Moved last libs, drivers and headers, cleaned up IO build

src/drivers/device/cdev.cpp

@@ -0,0 +1,398 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *
+ * 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 PX4 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.
+ *
+ ****************************************************************************/
+
+/**
+ * @file cdev.cpp
+ *
+ * Character device base class.
+ */
+
+#include "device.h"
+
+#include <sys/ioctl.h>
+#include <arch/irq.h>
+
+#include <stdlib.h>
+#include <stdio.h>
+
+#ifdef CONFIG_DISABLE_POLL
+# error This driver is not compatible with CONFIG_DISABLE_POLL
+#endif
+
+namespace device
+{
+
+/* how much to grow the poll waiter set each time it has to be increased */
+static const unsigned pollset_increment = 0;
+
+/*
+ * The standard NuttX operation dispatch table can't call C++ member functions
+ * directly, so we have to bounce them through this dispatch table.
+ */
+static int	cdev_open(struct file *filp);
+static int	cdev_close(struct file *filp);
+static ssize_t	cdev_read(struct file *filp, char *buffer, size_t buflen);
+static ssize_t	cdev_write(struct file *filp, const char *buffer, size_t buflen);
+static off_t	cdev_seek(struct file *filp, off_t offset, int whence);
+static int	cdev_ioctl(struct file *filp, int cmd, unsigned long arg);
+static int	cdev_poll(struct file *filp, struct pollfd *fds, bool setup);
+
+/**
+ * Character device indirection table.
+ *
+ * Every cdev we register gets the same function table; we use the private data
+ * field in the inode to store the instance pointer.
+ *
+ * Note that we use the GNU extension syntax here because we don't get designated
+ * initialisers in gcc 4.6.
+ */
+const struct file_operations CDev::fops = {
+open	: cdev_open,
+close	: cdev_close,
+read	: cdev_read,
+write	: cdev_write,
+seek	: cdev_seek,
+ioctl	: cdev_ioctl,
+poll	: cdev_poll,
+};
+
+CDev::CDev(const char *name,
+	   const char *devname,
+	   int irq) :
+	// base class
+	Device(name, irq),
+	// public
+	// protected
+	// private
+	_devname(devname),
+	_registered(false),
+	_open_count(0)
+{
+	for (unsigned i = 0; i < _max_pollwaiters; i++)
+		_pollset[i] = nullptr;
+}
+
+CDev::~CDev()
+{
+	if (_registered)
+		unregister_driver(_devname);
+}
+
+int
+CDev::init()
+{
+	int ret = OK;
+
+	// base class init first
+	ret = Device::init();
+
+	if (ret != OK)
+		goto out;
+
+	// now register the driver
+	ret = register_driver(_devname, &fops, 0666, (void *)this);
+
+	if (ret != OK)
+		goto out;
+
+	_registered = true;
+
+out:
+	return ret;
+}
+
+/*
+ * Default implementations of the character device interface
+ */
+int
+CDev::open(struct file *filp)
+{
+	int ret = OK;
+
+	lock();
+	/* increment the open count */
+	_open_count++;
+
+	if (_open_count == 1) {
+
+		/* first-open callback may decline the open */
+		ret = open_first(filp);
+
+		if (ret != OK)
+			_open_count--;
+	}
+
+	unlock();
+
+	return ret;
+}
+
+int
+CDev::open_first(struct file *filp)
+{
+	return OK;
+}
+
+int
+CDev::close(struct file *filp)
+{
+	int ret = OK;
+
+	lock();
+
+	if (_open_count > 0) {
+		/* decrement the open count */
+		_open_count--;
+
+		/* callback cannot decline the close */
+		if (_open_count == 0)
+			ret = close_last(filp);
+
+	} else {
+		ret = -EBADF;
+	}
+
+	unlock();
+
+	return ret;
+}
+
+int
+CDev::close_last(struct file *filp)
+{
+	return OK;
+}
+
+ssize_t
+CDev::read(struct file *filp, char *buffer, size_t buflen)
+{
+	return -ENOSYS;
+}
+
+ssize_t
+CDev::write(struct file *filp, const char *buffer, size_t buflen)
+{
+	return -ENOSYS;
+}
+
+off_t
