SPI

* SPI
@ 2005-09-26 11:12 dmitry pervushin
  2005-09-26 12:31 ` SPI Eric Piel
                   ` (4 more replies)
  0 siblings, 5 replies; 19+ messages in thread
From: dmitry pervushin @ 2005-09-26 11:12 UTC (permalink / raw)
  To: Linux Kernel Mailing List; +Cc: spi-devel-general

Hello guys,

I am attaching the next incarnation of SPI core; feel free to comment it.

 Documentation/spi.txt  |  351 +++++++++++++++++++++++++++++++++++++
 arch/arm/Kconfig       |    2
 drivers/Kconfig        |    2
 drivers/Makefile       |    1
 drivers/spi/Kconfig    |   33 +++
 drivers/spi/Makefile   |   11 +
 drivers/spi/spi-core.c |  456 +++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/spi/spi-dev.c  |  236 +++++++++++++++++++++++++
 include/linux/spi.h    |  214 ++++++++++++++++++++++
 9 files changed, 1306 insertions(+)

Index: linux-2.6.10/arch/arm/Kconfig
===================================================================

--- linux-2.6.10.orig/arch/arm/Kconfig
+++ linux-2.6.10/arch/arm/Kconfig
@@ -834,6 +834,8 @@ source "drivers/ssi/Kconfig"
 
 source "drivers/mmc/Kconfig"
 
+source "drivers/spi/Kconfig"
+
 endmenu
 
 source "ktools/Kconfig"
Index: linux-2.6.10/drivers/Kconfig
===================================================================
--- linux-2.6.10.orig/drivers/Kconfig
+++ linux-2.6.10/drivers/Kconfig
@@ -42,6 +42,8 @@ source "drivers/char/Kconfig"
 
 source "drivers/i2c/Kconfig"
 
+source "drivers/spi/Kconfig"
+
 source "drivers/w1/Kconfig"
 
 source "drivers/misc/Kconfig"
Index: linux-2.6.10/drivers/Makefile
===================================================================
--- linux-2.6.10.orig/drivers/Makefile
+++ linux-2.6.10/drivers/Makefile
@@ -67,3 +67,4 @@ obj-$(CONFIG_DPM)		+= dpm/
 obj-$(CONFIG_MMC)		+= mmc/
 obj-y				+= firmware/
 obj-$(CONFIG_EVENT_BROKER)	+= evb/
+obj-$(CONFIG_SPI)		+= spi/
Index: linux-2.6.10/drivers/spi/Kconfig
===================================================================
--- /dev/null
+++ linux-2.6.10/drivers/spi/Kconfig
@@ -0,0 +1,33 @@
+#
+# SPI device configuration
+#
+menu "SPI support"
+
+config SPI
+	default Y
+	tristate "SPI support"
+        default false
+	help
+	  Say Y if you need to enable SPI support on your kernel
+
+config SPI_DEBUG
+	bool "SPI debug output" 
+	depends on SPI 
+	default false 
+	help 
+          Say Y there if you'd like to see debug output from SPI drivers.
+	  If unsure, say N
+	
+config SPI_CHARDEV
+	default Y
+	tristate "SPI device interface"
+	depends on SPI
+	help
+	  Say Y here to use spi-* device files, usually found in the /dev
+	  directory on your system.  They make it possible to have user-space
+	  programs use the SPI bus. 
+	  This support is also available as a module.  If so, the module 
+	  will be called spi-dev.
+
+endmenu
+
Index: linux-2.6.10/drivers/spi/Makefile
===================================================================
--- /dev/null
+++ linux-2.6.10/drivers/spi/Makefile
@@ -0,0 +1,11 @@
+#
+# Makefile for the kernel spi bus driver.
+#
+
+obj-$(CONFIG_SPI) += spi-core.o 
+obj-$(CONFIG_SPI_CHARDEV) += spi-dev.o
+
+ifeq ($(CONFIG_SPI_DEBUG),y)
+EXTRA_CFLAGS += -DDEBUG
+endif
+
Index: linux-2.6.10/drivers/spi/spi-core.c
===================================================================
--- /dev/null
+++ linux-2.6.10/drivers/spi/spi-core.c
@@ -0,0 +1,456 @@
+/*
+ *  drivers/spi/spi-core.c
+ *
+ *  Copyright (C) 2005 MontaVista Software, Inc <sources@mvista.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/config.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/proc_fs.h>
+#include <linux/kmod.h>
+#include <linux/init.h>
+#include <linux/wait.h>
+#include <linux/kthread.h>
+#include <linux/spi.h>
+#include <asm/atomic.h>
+
+static int spi_thread(void *context);
+
+/*
+ * spi_bus_match_name
+ * 
+ * Drivers and devices on SPI bus are matched by name, just like the
+ * platform devices, with exception of SPI_DEV_CHAR. Driver with this name
+ * will be matched against any device
+ */
+static int spi_bus_match_name(struct device *dev, struct device_driver *drv)
+{
+	return  !strcmp (drv->name, SPI_DEV_CHAR) || 
+		!strcmp(TO_SPI_DEV(dev)->name, drv->name);
+}
+
+struct bus_type spi_bus = {
+	.name = "spi",
+	.match = spi_bus_match_name,
+};
+
+/*
+ * spi_bus_driver_init
+ *
+ * This function initializes the spi_bus_data structure for the 
+ * bus. Functions has to be called when bus driver gets probed
+ *
+ * Parameters:
+ * 	spi_bus_driver* 	pointer to bus driver structure
+ * 	device*			platform device to be attached to
+ * Return value:
+ * 	0 on success, error code otherwise
+ */
+int spi_bus_driver_init(struct spi_bus_driver *bus, struct device *dev)
+{
+	struct spi_bus_data *pd =
+	    kmalloc(sizeof(struct spi_bus_data), GFP_KERNEL);
+	int err = 0;
+	
+	if (!pd) {
+		err = -ENOMEM;
+		goto init_failed_1;
+	}
+	atomic_set(&pd->exiting, 0);
+	pd->bus = bus;
+	init_MUTEX(&pd->lock);
+	INIT_LIST_HEAD(&pd->msgs);
+	init_waitqueue_head(&pd->queue);
+	pd->thread = kthread_run(spi_thread, pd, "%s-work", dev->bus_id);
+	if (IS_ERR(pd->thread)) {
+		err = PTR_ERR(pd->thread);
+		goto init_failed_2;
+	}
+	dev->platform_data = pd;
+	return 0;
+	
+init_failed_2:
+	kfree(pd);	
+init_failed_1:	
+	return err;
+}
+
+/*
+ * __spi_bus_free
+ *
+ * This function called as part of unregistering bus device driver. It
+ * calls spi_device_del for each child (SPI) device on the bus
+ *
+ * Parameters:
+ * 	struct device* dev	the 'bus' device
+ * 	void* context		not used. Will be NULL
+ */
+int __spi_bus_free(struct device *dev, void *context)
+{
+	struct spi_bus_data *pd = dev->platform_data;
+
+	atomic_inc(&pd->exiting);
