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 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * 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/admin-guide/dell_rbu.rst for more info.
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #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>
 #include <asm/set_memory.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;
     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 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("entry\n");
 
     if (!rbu_data.packetsize) {
         pr_debug("packetsize not specified\n");
         retval = -EINVAL;
         goto out_noalloc;
     }
 
     spin_unlock(&rbu_data.lock);
 
     newpacket = kzalloc(sizeof (struct packet_data), GFP_KERNEL);
 
     if (!newpacket) {
         pr_warn("failed to allocate new packet\n");
         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_t(unsigned int, allocation_floor / rbu_data.packetsize, 1);
     invalid_addr_packet_array = kcalloc(packet_array_size, sizeof(void *),
                         GFP_KERNEL);
 
     if (!invalid_addr_packet_array) {
         pr_warn("failed to allocate invalid_addr_packet_array\n");
         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) {
             pr_warn("failed to allocate new packet\n");
             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\n",
                     (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;
         }
     }
     /*
      * set to uncachable or it may never get written back before reboot
      */
     set_memory_uc((unsigned long)packet_data_temp_buf, 1 << ordernum);
 
     spin_lock(&rbu_data.lock);
 
     newpacket->data = packet_data_temp_buf;
 
     pr_debug("newpacket at physical addr %lx\n",
         (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("exit\n");
 
 out_alloc_packet_array:
     /* always free packet array */
     while (idx--) {
         pr_debug("freeing unused packet below floor 0x%lx\n",
             (unsigned long)virt_to_phys(invalid_addr_packet_array[idx]));
         free_pages((unsigned long)invalid_addr_packet_array[idx], 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("data length %zd\n", length);
     if (!rbu_data.packetsize) {
         pr_warn("packetsize not specified\n");
         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\n", temp, (end - temp));
         temp += packet_length;
     }
 
     rbu_data.imagesize = length;
 
     return rc;
 }
 
 static int do_packet_read(char *data, struct packet_data *newpacket,
     int length, int bytes_read, int *list_read_count)
 {
     void *ptemp_buf;
     int bytes_copied = 0;
     int j = 0;
 
     *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 packet_data *newpacket;
     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;
 
     list_for_each_entry(newpacket, (&packet_data_head.list)->next, list) {
         bytes_copied = do_packet_read(pdest, newpacket,
             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;
     }
     /*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 packet_data *newpacket, *tmp;
 
     list_for_each_entry_safe(newpacket, tmp, (&packet_data_head.list)->next, list) {
         list_del(&newpacket->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);
         set_memory_wb((unsigned long)newpacket->data,
             1 << newpacket->ordernum);
         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);
     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;
 }
 
 /*
  * 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 img_buf_phys_addr;
     int ordernum;
 
     /*
      * 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)) {
             pr_err("corruption check failed\n");
             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_DMA32, ordernum);
     spin_lock(&rbu_data.lock);
     if (!image_update_buffer) {
         pr_debug("Not enough memory for image update: size = %ld\n", size);
         return -ENOMEM;
     }
 
     img_buf_phys_addr = (unsigned long)virt_to_phys(image_update_buffer);
     if (WARN_ON_ONCE(img_buf_phys_addr > BIOS_SCAN_LIMIT))
         return -EINVAL; /* can't happen per definition */
 
     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;
     return 0;
 }
 
 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("no packets written\n");
         retval = -ENOMEM;
         goto read_rbu_data_exit;
     }
 
     if (pos > rbu_data.imagesize) {
         retval = 0;
         pr_warn("data underrun\n");
         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("image_update_buffer %p, bios_image_size %lu\n",
             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 data_read(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("invalid image type specified\n");
 
     spin_unlock(&rbu_data.lock);
     return ret_count;
 }
 static BIN_ATTR_RO(data, 0);
 
 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\n");
     spin_unlock(&rbu_data.lock);
  out:
     release_firmware(fw);
 }
 
 static ssize_t image_type_read(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\n", image_type);
     return size;
 }
 
 static ssize_t image_type_write(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] == '\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_NOUEVENT, "dell_rbu",
                 &rbu_device->dev, GFP_KERNEL, &context,
                 callbackfn_rbu);
             if (req_firm_rc) {
                 pr_err("request_firmware_nowait failed %d\n", rc);
                 rc = -EIO;
             } else
                 rbu_data.entry_created = 1;
 
             spin_lock(&rbu_data.lock);
         }
     } else {
         pr_warn("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 BIN_ATTR_RW(image_type, 0);
 
 static ssize_t packet_size_read(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\n", rbu_data.packetsize);
         spin_unlock(&rbu_data.lock);
     }
     return size;
 }
 
 static ssize_t packet_size_write(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 BIN_ATTR_RW(packet_size, 0);
 
 static struct bin_attribute *rbu_bin_attrs[] = {
     &bin_attr_data,
     &bin_attr_image_type,
     &bin_attr_packet_size,
     NULL
 };
 
 static const struct attribute_group rbu_group = {
     .bin_attrs = rbu_bin_attrs,
 };
 
 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)) {
         pr_err("platform_device_register_simple failed\n");
         return PTR_ERR(rbu_device);
     }
 
     rc = sysfs_create_group(&rbu_device->dev.kobj, &rbu_group);
     if (rc)
         goto out_devreg;
 
     rbu_data.entry_created = 0;
     return 0;
 
 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);
     sysfs_remove_group(&rbu_device->dev.kobj, &rbu_group);
     platform_device_unregister(rbu_device);
 }
 
 module_exit(dcdrbu_exit);
 module_init(dcdrbu_init);

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