+CDev::seek(struct file *filp, off_t offset, int whence)
+{
+	return -ENOSYS;
+}
+
+int
+CDev::ioctl(struct file *filp, int cmd, unsigned long arg)
+{
+	switch (cmd) {
+
+		/* fetch a pointer to the driver's private data */
+	case DIOC_GETPRIV:
+		*(void **)(uintptr_t)arg = (void *)this;
+		return OK;
+	}
+
+	return -ENOTTY;
+}
+
+int
+CDev::poll(struct file *filp, struct pollfd *fds, bool setup)
+{
+	int ret = OK;
+
+	/*
+	 * Lock against pollnotify() (and possibly other callers)
+	 */
+	lock();
+
+	if (setup) {
+		/*
+		 * Save the file pointer in the pollfd for the subclass'
+		 * benefit.
+		 */
+		fds->priv = (void *)filp;
+
+		/*
+		 * Handle setup requests.
+		 */
+		ret = store_poll_waiter(fds);
+
+		if (ret == OK) {
+
+			/*
+			 * Check to see whether we should send a poll notification
+			 * immediately.
+			 */
+			fds->revents |= fds->events & poll_state(filp);
+
+			/* yes? post the notification */
+			if (fds->revents != 0)
+				sem_post(fds->sem);
+		}
+
+	} else {
+		/*
+		 * Handle a teardown request.
+		 */
+		ret = remove_poll_waiter(fds);
+	}
+
+	unlock();
+
+	return ret;
+}
+
+void
+CDev::poll_notify(pollevent_t events)
+{
+	/* lock against poll() as well as other wakeups */
+	irqstate_t state = irqsave();
+
+	for (unsigned i = 0; i < _max_pollwaiters; i++)
+		if (nullptr != _pollset[i])
+			poll_notify_one(_pollset[i], events);
+
+	irqrestore(state);
+}
+
+void
+CDev::poll_notify_one(struct pollfd *fds, pollevent_t events)
+{
+	/* update the reported event set */
+	fds->revents |= fds->events & events;
+
+	/* if the state is now interesting, wake the waiter if it's still asleep */
+	/* XXX semcount check here is a vile hack; counting semphores should not be abused as cvars */
+	if ((fds->revents != 0) && (fds->sem->semcount <= 0))
+		sem_post(fds->sem);
+}
+
+pollevent_t
+CDev::poll_state(struct file *filp)
+{
+	/* by default, no poll events to report */
+	return 0;
+}
+
+int
+CDev::store_poll_waiter(struct pollfd *fds)
+{
+	/*
+	 * Look for a free slot.
+	 */
+	for (unsigned i = 0; i < _max_pollwaiters; i++) {
+		if (nullptr == _pollset[i]) {
+
+			/* save the pollfd */
+			_pollset[i] = fds;
+
+			return OK;
+		}
+	}
+
+	return ENOMEM;
+}
+
+int
+CDev::remove_poll_waiter(struct pollfd *fds)
+{
+	for (unsigned i = 0; i < _max_pollwaiters; i++) {
+		if (fds == _pollset[i]) {
+
+			_pollset[i] = nullptr;
+			return OK;
+
+		}
+	}
+
+	puts("poll: bad fd state");
+	return -EINVAL;
+}
+
+static int
+cdev_open(struct file *filp)
+{
+	CDev *cdev = (CDev *)(filp->f_inode->i_private);
+
+	return cdev->open(filp);
+}
+
+static int
+cdev_close(struct file *filp)
+{
+	CDev *cdev = (CDev *)(filp->f_inode->i_private);
+
+	return cdev->close(filp);
+}
+
+static ssize_t
+cdev_read(struct file *filp, char *buffer, size_t buflen)
+{
+	CDev *cdev = (CDev *)(filp->f_inode->i_private);
+
+	return cdev->read(filp, buffer, buflen);
+}
+
+static ssize_t
+cdev_write(struct file *filp, const char *buffer, size_t buflen)
+{
+	CDev *cdev = (CDev *)(filp->f_inode->i_private);
+
+	return cdev->write(filp, buffer, buflen);
+}
+
+static off_t
+cdev_seek(struct file *filp, off_t offset, int whence)
+{
+	CDev *cdev = (CDev *)(filp->f_inode->i_private);
+
+	return cdev->seek(filp, offset, whence);
+}
+
+static int
+cdev_ioctl(struct file *filp, int cmd, unsigned long arg)
+{
+	CDev *cdev = (CDev *)(filp->f_inode->i_private);
+
+	return cdev->ioctl(filp, cmd, arg);
+}
+
+static int
+cdev_poll(struct file *filp, struct pollfd *fds, bool setup)
+{
+	CDev *cdev = (CDev *)(filp->f_inode->i_private);
+
+	return cdev->poll(filp, fds, setup);
+}
+
+} // namespace device