+	kthread_stop(pd->thread);
+	kfree(pd);
+
+	dev_dbg( dev, "unregistering children\n" );
+	/* 
+	 * NOTE: the loop below might needs redesign. Currently
+	 *       we delete devices from the head of children list
+	 *       until the list is empty; that's because the function
+	 *       device_for_each_child will hold the semaphore needed 
+	 *       for deletion of device
+	 */
+	while( !list_empty( &dev->children ) ) {
+		struct device* child = list_entry ( dev->children.next, struct device, node );
+	    	spi_device_del (TO_SPI_DEV (child) );
+	}
+	return 0;
+}
+
+/*
+ * spi_bus_driver_unregister
+ *
+ * unregisters the SPI bus from the system. Before unregistering, it deletes
+ * each SPI device on the bus using call to __spi_device_free
+ *
+ * Parameters:
+ *  	struct spi_bus_driver* bus_driver	the bus driver
+ * Return value:
+ *  	void
+ */
+void spi_bus_driver_unregister(struct spi_bus_driver *bus_driver)
+{
+	if (bus_driver) {
+		driver_for_each_dev( &bus_driver->driver, NULL, __spi_bus_free);
+		driver_unregister(&bus_driver->driver);
+	}
+}
+
+/*
+ * spi_device_release
+ * 
+ * Pointer to this function will be put to dev->release place
+ * This function gets called as a part of device removing
+ * 
+ * Parameters:
+ * 	struct device* dev
+ * Return value:
+ * 	none
+ */
+void spi_device_release( struct device* dev )
+{
+/* just a placeholder */
+}
+
+/*
+ * spi_device_add
+ *
+ * Add the new (discovered) SPI device to the bus. Mostly used by bus drivers
+ *
+ * Parameters:
+ * 	struct device* parent		the 'bus' device
+ * 	struct spi_device* dev		new device to be added
+ * 	char* name			name of device. Should not be NULL
+ * Return value:
+ * 	error code, or 0 on success
+ */
+int spi_device_add(struct device *parent, struct spi_device *dev, char *name)
+{
+	if (!name || !dev) 
+	    return -EINVAL;
+	    
+	memset(&dev->dev, 0, sizeof(dev->dev));
+	dev->dev.parent = parent;
+	dev->dev.bus = &spi_bus;
+	strncpy( dev->name, name, sizeof(dev->name));
+	strncpy( dev->dev.bus_id, name, sizeof( dev->dev.bus_id ) );
+	dev->dev.release = spi_device_release;
+
+	return device_register(&dev->dev);
+}
+
+/*
+ * spi_queue
+ *
+ * Queue the message to be processed asynchronously
+ *
+ * Parameters:
+ *  	struct spi_msg* msg            message to be sent
+ * Return value:
+ *  	0 on no errors, negative error code otherwise
+ */
+int spi_queue( struct spi_msg *msg)
+{
+	struct device* dev = &msg->device->dev;
+	struct spi_bus_data *pd = dev->parent->platform_data;
+
+	down(&pd->lock);
+	list_add_tail(&msg->link, &pd->msgs);
+	dev_dbg(dev->parent, "message has been queued\n" );
+	up(&pd->lock);
+	wake_up_interruptible(&pd->queue);
+	return 0;
+}
+
+/*
+ * __spi_transfer_callback
+ *
+ * callback for synchronously processed message. If spi_transfer determines
+ * that there is no callback provided neither by msg->status nor callback
+ * parameter, the __spi_transfer_callback will be used, and spi_transfer
+ * does not return until transfer is finished
+ *
+ * Parameters:
+ * 	struct spimsg* msg	message that is being processed now
+ * 	int code		status of processing
+ */
+static void __spi_transfer_callback( struct spi_msg* msg, int code )
+{
+	if( code & (SPIMSG_OK|SPIMSG_FAILED) ) 
+		complete( (struct completion*)msg->context );
+}
+
+/*
+ * spi_transfer
+ *
+ * Process the SPI message, by queuing it to the driver and either
+ * immediately return or waiting till the end-of-processing
+ *
+ * Parameters:
+ * 	struct spi_msg* msg	message to process
+ * 	callback		user-supplied callback. If both msg->status and
+ * 				callback are set, the error code of -EINVAL
+ * 				will be returned
+ * Return value:
+ * 	0 on success, error code otherwise. This code does not reflect
+ * 	status of message, just status of queueing
+ */
+int spi_transfer( struct spi_msg* msg, void (*callback)( struct spi_msg*, int ) )
+{
+	struct completion msg_done;
+	int err = -EINVAL;
+
+	if( callback && !msg->status ) {
+		msg->status = callback;
+		callback = NULL;
+	}
+	
+	if( !callback ) {
+		if( !msg->status ) {
+			init_completion( &msg_done );
+			msg->context = &msg_done;
+			msg->status = __spi_transfer_callback;
+			spi_queue( msg );
+			wait_for_completion( &msg_done );
+			err = 0;
+		} else {
+			err = spi_queue( msg );
+		}
+	}
+		
+	return err;
+}
+/*
+ * spi_thread
+ * 
+ * This function is started as separate thread to perform actual 
+ * transfers on SPI bus
+ *
+ * Parameters:
+ *	void* context 		pointer to struct spi_bus_data 
+ */
+static int spi_thread_awake(struct spi_bus_data *bd)
+{
+	int ret;
+
+	if (atomic_read(&bd->exiting)) {
+		return 1;
+	}
+	down(&bd->lock);
+	ret = !list_empty(&bd->msgs);
+	up(&bd->lock);
+	return ret;
+}
+
+static int spi_thread(void *context)
+{
+	struct spi_bus_data *bd = context;
+	struct spi_msg *msg;
+	int xfer_status;
+	int found;
+
+	while (!kthread_should_stop()) {
+
+		wait_event_interruptible(bd->queue, spi_thread_awake(bd));
+
+		if (atomic_read(&bd->exiting))
+			goto thr_exit;
+
+		down(&bd->lock);
+		while (!list_empty(&bd->msgs)) {
+			/* 
+			 * this part is locked by bus_data->lock, 
+			 * to protect spi_msg extraction
+			 */
+			found = 0;
+			list_for_each_entry(msg, &bd->msgs, link) {
+				if (!bd->selected_device) {
+					bd->selected_device = msg->device;
+					if (bd->bus->select)
+						bd->bus->select(bd->
+								selected_device);
+					found = 1;
+					break;
+				}
+				if (msg->device == bd->selected_device) {
+					found = 1;
+					break;
+				}
+			}
+			if (!found) {
+				/* 
+				 * all messages for current selected_device 
+				 * are processed. 
