Add a file missed in the last commit

ChangeLog

@@ -11030,3 +11030,6 @@
 	* drivers/sensors/zerocross.c and include/nuttx/sensors/zerocross.h:
 	  Add Zero Cross device driver support.  From Alan Carvalho de Assis
 	  (2015-10-13).
+	* configs/stm32f4discovery/src/stm32_zerocross.c: Add low level support
+	  for the Zero Cross driver for the STM32F4-Discovery.  From Alan
+	  Carvalho de Assis (2015-10-13).

include/nuttx/sensors/zerocross.h

@@ -0,0 +1,151 @@
+/****************************************************************************
+ * include/nuttx/zerocross.h
+ *
+ *   Copyright (C) 2015 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#ifndef __NUTTX_SENSORS_ZEROCROSS_H
+#define __NUTTX_SENSORS_ZEROCROSS_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/fs/ioctl.h>
+
+#ifdef CONFIG_ZEROCROSS
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+/* Configuration ************************************************************
+ * CONFIG_ZEROCROSS - Enables support for the zero cross AC detection upper
+ *   half
+ */
+
+/* Command:     ZCIOC_REGISTER
+ * Description: Register to receive a signal whenever there is zero cross
+ *              interrupt event.
+ * Argument:    A read-only pointer to an instance of struct zc_notify_s
+ * Return:      Zero (OK) on success.  Minus one will be returned on failure
+ *              with the errno value set appropriately.
+ */
+
+#define ZCIOC_REGISTER   _ZCIOC(0x0001)
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/* This is the vtable that is used to by the upper half of the zero cross
+ * to call back into the lower half of the zero cross driver.
+ */
+
+struct zc_lowerhalf_s;
+
+/* This is the type of the discrete zero cross interrupt handler used with
+ * the struct zc_lowerhalf_s enable() method.
+ */
+
+typedef CODE void (*zc_interrupt_t)
+  (FAR const struct zc_lowerhalf_s *lower, FAR void *arg);
+
+/* This is the interface between the lower half zero cross detection driver
+ * and the upper half zero cross detection driver.  A (device-specific)
+ * instance of this structure is passed to the upper-half driver when the
+ * zero cross driver is registered.
+ *
+ * Normally that lower half logic will have its own, custom state structure
+ * that is simply cast to struct zc_lowerhalf_s.  In order to perform such
+ * casts, the initial fields of the custom state structure match the initial
+ * fields of the following generic lower half state structure.
+ */
+
+/* A reference to this structure is provided with the ZCIOC_REGISTER IOCTL
+ * command and describes the conditions under which the client would like
+ * to receive notification.
+ */
+
+struct zc_notify_s
+{
+  uint8_t          zc_signo;   /* Signal number to use in the notification */
+};
+
+struct zc_lowerhalf_s
+{
+  /* Enable interrupt on the defined pin used to zero cross detection */
+
+  CODE void (*zc_enable)(FAR const struct zc_lowerhalf_s *lower,
+                         zc_interrupt_t handler, FAR void *arg);
+};
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: zc_register
+ *
+ * Description:
+ *   Register the Zero Cross lower half device as 'devpath'
+ *
+ * Input Parameters:
+ *   devpath - The full path to the driver to register. E.g., "/dev/zc0"
+ *   lower - An instance of the lower half interface
+ *
+ * Returned Value:
+ *   Zero (OK) on success; a negated errno value on failure.
+ *
+ ****************************************************************************/
+
+int zc_register(FAR const char *devpath, FAR struct zc_lowerhalf_s *lower);
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* CONFIG_ZEROCROSS */
+#endif /* __NUTTX_SENSORS_ZEROCROSS_H */