drivers/firmware/dell_rbu.c - fp2-dev/kernel/msm - Gitiles

 /*
  * dell_rbu.c
  * Bios Update driver for Dell systems
  * Author: Dell Inc
  *         Abhay Salunke <abhay_salunke@dell.com>
  *
  * Copyright (C) 2005 Dell Inc.
  *
  * Remote BIOS Update (rbu) driver is used for updating DELL BIOS by
  * creating entries in the /sys file systems on Linux 2.6 and higher
  * kernels. The driver supports two mechanism to update the BIOS namely
  * contiguous and packetized. Both these methods still require having some
  * application to set the CMOS bit indicating the BIOS to update itself
  * after a reboot.
  *
  * Contiguous method:
  * This driver writes the incoming data in a monolithic image by allocating
  * contiguous physical pages large enough to accommodate the incoming BIOS
  * image size.
  *
  * Packetized method:
  * The driver writes the incoming packet image by allocating a new packet
  * on every time the packet data is written. This driver requires an
  * application to break the BIOS image in to fixed sized packet chunks.
  *
  * See Documentation/dell_rbu.txt for more info.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License v2.0 as published by
  * the Free Software Foundation
  *
  * 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.
  */
 #include <linux/version.h>
 #include <linux/config.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/string.h>
 #include <linux/errno.h>
 #include <linux/blkdev.h>
 #include <linux/device.h>
 #include <linux/spinlock.h>
 #include <linux/moduleparam.h>
 #include <linux/firmware.h>
 #include <linux/dma-mapping.h>

 MODULE_AUTHOR("Abhay Salunke <abhay_salunke@dell.com>");
 MODULE_DESCRIPTION("Driver for updating BIOS image on DELL systems");
 MODULE_LICENSE("GPL");
 MODULE_VERSION("2.0");

 #define BIOS_SCAN_LIMIT 0xffffffff
 #define MAX_IMAGE_LENGTH 16
 static struct _rbu_data {
 	void *image_update_buffer;
 	unsigned long image_update_buffer_size;
 	unsigned long bios_image_size;
 	int image_update_ordernum;
 	int dma_alloc;
 	spinlock_t lock;
 	unsigned long packet_read_count;
 	unsigned long packet_write_count;
 	unsigned long num_packets;
 	unsigned long packetsize;
 	int entry_created;
 } rbu_data;

 static char image_type[MAX_IMAGE_LENGTH + 1] = "mono";
 module_param_string(image_type, image_type, sizeof (image_type), 0);
 MODULE_PARM_DESC(image_type, "BIOS image type. choose- mono or packet");

 struct packet_data {
 	struct list_head list;
 	size_t length;
 	void *data;
 	int ordernum;
 };

 static struct packet_data packet_data_head;

 static struct platform_device *rbu_device;
 static int context;
 static dma_addr_t dell_rbu_dmaaddr;

 static void init_packet_head(void)
 {
 	INIT_LIST_HEAD(&packet_data_head.list);
 	rbu_data.packet_write_count = 0;
 	rbu_data.packet_read_count = 0;
 	rbu_data.num_packets = 0;
 	rbu_data.packetsize = 0;
 }

 static int fill_last_packet(void *data, size_t length)
 {
 	struct list_head *ptemp_list;
 	struct packet_data *packet = NULL;
 	int packet_count = 0;

 	pr_debug("fill_last_packet: entry \n");

 	if (!rbu_data.num_packets) {
 		pr_debug("fill_last_packet: num_packets=0\n");
 		return -ENOMEM;
 	}

 	packet_count = rbu_data.num_packets;

 	ptemp_list = (&packet_data_head.list)->prev;

 	packet = list_entry(ptemp_list, struct packet_data, list);

 	if ((rbu_data.packet_write_count + length) > rbu_data.packetsize) {
 		pr_debug("dell_rbu:%s: packet size data "
 			"overrun\n", __FUNCTION__);
 		return -EINVAL;
 	}

 	pr_debug("fill_last_packet : buffer = %p\n", packet->data);

 	memcpy((packet->data + rbu_data.packet_write_count), data, length);

 	if ((rbu_data.packet_write_count + length) == rbu_data.packetsize) {
 		/*
 		 * this was the last data chunk in the packet
 		 * so reinitialize the packet data counter to zero
 		 */
 		rbu_data.packet_write_count = 0;
 	} else
 		rbu_data.packet_write_count += length;

 	pr_debug("fill_last_packet: exit \n");
 	return 0;
 }

 static int create_packet(size_t length)
 {
 	struct packet_data *newpacket;
 	int ordernum = 0;

 	pr_debug("create_packet: entry \n");

 	if (!rbu_data.packetsize) {
 		pr_debug("create_packet: packetsize not specified\n");
 		return -EINVAL;
 	}
 	spin_unlock(&rbu_data.lock);
 	newpacket = kmalloc(sizeof (struct packet_data), GFP_KERNEL);
 	spin_lock(&rbu_data.lock);

 	if (!newpacket) {
 		printk(KERN_WARNING
 			"dell_rbu:%s: failed to allocate new "
 			"packet\n", __FUNCTION__);
 		return -ENOMEM;
 	}

 	ordernum = get_order(length);
 	/*
 	 * there is no upper limit on memory
 	 * address for packetized mechanism
 	 */
 	spin_unlock(&rbu_data.lock);
 	newpacket->data = (unsigned char *) __get_free_pages(GFP_KERNEL,
 		ordernum);
 	spin_lock(&rbu_data.lock);