src/drivers/device/device.cpp

@@ -0,0 +1,227 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *
+ * 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 PX4 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.
+ *
+ ****************************************************************************/
+
+/**
+ * @file device.cpp
+ *
+ * Fundamental driver base class for the device framework.
+ */
+
+#include "device.h"
+
+#include <nuttx/arch.h>
+#include <stdio.h>
+#include <unistd.h>
+
+namespace device
+{
+
+/**
+ * Interrupt dispatch table entry.
+ */
+struct irq_entry {
+	int	irq;
+	Device	*owner;
+};
+
+static const unsigned	irq_nentries = 8;		/**< size of the interrupt dispatch table */
+static irq_entry	irq_entries[irq_nentries];	/**< interrupt dispatch table (XXX should be a vector) */
+
+/**
+ * Register an interrupt to a specific device.
+ *
+ * @param irq		The interrupt number to register.
+ * @param owner		The device receiving the interrupt.
+ * @return		OK if the interrupt was registered.
+ */
+static int	register_interrupt(int irq, Device *owner);
+
+/**
+ * Unregister an interrupt.
+ *
+ * @param irq		The previously-registered interrupt to be de-registered.
+ */
+static void	unregister_interrupt(int irq);
+
+/**
+ * Handle an interrupt.
+ *
+ * @param irq		The interrupt being invoked.
+ * @param context	The interrupt register context.
+ * @return		Always returns OK.
+ */
+static int	interrupt(int irq, void *context);
+
+Device::Device(const char *name,
+	       int irq) :
+	// public
+	// protected
+	_name(name),
+	_debug_enabled(false),
+	// private
+	_irq(irq),
+	_irq_attached(false)
+{
+	sem_init(&_lock, 0, 1);
+}
+
+Device::~Device()
+{
+	sem_destroy(&_lock);
+
+	if (_irq_attached)
+		unregister_interrupt(_irq);
+}
+
+int
+Device::init()
+{
+	int ret = OK;
+
+	// If assigned an interrupt, connect it
+	if (_irq) {
+		/* ensure it's disabled */
+		up_disable_irq(_irq);
+
+		/* register */
+		ret = register_interrupt(_irq, this);
+
+		if (ret != OK)
+			goto out;
+
+		_irq_attached = true;
+	}
+
+out:
+	return ret;
+}
+
+void
+Device::interrupt_enable()
+{
+	if (_irq_attached)
+		up_enable_irq(_irq);
+}
+
+void
+Device::interrupt_disable()
+{
+	if (_irq_attached)
+		up_disable_irq(_irq);
+}
+
+void
+Device::interrupt(void *context)
+{
+	// default action is to disable the interrupt so we don't get called again
+	interrupt_disable();
+}
+
+void
+Device::log(const char *fmt, ...)
+{
+	va_list	ap;
+
+	printf("[%s] ", _name);
+	va_start(ap, fmt);
+	vprintf(fmt, ap);
+	va_end(ap);
+	printf("\n");
+	fflush(stdout);
+}
+
+void
+Device::debug(const char *fmt, ...)
+{
+	va_list	ap;
+
+	if (_debug_enabled) {
+		printf("<%s> ", _name);
+		va_start(ap, fmt);
+		vprintf(fmt, ap);
+		va_end(ap);
+		printf("\n");
+		fflush(stdout);
+	}
+}
+
+static int
+register_interrupt(int irq, Device *owner)
+{
+	int ret = -ENOMEM;
+
+	// look for a slot where we can register the interrupt
+	for (unsigned i = 0; i < irq_nentries; i++) {
+		if (irq_entries[i].irq == 0) {
+
+			// great, we could put it here; try attaching it
+			ret = irq_attach(irq, &interrupt);
+
+			if (ret == OK) {
+				irq_entries[i].irq = irq;
+				irq_entries[i].owner = owner;
+			}
+
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static void
+unregister_interrupt(int irq)
+{
+	for (unsigned i = 0; i < irq_nentries; i++) {
+		if (irq_entries[i].irq == irq) {
+			irq_entries[i].irq = 0;
+			irq_entries[i].owner = nullptr;
+		}
+	}
+}
+
+static int
+interrupt(int irq, void *context)
+{
+	for (unsigned i = 0; i < irq_nentries; i++) {
+		if (irq_entries[i].irq == irq) {
+			irq_entries[i].owner->interrupt(context);
+			break;
+		}
+	}
+
+	return OK;
+}
+
+
+} // namespace device

