From 80839635abdc1c7cff0b3f5d2b31cc300f68fb7b Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Wed, 8 Apr 2015 15:27:31 -0600
Subject: SAMA5 Serial: Reading IMR and disabling interrupt must be atomic

---
 nuttx/ChangeLog                       |  4 ++++
 nuttx/arch/arm/src/sam34/sam_serial.c |  2 +-
 nuttx/arch/arm/src/sama5/sam_serial.c | 41 +++++++++++++++++++++++++----------
 nuttx/arch/arm/src/samv7/sam_serial.c |  2 +-
 4 files changed, 35 insertions(+), 14 deletions(-)

diff --git a/nuttx/ChangeLog b/nuttx/ChangeLog
index efa398960..e8383ba8f 100755
--- a/nuttx/ChangeLog
+++ b/nuttx/ChangeLog
@@ -10122,3 +10122,7 @@
 	  interrupts disabled (2015-04-08)
 	* arch/arm/src/sama5/sam_serial.c:  Backport support for flowcontrol and
 	  termios from SAM3/4 -- UNVERIFIED. (2015-04-08).
+	* arch/arm/src/sam34/sam_serial.c and samv7/sam_serial.c: The IMR
+	  register is read-only.  This means that sam_restoreints() did not
+	  actually re-enable UART interrupts (2015-04-08).
+
diff --git a/nuttx/arch/arm/src/sam34/sam_serial.c b/nuttx/arch/arm/src/sam34/sam_serial.c
index b2f98a582..d264aa349 100644
--- a/nuttx/arch/arm/src/sam34/sam_serial.c
+++ b/nuttx/arch/arm/src/sam34/sam_serial.c
@@ -650,7 +650,7 @@ static inline void up_serialout(struct up_dev_s *priv, int offset, uint32_t valu
 
 static inline void up_restoreusartint(struct up_dev_s *priv, uint32_t imr)
 {
-  /* Restore the previous interrupt state */
+  /* Restore the previous interrupt state (assuming all interrupts disabled) */
 
   up_serialout(priv, SAM_UART_IER_OFFSET, imr);
 }
diff --git a/nuttx/arch/arm/src/sama5/sam_serial.c b/nuttx/arch/arm/src/sama5/sam_serial.c
index 2f5f54870..935ee0e56 100644
--- a/nuttx/arch/arm/src/sama5/sam_serial.c
+++ b/nuttx/arch/arm/src/sama5/sam_serial.c
@@ -727,11 +727,22 @@ static inline void up_serialout(struct up_dev_s *priv, int offset, uint32_t valu
   putreg32(value, priv->usartbase + offset);
 }
 
+/****************************************************************************
+ * Name: up_restoreusartint
+ ****************************************************************************/
+
+static inline void up_restoreusartint(struct up_dev_s *priv, uint32_t imr)
+{
+  /* Restore the previous interrupt state (assuming all interrupts disabled) */
+
+  up_serialout(priv, SAM_UART_IER_OFFSET, imr);
+}
+
 /****************************************************************************
  * Name: up_disableallints
  ****************************************************************************/
 
-static void up_disableallints(struct up_dev_s *priv)
+static void up_disableallints(struct up_dev_s *priv, uint32_t *imr)
 {
   irqstate_t flags;
 
@@ -739,6 +750,13 @@ static void up_disableallints(struct up_dev_s *priv)
 
   flags = irqsave();
 
+  /* Return the current interrupt state */
+
+  if (imr)
+    {
+      *imr = up_serialin(priv, SAM_UART_IMR_OFFSET);
+    }
+
   /* Disable all interrupts */
 
   up_serialout(priv, SAM_UART_IDR_OFFSET, UART_INT_ALLINTS);
@@ -887,7 +905,7 @@ static void up_shutdown(struct uart_dev_s *dev)
 
   /* Disable all interrupts */
 
-  up_disableallints(priv);
+  up_disableallints(priv, NULL);
 }
 
 /****************************************************************************
@@ -1243,13 +1261,12 @@ static int up_ioctl(struct file *filep, int cmd, unsigned long arg)
              * implement TCSADRAIN / TCSAFLUSH
              */
 
-            imr = up_serialin(priv, SAM_UART_IMR_OFFSET);
-            up_disableallints(priv);
+            up_disableallints(priv, &imr);
             ret = up_setup(dev);
 
             /* Restore the interrupt state */
 
-            up_serialout(priv, SAM_UART_IER_OFFSET, imr);
+            up_restoreusartint(priv, imr);
           }
       }
       break;
@@ -1437,25 +1454,25 @@ void sam_earlyserialinit(void)
   /* Disable all USARTS */
 
 #ifdef TTYS0_DEV
-  up_disableallints(TTYS0_DEV.priv);
+  up_disableallints(TTYS0_DEV.priv, NULL);
 #endif
 #ifdef TTYS1_DEV
-  up_disableallints(TTYS1_DEV.priv);
+  up_disableallints(TTYS1_DEV.priv, NULL);
 #endif
 #ifdef TTYS2_DEV
-  up_disableallints(TTYS2_DEV.priv);
+  up_disableallints(TTYS2_DEV.priv, NULL);
 #endif
 #ifdef TTYS3_DEV
-  up_disableallints(TTYS3_DEV.priv);
+  up_disableallints(TTYS3_DEV.priv, NULL);
 #endif
 #ifdef TTYS4_DEV
-  up_disableallints(TTYS4_DEV.priv);
+  up_disableallints(TTYS4_DEV.priv, NULL);
 #endif
 #ifdef TTYS5_DEV
-  up_disableallints(TTYS5_DEV.priv);
+  up_disableallints(TTYS5_DEV.priv, NULL);
 #endif
 #ifdef TTYS6_DEV
-  up_disableallints(TTYS6_DEV.priv);
+  up_disableallints(TTYS6_DEV.priv, NULL);
 #endif
 
   /* Configuration whichever one is the console */
diff --git a/nuttx/arch/arm/src/samv7/sam_serial.c b/nuttx/arch/arm/src/samv7/sam_serial.c
index 896fcd405..1ffa8539b 100644
--- a/nuttx/arch/arm/src/samv7/sam_serial.c
+++ b/nuttx/arch/arm/src/samv7/sam_serial.c
@@ -710,7 +710,7 @@ static inline void sam_serialout(struct sam_dev_s *priv, int offset, uint32_t va
 
 static inline void sam_restoreusartint(struct sam_dev_s *priv, uint32_t imr)
 {
-  /* Restore the previous interrupt state */
+  /* Restore the previous interrupt state (assuming all interrupts disabled) */
 
   sam_serialout(priv, SAM_UART_IER_OFFSET, imr);
 }
-- 
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