 	pr_debug("create_packet: newpacket %p\n", newpacket->data);

 	if (!newpacket->data) {
 		printk(KERN_WARNING
 			"dell_rbu:%s: failed to allocate new "
 			"packet\n", __FUNCTION__);
 		kfree(newpacket);
 		return -ENOMEM;
 	}

 	newpacket->ordernum = ordernum;
 	++rbu_data.num_packets;
 	/*
 	 * initialize the newly created packet headers
 	 */
 	INIT_LIST_HEAD(&newpacket->list);
 	list_add_tail(&newpacket->list, &packet_data_head.list);
 	/*
 	 * packets have fixed size
 	 */
 	newpacket->length = rbu_data.packetsize;

 	pr_debug("create_packet: exit \n");

 	return 0;
 }

 static int packetize_data(void *data, size_t length)
 {
 	int rc = 0;

 	if (!rbu_data.packet_write_count) {
 		if ((rc = create_packet(length)))
 			return rc;
 	}
 	if ((rc = fill_last_packet(data, length)))
 		return rc;

 	return rc;
 }

 static int do_packet_read(char *data, struct list_head *ptemp_list,
 	int length, int bytes_read, int *list_read_count)
 {
 	void *ptemp_buf;
 	struct packet_data *newpacket = NULL;
 	int bytes_copied = 0;
 	int j = 0;

 	newpacket = list_entry(ptemp_list, struct packet_data, list);
 	*list_read_count += newpacket->length;

 	if (*list_read_count > bytes_read) {
 		/* point to the start of unread data */
 		j = newpacket->length - (*list_read_count - bytes_read);
 		/* point to the offset in the packet buffer */
 		ptemp_buf = (u8 *) newpacket->data + j;
 		/*
 		 * check if there is enough room in
 		 * * the incoming buffer
 		 */
 		if (length > (*list_read_count - bytes_read))
 			/*
 			 * copy what ever is there in this
 			 * packet and move on
 			 */
 			bytes_copied = (*list_read_count - bytes_read);
 		else
 			/* copy the remaining */
 			bytes_copied = length;
 		memcpy(data, ptemp_buf, bytes_copied);
 	}
 	return bytes_copied;
 }

 static int packet_read_list(char *data, size_t *pread_length)
 {
 	struct list_head *ptemp_list;
 	int temp_count = 0;
 	int bytes_copied = 0;
 	int bytes_read = 0;
 	int remaining_bytes = 0;
 	char *pdest = data;

 	/* check if we have any packets */
 	if (0 == rbu_data.num_packets)
 		return -ENOMEM;

 	remaining_bytes = *pread_length;
 	bytes_read = rbu_data.packet_read_count;

 	ptemp_list = (&packet_data_head.list)->next;
 	while (!list_empty(ptemp_list)) {
 		bytes_copied = do_packet_read(pdest, ptemp_list,
 			remaining_bytes, bytes_read, &temp_count);
 		remaining_bytes -= bytes_copied;
 		bytes_read += bytes_copied;
 		pdest += bytes_copied;
 		/*
 		 * check if we reached end of buffer before reaching the
 		 * last packet
 		 */
 		if (remaining_bytes == 0)
 			break;

 		ptemp_list = ptemp_list->next;
 	}
 	/*finally set the bytes read */
 	*pread_length = bytes_read - rbu_data.packet_read_count;
 	rbu_data.packet_read_count = bytes_read;
 	return 0;
 }

 static void packet_empty_list(void)
 {
 	struct list_head *ptemp_list;
 	struct list_head *pnext_list;
 	struct packet_data *newpacket;

 	ptemp_list = (&packet_data_head.list)->next;
 	while (!list_empty(ptemp_list)) {
 		newpacket =
 			list_entry(ptemp_list, struct packet_data, list);
 		pnext_list = ptemp_list->next;
 		list_del(ptemp_list);
 		ptemp_list = pnext_list;
 		/*
 		 * zero out the RBU packet memory before freeing
 		 * to make sure there are no stale RBU packets left in memory
 		 */
 		memset(newpacket->data, 0, rbu_data.packetsize);
 		free_pages((unsigned long) newpacket->data,
 			newpacket->ordernum);
 		kfree(newpacket);
 	}
 	rbu_data.packet_write_count = 0;
 	rbu_data.packet_read_count = 0;
 	rbu_data.num_packets = 0;
 	rbu_data.packetsize = 0;
 }

 /*
  * img_update_free: Frees the buffer allocated for storing BIOS image
  * Always called with lock held and returned with lock held
  */
 static void img_update_free(void)
 {
 	if (!rbu_data.image_update_buffer)
 		return;
 	/*
 	 * zero out this buffer before freeing it to get rid of any stale
 	 * BIOS image copied in memory.
 	 */
 	memset(rbu_data.image_update_buffer, 0,
 		rbu_data.image_update_buffer_size);
 	if (rbu_data.dma_alloc == 1)
 		dma_free_coherent(NULL, rbu_data.bios_image_size,
 			rbu_data.image_update_buffer, dell_rbu_dmaaddr);
 	else
 		free_pages((unsigned long) rbu_data.image_update_buffer,
 			rbu_data.image_update_ordernum);