src/drivers/device/device.h

@@ -0,0 +1,447 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *
+ * 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 PX4 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.
+ *
+ ****************************************************************************/
+
+/**
+ * @file device.h
+ *
+ * Definitions for the generic base classes in the device framework.
+ */
+
+#ifndef _DEVICE_DEVICE_H
+#define _DEVICE_DEVICE_H
+
+/*
+ * Includes here should only cover the needs of the framework definitions.
+ */
+#include <nuttx/config.h>
+
+#include <errno.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <poll.h>
+
+#include <nuttx/fs/fs.h>
+
+/**
+ * Namespace encapsulating all device framework classes, functions and data.
+ */
+namespace device __EXPORT
+{
+
+/**
+ * Fundamental base class for all device drivers.
+ *
+ * This class handles the basic "being a driver" things, including
+ * interrupt registration and dispatch.
+ */
+class __EXPORT Device
+{
+public:
+	/**
+	 * Interrupt handler.
+	 */
+	virtual void	interrupt(void *ctx);	/**< interrupt handler */
+
+protected:
+	const char	*_name;			/**< driver name */
+	bool		_debug_enabled;		/**< if true, debug messages are printed */
+
+	/**
+	 * Constructor
+	 *
+	 * @param name		Driver name
+	 * @param irq		Interrupt assigned to the device.
+	 */
+	Device(const char *name,
+	       int irq = 0);
+	~Device();
+
+	/**
+	 * Initialise the driver and make it ready for use.
+	 *
+	 * @return	OK if the driver initialised OK.
+	 */
+	virtual int	init();
+
+	/**
+	 * Enable the device interrupt
+	 */
+	void		interrupt_enable();
+
+	/**
+	 * Disable the device interrupt
+	 */
+	void		interrupt_disable();
+
+	/**
+	 * Take the driver lock.
+	 *
+	 * Each driver instance has its own lock/semaphore.
+	 *
+	 * Note that we must loop as the wait may be interrupted by a signal.
+	 */
+	void		lock() {
+		do {} while (sem_wait(&_lock) != 0);
+	}
+
+	/**
+	 * Release the driver lock.
+	 */
+	void		unlock() {
+		sem_post(&_lock);
+	}
+
+	/**
+	 * Log a message.
+	 *
+	 * The message is prefixed with the driver name, and followed
+	 * by a newline.
+	 */
+	void		log(const char *fmt, ...);
+
+	/**
+	 * Print a debug message.
+	 *
+	 * The message is prefixed with the driver name, and followed
+	 * by a newline.
+	 */
+	void		debug(const char *fmt, ...);
+
+private:
+	int		_irq;
+	bool		_irq_attached;
+	sem_t		_lock;
+
+	/** disable copy construction for this and all subclasses */
+	Device(const Device &);
+
+	/** disable assignment for this and all subclasses */
+	Device &operator = (const Device &);
+
+	/**
+	 * Register ourselves as a handler for an interrupt
+	 *
+	 * @param irq		The interrupt to claim
+	 * @return		OK if the interrupt was registered
+	 */
+	int		dev_register_interrupt(int irq);
+
+	/**
+	 * Unregister ourselves as a handler for any interrupt
+	 */
+	void		dev_unregister_interrupt();
+
+	/**
+	 * Interrupt dispatcher
+	 *
+	 * @param irq		The interrupt that has been triggered.
+	 * @param context	Pointer to the interrupted context.
+	 */
+	static void	dev_interrupt(int irq, void *context);
+};
+
+/**
+ * Abstract class for any character device
+ */
+class __EXPORT CDev : public Device
+{
+public:
+	/**
+	 * Constructor
+	 *
+	 * @param name		Driver name
+	 * @param devname	Device node name
+	 * @param irq		Interrupt assigned to the device
+	 */
+	CDev(const char *name, const char *devname, int irq = 0);
+
+	/**
+	 * Destructor
+	 */
+	~CDev();
+
+	virtual int	init();
+
+	/**
+	 * Handle an open of the device.
+	 *
+	 * This function is called for every open of the device. The default
+	 * implementation maintains _open_count and always returns OK.
+	 *
+	 * @param filp		Pointer to the NuttX file structure.
+	 * @return		OK if the open is allowed, -errno otherwise.
+	 */
+	virtual int	open(struct file *filp);
+
+	/**
+	 * Handle a close of the device.
+	 *
+	 * This function is called for every close of the device. The default
+	 * implementation maintains _open_count and returns OK as long as it is not zero.
+	 *
+	 * @param filp		Pointer to the NuttX file structure.
+	 * @return		OK if the close was successful, -errno otherwise.
+	 */
+	virtual int	close(struct file *filp);
+
+	/**
+	 * Perform a read from the device.
+	 *
+	 * The default implementation returns -ENOSYS.
+	 *
+	 * @param filp		Pointer to the NuttX file structure.
+	 * @param buffer	Pointer to the buffer into which data should be placed.
+	 * @param buflen	The number of bytes to be read.
+	 * @return		The number of bytes read or -errno otherwise.
+	 */
+	virtual ssize_t	read(struct file *filp, char *buffer, size_t buflen);
+
+	/**
+	 * Perform a write to the device.
+	 *
+	 * The default implementation returns -ENOSYS.
+	 *
+	 * @param filp		Pointer to the NuttX file structure.
+	 * @param buffer	Pointer to the buffer from which data should be read.
+	 * @param buflen	The number of bytes to be written.
+	 * @return		The number of bytes written or -errno otherwise.
+	 */
+	virtual ssize_t	write(struct file *filp, const char *buffer, size_t buflen);
+
+	/**
+	 * Perform a logical seek operation on the device.
+	 *
+	 * The default implementation returns -ENOSYS.
+	 *
+	 * @param filp		Pointer to the NuttX file structure.
+	 * @param offset	The new file position relative to whence.
+	 * @param whence	SEEK_OFS, SEEK_CUR or SEEK_END.
+	 * @return		The previous offset, or -errno otherwise.
+	 */