+				 * let's switch to another device 
+				 */
+				msg =
+				    list_entry(bd->msgs.next, struct spi_msg,
+					       link);
+				if (bd->bus->deselect)
+					bd->bus->deselect(bd->selected_device);
+				bd->selected_device = msg->device;
+				if (bd->bus->select)
+					bd->bus->select(bd->selected_device);
+			}
+			list_del(&msg->link);
+			up(&bd->lock);
+
+			/* 
+			 * and this part is locked by device's lock; 
+			 * spi_queue will be able to queue new 
+			 * messages
+			 */
+			spi_device_lock(&msg->device);
+			if (msg->status)
+				msg->status(msg, SPIMSG_STARTED);
+			if( bd->bus->set_clock && msg->clock )
+				bd->bus->set_clock( 
+					msg->device->dev.parent, msg->clock );
+			xfer_status = bd->bus->xfer( msg );
+			if (msg->status) {
+				msg->status(msg, SPIMSG_DONE);
+				msg->status(msg,
+					    xfer_status ? SPIMSG_OK :
+					    SPIMSG_FAILED);
+			}
+			spi_device_unlock(&msg->device);
+
+			/* lock the bus_data again... */
+			down(&bd->lock);
+		}
+		if (bd->bus->deselect)
+			bd->bus->deselect(bd->selected_device);
+		bd->selected_device = NULL;
+		/* device has been just deselected, unlocking the bus */
+		up(&bd->lock);
+	}
+thr_exit:
+	return 0;
+}
+
+/*
+ * spi_write 
+ * 	send data to a device on an SPI bus
+ * Parameters:
+ * 	spi_device* dev		the target device
+ *	char* buf		buffer to be sent
+ *	int len			buffer length
+ * Return:
+ * 	the number of bytes transferred, or negative error code.
+ */
+int spi_write(struct spi_device *dev, const char *buf, int len)
+{
+	struct spi_msg *msg = spimsg_alloc(dev, SPI_M_WR, len, NULL);
+	int ret;
+
+	memcpy(spimsg_buffer_wr(msg), buf, len);
+	ret = spi_transfer( msg, NULL );
+	return ret == 1 ? len : ret;
+}
+
+/*
+ * spi_write 
+ * 	receive data from a device on an SPI bus
+ * Parameters:
+ * 	spi_device* dev		the target device
+ *	char* buf		buffer to be sent
+ *	int len			number of bytes to receive
+ * Return:
+ * 	 the number of bytes transferred, or negative error code.
+ */
+int spi_read(struct spi_device *dev, char *buf, int len)
+{
+	int ret;
+	struct spimsg *msg = spimsg_alloc(dev, SPI_M_RD, len, NULL);
+
+	ret = spi_transfer( msg, NULL );
+	memcpy(buf, spimsg_buffer_rd(msg), len);
+	return ret == 1 ? len : ret;
+}
+
+int spi_bus_populate(struct device *parent,
+		     char *devices,
+		     void (*callback) (struct device * bus,
+				       struct spi_device * new_dev))
+{
+	struct spi_device *new_device;
+	int count = 0;
+
+	while (devices[0]) {
+		dev_dbg(parent, "discovered new SPI device, name '%s'\n",
+			devices);
+		new_device = kmalloc(sizeof(struct spi_device), GFP_KERNEL);
+		if (!new_device) {
+			break;
+		}
+		if (spi_device_add(parent, new_device, devices)) {
+			break;
+		}
+		if (callback) {
+			callback(parent, new_device);
+		}
+		devices += (strlen(devices) + 1);
+		count++;
+	}
+	return count;
+}
+
+int __init spi_core_init( void )
+{
+	return bus_register(&spi_bus);
+}
+
+subsys_initcall(spi_core_init);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("dmitry pervushin <dpervushin@ru.mvista.com>");
+
+EXPORT_SYMBOL_GPL(spi_queue);
+EXPORT_SYMBOL_GPL(spi_device_add);
+EXPORT_SYMBOL_GPL(spi_bus_driver_unregister);
+EXPORT_SYMBOL_GPL(spi_bus_populate);
+EXPORT_SYMBOL_GPL(spi_transfer);
+EXPORT_SYMBOL_GPL(spi_write);
+EXPORT_SYMBOL_GPL(spi_read);
+EXPORT_SYMBOL_GPL(spi_bus);
+EXPORT_SYMBOL_GPL(spi_bus_driver_init);
Index: linux-2.6.10/drivers/spi/spi-dev.c
===================================================================
--- /dev/null
+++ linux-2.6.10/drivers/spi/spi-dev.c
@@ -0,0 +1,236 @@
+/*
+    spi-dev.c - spi-bus driver, char device interface  
+
+    Copyright (C) 1995-97 Simon G. Vogl
+    Copyright (C) 1998-99 Frodo Looijaard <frodol@dds.nl>
+    Copyright (C) 2002 Compaq Computer Corporation
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+/* Adapted from i2c-dev module by Jamey Hicks <jamey.hicks@compaq.com> */
+
+/* Note that this is a complete rewrite of Simon Vogl's i2c-dev module.
