drivers/staging/vboxvideo/vbox_hgsmi.c

   1 /*
   2  * Copyright (C) 2017 Oracle Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the
   6  * "Software"), to deal in the Software without restriction, including
   7  * without limitation the rights to use, copy, modify, merge, publish,
   8  * distribute, sub license, and/or sell copies of the Software, and to
   9  * permit persons to whom the Software is furnished to do so, subject to
  10  * the following conditions:
  11  *
  12  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  13  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  14  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  15  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  16  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  17  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  18  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  19  *
  20  * The above copyright notice and this permission notice (including the
  21  * next paragraph) shall be included in all copies or substantial portions
  22  * of the Software.
  23  *
  24  * Authors: Hans de Goede <hdegoede@redhat.com>
  25  */
  26
  27 #include "vbox_drv.h"
  28 #include "vboxvideo_vbe.h"
  29 #include "hgsmi_defs.h"
  30
  31 /* One-at-a-Time Hash from http://www.burtleburtle.net/bob/hash/doobs.html */
  32 static u32 hgsmi_hash_process(u32 hash, const u8 *data, int size)
  33 {
  34         while (size--) {
  35                 hash += *data++;
  36                 hash += (hash << 10);
  37                 hash ^= (hash >> 6);
  38         }
  39
  40         return hash;
  41 }
  42
  43 static u32 hgsmi_hash_end(u32 hash)
  44 {
  45         hash += (hash << 3);
  46         hash ^= (hash >> 11);
  47         hash += (hash << 15);
  48
  49         return hash;
  50 }
  51
  52 /* Not really a checksum but that is the naming used in all vbox code */
  53 static u32 hgsmi_checksum(u32 offset,
  54                           const struct hgsmi_buffer_header *header,
  55                           const struct hgsmi_buffer_tail *tail)
  56 {
  57         u32 checksum;
  58
  59         checksum = hgsmi_hash_process(0, (u8 *)&offset, sizeof(offset));
  60         checksum = hgsmi_hash_process(checksum, (u8 *)header, sizeof(*header));
  61         /* 4 -> Do not checksum the checksum itself */
  62         checksum = hgsmi_hash_process(checksum, (u8 *)tail, 4);
  63
  64         return hgsmi_hash_end(checksum);
  65 }
  66
  67 void *hgsmi_buffer_alloc(struct gen_pool *guest_pool, size_t size,
  68                          u8 channel, u16 channel_info)
  69 {
  70         struct hgsmi_buffer_header *h;
  71         struct hgsmi_buffer_tail *t;
  72         size_t total_size;
  73         dma_addr_t offset;
  74
  75         total_size = size + sizeof(*h) + sizeof(*t);
  76         h = gen_pool_dma_alloc(guest_pool, total_size, &offset);
  77         if (!h)
  78                 return NULL;
  79
  80         t = (struct hgsmi_buffer_tail *)((u8 *)h + sizeof(*h) + size);
  81
  82         h->flags = HGSMI_BUFFER_HEADER_F_SEQ_SINGLE;
  83         h->data_size = size;
  84         h->channel = channel;
  85         h->channel_info = channel_info;
  86         memset(&h->u.header_data, 0, sizeof(h->u.header_data));
  87
  88         t->reserved = 0;
  89         t->checksum = hgsmi_checksum(offset, h, t);
  90
  91         return (u8 *)h + sizeof(*h);
  92 }
  93
  94 void hgsmi_buffer_free(struct gen_pool *guest_pool, void *buf)
  95 {
  96         struct hgsmi_buffer_header *h =
  97                 (struct hgsmi_buffer_header *)((u8 *)buf - sizeof(*h));
  98         size_t total_size = h->data_size + sizeof(*h) +
  99                                              sizeof(struct hgsmi_buffer_tail);
 100
 101         gen_pool_free(guest_pool, (unsigned long)h, total_size);
 102 }
 103
 104 int hgsmi_buffer_submit(struct gen_pool *guest_pool, void *buf)
 105 {
 106         phys_addr_t offset;
 107
 108         offset = gen_pool_virt_to_phys(guest_pool, (unsigned long)buf -
 109                                        sizeof(struct hgsmi_buffer_header));
 110         outl(offset, VGA_PORT_HGSMI_GUEST);
 111         /* Make the compiler aware that the host has changed memory. */
 112         mb();
 113
 114         return 0;
 115 }