+	virtual off_t	seek(struct file *filp, off_t offset, int whence);
+
+	/**
+	 * Perform an ioctl operation on the device.
+	 *
+	 * The default implementation handles DIOC_GETPRIV, and otherwise
+	 * returns -ENOTTY. Subclasses should call the default implementation
+	 * for any command they do not handle themselves.
+	 *
+	 * @param filp		Pointer to the NuttX file structure.
+	 * @param cmd		The ioctl command value.
+	 * @param arg		The ioctl argument value.
+	 * @return		OK on success, or -errno otherwise.
+	 */
+	virtual int	ioctl(struct file *filp, int cmd, unsigned long arg);
+
+	/**
+	 * Perform a poll setup/teardown operation.
+	 *
+	 * This is handled internally and should not normally be overridden.
+	 *
+	 * @param filp		Pointer to the NuttX file structure.
+	 * @param fds		Poll descriptor being waited on.
+	 * @param arg		True if this is establishing a request, false if
+	 *			it is being torn down.
+	 * @return		OK on success, or -errno otherwise.
+	 */
+	virtual int	poll(struct file *filp, struct pollfd *fds, bool setup);
+
+	/**
+	 * Test whether the device is currently open.
+	 *
+	 * This can be used to avoid tearing down a device that is still active.
+	 *
+	 * @return              True if the device is currently open.
+	 */
+	bool            is_open() { return _open_count > 0; }
+
+protected:
+	/**
+	 * Pointer to the default cdev file operations table; useful for
+	 * registering clone devices etc.
+	 */
+	static const struct file_operations	fops;
+
+	/**
+	 * Check the current state of the device for poll events from the
+	 * perspective of the file.
+	 *
+	 * This function is called by the default poll() implementation when
+	 * a poll is set up to determine whether the poll should return immediately.
+	 *
+	 * The default implementation returns no events.
+	 *
+	 * @param filp		The file that's interested.
+	 * @return		The current set of poll events.
+	 */
+	virtual pollevent_t poll_state(struct file *filp);
+
+	/**
+	 * Report new poll events.
+	 *
+	 * This function should be called anytime the state of the device changes
+	 * in a fashion that might be interesting to a poll waiter.
+	 *
+	 * @param events	The new event(s) being announced.
+	 */
+	virtual void	poll_notify(pollevent_t events);
+
+	/**
+	 * Internal implementation of poll_notify.
+	 *
+	 * @param fds		A poll waiter to notify.
+	 * @param events	The event(s) to send to the waiter.
+	 */
+	virtual void	poll_notify_one(struct pollfd *fds, pollevent_t events);
+
+	/**
+	 * Notification of the first open.
+	 *
+	 * This function is called when the device open count transitions from zero
+	 * to one.  The driver lock is held for the duration of the call.
+	 *
+	 * The default implementation returns OK.
+	 *
+	 * @param filp		Pointer to the NuttX file structure.
+	 * @return		OK if the open should proceed, -errno otherwise.
+	 */
+	virtual int	open_first(struct file *filp);
+
+	/**
+	 * Notification of the last close.
+	 *
+	 * This function is called when the device open count transitions from
+	 * one to zero.  The driver lock is held for the duration of the call.
+	 *
+	 * The default implementation returns OK.
+	 *
+	 * @param filp		Pointer to the NuttX file structure.
+	 * @return		OK if the open should return OK, -errno otherwise.
+	 */
+	virtual int	close_last(struct file *filp);
+
+private:
+	static const unsigned _max_pollwaiters = 8;
+
+	const char	*_devname;		/**< device node name */
+	bool		_registered;		/**< true if device name was registered */
+	unsigned	_open_count;		/**< number of successful opens */
+
+	struct pollfd	*_pollset[_max_pollwaiters];
+
+	/**
+	 * Store a pollwaiter in a slot where we can find it later.
+	 *
+	 * Expands the pollset as required.  Must be called with the driver locked.
+	 *
+	 * @return		OK, or -errno on error.
+	 */
+	int		store_poll_waiter(struct pollfd *fds);
+
+	/**
+	 * Remove a poll waiter.
+	 *
+	 * @return		OK, or -errno on error.
+	 */
+	int		remove_poll_waiter(struct pollfd *fds);
+};
+
+/**
+ * Abstract class for character device accessed via PIO
+ */
+class __EXPORT PIO : public CDev
+{
+public:
+	/**
+	 * Constructor
+	 *
+	 * @param name		Driver name
+	 * @param devname	Device node name
+	 * @param base		Base address of the device PIO area
+	 * @param irq		Interrupt assigned to the device (or zero if none)
+	 */
+	PIO(const char *name,
+	    const char *devname,
+	    uint32_t base,
+	    int irq = 0);
+	~PIO();
+
+	int		init();
+
+protected:
+
+	/**
+	 * Read a register
+	 *
+	 * @param offset	Register offset in bytes from the base address.
+	 */
+	uint32_t reg(uint32_t offset) {
+		return *(volatile uint32_t *)(_base + offset);
+	}
+
+	/**
+	 * Write a register
+	 *
+	 * @param offset	Register offset in bytes from the base address.
+	 * @param value	Value to write.
+	 */
+	void		reg(uint32_t offset, uint32_t value) {
+		*(volatile uint32_t *)(_base + offset) = value;
+	}
+
+	/**
+	 * Modify a register
+	 *
+	 * Note that there is a risk of a race during the read/modify/write cycle
+	 * that must be taken care of by the caller.
+	 *
+	 * @param offset	Register offset in bytes from the base address.
+	 * @param clearbits	Bits to clear in the register
+	 * @param setbits	Bits to set in the register
+	 */
+	void		modify(uint32_t offset, uint32_t clearbits, uint32_t setbits) {
+		uint32_t val = reg(offset);
+		val &= ~clearbits;
+		val |= setbits;
+		reg(offset, val);
+	}
+
+private:
+	uint32_t	_base;
+};
+
+} // namespace device
+
+#endif /* _DEVICE_DEVICE_H */