+   But I have used so much of his original code and ideas that it seems
+   only fair to recognize him as co-author -- Frodo */
+
+/* The devfs code is contributed by Philipp Matthias Hahn 
+   <pmhahn@titan.lahn.de> */
+
+/* Modifications to allow work with current spi-core by 
+   Andrey Ivolgin <aivolgin@ru.mvista.com>, Sep 2004
+ */
+
+/* devfs code corrected to support automatic device addition/deletion
+   by Vitaly Wool <vwool@ru.mvista.com> (C) 2004 MontaVista Software, Inc. 
+ */
+#include <linux/init.h>
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/version.h>
+#include <linux/smp_lock.h>
+
+#include <linux/init.h>
+#include <asm/uaccess.h>
+#include <linux/spi.h>
+
+#define SPI_TRANSFER_MAX	65535L
+
+struct spidev_driver_data
+{
+	int minor;
+};
+
+static ssize_t spidev_read(struct file *file, char *buf, size_t count,
+			   loff_t * offset);
+static ssize_t spidev_write(struct file *file, const char *buf, size_t count,
+			    loff_t * offset);
+
+static int spidev_open(struct inode *inode, struct file *file);
+static int spidev_release(struct inode *inode, struct file *file);
+static int __init spidev_init(void);
+
+static void spidev_cleanup(void);
+
+static int spidev_probe(struct device *dev);
+static int spidev_remove(struct device *dev);
+
+static struct file_operations spidev_fops = {
+	.owner = THIS_MODULE,
+	.llseek = no_llseek,
+	.read = spidev_read,
+	.write = spidev_write,
+	.open = spidev_open,
+	.release = spidev_release,
+};
+
+static struct class_simple *spidev_class;
+
+static struct spi_driver spidev_driver = {
+	.driver = {
+		   .name = SPI_DEV_CHAR,
+		   .probe = spidev_probe,
+		   .remove = spidev_remove,
+		   },
+};
+
+static int spidev_minor;
+
+static int spidev_probe(struct device *dev)
+{
+	struct spidev_driver_data *drvdata;
+
+	drvdata = kmalloc(sizeof(struct spidev_driver_data), GFP_KERNEL);
+	if ( !drvdata) {
+		dev_dbg( dev, "allocating drvdata failed\n" );
+		return -ENOMEM;
+	}
+
+	drvdata->minor = spidev_minor++;
+	dev_dbg( dev, "setting device's(%p) minor to %d\n",
+		 dev, drvdata->minor);
+	dev_set_drvdata(dev, drvdata);
+
+	class_simple_device_add(spidev_class,
+				MKDEV(SPI_MAJOR, drvdata->minor),
+				NULL, "spi%d", drvdata->minor);
+	dev_dbg( dev, " added\n" );
+	return 0;
+}
+
+static int spidev_remove(struct device *dev)
+{
+	struct spidev_driver_data *drvdata;
+
+	drvdata = (struct spidev_driver_data *)dev_get_drvdata(dev);
+	class_simple_device_remove(MKDEV(SPI_MAJOR, drvdata->minor));
+	kfree(drvdata);
+	dev_dbg( dev, " removed\n" );
+	return 0;
+}
+
+static ssize_t spidev_read(struct file *file, char *buf, size_t count,
+			   loff_t * offset)
+{
+	struct spi_device *dev = (struct spi_device *)file->private_data;
+	if( count > SPI_TRANSFER_MAX ) count = SPI_TRANSFER_MAX;
+	return spi_read(dev, buf, count );
+}
+
+static ssize_t spidev_write(struct file *file, const char *buf, size_t count,
+			    loff_t * offset)
+{
+	struct spi_device *dev = (struct spi_device *)file->private_data;
+	if( count > SPI_TRANSFER_MAX ) count = SPI_TRANSFER_MAX;
+	return spi_write( dev, buf, count );
+}
+
+struct spidev_openclose {
+	unsigned int minor;
+	struct file *file;
+};
+
+static int spidev_do_open(struct device *the_dev, void *context)
+{
+	struct spidev_openclose *o = (struct spidev_openclose *)context;
+	struct spi_device *dev = TO_SPI_DEV(the_dev);
+	struct spidev_driver_data *drvdata;
+
+	drvdata = (struct spidev_driver_data *)dev_get_drvdata(the_dev);
+	if (NULL == drvdata) {
+		pr_debug("%s: oops, drvdata is NULL !\n", __FUNCTION__);
+		return 0;
+	}
+
+	pr_debug("drvdata->minor = %d vs %d\n", drvdata->minor, o->minor);
+	if (drvdata->minor == o->minor) {
+		get_device(&dev->dev);
+		o->file->private_data = dev;
+		return 1;
+	}
+	return 0;
+}
+
+int spidev_open(struct inode *inode, struct file *file)
+{
+	struct spidev_openclose o;
+	int status;
+
+	o.minor = iminor(inode);
+	o.file = file;
+	status = driver_for_each_dev(&spidev_driver.driver, &o, spidev_do_open);
+	if (status == 0) {
+		status = -ENODEV;
+	}
+	return status < 0 ? status : 0;
+}
+
+static int spidev_release(struct inode *inode, struct file *file)
+{
+	struct spi_device *dev = file->private_data;
+
+	if (dev) {
+		put_device(&dev->dev);
+	}
+	file->private_data = NULL;
+
+	return 0;
+}
+
+static int __init spidev_init(void)
+{
+	int res;
+
+	if (0 != (res = register_chrdev(SPI_MAJOR, "spi", &spidev_fops))) {
+		goto out;
+	}
+
+	spidev_class = class_simple_create(THIS_MODULE, "spi");
+	if (IS_ERR(spidev_class)) {
+		printk(KERN_ERR "%s: error creating class\n", __FUNCTION__);
+		res = -EINVAL;
+		goto out_unreg;
+	}
+
+	if (0 != (res = spi_driver_add(&spidev_driver))) {
+		goto out_unreg;
+	}
+	printk("SPI /dev entries driver.\n");
+	return 0;
+
+out_unreg:
+	unregister_chrdev(SPI_MAJOR, "spi");
+out:
+	printk(KERN_ERR "%s: Driver initialization failed\n", __FILE__);
+	return res;
+}
+
+static void spidev_cleanup(void)
+{
+	spi_driver_del(&spidev_driver);
+	class_simple_destroy(spidev_class);
+	unregister_chrdev(SPI_MAJOR, "spi");
+}
+
+MODULE_AUTHOR("dmitry pervushin <dpervushin@ru.mvista.com>");
+MODULE_DESCRIPTION("SPI /dev entries driver");
+MODULE_LICENSE("GPL");
+
+module_init(spidev_init);
+module_exit(spidev_cleanup);
Index: linux-2.6.10/include/linux/spi.h
===================================================================
--- /dev/null
+++ linux-2.6.10/include/linux/spi.h
@@ -0,0 +1,214 @@
+/*
+ *  linux/include/linux/spi/spi.h
+ *
+ *  Copyright (C) 2005 MontaVista Software, Inc <sources@mvista.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License.