 	/*
 	 * Re-initialize the rbu_data variables after a free
 	 */
 	rbu_data.image_update_ordernum = -1;
 	rbu_data.image_update_buffer = NULL;
 	rbu_data.image_update_buffer_size = 0;
 	rbu_data.bios_image_size = 0;
 	rbu_data.dma_alloc = 0;
 }

 /*
  * img_update_realloc: This function allocates the contiguous pages to
  * accommodate the requested size of data. The memory address and size
  * values are stored globally and on every call to this function the new
  * size is checked to see if more data is required than the existing size.
  * If true the previous memory is freed and new allocation is done to
  * accommodate the new size. If the incoming size is less then than the
  * already allocated size, then that memory is reused. This function is
  * called with lock held and returns with lock held.
  */
 static int img_update_realloc(unsigned long size)
 {
 	unsigned char *image_update_buffer = NULL;
 	unsigned long rc;
 	unsigned long img_buf_phys_addr;
 	int ordernum;
 	int dma_alloc = 0;

 	/*
 	 * check if the buffer of sufficient size has been
 	 * already allocated
 	 */
 	if (rbu_data.image_update_buffer_size >= size) {
 		/*
 		 * check for corruption
 		 */
 		if ((size != 0) && (rbu_data.image_update_buffer == NULL)) {
 			printk(KERN_ERR "dell_rbu:%s: corruption "
 				"check failed\n", __FUNCTION__);
 			return -EINVAL;
 		}
 		/*
 		 * we have a valid pre-allocated buffer with
 		 * sufficient size
 		 */
 		return 0;
 	}

 	/*
 	 * free any previously allocated buffer
 	 */
 	img_update_free();

 	spin_unlock(&rbu_data.lock);

 	ordernum = get_order(size);
 	image_update_buffer =
 		(unsigned char *) __get_free_pages(GFP_KERNEL, ordernum);

 	img_buf_phys_addr =
 		(unsigned long) virt_to_phys(image_update_buffer);

 	if (img_buf_phys_addr > BIOS_SCAN_LIMIT) {
 		free_pages((unsigned long) image_update_buffer, ordernum);
 		ordernum = -1;
 		image_update_buffer = dma_alloc_coherent(NULL, size,
 			&dell_rbu_dmaaddr, GFP_KERNEL);
 		dma_alloc = 1;
 	}

 	spin_lock(&rbu_data.lock);

 	if (image_update_buffer != NULL) {
 		rbu_data.image_update_buffer = image_update_buffer;
 		rbu_data.image_update_buffer_size = size;
 		rbu_data.bios_image_size =
 			rbu_data.image_update_buffer_size;
 		rbu_data.image_update_ordernum = ordernum;
 		rbu_data.dma_alloc = dma_alloc;
 		rc = 0;
 	} else {
 		pr_debug("Not enough memory for image update:"
 			"size = %ld\n", size);
 		rc = -ENOMEM;
 	}

 	return rc;
 }

 static ssize_t read_packet_data(char *buffer, loff_t pos, size_t count)
 {
 	int retval;
 	size_t bytes_left;
 	size_t data_length;
 	char *ptempBuf = buffer;
 	unsigned long imagesize;

 	/* check to see if we have something to return */
 	if (rbu_data.num_packets == 0) {
 		pr_debug("read_packet_data: no packets written\n");
 		retval = -ENOMEM;
 		goto read_rbu_data_exit;
 	}

 	imagesize = rbu_data.num_packets * rbu_data.packetsize;

 	if (pos > imagesize) {
 		retval = 0;
 		printk(KERN_WARNING "dell_rbu:read_packet_data: "
 			"data underrun\n");
 		goto read_rbu_data_exit;
 	}

 	bytes_left = imagesize - pos;
 	data_length = min(bytes_left, count);

 	if ((retval = packet_read_list(ptempBuf, &data_length)) < 0)
 		goto read_rbu_data_exit;

 	if ((pos + count) > imagesize) {
 		rbu_data.packet_read_count = 0;
 		/* this was the last copy */
 		retval = bytes_left;
 	} else
 		retval = count;

       read_rbu_data_exit:
 	return retval;
 }

 static ssize_t read_rbu_mono_data(char *buffer, loff_t pos, size_t count)
 {
 	unsigned char *ptemp = NULL;
 	size_t bytes_left = 0;
 	size_t data_length = 0;
 	ssize_t ret_count = 0;

 	/* check to see if we have something to return */
 	if ((rbu_data.image_update_buffer == NULL) ||
 		(rbu_data.bios_image_size == 0)) {
 		pr_debug("read_rbu_data_mono: image_update_buffer %p ,"
 			"bios_image_size %lu\n",
 			rbu_data.image_update_buffer,
 			rbu_data.bios_image_size);
 		ret_count = -ENOMEM;
 		goto read_rbu_data_exit;
 	}

 	if (pos > rbu_data.bios_image_size) {
 		ret_count = 0;
 		goto read_rbu_data_exit;
 	}

 	bytes_left = rbu_data.bios_image_size - pos;
 	data_length = min(bytes_left, count);

 	ptemp = rbu_data.image_update_buffer;
 	memcpy(buffer, (ptemp + pos), data_length);

 	if ((pos + count) > rbu_data.bios_image_size)
 		/* this was the last copy */
 		ret_count = bytes_left;
 	else
 		ret_count = count;
       read_rbu_data_exit:
 	return ret_count;
 }

 static ssize_t read_rbu_data(struct kobject *kobj, char *buffer,
 			loff_t pos, size_t count)
 {
 	ssize_t ret_count = 0;

 	spin_lock(&rbu_data.lock);

 	if (!strcmp(image_type, "mono"))
 		ret_count = read_rbu_mono_data(buffer, pos, count);
 	else if (!strcmp(image_type, "packet"))
 		ret_count = read_packet_data(buffer, pos, count);
 	else
 		pr_debug("read_rbu_data: invalid image type specified\n");

 	spin_unlock(&rbu_data.lock);
 	return ret_count;
 }

 static void callbackfn_rbu(const struct firmware *fw, void *context)
 {
 	int rc = 0;

 	if (!fw || !fw->size) {
 		rbu_data.entry_created = 0;
 		return;
 	}

 	spin_lock(&rbu_data.lock);
 	if (!strcmp(image_type, "mono")) {
 		if (!img_update_realloc(fw->size))
 			memcpy(rbu_data.image_update_buffer,
 				fw->data, fw->size);
 	} else if (!strcmp(image_type, "packet")) {
 		if (!rbu_data.packetsize)
 			rbu_data.packetsize = fw->size;
 		else if (rbu_data.packetsize != fw->size) {
 			packet_empty_list();
 			rbu_data.packetsize = fw->size;
 		}
 		packetize_data(fw->data, fw->size);
 	} else
 		pr_debug("invalid image type specified.\n");
 	spin_unlock(&rbu_data.lock);

 	rc = request_firmware_nowait(THIS_MODULE, FW_ACTION_NOHOTPLUG,
 		"dell_rbu", &rbu_device->dev, &context, callbackfn_rbu);
 	if (rc)
 		printk(KERN_ERR
 			"dell_rbu:%s request_firmware_nowait failed"
 			" %d\n", __FUNCTION__, rc);
 	else
 		rbu_data.entry_created = 1;
 }

 static ssize_t read_rbu_image_type(struct kobject *kobj, char *buffer,
 			loff_t pos, size_t count)
 {
 	int size = 0;
 	if (!pos)
 		size = sprintf(buffer, "%s\n", image_type);
 	return size;
 }

 static ssize_t write_rbu_image_type(struct kobject *kobj, char *buffer,
 			loff_t pos, size_t count)
 {
 	int rc = count;
 	int req_firm_rc = 0;
 	int i;
 	spin_lock(&rbu_data.lock);
 	/*
 	 * Find the first newline or space
 	 */
 	for (i = 0; i < count; ++i)
 		if (buffer[i] == '\n' || buffer[i] == ' ') {
 			buffer[i] = '\0';
 			break;
 		}
 	if (i == count)
 		buffer[count] = '\0';

 	if (strstr(buffer, "mono"))
 		strcpy(image_type, "mono");
 	else if (strstr(buffer, "packet"))
 		strcpy(image_type, "packet");
 	else if (strstr(buffer, "init")) {
 		/*
 		 * If due to the user error the driver gets in a bad
 		 * state where even though it is loaded , the
 		 * /sys/class/firmware/dell_rbu entries are missing.
 		 * to cover this situation the user can recreate entries
 		 * by writing init to image_type.
 		 */
 		if (!rbu_data.entry_created) {
 			spin_unlock(&rbu_data.lock);
 			req_firm_rc = request_firmware_nowait(THIS_MODULE,
 				FW_ACTION_NOHOTPLUG, "dell_rbu",
 				&rbu_device->dev, &context,
 				callbackfn_rbu);
 			if (req_firm_rc) {
 				printk(KERN_ERR
 					"dell_rbu:%s request_firmware_nowait"
 					" failed %d\n", __FUNCTION__, rc);
 				rc = -EIO;
 			} else
 				rbu_data.entry_created = 1;

 			spin_lock(&rbu_data.lock);
 		}
 	} else {
 		printk(KERN_WARNING "dell_rbu: image_type is invalid\n");
 		spin_unlock(&rbu_data.lock);
 		return -EINVAL;
 	}

 	/* we must free all previous allocations */
 	packet_empty_list();
 	img_update_free();
 	spin_unlock(&rbu_data.lock);

 	return rc;
 }

 static struct bin_attribute rbu_data_attr = {
 	.attr = {
 		.name = "data",
 		.owner = THIS_MODULE,
 		.mode = 0444,
 	},
 	.read = read_rbu_data,
 };

 static struct bin_attribute rbu_image_type_attr = {
 	.attr = {
 		.name = "image_type",
 		.owner = THIS_MODULE,
 		.mode = 0644,
 	},
 	.read = read_rbu_image_type,
 	.write = write_rbu_image_type,
 };

 static int __init dcdrbu_init(void)
 {
 	int rc = 0;
 	spin_lock_init(&rbu_data.lock);

 	init_packet_head();
 	rbu_device =
 		platform_device_register_simple("dell_rbu", -1, NULL, 0);
 	if (!rbu_device) {
 		printk(KERN_ERR
 			"dell_rbu:%s:platform_device_register_simple "
 			"failed\n", __FUNCTION__);
 		return -EIO;
 	}

 	sysfs_create_bin_file(&rbu_device->dev.kobj, &rbu_data_attr);
 	sysfs_create_bin_file(&rbu_device->dev.kobj, &rbu_image_type_attr);

 	rc = request_firmware_nowait(THIS_MODULE, FW_ACTION_NOHOTPLUG,
 		"dell_rbu", &rbu_device->dev, &context, callbackfn_rbu);
 	if (rc)
 		printk(KERN_ERR "dell_rbu:%s:request_firmware_nowait"
 			" failed %d\n", __FUNCTION__, rc);
 	else
 		rbu_data.entry_created = 1;

 	return rc;