src/drivers/device/i2c.cpp

@@ -0,0 +1,204 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *
+ * 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 PX4 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.
+ *
+ ****************************************************************************/
+
+/**
+ * @file i2c.cpp
+ *
+ * Base class for devices attached via the I2C bus.
+ *
+ * @todo Bus frequency changes; currently we do nothing with the value
+ *       that is supplied.  Should we just depend on the bus knowing?
+ */
+
+#include "i2c.h"
+
+namespace device
+{
+
+I2C::I2C(const char *name,
+	 const char *devname,
+	 int bus,
+	 uint16_t address,
+	 uint32_t frequency,
+	 int irq) :
+	// base class
+	CDev(name, devname, irq),
+	// public
+	// protected
+	_retries(0),
+	// private
+	_bus(bus),
+	_address(address),
+	_frequency(frequency),
+	_dev(nullptr)
+{
+}
+
+I2C::~I2C()
+{
+	if (_dev)
+		up_i2cuninitialize(_dev);
+}
+
+int
+I2C::init()
+{
+	int ret = OK;
+
+	/* attach to the i2c bus */
+	_dev = up_i2cinitialize(_bus);
+
+	if (_dev == nullptr) {
+		debug("failed to init I2C");
+		ret = -ENOENT;
+		goto out;
+	}
+
+	// call the probe function to check whether the device is present
+	ret = probe();
+
+	if (ret != OK) {
+		debug("probe failed");
+		goto out;
+	}
+
+	// do base class init, which will create device node, etc
+	ret = CDev::init();
+
+	if (ret != OK) {
+		debug("cdev init failed");
+		goto out;
+	}
+
+	// tell the world where we are
+	log("on I2C bus %d at 0x%02x", _bus, _address);
+
+out:
+	return ret;
+}
+
+int
+I2C::probe()
+{
+	// Assume the device is too stupid to be discoverable.
+	return OK;
+}
+
+int
+I2C::transfer(const uint8_t *send, unsigned send_len, uint8_t *recv, unsigned recv_len)
+{
+	struct i2c_msg_s msgv[2];
+	unsigned msgs;
+	int ret;
+	unsigned retry_count = 0;
+
+	do {
+		//	debug("transfer out %p/%u  in %p/%u", send, send_len, recv, recv_len);
+
+		msgs = 0;
+
+		if (send_len > 0) {
+			msgv[msgs].addr = _address;
+			msgv[msgs].flags = 0;
+			msgv[msgs].buffer = const_cast<uint8_t *>(send);
+			msgv[msgs].length = send_len;
+			msgs++;
+		}
+
+		if (recv_len > 0) {
+			msgv[msgs].addr = _address;
+			msgv[msgs].flags = I2C_M_READ;
+			msgv[msgs].buffer = recv;
+			msgv[msgs].length = recv_len;
+			msgs++;
+		}
+
+		if (msgs == 0)
+			return -EINVAL;
+
+		/*
+		 * I2C architecture means there is an unavoidable race here
+		 * if there are any devices on the bus with a different frequency
+		 * preference.  Really, this is pointless.
+		 */
+		I2C_SETFREQUENCY(_dev, _frequency);
+		ret = I2C_TRANSFER(_dev, &msgv[0], msgs);
+
+		/* success */
+		if (ret == OK)
+			break;
+
+		/* if we have already retried once, or we are going to give up, then reset the bus */
+		if ((retry_count >= 1) || (retry_count >= _retries))
+			up_i2creset(_dev);
+
+	} while (retry_count++ < _retries);
+
+	return ret;
+
+}
+
+int
+I2C::transfer(i2c_msg_s *msgv, unsigned msgs)
+{
+	int ret;
+	unsigned retry_count = 0;
+
+	/* force the device address into the message vector */
+	for (unsigned i = 0; i < msgs; i++)
+		msgv[i].addr = _address;
+
+
+	do {
+		/*
+		 * I2C architecture means there is an unavoidable race here
+		 * if there are any devices on the bus with a different frequency
+		 * preference.  Really, this is pointless.
+		 */
+		I2C_SETFREQUENCY(_dev, _frequency);
+		ret = I2C_TRANSFER(_dev, msgv, msgs);
+
+		/* success */
+		if (ret == OK)
+			break;
+
+		/* if we have already retried once, or we are going to give up, then reset the bus */
+		if ((retry_count >= 1) || (retry_count >= _retries))
+			up_i2creset(_dev);
+
+	} while (retry_count++ < _retries);
+
+	return ret;
+}
+
+} // namespace device