+ *
+ * Derived from l3.h by Jamey Hicks
+ */
+#ifndef SPI_H
+#define SPI_H
+
+#include <linux/types.h>
+
+struct spi_device;
+struct spi_driver;
+struct spi_msg;
+struct spi_bus_driver;
+
+extern struct bus_type spi_bus;
+
+struct spi_bus_data
+{
+	struct semaphore lock;
+	struct list_head msgs;
+	atomic_t exiting;
+	struct task_struct* thread;
+	wait_queue_head_t queue; 
+	struct spi_device* selected_device;
+	struct spi_bus_driver* bus;
+};
+
+#define TO_SPI_BUS_DRIVER(drv) container_of( drv, struct spi_bus_driver, driver )
+struct spi_bus_driver
+{
+	int (*xfer)( struct spi_msg* msg );
+	void (*select)( struct spi_device* dev );
+	void (*deselect)( struct spi_device* dev );
+	void (*set_clock)( struct device* bus_device, u32 clock_hz );
+	struct device_driver driver;
+};
+
+#define TO_SPI_DEV(device) container_of( device, struct spi_device, dev )
+struct spi_device 
+{
+	char name[ BUS_ID_SIZE ];
+	struct device dev;
+};
+
+#define TO_SPI_DRIVER(drv) container_of( drv, struct spi_driver, driver )
+struct spi_driver {
+    	void* (*alloc)( size_t, int );
+    	void  (*free)( const void* );
+    	unsigned char* (*get_buffer)( struct spi_device*, void* );
+    	void (*release_buffer)( struct spi_device*, unsigned char*);
+    	void (*control)( struct spi_device*, int mode, u32 ctl );
+	struct device_driver driver;
+};
+
+#define SPI_DEV_DRV( device )  TO_SPI_DRIVER( (device)->dev.driver )
+
+#define spi_device_lock( dev ) /* down( dev->dev.sem ) */
+#define spi_device_unlock( dev ) /* up( dev->dev.sem ) */
+
+/*
+ * struct spi_msg
+ *
+ * This structure represent the SPI message internally. You should never use fields of this structure directly
+ * Please use corresponding functions to create/destroy/access fields
+ *
+ */
+struct spi_msg {
+	unsigned char flags;
+#define SPI_M_RD	0x01
+#define SPI_M_WR	0x02	/**< Write mode flag */
+#define SPI_M_CSREL	0x04	/**< CS release level at end of the frame  */
+#define SPI_M_CS	0x08	/**< CS active level at begining of frame ( default low ) */
+#define SPI_M_CPOL	0x10	/**< Clock polarity */
+#define SPI_M_CPHA	0x20	/**< Clock Phase */
+	unsigned short len;	/* msg length           */
+	unsigned long clock;
+	struct spi_device* device;
+	void	      *context;
+	struct list_head link; 
+	void (*status)( struct spi_msg* msg, int code );
+	void *devbuf_rd, *devbuf_wr;
+	u8 *databuf_rd, *databuf_wr;
+};
+
+static inline struct spi_msg* spimsg_alloc( struct spi_device* device, 
+					    unsigned flags,
+					    unsigned short len, 
+					    void (*status)( struct spi_msg*, int code ) )
+{
+    struct spi_msg* msg;
+    struct spi_driver* drv = SPI_DEV_DRV( device );
+    
+    msg = kmalloc( sizeof( struct spi_msg ), GFP_KERNEL );
+    if( !msg )
+	return NULL;
+    memset( msg, 0, sizeof( struct spi_msg ) );
+    msg->len = len;
+    msg->status = status;
+    msg->device = device;
+    msg->flags = flags;
+    INIT_LIST_HEAD( &msg->link );
+    if( flags & SPI_M_RD ) {
+        msg->devbuf_rd =  drv->alloc ? 
+	    drv->alloc( len, GFP_KERNEL ):kmalloc( len, GFP_KERNEL);
+	msg->databuf_rd = drv->get_buffer ? 
+	    drv->get_buffer( device, msg->devbuf_rd ) : msg->devbuf_rd;
+    }
+    if( flags & SPI_M_WR ) {
+        msg->devbuf_wr =  drv->alloc ? 
+	    drv->alloc( len, GFP_KERNEL ):kmalloc( len, GFP_KERNEL);
+	msg->databuf_wr = drv->get_buffer ? 
