Add generic, upper-half PWM driver

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@4191 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 422 insertions, 0 deletions

diff --git a/nuttx/drivers/pwm.c b/nuttx/drivers/pwm.c
new file mode 100644
index 000000000..c870adfe4
--- /dev/null
+++ b/nuttx/drivers/pwm.c
@@ -0,0 +1,422 @@
+/****************************************************************************
+ * drivers/pwm.c
+ *
+ *   Copyright (C) 2011 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Compilation Switches
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <semaphore.h>
+#include <fcntl.h>
+#include <assert.h>
+#include <errno.h>
+#include <debug.h>
+
+#include <nuttx/fs.h>
+#include <nuttx/arch.h>
+#include <nuttx/pwm.h>
+
+#include <arch/irq.h>
+
+#ifdef CONFIG_PWM
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Type Definitions
+ ****************************************************************************/
+
+/* This structure describes the state of the upper half drivere */
+
+struct pwm_upperhalf_s
+{
+  uint8_t           crefs;          /* The number of times the device has been opened */
+  bool              started;        /* True: pulsed output is being generated */
+  sem_t             sem;            /* Supports mutual exclusion */
+  struct pwm_info_s info;           /* Pulsed output characteristics */
+  FAR struct pwm_lowerhalf_s *dev;  /* lower-half state */
+};
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+static int     pwm_open(FAR struct file *filep);
+static int     pwm_close(FAR struct file *filep);
+static ssize_t pwm_read(FAR struct file *filep, FAR char *buffer, size_t buflen);
+static ssize_t pwm_write(FAR struct file *filep, FAR const char *buffer, size_t buflen);
+static int     pwm_ioctl(FAR struct file *filep, int cmd, unsigned long arg);
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct file_operations g_pwmops =
+{
+  pwm_open,  /* open */
+  pwm_close, /* close */
+  pwm_read,  /* read */
+  pwm_write, /* write */
+  0,         /* seek */
+  pwm_ioctl  /* ioctl */
+#ifndef CONFIG_DISABLE_POLL
+  , 0        /* poll */
+#endif
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/************************************************************************************
+ * Name: pwm_open
+ *
+ * Description:
+ *   This function is called whenever the PWM device is opened.
+ *
+ ************************************************************************************/
+
+static int pwm_open(FAR struct file *filep)
+{
+  FAR struct inode           *inode = filep->f_inode;
+  FAR struct pwm_upperhalf_s *upper = inode->i_private;
+  uint8_t                     tmp;
+  int                         ret;
+
+  /* Get exclusive access to the device structures */
+
+  ret = sem_wait(&upper->sem);
+  if (ret < 0)
+    {
+      ret = -errno;
+      goto errout;
+    }
+
+  /* Increment the count of references to the device.  If this the first
+   * time that the driver has been opened for this device, then initialize
+   * the device.
+   */
+
+  tmp = upper->crefs + 1;
+  if (tmp == 0)
+    {
+      /* More than 255 opens; uint8_t overflows to zero */
+
+      ret = -EMFILE;
+      goto errout_with_sem;
+    }
+
+  /* Check if this is the first time that the driver has been opened. */
+
+  if (tmp == 1)
+    {
+      FAR struct pwm_lowerhalf_s *lower = upper->dev;
+
+      /* Yes.. perform one time hardware initialization. */
+
+      ret = lower->ops->setup(lower);
+      if (ret < 0)
+        {
+          goto errout_with_sem;
+        }
+    }
+
+  /* Save the new open count on success */
+
+  upper->crefs = tmp;
+  ret = OK;
+
+errout_with_sem:
+  sem_post(&upper->sem);
+  
+errout:
+  return ret;
+}
+
+/************************************************************************************
+ * Name: pwm_close
+ *
+ * Description:
+ *   This function is called when the PWM device is closed.
+ *
+ ************************************************************************************/
+
+static int pwm_close(FAR struct file *filep)
+{
+  FAR struct inode           *inode = filep->f_inode;
+  FAR struct pwm_upperhalf_s *upper = inode->i_private;
+  int                         ret;
+
+  /* Get exclusive access to the device structures */
+
+  ret = sem_wait(&upper->sem);
+  if (ret < 0)
+    {
+      ret = -errno;
+      goto errout;
+    }
+
+  /* Decrement the references to the driver.  If the reference count will
+   * decrement to 0, then uninitialize the driver.
+   */
+
+  if (upper->crefs > 1)
+    {
+      upper->crefs--;
+    }
+  else
+    {
+      FAR struct pwm_lowerhalf_s *lower = upper->dev;
+
+      /* There are no more references to the port */
+
+      upper->crefs = 0;
+
+      /* Disable the PWM device */
+
+      lower->ops->shutdown(lower);
+    }
+  ret = OK;
+
+//errout_with_sem:
+  sem_post(&upper->sem);
+  
+errout:
+  return ret;
+}
+
+/************************************************************************************
+ * Name: pwm_read
+ *
+ * Description:
+ *   A dummy read method.  This is provided only to satsify the VFS layer.
+ *
+ ************************************************************************************/
+
+static ssize_t pwm_read(FAR struct file *filep, FAR char *buffer, size_t buflen)
+{
+  /* Return zero -- usually meaning end-of-file */
+
+  return 0;
+}
+
+/************************************************************************************
+ * Name: pwm_write
+ *
+ * Description:
+ *   A dummy write method.  This is provided only to satsify the VFS layer.
