From 9685fd8c99c727e5e8558a50252031b48baee44a Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Mon, 1 Aug 2016 13:52:27 -0600
Subject: [PATCH] GPIO driver:  Add an IOCTL to unregister a signal handler

---
 drivers/ioexpander/gpio.c       | 27 +++++++++++++++++++++++++++
 include/nuttx/ioexpander/gpio.h | 13 +++++++++----
 2 files changed, 36 insertions(+), 4 deletions(-)

diff --git a/drivers/ioexpander/gpio.c b/drivers/ioexpander/gpio.c
index 137d988ee8..bf256e8a0a 100644
--- a/drivers/ioexpander/gpio.c
+++ b/drivers/ioexpander/gpio.c
@@ -268,6 +268,33 @@ static int gpio_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
           }
         break;
 
+      /* Command:     GPIOC_UNREGISTER
+       * Description: Stop receiving signals for pin interrupts.
+       * Argument:    None.
+       */
+
+      case GPIOC_UNREGISTER:
+        if (dev->gp_pintype == GPIO_INTERRUPT_PIN)
+          {
+            /* Make sure that the pin interrupt is disabled */
+
+            ret = dev->gp_ops->go_enable(dev, false);
+            if (ret >= 0)
+              {
+                /* Detach the handler */
+
+                ret = dev->gp_ops->go_attach(dev, NULL);
+
+                dev->gp_pid   = 0;
+                dev->gp_signo = 0;
+              }
+          }
+        else
+          {
+            ret = -EACCES;
+          }
+        break;
+
       /* Unrecognized command */
 
       default:
diff --git a/include/nuttx/ioexpander/gpio.h b/include/nuttx/ioexpander/gpio.h
index 7d8028e86f..287d0fa9d2 100644
--- a/include/nuttx/ioexpander/gpio.h
+++ b/include/nuttx/ioexpander/gpio.h
@@ -70,12 +70,17 @@
  *              depends upon interrupt GPIO support from the platform.
  * Argument:    The number of signal to be generated when the interrupt
  *              occurs.
+ *
+ * Command:     GPIOC_UNREGISTER
+ * Description: Stop receiving signals for pin interrupts.
+ * Argument:    None.
  */
 
-#define GPIOC_WRITE    _GPIOC(1)
-#define GPIOC_READ     _GPIOC(2)
-#define GPIOC_PINTYPE  _GPIOC(3)
-#define GPIOC_REGISTER _GPIOC(4)
+#define GPIOC_WRITE      _GPIOC(1)
+#define GPIOC_READ       _GPIOC(2)
+#define GPIOC_PINTYPE    _GPIOC(3)
+#define GPIOC_REGISTER   _GPIOC(4)
+#define GPIOC_UNREGISTER _GPIOC(5)
 
 /****************************************************************************
  * Public Types