+	    drv->get_buffer( device, msg->devbuf_wr ) : msg->devbuf_wr;
+    }
+    pr_debug( "%s: msg = %p, RD=(%p,%p) WR=(%p,%p). Actual flags = %s+%s\n",
+		   __FUNCTION__,
+		  msg, 
+		  msg->devbuf_rd, msg->databuf_rd,
+		  msg->devbuf_wr, msg->databuf_wr, 
+		  msg->flags & SPI_M_RD ? "RD" : "~rd",
+		  msg->flags & SPI_M_WR ? "WR" : "~wr" );
+    return msg;
+}
+
+static inline void spimsg_free( struct spi_msg * msg )
+{
+    void (*do_free)( const void* ) = kfree;
+    struct spi_driver* drv = SPI_DEV_DRV( msg->device );
+    
+    if( msg ) {
+	    if( drv->free ) 
+		do_free = drv->free;
+	    if( drv->release_buffer ) {
+		if( msg->databuf_rd) 
+		    drv->release_buffer( msg->device, msg->databuf_rd );
+    		if( msg->databuf_wr) 
+		    drv->release_buffer( msg->device, msg->databuf_wr );
+	}
+	if( msg->devbuf_rd ) 
+	    do_free( msg->devbuf_rd );
+	if( msg->devbuf_wr)
+	    do_free( msg->devbuf_wr );
+	kfree( msg );
+    }
+}
+
+static inline u8* spimsg_buffer_rd( struct spi_msg* msg ) 
+{
+    return msg ? msg->databuf_rd : NULL;
+}
+
+static inline u8* spimsg_buffer_wr( struct spi_msg* msg ) 
+{
+    return msg ? msg->databuf_wr : NULL;
+}
+
+static inline u8* spimsg_buffer( struct spi_msg* msg ) 
+{
+    if( !msg ) return NULL;
+    if( ( msg->flags & (SPI_M_RD|SPI_M_WR) ) == (SPI_M_RD|SPI_M_WR) ) {
+	printk( KERN_ERR"%s: what buffer do you really want ?\n", __FUNCTION__ );
+	return NULL;
+    }
+    if( msg->flags & SPI_M_RD) return msg->databuf_rd;
+    if( msg->flags & SPI_M_WR) return msg->databuf_wr;
+}
+
+#define SPIMSG_OK 	0x01
+#define SPIMSG_FAILED 	0x80
+#define SPIMSG_STARTED  0x02 
+#define SPIMSG_DONE	0x04
+
+#define SPI_MAJOR	98
+
+struct spi_driver;
+struct spi_device;
+
+static inline int spi_bus_driver_register( struct spi_bus_driver* bus_driver )
+{
+	return driver_register( &bus_driver->driver );
+}
+
+void spi_bus_driver_unregister( struct spi_bus_driver* );
+int spi_bus_driver_init( struct spi_bus_driver* driver, struct device* dev );
+int spi_device_add( struct device* parent, struct spi_device*, char* name );
+static inline void spi_device_del( struct spi_device* dev )
+{
+	device_unregister( &dev->dev );
+}
+static inline int spi_driver_add( struct spi_driver* drv ) 
+{
+	return driver_register( &drv->driver );
+}
+static inline void spi_driver_del( struct spi_driver* drv ) 
+{
+	driver_unregister( &drv->driver );
+}
+
+#define SPI_DEV_CHAR "spi-char"
+
+extern int spi_write(struct spi_device *dev, const char *buf, int len);
+extern int spi_read(struct spi_device *dev, char *buf, int len);
+
+extern int spi_queue( struct spi_msg* message );
+extern int spi_transfer( struct spi_msg* message, void (*status)( struct spi_msg*, int ) );
+extern int spi_bus_populate( struct device* parent, char* device, void (*assign)( struct device* parent, struct spi_device* ) );
+
+#endif				/* SPI_H */
Index: linux-2.6.10/Documentation/spi.txt
===================================================================
--- /dev/null
+++ linux-2.6.10/Documentation/spi.txt
@@ -0,0 +1,351 @@
+Documentation/spi.txt
+========================================================
+Table of contents
+1. Introduction -- what is SPI ?
+2. Purposes of this code
+3. SPI devices stack
+3.1 SPI outline
+3.2 How the SPI devices gets discovered and probed ?
+3.3 DMA and SPI messages
+4. SPI functions and structures reference
+5. How to contact authors
+========================================================
+
+1. What is SPI ?
+----------------
+SPI stands for "Serial Peripheral Interface", a full-duplex synchronous 
+serial interface for connecting low-/medium-bandwidth external devices 
+using four wires. SPI devices communicate using a master/slave relation-
+ship over two data lines and two control lines:
+- Master Out Slave In (MOSI): supplies the output data from the master 
+  to the inputs of the slaves;
+- Master In Slave Out (MISO): supplies the output data from a slave to 
+  the input of the master. It is important to note that there can be no 
+  more than one slave that is transmitting data during any particular 
+  transfer;
+- Serial Clock (SCLK): a control line driven by the master, regulating 
+  the flow of data bits;
+- Slave Select (SS): a control line that allows slaves to be turned on 
+  and off with  hardware control.
+More information is also available at http://en.wikipedia.org/wiki/Serial_Peripheral_Interface/ .
+
+2. Purposes of this code
+------------------------
+The supplied patch is starting point for implementing drivers for various
+SPI busses as well as devices connected to these busses. Currently, the 
+SPI core supports only for MASTER mode for system running Linux.
+
+3. SPI devices stack
+--------------------
+
+3.1 The SPI outline
+
+The SPI infrastructure deals with several levels of abstraction. They are 
+"SPI bus", "SPI bus driver", "SPI device" and "SPI device driver". The 
+"SPI bus" is hardware device, which usually called "SPI adapter", and has 
+"SPI devices" connected. From the Linux' point of view, the "SPI bus" is
+structure of type platform_device, and "SPI device" is structure of type
+spi_device. The "SPI bus driver" is the driver which controls the whole 
+SPI bus (and, particularly, creates and destroys "SPI devices" on the bus),
+and "SPI device driver" is driver that controls the only device on the SPI 
+bus, controlled by "SPI bus driver". "SPI device driver" can indirectly 
+call "SPI bus driver" to send/receive messages using API provided by SPI 
+core, and provide its own interface to the kernel and/or userland.
