speeds due to data overrun problems.
+     The current HSMCI driver supports DMA via the DMAC.  However, the data
+     sheet only discusses PDC-based HSMCI DMA (although there is a DMA
+     channel interface definition for HSMCI).
+
 Touchscreen
 ===========
 
@@ -1171,7 +1180,12 @@ Configurations
        instructions provided above in the paragraph entitled "HSMCI."
 
        STATUS:
-         2014-3-21:  The HSMCI SD card slot has not yet been tested.
+         2014-3-24:  DMA is not currently functional and without DMA, there
+                     may not be reliable data transfers at high speeds due
+                     to data overrun problems.  The current HSMCI driver
+                     supports DMA via the DMAC.  However, the data sheet
+                     only discusses PDC-based HSMCI DMA (although there is
+                     a DMA channel interface definition for HSMCI).
 
   usbnsh: