/*
   * 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/init.h>
  #include <linux/module.h>

  #include <linux/slab.h>

  #include <linux/string.h>
  #include <linux/errno.h>
  #include <linux/blkdev.h>

  #include <linux/platform_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("3.2");

  
  #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 num_packets;
  	unsigned long packetsize;

  	unsigned long imagesize;

  	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 or init");

  static unsigned long allocation_floor = 0x100000;
  module_param(allocation_floor, ulong, 0644);
  MODULE_PARM_DESC(allocation_floor,
      "Minimum address for allocations when using Packet mode");

  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_read_count = 0;
  	rbu_data.num_packets = 0;
  	rbu_data.packetsize = 0;

  	rbu_data.imagesize = 0;

  }

  static int create_packet(void *data, size_t length)

  {
  	struct packet_data *newpacket;
  	int ordernum = 0;

  	int retval = 0;
  	unsigned int packet_array_size = 0;

  	void **invalid_addr_packet_array = NULL;
  	void *packet_data_temp_buf = NULL;

  	unsigned int idx = 0;

  
  	pr_debug("create_packet: entry 
  ");
  
  	if (!rbu_data.packetsize) {
  		pr_debug("create_packet: packetsize not specified
  ");

  		retval = -EINVAL;
  		goto out_noalloc;

  	}

  	spin_unlock(&rbu_data.lock);

  
  	newpacket = kzalloc(sizeof (struct packet_data), GFP_KERNEL);

  	if (!newpacket) {
  		printk(KERN_WARNING

  			"dell_rbu:%s: failed to allocate new "

  			"packet
  ", __func__);

  		retval = -ENOMEM;
  		spin_lock(&rbu_data.lock);
  		goto out_noalloc;

  	}
  
  	ordernum = get_order(length);

  	/*

  	 * BIOS errata mean we cannot allocate packets below 1MB or they will
  	 * be overwritten by BIOS.
  	 *
  	 * array to temporarily hold packets
  	 * that are below the allocation floor
  	 *
  	 * NOTE: very simplistic because we only need the floor to be at 1MB
  	 *       due to BIOS errata. This shouldn't be used for higher floors
  	 *       or you will run out of mem trying to allocate the array.

  	 */

  	packet_array_size = max(
  	       		(unsigned int)(allocation_floor / rbu_data.packetsize),
  			(unsigned int)1);
  	invalid_addr_packet_array = kzalloc(packet_array_size * sizeof(void*),
  						GFP_KERNEL);

  	if (!invalid_addr_packet_array) {

  		printk(KERN_WARNING

  			"dell_rbu:%s: failed to allocate "
  			"invalid_addr_packet_array 
  ",

  			__func__);

  		retval = -ENOMEM;
  		spin_lock(&rbu_data.lock);
  		goto out_alloc_packet;

  	}

  	while (!packet_data_temp_buf) {
  		packet_data_temp_buf = (unsigned char *)
  			__get_free_pages(GFP_KERNEL, ordernum);
  		if (!packet_data_temp_buf) {
  			printk(KERN_WARNING
  				"dell_rbu:%s: failed to allocate new "

  				"packet
  ", __func__);

  			retval = -ENOMEM;
  			spin_lock(&rbu_data.lock);
  			goto out_alloc_packet_array;
  		}
  
  		if ((unsigned long)virt_to_phys(packet_data_temp_buf)
  				< allocation_floor) {
  			pr_debug("packet 0x%lx below floor at 0x%lx.
  ",
  					(unsigned long)virt_to_phys(
  						packet_data_temp_buf),
  					allocation_floor);
  			invalid_addr_packet_array[idx++] = packet_data_temp_buf;

  			packet_data_temp_buf = NULL;

  		}
  	}
  	spin_lock(&rbu_data.lock);
  
  	newpacket->data = packet_data_temp_buf;
  
  	pr_debug("create_packet: newpacket at physical addr %lx
  ",
  		(unsigned long)virt_to_phys(newpacket->data));
  
  	/* packets may not have fixed size */
  	newpacket->length = length;

  	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);

  
  	memcpy(newpacket->data, data, length);

  
  	pr_debug("create_packet: exit 
  ");

  out_alloc_packet_array:
  	/* always free packet array */
  	for (;idx>0;idx--) {
  		pr_debug("freeing unused packet below floor 0x%lx.
  ",
  			(unsigned long)virt_to_phys(
  				invalid_addr_packet_array[idx-1]));
  		free_pages((unsigned long)invalid_addr_packet_array[idx-1],
  			ordernum);
  	}
  	kfree(invalid_addr_packet_array);
  
  out_alloc_packet:
  	/* if error, free data */
  	if (retval)
  		kfree(newpacket);
  
  out_noalloc:
  	return retval;

  }

  static int packetize_data(const u8 *data, size_t length)

  {
  	int rc = 0;

  	int done = 0;
  	int packet_length;
  	u8 *temp;
  	u8 *end = (u8 *) data + length;

  	pr_debug("packetize_data: data length %zd
  ", length);

  	if (!rbu_data.packetsize) {
  		printk(KERN_WARNING
  			"dell_rbu: packetsize not specified
  ");
  		return -EIO;
  	}

  	temp = (u8 *) data;
  
  	/* packetize the hunk */
  	while (!done) {
  		if ((temp + rbu_data.packetsize) < end)
  			packet_length = rbu_data.packetsize;
  		else {
  			/* this is the last packet */
  			packet_length = end - temp;
  			done = 1;
  		}
  
  		if ((rc = create_packet(temp, packet_length)))

  			return rc;

  		pr_debug("%p:%td
  ", temp, (end - temp));

  		temp += packet_length;

  	}

  
  	rbu_data.imagesize = length;

  
  	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_read_count = 0;
  	rbu_data.num_packets = 0;

  	rbu_data.imagesize = 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
  ", __func__);

  			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
  ", 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;

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

  	if (pos > rbu_data.imagesize) {

  		retval = 0;
  		printk(KERN_WARNING "dell_rbu:read_packet_data: "

  			"data underrun
  ");

  		goto read_rbu_data_exit;
  	}

  	bytes_left = rbu_data.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) > rbu_data.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)

  {

  	/* 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
  ",
  			rbu_data.image_update_buffer,
  			rbu_data.bios_image_size);

  		return -ENOMEM;

  	}

  	return memory_read_from_buffer(buffer, count, &pos,
  			rbu_data.image_update_buffer, rbu_data.bios_image_size);

  }

  static ssize_t read_rbu_data(struct file *filp, struct kobject *kobj,

  			     struct bin_attribute *bin_attr,
  			     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
  ");
  
  	spin_unlock(&rbu_data.lock);
  	return ret_count;
  }

  static void callbackfn_rbu(const struct firmware *fw, void *context)

  {

  	rbu_data.entry_created = 0;

  	if (!fw)

  		return;

  	if (!fw->size)
  		goto out;

  	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")) {

  		/*
  		 * we need to free previous packets if a
  		 * new hunk of packets needs to be downloaded
  		 */
  		packet_empty_list();
  		if (packetize_data(fw->data, fw->size))
  			/* Incase something goes wrong when we are
  			 * in middle of packetizing the data, we
  			 * need to free up whatever packets might
  			 * have been created before we quit.
  			 */

  			packet_empty_list();

  	} else
  		pr_debug("invalid image type specified.
  ");
  	spin_unlock(&rbu_data.lock);

   out:
  	release_firmware(fw);

  }

  static ssize_t read_rbu_image_type(struct file *filp, struct kobject *kobj,

  				   struct bin_attribute *bin_attr,
  				   char *buffer, loff_t pos, size_t count)

  {
  	int size = 0;
  	if (!pos)

  		size = scnprintf(buffer, count, "%s
  ", image_type);

  	return size;
  }

  static ssize_t write_rbu_image_type(struct file *filp, struct kobject *kobj,

  				    struct bin_attribute *bin_attr,
  				    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] == '
  ' || 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, GFP_KERNEL, &context,

  				callbackfn_rbu);
  			if (req_firm_rc) {
  				printk(KERN_ERR
  					"dell_rbu:%s request_firmware_nowait"

  					" failed %d
  ", __func__, rc);

  				rc = -EIO;
  			} else
  				rbu_data.entry_created = 1;
  
  			spin_lock(&rbu_data.lock);
  		}
  	} else {
  		printk(KERN_WARNING "dell_rbu: image_type is invalid
  ");
  		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 ssize_t read_rbu_packet_size(struct file *filp, struct kobject *kobj,

  				    struct bin_attribute *bin_attr,
  				    char *buffer, loff_t pos, size_t count)

  {
  	int size = 0;
  	if (!pos) {
  		spin_lock(&rbu_data.lock);

  		size = scnprintf(buffer, count, "%lu
  ", rbu_data.packetsize);

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

  static ssize_t write_rbu_packet_size(struct file *filp, struct kobject *kobj,

  				     struct bin_attribute *bin_attr,
  				     char *buffer, loff_t pos, size_t count)

  {
  	unsigned long temp;
  	spin_lock(&rbu_data.lock);
  	packet_empty_list();
  	sscanf(buffer, "%lu", &temp);
  	if (temp < 0xffffffff)
  		rbu_data.packetsize = temp;
  
  	spin_unlock(&rbu_data.lock);
  	return count;
  }

  static struct bin_attribute rbu_data_attr = {

  	.attr = {.name = "data", .mode = 0444},

  	.read = read_rbu_data,
  };
  
  static struct bin_attribute rbu_image_type_attr = {

  	.attr = {.name = "image_type", .mode = 0644},

  	.read = read_rbu_image_type,
  	.write = write_rbu_image_type,
  };

  static struct bin_attribute rbu_packet_size_attr = {

  	.attr = {.name = "packet_size", .mode = 0644},

  	.read = read_rbu_packet_size,
  	.write = write_rbu_packet_size,
  };

  static int __init dcdrbu_init(void)

  {

  	int rc;

  	spin_lock_init(&rbu_data.lock);
  
  	init_packet_head();

  	rbu_device = platform_device_register_simple("dell_rbu", -1, NULL, 0);
  	if (IS_ERR(rbu_device)) {

  		printk(KERN_ERR

  			"dell_rbu:%s:platform_device_register_simple "

  			"failed
  ", __func__);

  		return PTR_ERR(rbu_device);

  	}

  	rc = sysfs_create_bin_file(&rbu_device->dev.kobj, &rbu_data_attr);
  	if (rc)
  		goto out_devreg;
  	rc = sysfs_create_bin_file(&rbu_device->dev.kobj, &rbu_image_type_attr);
  	if (rc)
  		goto out_data;
  	rc = sysfs_create_bin_file(&rbu_device->dev.kobj,

  		&rbu_packet_size_attr);

  	if (rc)
  		goto out_imtype;

  	rbu_data.entry_created = 0;

  	return 0;

  out_imtype:
  	sysfs_remove_bin_file(&rbu_device->dev.kobj, &rbu_image_type_attr);
  out_data:
  	sysfs_remove_bin_file(&rbu_device->dev.kobj, &rbu_data_attr);
  out_devreg:
  	platform_device_unregister(rbu_device);
  	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);

  
  /* vim:noet:ts=8:sw=8
  */