+So, the device stack looks as follows:
+
+  +--------------+                    +---------+
+  | platform_bus |                    | spi_bus |
+  +--------------+                    +---------+
+       |..|                                |
+       |..|--------+               +---------------+   
+     +------------+| is parent to  |  SPI devices  | 
+     | SPI busses |+-------------> |               |
+     +------------+                +---------------+
+           |                               |
+     +----------------+          +----------------------+
+     | SPI bus driver |          |    SPI device driver |
+     +----------------+          +----------------------+
+
+3.2 How do the SPI devices gets discovered and probed ?
+
+In general, the SPI bus driver cannot effective discover devices
+on its bus. Fortunately, the devices on SPI bus usually implemented
+onboard, so the following method has been chosen: the SPI bus driver
+calls the function named spi_bus_populate and passed the `topology
+string' to it. The function will parse the string and call the callback
+for each device, just before registering it. This allows bus driver
+to determine parameters like CS# for each device, retrieve them from
+string and store somewhere like spi_device->platform_data. An example:
+	err = spi_bus_populate( the_spi_bus,
+			"Dev1 0 1 2\0" "Dev2 2 1 0\0",
+			extract_name )
+In this example, function like extract_name would put the '\0' on the 
+1st space of device's name, so names will become just "Dev1", "Dev2", 
+and the rest of string will become parameters of device.
+
+3.3. DMA and SPI messages
+-------------------------
+
+To handle DMA transfers on SPI bus, any device driver might provide special
+callbacks to allocate/free/get access to buffer. These callbacks are defined 
+in subsection iii of section 4.
+To send data using DMA, the buffers should be allocated using 
+dma_alloc_coherent function. Usually buffers are allocated statically or
+using kmalloc function. 
+To allow drivers to allocate buffers in non-standard 
+When one allocates the structure for spi message, it needs to provide target
+device. If its driver wants to allocate buffer in driver-specific way, it may
+provide its own allocation/free methods: alloc and free. If driver does not
+provide these methods, kmalloc and kfree will be used.
+After allocation, the buffer must be accessed to copy the buffer to be send 
+or retrieve buffer that has been just received from device. If buffer was
+allocated using driver's alloc method, it(buffer) will be accessed using 
+get_buffer. Driver should provide accessible buffer that corresponds buffer
+allocated by driver's alloc method. If there is no get_buffer method, 
+the result of alloc will be used.
+After reading/writing from/to buffer, it will be released by call to driver's
+release_buffer method.
+
+ 
+4. SPI functions are structures reference
+-----------------------------------------
+This section describes structures and functions that listed
+in include/linux/spi.h
+
+i. struct spi_msg 
+~~~~~~~~~~~~~~~~~
+
+struct spi_msg {
+        unsigned char flags;
+        unsigned short len;     
+        unsigned long clock;
+        struct spi_device* device;
+        void          *context;
+        struct list_head link;
+        void (*status)( struct spi_msg* msg, int code );
+        void *devbuf_rd, *devbuf_wr;
+        u8 *databuf_rd, *databuf_wr;
+};
+This structure represents the message that SPI device driver sends to the
+SPI bus driver to handle.
+Fields:
+	flags 	combination of message flags
+		SPI_M_RD	"read" operation (from device to host)
+		SPI_M_WR	"write" operation (from host to device)
+		SPI_M_CS	assert the CS signal before sending the message
+		SPI_M_CSREL	clear the CS signal after sending the message
+		SPI_M_CSPOL	set clock polarity to high
+		SPI_M_CPHA	set clock phase to high
+	len	length, in bytes, of allocated buffer
+	clock	reserved, set to zero
+	device	the target device of the message
+	context	user-defined field; to associate any user data with the message
+	link	used by bus driver to queue messages
+	status	user-provided callback function to inform about message flow
+	devbuf_rd, devbuf_wr
+		so-called "device buffers". These buffers allocated by the
+		device driver, if device driver provides approproate callback.
+		Otherwise, the kmalloc API will be used.
+	databuf_rd, databuf_wr
+		pointers to access content of device buffers. They are acquired
+		using get_buffer callback, if device driver provides one.
+		Otherwise, they are just pointers to corresponding
+		device buffers
+
+struct spi_msg* spimsg_alloc( struct spi_device* device,
+                              unsigned flags,
+                              unsigned short len,
+                              void (*status)( struct spi_msg*, int code ) )
+This functions is called to allocate the spi_msg structure and set the 
+corresponding fields in structure. If device->platform_data provides callbacks
+to handle buffers, alloc/get_buffer are to be used. Returns NULL on errors.
+
+struct void spimsg_free( struct spi_msg* msg )
+Deallocate spi_msg as well as internal buffers. If msg->device->platform_data
+provides callbacks to handle buffers, release_buffer and free are to be used.
+
+u8* spimsg_buffer_rd( struct spi_msg* msg )
+u8* spimsg_buffer_wr( struct spi_msg* msg )
+u8* spimsg_buffer( struct spi_msg* )
+Return the corresponding data buffer, which can be directly modified by driver.
+spimsg_buffer checks flags and return either databuf_rd or databuf_wr basing on
+value of `flags' in spi_msg structure.
+
+ii. struct spi_device
+~~~~~~~~~~~~~~~~~~~~~
+
+struct spi_device
+{
+        char name[ BUS_ID_SIZE ];
+        struct device dev;
+};
+This structure represents the physical device on SPI bus. The SPI bus driver 
+will create and register this structure for you.
+	name	the name of the device. It should match to the SPI device
+		driver name
+	dev	field used to be registered with core
+
+int spi_device_add( struct device* parent, 
+                    struct spi_device* dev, 
+                    char* name )
+This function registers the device `dev' on the spi bus, and set its parent
+to `parent', which represents the SPI bus. The device name will be set to name,
+that should be non-empty, non-NULL string. Returns 0 on no error, error code 
+otherwise.