src/drivers/device/i2c.h

@@ -0,0 +1,138 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *
+ * 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 PX4 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.
+ *
+ ****************************************************************************/
+
+/**
+ * @file i2c.h
+ *
+ * Base class for devices connected via I2C.
+ */
+
+#ifndef _DEVICE_I2C_H
+#define _DEVICE_I2C_H
+
+#include "device.h"
+
+#include <nuttx/i2c.h>
+
+namespace device __EXPORT
+{
+
+/**
+ * Abstract class for character device on I2C
+ */
+class __EXPORT I2C : public CDev
+{
+
+protected:
+	/**
+	 * The number of times a read or write operation will be retried on
+	 * error.
+	 */
+	unsigned		_retries;
+
+	/**
+	 * The I2C bus number the device is attached to.
+	 */
+	int			_bus;
+
+	/**
+	 * @ Constructor
+	 *
+	 * @param name		Driver name
+	 * @param devname	Device node name
+	 * @param bus		I2C bus on which the device lives
+	 * @param address	I2C bus address, or zero if set_address will be used
+	 * @param frequency	I2C bus frequency for the device (currently not used)
+	 * @param irq		Interrupt assigned to the device (or zero if none)
+	 */
+	I2C(const char *name,
+	    const char *devname,
+	    int bus,
+	    uint16_t address,
+	    uint32_t frequency,
+	    int irq = 0);
+	~I2C();
+
+	virtual int	init();
+
+	/**
+	 * Check for the presence of the device on the bus.
+	 */
+	virtual int	probe();
+
+	/**
+	 * Perform an I2C transaction to the device.
+	 *
+	 * At least one of send_len and recv_len must be non-zero.
+	 *
+	 * @param send		Pointer to bytes to send.
+	 * @param send_len	Number of bytes to send.
+	 * @param recv		Pointer to buffer for bytes received.
+	 * @param recv_len	Number of bytes to receive.
+	 * @return		OK if the transfer was successful, -errno
+	 *			otherwise.
+	 */
+	int		transfer(const uint8_t *send, unsigned send_len,
+				 uint8_t *recv, unsigned recv_len);
+
+	/**
+	 * Perform a multi-part I2C transaction to the device.
+	 *
+	 * @param msgv		An I2C message vector.
+	 * @param msgs		The number of entries in the message vector.
+	 * @return		OK if the transfer was successful, -errno
+	 *			otherwise.
+	 */
+	int		transfer(i2c_msg_s *msgv, unsigned msgs);
+
+	/**
+	 * Change the bus address.
+	 *
+	 * Most often useful during probe() when the driver is testing
+	 * several possible bus addresses.
+	 *
+	 * @param address	The new bus address to set.
+	 */
+	void		set_address(uint16_t address) {
+		_address = address;
+	}
+
+private:
+	uint16_t		_address;
+	uint32_t		_frequency;
+	struct i2c_dev_s	*_dev;
+};
+
+} // namespace device
+
+#endif /* _DEVICE_I2C_H */

src/drivers/device/module.mk

@@ -0,0 +1,42 @@
+############################################################################
+#
+#   Copyright (c) 2012, 2013 PX4 Development Team. All rights reserved.
+#
+# 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 PX4 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.
+#
+############################################################################
+
+#
+# Build the device driver framework.
+#
+
+SRCS		= cdev.cpp \
+		  device.cpp \
+		  i2c.cpp \
+		  pio.cpp \
+		  spi.cpp

src/drivers/device/pio.cpp

@@ -0,0 +1,74 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *
+ * 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 PX4 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.
+ *
+ ****************************************************************************/
+
+/**
+ * @file pio.cpp
+ *
+ * Base class for devices accessed via PIO to registers.
+ */
+
+#include "device.h"
+
+namespace device
+{
+
+PIO::PIO(const char *name,
+	 const char *devname,
+	 uint32_t base,
+	 int irq) :
+	// base class
+	CDev(name, devname, irq),
+	// public
+	// protected
+	// private
+	_base(base)
+{
+}
+
+PIO::~PIO()
+{
+	// nothing to do here...
+}
+
+int
+PIO::init()
+{
+	int ret = OK;
+
+	// base class init first
+	ret = CDev::init();
+
+	return ret;
+}
+
+} // namespace device