+ *
+ ************************************************************************************/
+
+static ssize_t pwm_write(FAR struct file *filep, FAR const char *buffer, size_t buflen)
+{
+  return 0;
+}
+
+/************************************************************************************
+ * Name: pwm_ioctl
+ *
+ * Description:
+ *   The standard ioctl method.  This is where ALL of the PWM work is done.
+ *   
+ ************************************************************************************/
+
+static int pwm_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
+{
+  FAR struct inode           *inode = filep->f_inode;
+  FAR struct pwm_upperhalf_s *upper = inode->i_private;
+  FAR struct pwm_lowerhalf_s *lower = upper->dev;
+  int                         ret   = OK;
+
+  /* Handle built-in ioctl commands */
+
+  switch (cmd)
+    {
+      /* PWMIOC_SETCHARACTERISTICS - Set the characteristics of the next pulsed
+       *   output.  This command will neither start nor stop the pulsed output.
+       *   It will either setup the configuration that will be used when the
+       *   output is started; or it will change the characteristics of the pulsed
+       *   output on the fly if the timer is already started.
+       *
+       *   ioctl argument:  A read-only reference to struct pwm_info_s that provides
+       *   the characteristics of the pulsed output.
+       */
+
+      case PWMIOC_SETCHARACTERISTICS:
+        {
+          FAR const struct pwm_info_s *info = (FAR const struct pwm_info_s*)((uintptr_t)arg);
+          memcpy(&upper->info, info, sizeof(struct pwm_info_s));
+          if (upper->started)
+            {
+              ret = lower->ops->start(lower, &upper->info);
+            }
+        }
+        break;
+
+      /* PWMIOC_GETCHARACTERISTICS - Get the currently selected characteristics of
+       *   the pulsed output (independent of whether the output is start or stopped).
+       *
+       *   ioctl argument:  A reference to struct pwm_info_s to recevie the
+       *   characteristics of the pulsed output.
+       */
+
+      case PWMIOC_GETCHARACTERISTICS:
+        {
+          FAR struct pwm_info_s *info = (FAR struct pwm_info_s*)((uintptr_t)arg);
+          memcpy(info, &upper->info, sizeof(struct pwm_info_s));
+        }
+        break;
+
+      /* PWMIOC_START - Start the pulsed output.  The PWMIOC_SETCHARACTERISTICS
+       *   command must have previously been sent.
+       *
+       *   ioctl argument:  None
+       */
+
+      case PWMIOC_START:
+        {
+          if (!upper->started)
+            {
+              ret = lower->ops->start(lower, &upper->info);
+              upper->started = true;
+            }
+        }
+        break;
+
+      /* PWMIOC_STOP - Stop the pulsed output.
+       *
+       *   ioctl argument:  None
+       */
+
+      case PWMIOC_STOP:
+        {
+          if (upper->started)
+            {
+              ret = lower->ops->stop(lower);
+              upper->started = false;
+            }
+        }
+        break;
+
+      /* PWMIOC_GETPULSECOUNT - Return the number of pulses generated.
+       *
+       *   ioctl argument:  A pointer to a pwm_count_t variable that will be used to
+       *     receive the pulse count
+       */
+
+      case PWMIOC_GETPULSECOUNT:
+        {
+          FAR pwm_count_t *count = (FAR pwm_count_t *)((uintptr_t)arg);
+          ret = lower->ops->pulsecount(lower, count);
+        }
+        break;
+
+      /* Any unrecognized IOCTL commands might be platform-specific ioctl commands */
+
+      default:
+        {
+          ret = lower->ops->ioctl(lower, cmd, arg);
+        }
+        break;
+    }
+  return ret;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: pwm_register
+ *
+ * Description:
+ *   This function binds an instance of a "lower half" timer driver with the
+ *   "upper half" PWM device and registers that device so that can be used
+ *   by application code.
+ *
+ *   When this function is called, the "lower half" driver should be in the
+ *   reset state (as if the shutdown() method had already been called).
+ *
+ * Input parameters:
+ *   path - The full path to the driver to be registers in the NuttX pseudo-
+ *     filesystem.  The recommended convention is to name all PWM drivers
+ *     as "/dev/pwm0", "/dev/pwm1", etc.  where the driver path differs only
+ *     in the "minor" number at the end of the device name.
+ *   dev - A pointer to an instance of lower half timer driver.  This instance
+ *     is bound to the PWM driver and must persists as long as the driver
+ *     persists.
+ *
+ * Returned Value:
+ *   Zero on success; a negated errno value on failure.
+ *
+ ****************************************************************************/
+
+int pwm_register(FAR const char *path, FAR struct pwm_lowerhalf_s *dev)
+{
+  FAR struct pwm_upperhalf_s *upper;
+
+  /* Allocate the upper-half data structure */
+
+  upper = (FAR struct pwm_upperhalf_s *)zalloc(sizeof(struct pwm_upperhalf_s));
+  if (!upper)
+    {
+      return -ENOMEM;
+    }
+
+  /* Initialize the PWM device structure (it was already zeroed by zalloc()) */
+
+  sem_init(&upper->sem, 0, 1);
+  upper->dev = dev;
+
+  /* Register the PWM device */
+
+  vdbg("Registering %s\n", path);
+  return register_driver(path, &g_pwmops, 0666, dev);
+}
+
+#endif /* CONFIG_PWM */