+
+void spi_device_del( struct spi_device* dev )
+Unregister the SPI device. Return value is ignored
+
+iii. struct spi_driver
+~~~~~~~~~~~~~~~~~~~~~~
+
+struct spi_driver {
+    	void* (*alloc)( size_t, int );
+    	void  (*free)( const void* );
+    	unsigned char* (*get_buffer)( struct spi_device*, void* );
+    	void (*release_buffer)( struct spi_device*, unsigned char*);
+    	void (*control)( struct spi_device*, int mode, u32 ctl );
+        struct device_driver driver;
+};
+This structure represents the SPI device driver object. Before registering,
+all fields of driver sub-structure should be properly filled, e.g., the 
+`bus_type' should be set to spi_bus. Otherwise, the driver will be incorrectly 
+registered and its callbacks might never been called. An example of will-
+formed spi_driver structure:
+	extern struct bus_type spi_bus;
+	static struct spi_driver pnx4008_eeprom_driver = {
+        	.driver = {
+                   	.bus = &spi_bus,
+                   	.name = "pnx4008-eeprom",
+                   	.probe = pnx4008_spiee_probe,
+                   	.remove = pnx4008_spiee_remove,
+                   	.suspend = pnx4008_spiee_suspend,
+                   	.resume = pnx4008_spiee_resume,
+               	},
+};
+The method control gets called during the processing of SPI message.
+For detailed description of malloc/free/get_buffer/release_buffer, please
+look to section 3.3, "DMA and SPI messages"
+
+
+int spi_driver_add( struct spi_driver* driver )
+Register the SPI device driver with core; returns 0 on no errors, error code
+otherwise.
+
+void spi_driver_del( struct spi_driver* driver )
+Unregisters the SPI device driver; return value ignored.
+
+iv. struct spi_bus_driver
+~~~~~~~~~~~~~~~~~~~~~~~~~
+To handle transactions over the SPI bus, the spi_bus_driver structure must 
+be prepared and registered with core. Any transactions, either synchronous 
+or asynchronous, go through spi_bus_driver->xfer function. 
+
+struct spi_bus_driver
+{
+        int (*xfer)( struct spi_msg* msgs );
+        void (*select) ( struct spi_device* arg );
+        void (*deselect)( struct spi_device* arg );
+
+        struct device_driver driver;
+};
+
+Fields:
+	xfer	pointer to function to execute actual transaction on SPI bus
+		msg	message to handle
+	select	pointer to function that gets called when bus needs to 
+		select another device to be target of transfers
+	deselect
+		pointer to function that gets called before another device
+		is selected to be the target of transfers
+
+
+spi_bus_driver_register( struct spi_bus_driver* )
+
+Register the SPI bus driver with the system. The driver sub-structure should
+be properly filled before using this function, otherwise you may get unpredi-
+ctable results when trying to exchange data. An example of correctly prepared
+spi_bus_driver structure:
+	static struct spi_bus_driver spipnx_driver = {
+        .driver = {
+                   .bus = &platform_bus_type,
+                   .name = "spipnx",
+                   .probe = spipnx_probe,
+                   .remove = spipnx_remove,
+                   .suspend = spipnx_suspend,
+                   .resume = spipnx_resume,
+                   },
+        .xfer = spipnx_xfer,
+};
+The driver and corresponding platform device are matched by name, so, in 
+order the example abive to work, the platform_device named "spipnx" should
+be registered somewhere.
+
+void spi_bus_driver_unregister( struct spi_bus_driver* )
+
+Unregister the SPI bus driver registered by call to spi_buys_driver_register
+function; returns void.
+
+void spi_bus_populate( struct device* parent, 
+			      char* devices,
+			      void (*callback)( struct device* parent, struct spi_device* new_one ) )
+This function usually called by SPI bus drivers in order to populate the SPI
+bus (see also section 3.2, "How the SPI devices gets discovered and probed ?").
+After creating the spi_device, the spi_bus_populate calls the `callback' 
+function to allow to modify spi_device's fields before registering it with core.
+	parent	pointer to SPI bus
+	devices	string representing the current topology of SPI bus. It should
+		be formed like
+		"dev-1_and_its_info\0dev-2_and_its_info\0another_device\0\0"
+		the spi_bus_populate delimits this string by '\0' characters,
+		creates spi_device and after calling the callback registers the
+		spi_device
+	callback
+		pointer to function which could modify spi_device fields just
+		before registering them with core
+
+v. spi_transfer and spi_queue
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The driver that uses SPI core can initiate transfers either by calling 
+spi_transfer function (that will wait till the transfer is funished) or
+queueing the message using spi_queue function (you need to provide function
+that will be called during message is processed). In any way, you need to
+prepare the spimsg structure and know the target device to your message to 
+be sent.
+
+int spi_transfer( struct spi_msg msgs, 
+                  void (*callback)( struct spi_msg* msg, int ) )
+If callback is zero, start synchronous transfer. Otherwise, queue 
+the message.
+	msg		message to be handled
+	callback	the callback function to be called during
+			message processing. If NULL, the function
+			will wait until end of processing.
+
+int spi_queue( struct spi_msg* msg )
+
+Queue the only message to the device. Returns status of queueing. To obtain
+status of message processing, you have to provide `status' callback in message
+and examine its parameters
+	msg	message to be queued
+
+vi. the spi_bus variable
+~~~~~~~~~~~~~~~~~~~~~~~~
+This variable is created during initialization of spi core, and has to be 
+specified as `bus' on any SPI device driver (look to section iii, "struct
+spi_driver" ). If you do not specify spi_bus, your driver will be never
+matched to spi_device and never be probed with hardware. Note that 
+spi_bus.match points to function that matches drivers and devices by name,
+so SPI devices and their drivers should have the same name.
+
+5. How to contact authors
+-------------------------
+Do you have any comments ? Enhancements ? Device driver ? Feel free
+to contact me: 
+	dpervushin@gmail.com
+	dimka@pervushin.msk.ru
+Visit our project page:
+	http://spi-devel.sourceforge.net
+Subscribe to mailing list:
+	spi-devel-general@lists.sourceforge.net
+



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