src/drivers/device/spi.cpp

@@ -0,0 +1,160 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *
+ * 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 PX4 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.
+ *
+ ****************************************************************************/
+
+/**
+ * @file spi.cpp
+ *
+ * Base class for devices connected via SPI.
+ *
+ * @todo Work out if caching the mode/frequency would save any time.
+ *
+ * @todo A separate bus/device abstraction would allow for mixed interrupt-mode
+ * and non-interrupt-mode clients to arbitrate for the bus.  As things stand,
+ * a bus shared between clients of both kinds is vulnerable to races between
+ * the two, where an interrupt-mode client will ignore the lock held by the
+ * non-interrupt-mode client.
+ */
+
+#include <nuttx/arch.h>
+
+#include "spi.h"
+
+#ifndef CONFIG_SPI_EXCHANGE
+# error This driver requires CONFIG_SPI_EXCHANGE
+#endif
+
+namespace device
+{
+
+SPI::SPI(const char *name,
+	 const char *devname,
+	 int bus,
+	 enum spi_dev_e device,
+	 enum spi_mode_e mode,
+	 uint32_t frequency,
+	 int irq) :
+	// base class
+	CDev(name, devname, irq),
+	// public
+	// protected
+	// private
+	_bus(bus),
+	_device(device),
+	_mode(mode),
+	_frequency(frequency),
+	_dev(nullptr)
+{
+}
+
+SPI::~SPI()
+{
+	// XXX no way to let go of the bus...
+}
+
+int
+SPI::init()
+{
+	int ret = OK;
+
+	/* attach to the spi bus */
+	if (_dev == nullptr)
+		_dev = up_spiinitialize(_bus);
+
+	if (_dev == nullptr) {
+		debug("failed to init SPI");
+		ret = -ENOENT;
+		goto out;
+	}
+
+	/* deselect device to ensure high to low transition of pin select */
+	SPI_SELECT(_dev, _device, false);
+
+	/* call the probe function to check whether the device is present */
+	ret = probe();
+
+	if (ret != OK) {
+		debug("probe failed");
+		goto out;
+	}
+
+	/* do base class init, which will create the device node, etc. */
+	ret = CDev::init();
+
+	if (ret != OK) {
+		debug("cdev init failed");
+		goto out;
+	}
+
+	/* tell the workd where we are */
+	log("on SPI bus %d at %d", _bus, _device);
+
+out:
+	return ret;
+}
+
+int
+SPI::probe()
+{
+	// assume the device is too stupid to be discoverable
+	return OK;
+}
+
+int
+SPI::transfer(uint8_t *send, uint8_t *recv, unsigned len)
+{
+
+	if ((send == nullptr) && (recv == nullptr))
+		return -EINVAL;
+
+	/* do common setup */
+	if (!up_interrupt_context())
+		SPI_LOCK(_dev, true);
+
+	SPI_SETFREQUENCY(_dev, _frequency);
+	SPI_SETMODE(_dev, _mode);
+	SPI_SETBITS(_dev, 8);
+	SPI_SELECT(_dev, _device, true);
+
+	/* do the transfer */
+	SPI_EXCHANGE(_dev, send, recv, len);
+
+	/* and clean up */
+	SPI_SELECT(_dev, _device, false);
+
+	if (!up_interrupt_context())
+		SPI_LOCK(_dev, false);
+
+	return OK;
+}
+
+} // namespace device

src/drivers/device/spi.h

@@ -0,0 +1,114 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *
+ * 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 PX4 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.
+ *
+ ****************************************************************************/
+
+/**
+ * @file spi.h
+ *
+ * Base class for devices connected via SPI.
+ */
+
+#ifndef _DEVICE_SPI_H
+#define _DEVICE_SPI_H
+
+#include "device.h"
+
+#include <nuttx/spi.h>
+
+namespace device __EXPORT
+{
+
+/**
+ * Abstract class for character device on SPI
+ */
+class __EXPORT SPI : public CDev
+{
+protected:
+	/**
+	 * Constructor
+	 *
+	 * @param name		Driver name
+	 * @param devname	Device node name
+	 * @param bus		SPI bus on which the device lives
+	 * @param device	Device handle (used by SPI_SELECT)
+	 * @param mode		SPI clock/data mode
+	 * @param frequency	SPI clock frequency
+	 * @param irq		Interrupt assigned to the device (or zero if none)
+	 */
+	SPI(const char *name,
+	    const char *devname,
+	    int bus,
+	    enum spi_dev_e device,
+	    enum spi_mode_e mode,
+	    uint32_t frequency,
+	    int irq = 0);
+	~SPI();
+
+	virtual int	init();
+
+	/**
+	 * Check for the presence of the device on the bus.
+	 */
+	virtual int	probe();
+
+	/**
+	 * Perform a SPI transfer.
+	 *
+	 * If called from interrupt context, this interface does not lock
+	 * the bus and may interfere with non-interrupt-context callers.
+	 *
+	 * Clients in a mixed interrupt/non-interrupt configuration must
+	 * ensure appropriate interlocking.
+	 *
+	 * At least one of send or recv must be non-null.
+	 *
+	 * @param send		Bytes to send to the device, or nullptr if
+	 *			no data is to be sent.
+	 * @param recv		Buffer for receiving bytes from the device,
+	 *			or nullptr if no bytes are to be received.
+	 * @param len		Number of bytes to transfer.
+	 * @return		OK if the exchange was successful, -errno
+	 *			otherwise.
+	 */
+	int		transfer(uint8_t *send, uint8_t *recv, unsigned len);
+
+private:
+	int			_bus;
+	enum spi_dev_e		_device;
+	enum spi_mode_e		_mode;
+	uint32_t		_frequency;
+	struct spi_dev_s	*_dev;
+};
+
+} // namespace device
+
+#endif /* _DEVICE_SPI_H */