 }

 static __exit void dcdrbu_exit(void)
 {
 	spin_lock(&rbu_data.lock);
 	packet_empty_list();
 	img_update_free();
 	spin_unlock(&rbu_data.lock);
 	platform_device_unregister(rbu_device);
 }

 module_exit(dcdrbu_exit);
 module_init(dcdrbu_init);
	/*
	* dell_rbu.c
	* Bios Update driver for Dell systems
	* Author: Dell Inc
	* Abhay Salunke <abhay_salunke@dell.com>
	*
	* Copyright (C) 2005 Dell Inc.
	*
	* Remote BIOS Update (rbu) driver is used for updating DELL BIOS by
	* creating entries in the /sys file systems on Linux 2.6 and higher
	* kernels. The driver supports two mechanism to update the BIOS namely
	* contiguous and packetized. Both these methods still require having some
	* application to set the CMOS bit indicating the BIOS to update itself
	* after a reboot.
	*
	* Contiguous method:
	* This driver writes the incoming data in a monolithic image by allocating
	* contiguous physical pages large enough to accommodate the incoming BIOS
	* image size.
	*
	* Packetized method:
	* The driver writes the incoming packet image by allocating a new packet
	* on every time the packet data is written. This driver requires an
	* application to break the BIOS image in to fixed sized packet chunks.
	*
	* See Documentation/dell_rbu.txt for more info.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License v2.0 as published by
	* the Free Software Foundation
	*
	* 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.
	*/
	#include <linux/version.h>
	#include <linux/config.h>
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/string.h>
	#include <linux/errno.h>
	#include <linux/blkdev.h>
	#include <linux/device.h>
	#include <linux/spinlock.h>
	#include <linux/moduleparam.h>
	#include <linux/firmware.h>
	#include <linux/dma-mapping.h>

	MODULE_AUTHOR("Abhay Salunke <abhay_salunke@dell.com>");
	MODULE_DESCRIPTION("Driver for updating BIOS image on DELL systems");
	MODULE_LICENSE("GPL");
	MODULE_VERSION("2.0");

	#define BIOS_SCAN_LIMIT 0xffffffff
	#define MAX_IMAGE_LENGTH 16
	static struct _rbu_data {
	void *image_update_buffer;
	unsigned long image_update_buffer_size;
	unsigned long bios_image_size;
	int image_update_ordernum;
	int dma_alloc;
	spinlock_t lock;
	unsigned long packet_read_count;
	unsigned long packet_write_count;
	unsigned long num_packets;
	unsigned long packetsize;
	int entry_created;
	} rbu_data;

	static char image_type[MAX_IMAGE_LENGTH + 1] = "mono";
	module_param_string(image_type, image_type, sizeof (image_type), 0);
	MODULE_PARM_DESC(image_type, "BIOS image type. choose- mono or packet");

	struct packet_data {
	struct list_head list;
	size_t length;
	void *data;
	int ordernum;
	};

	static struct packet_data packet_data_head;

	static struct platform_device *rbu_device;
	static int context;
	static dma_addr_t dell_rbu_dmaaddr;

	static void init_packet_head(void)
	{
	INIT_LIST_HEAD(&packet_data_head.list);
	rbu_data.packet_write_count = 0;
	rbu_data.packet_read_count = 0;
	rbu_data.num_packets = 0;
	rbu_data.packetsize = 0;
	}

	static int fill_last_packet(void *data, size_t length)
	{
	struct list_head *ptemp_list;
	struct packet_data *packet = NULL;
	int packet_count = 0;

	pr_debug("fill_last_packet: entry \n");

	if (!rbu_data.num_packets) {
	pr_debug("fill_last_packet: num_packets=0\n");
	return -ENOMEM;
	}

	packet_count = rbu_data.num_packets;

	ptemp_list = (&packet_data_head.list)->prev;

	packet = list_entry(ptemp_list, struct packet_data, list);

	if ((rbu_data.packet_write_count + length) > rbu_data.packetsize) {
	pr_debug("dell_rbu:%s: packet size data "
	"overrun\n", __FUNCTION__);
	return -EINVAL;
	}

	pr_debug("fill_last_packet : buffer = %p\n", packet->data);

	memcpy((packet->data + rbu_data.packet_write_count), data, length);

	if ((rbu_data.packet_write_count + length) == rbu_data.packetsize) {
	/*
	* this was the last data chunk in the packet
	* so reinitialize the packet data counter to zero
	*/
	rbu_data.packet_write_count = 0;
	} else
	rbu_data.packet_write_count += length;

	pr_debug("fill_last_packet: exit \n");
	return 0;
	}

	static int create_packet(size_t length)
	{
	struct packet_data *newpacket;
	int ordernum = 0;

	pr_debug("create_packet: entry \n");

	if (!rbu_data.packetsize) {
	pr_debug("create_packet: packetsize not specified\n");
	return -EINVAL;
	}
	spin_unlock(&rbu_data.lock);
	newpacket = kmalloc(sizeof (struct packet_data), GFP_KERNEL);
	spin_lock(&rbu_data.lock);

	if (!newpacket) {
	printk(KERN_WARNING
	"dell_rbu:%s: failed to allocate new "
	"packet\n", __FUNCTION__);
	return -ENOMEM;
	}

	ordernum = get_order(length);
	/*
	* there is no upper limit on memory
	* address for packetized mechanism
	*/
	spin_unlock(&rbu_data.lock);
	newpacket->data = (unsigned char *) __get_free_pages(GFP_KERNEL,
	ordernum);
	spin_lock(&rbu_data.lock);

	pr_debug("create_packet: newpacket %p\n", newpacket->data);

	if (!newpacket->data) {
	printk(KERN_WARNING
	"dell_rbu:%s: failed to allocate new "
	"packet\n", __FUNCTION__);
	kfree(newpacket);
	return -ENOMEM;
	}

	newpacket->ordernum = ordernum;
	++rbu_data.num_packets;
	/*
	* initialize the newly created packet headers
	*/
	INIT_LIST_HEAD(&newpacket->list);
	list_add_tail(&newpacket->list, &packet_data_head.list);
	/*
	* packets have fixed size
	*/
	newpacket->length = rbu_data.packetsize;

	pr_debug("create_packet: exit \n");

	return 0;
	}

	static int packetize_data(void *data, size_t length)
	{
	int rc = 0;

	if (!rbu_data.packet_write_count) {
	if ((rc = create_packet(length)))
	return rc;
	}
	if ((rc = fill_last_packet(data, length)))
	return rc;

	return rc;
	}

	static int do_packet_read(char data, struct list_head ptemp_list,
	int length, int bytes_read, int *list_read_count)
	{
	void *ptemp_buf;
	struct packet_data *newpacket = NULL;
	int bytes_copied = 0;
	int j = 0;

	newpacket = list_entry(ptemp_list, struct packet_data, list);
	*list_read_count += newpacket->length;

	if (*list_read_count > bytes_read) {
	/* point to the start of unread data */
	j = newpacket->length - (*list_read_count - bytes_read);
	/* point to the offset in the packet buffer */
	ptemp_buf = (u8 *) newpacket->data + j;
	/*
	* check if there is enough room in
	* * the incoming buffer
	*/
	if (length > (*list_read_count - bytes_read))
	/*
	* copy what ever is there in this
	* packet and move on
	*/
	bytes_copied = (*list_read_count - bytes_read);
	else
	/* copy the remaining */
	bytes_copied = length;
	memcpy(data, ptemp_buf, bytes_copied);
	}
	return bytes_copied;
	}

	static int packet_read_list(char data, size_t pread_length)
	{
	struct list_head *ptemp_list;
	int temp_count = 0;
	int bytes_copied = 0;
	int bytes_read = 0;
	int remaining_bytes = 0;
	char *pdest = data;

	/* check if we have any packets */
	if (0 == rbu_data.num_packets)
	return -ENOMEM;

	remaining_bytes = *pread_length;
	bytes_read = rbu_data.packet_read_count;

	ptemp_list = (&packet_data_head.list)->next;
	while (!list_empty(ptemp_list)) {
	bytes_copied = do_packet_read(pdest, ptemp_list,
	remaining_bytes, bytes_read, &temp_count);
	remaining_bytes -= bytes_copied;
	bytes_read += bytes_copied;
	pdest += bytes_copied;
	/*
	* check if we reached end of buffer before reaching the
	* last packet
	*/
	if (remaining_bytes == 0)
	break;

	ptemp_list = ptemp_list->next;
	}
	/finally set the bytes read /
	*pread_length = bytes_read - rbu_data.packet_read_count;
	rbu_data.packet_read_count = bytes_read;
	return 0;
	}

	static void packet_empty_list(void)
	{
	struct list_head *ptemp_list;
	struct list_head *pnext_list;
	struct packet_data *newpacket;

	ptemp_list = (&packet_data_head.list)->next;
	while (!list_empty(ptemp_list)) {
	newpacket =
	list_entry(ptemp_list, struct packet_data, list);
	pnext_list = ptemp_list->next;
	list_del(ptemp_list);
	ptemp_list = pnext_list;
	/*
	* zero out the RBU packet memory before freeing
	* to make sure there are no stale RBU packets left in memory
	*/
	memset(newpacket->data, 0, rbu_data.packetsize);
	free_pages((unsigned long) newpacket->data,
	newpacket->ordernum);
	kfree(newpacket);
	}
	rbu_data.packet_write_count = 0;
	rbu_data.packet_read_count = 0;
	rbu_data.num_packets = 0;
	rbu_data.packetsize = 0;
	}

	/*
	* img_update_free: Frees the buffer allocated for storing BIOS image
	* Always called with lock held and returned with lock held
	*/
	static void img_update_free(void)
	{
	if (!rbu_data.image_update_buffer)
	return;
	/*
	* zero out this buffer before freeing it to get rid of any stale
	* BIOS image copied in memory.
	*/
	memset(rbu_data.image_update_buffer, 0,
	rbu_data.image_update_buffer_size);
	if (rbu_data.dma_alloc == 1)
	dma_free_coherent(NULL, rbu_data.bios_image_size,
	rbu_data.image_update_buffer, dell_rbu_dmaaddr);
	else
	free_pages((unsigned long) rbu_data.image_update_buffer,
	rbu_data.image_update_ordernum);

	/*
	* Re-initialize the rbu_data variables after a free
	*/
	rbu_data.image_update_ordernum = -1;
	rbu_data.image_update_buffer = NULL;
	rbu_data.image_update_buffer_size = 0;
	rbu_data.bios_image_size = 0;
	rbu_data.dma_alloc = 0;
	}

	/*
	* img_update_realloc: This function allocates the contiguous pages to
	* accommodate the requested size of data. The memory address and size
	* values are stored globally and on every call to this function the new
	* size is checked to see if more data is required than the existing size.
	* If true the previous memory is freed and new allocation is done to
	* accommodate the new size. If the incoming size is less then than the
	* already allocated size, then that memory is reused. This function is
	* called with lock held and returns with lock held.
	*/
	static int img_update_realloc(unsigned long size)
	{
	unsigned char *image_update_buffer = NULL;
	unsigned long rc;
	unsigned long img_buf_phys_addr;
	int ordernum;
	int dma_alloc = 0;

	/*
	* check if the buffer of sufficient size has been
	* already allocated
	*/
	if (rbu_data.image_update_buffer_size >= size) {
	/*
	* check for corruption
	*/
	if ((size != 0) && (rbu_data.image_update_buffer == NULL)) {
	printk(KERN_ERR "dell_rbu:%s: corruption "
	"check failed\n", __FUNCTION__);
	return -EINVAL;
	}
	/*
	* we have a valid pre-allocated buffer with
	* sufficient size
	*/
	return 0;
	}

	/*
	* free any previously allocated buffer
	*/
	img_update_free();

	spin_unlock(&rbu_data.lock);

	ordernum = get_order(size);
	image_update_buffer =
	(unsigned char *) __get_free_pages(GFP_KERNEL, ordernum);

	img_buf_phys_addr =
	(unsigned long) virt_to_phys(image_update_buffer);

	if (img_buf_phys_addr > BIOS_SCAN_LIMIT) {
	free_pages((unsigned long) image_update_buffer, ordernum);
	ordernum = -1;
	image_update_buffer = dma_alloc_coherent(NULL, size,
	&dell_rbu_dmaaddr, GFP_KERNEL);
	dma_alloc = 1;
	}

	spin_lock(&rbu_data.lock);

	if (image_update_buffer != NULL) {
	rbu_data.image_update_buffer = image_update_buffer;
	rbu_data.image_update_buffer_size = size;
	rbu_data.bios_image_size =
	rbu_data.image_update_buffer_size;
	rbu_data.image_update_ordernum = ordernum;
	rbu_data.dma_alloc = dma_alloc;
	rc = 0;
	} else {
	pr_debug("Not enough memory for image update:"
	"size = %ld\n", size);
	rc = -ENOMEM;
	}

	return rc;
	}

	static ssize_t read_packet_data(char *buffer, loff_t pos, size_t count)
	{
	int retval;
	size_t bytes_left;
	size_t data_length;
	char *ptempBuf = buffer;
	unsigned long imagesize;

	/* check to see if we have something to return */
	if (rbu_data.num_packets == 0) {
	pr_debug("read_packet_data: no packets written\n");
	retval = -ENOMEM;
	goto read_rbu_data_exit;
	}

	imagesize = rbu_data.num_packets * rbu_data.packetsize;

	if (pos > imagesize) {
	retval = 0;
	printk(KERN_WARNING "dell_rbu:read_packet_data: "
	"data underrun\n");
	goto read_rbu_data_exit;
	}

	bytes_left = imagesize - pos;
	data_length = min(bytes_left, count);

	if ((retval = packet_read_list(ptempBuf, &data_length)) < 0)
	goto read_rbu_data_exit;

	if ((pos + count) > imagesize) {
	rbu_data.packet_read_count = 0;
	/* this was the last copy */
	retval = bytes_left;
	} else
	retval = count;

	read_rbu_data_exit:
	return retval;
	}

	static ssize_t read_rbu_mono_data(char *buffer, loff_t pos, size_t count)
	{
	unsigned char *ptemp = NULL;
	size_t bytes_left = 0;
	size_t data_length = 0;
	ssize_t ret_count = 0;

	/* check to see if we have something to return */
	if ((rbu_data.image_update_buffer == NULL) \|\|
	(rbu_data.bios_image_size == 0)) {
	pr_debug("read_rbu_data_mono: image_update_buffer %p ,"
	"bios_image_size %lu\n",
	rbu_data.image_update_buffer,
	rbu_data.bios_image_size);
	ret_count = -ENOMEM;
	goto read_rbu_data_exit;
	}

	if (pos > rbu_data.bios_image_size) {
	ret_count = 0;
	goto read_rbu_data_exit;
	}

	bytes_left = rbu_data.bios_image_size - pos;
	data_length = min(bytes_left, count);

	ptemp = rbu_data.image_update_buffer;
	memcpy(buffer, (ptemp + pos), data_length);

	if ((pos + count) > rbu_data.bios_image_size)
	/* this was the last copy */
	ret_count = bytes_left;
	else
	ret_count = count;
	read_rbu_data_exit:
	return ret_count;
	}

	static ssize_t read_rbu_data(struct kobject kobj, char buffer,
	loff_t pos, size_t count)
	{
	ssize_t ret_count = 0;

	spin_lock(&rbu_data.lock);

	if (!strcmp(image_type, "mono"))
	ret_count = read_rbu_mono_data(buffer, pos, count);
	else if (!strcmp(image_type, "packet"))
	ret_count = read_packet_data(buffer, pos, count);
	else
	pr_debug("read_rbu_data: invalid image type specified\n");

	spin_unlock(&rbu_data.lock);
	return ret_count;
	}

	static void callbackfn_rbu(const struct firmware fw, void context)
	{
	int rc = 0;

	if (!fw \|\| !fw->size) {
	rbu_data.entry_created = 0;
	return;
	}

	spin_lock(&rbu_data.lock);
	if (!strcmp(image_type, "mono")) {
	if (!img_update_realloc(fw->size))
	memcpy(rbu_data.image_update_buffer,
	fw->data, fw->size);
	} else if (!strcmp(image_type, "packet")) {
	if (!rbu_data.packetsize)
	rbu_data.packetsize = fw->size;
	else if (rbu_data.packetsize != fw->size) {
	packet_empty_list();
	rbu_data.packetsize = fw->size;
	}
	packetize_data(fw->data, fw->size);
	} else
	pr_debug("invalid image type specified.\n");
	spin_unlock(&rbu_data.lock);

	rc = request_firmware_nowait(THIS_MODULE, FW_ACTION_NOHOTPLUG,
	"dell_rbu", &rbu_device->dev, &context, callbackfn_rbu);
	if (rc)
	printk(KERN_ERR
	"dell_rbu:%s request_firmware_nowait failed"
	" %d\n", __FUNCTION__, rc);
	else
	rbu_data.entry_created = 1;
	}

	static ssize_t read_rbu_image_type(struct kobject kobj, char buffer,
	loff_t pos, size_t count)
	{
	int size = 0;
	if (!pos)
	size = sprintf(buffer, "%s\n", image_type);
	return size;
	}

	static ssize_t write_rbu_image_type(struct kobject kobj, char buffer,
	loff_t pos, size_t count)
	{
	int rc = count;
	int req_firm_rc = 0;
	int i;
	spin_lock(&rbu_data.lock);
	/*
	* Find the first newline or space
	*/
	for (i = 0; i < count; ++i)
	if (buffer[i] == '\n' \|\| buffer[i] == ' ') {
	buffer[i] = '\0';
	break;
	}
	if (i == count)
	buffer[count] = '\0';

	if (strstr(buffer, "mono"))
	strcpy(image_type, "mono");
	else if (strstr(buffer, "packet"))
	strcpy(image_type, "packet");
	else if (strstr(buffer, "init")) {
	/*
	* If due to the user error the driver gets in a bad
	* state where even though it is loaded , the
	* /sys/class/firmware/dell_rbu entries are missing.
	* to cover this situation the user can recreate entries
	* by writing init to image_type.
	*/
	if (!rbu_data.entry_created) {
	spin_unlock(&rbu_data.lock);
	req_firm_rc = request_firmware_nowait(THIS_MODULE,
	FW_ACTION_NOHOTPLUG, "dell_rbu",
	&rbu_device->dev, &context,
	callbackfn_rbu);
	if (req_firm_rc) {
	printk(KERN_ERR
	"dell_rbu:%s request_firmware_nowait"
	" failed %d\n", __FUNCTION__, rc);
	rc = -EIO;
	} else
	rbu_data.entry_created = 1;

	spin_lock(&rbu_data.lock);
	}
	} else {
	printk(KERN_WARNING "dell_rbu: image_type is invalid\n");
	spin_unlock(&rbu_data.lock);
	return -EINVAL;
	}

	/* we must free all previous allocations */
	packet_empty_list();
	img_update_free();
	spin_unlock(&rbu_data.lock);

	return rc;
	}

	static struct bin_attribute rbu_data_attr = {
	.attr = {
	.name = "data",
	.owner = THIS_MODULE,
	.mode = 0444,
	},
	.read = read_rbu_data,
	};

	static struct bin_attribute rbu_image_type_attr = {
	.attr = {
	.name = "image_type",
	.owner = THIS_MODULE,
	.mode = 0644,
	},
	.read = read_rbu_image_type,
	.write = write_rbu_image_type,
	};

	static int __init dcdrbu_init(void)
	{
	int rc = 0;
	spin_lock_init(&rbu_data.lock);

	init_packet_head();
	rbu_device =
	platform_device_register_simple("dell_rbu", -1, NULL, 0);
	if (!rbu_device) {
	printk(KERN_ERR
	"dell_rbu:%s:platform_device_register_simple "
	"failed\n", __FUNCTION__);
	return -EIO;
	}

	sysfs_create_bin_file(&rbu_device->dev.kobj, &rbu_data_attr);
	sysfs_create_bin_file(&rbu_device->dev.kobj, &rbu_image_type_attr);

	rc = request_firmware_nowait(THIS_MODULE, FW_ACTION_NOHOTPLUG,
	"dell_rbu", &rbu_device->dev, &context, callbackfn_rbu);
	if (rc)
	printk(KERN_ERR "dell_rbu:%s:request_firmware_nowait"
	" failed %d\n", __FUNCTION__, rc);
	else
	rbu_data.entry_created = 1;

	return rc;

	}

	static __exit void dcdrbu_exit(void)
	{
	spin_lock(&rbu_data.lock);
	packet_empty_list();
	img_update_free();
	spin_unlock(&rbu_data.lock);
	platform_device_unregister(rbu_device);
	}

	module_exit(dcdrbu_exit);
	module_init(dcdrbu_init);