1 /* $NetBSD: vbox_hgsmi.c,v 1.2 2021/12/18 23:45:44 riastradh Exp $ */
2
3 // SPDX-License-Identifier: MIT
4 /*
5 * Copyright (C) 2017 Oracle Corporation
6 * Authors: Hans de Goede <hdegoede@redhat.com>
7 */
8
9 #include <sys/cdefs.h>
10 __KERNEL_RCSID(0, "$NetBSD: vbox_hgsmi.c,v 1.2 2021/12/18 23:45:44 riastradh Exp $");
11
12 #include "vbox_drv.h"
13 #include "vboxvideo_vbe.h"
14 #include "hgsmi_defs.h"
15
16 /* One-at-a-Time Hash from http://www.burtleburtle.net/bob/hash/doobs.html */
hgsmi_hash_process(u32 hash,const u8 * data,int size)17 static u32 hgsmi_hash_process(u32 hash, const u8 *data, int size)
18 {
19 while (size--) {
20 hash += *data++;
21 hash += (hash << 10);
22 hash ^= (hash >> 6);
23 }
24
25 return hash;
26 }
27
hgsmi_hash_end(u32 hash)28 static u32 hgsmi_hash_end(u32 hash)
29 {
30 hash += (hash << 3);
31 hash ^= (hash >> 11);
32 hash += (hash << 15);
33
34 return hash;
35 }
36
37 /* Not really a checksum but that is the naming used in all vbox code */
hgsmi_checksum(u32 offset,const struct hgsmi_buffer_header * header,const struct hgsmi_buffer_tail * tail)38 static u32 hgsmi_checksum(u32 offset,
39 const struct hgsmi_buffer_header *header,
40 const struct hgsmi_buffer_tail *tail)
41 {
42 u32 checksum;
43
44 checksum = hgsmi_hash_process(0, (u8 *)&offset, sizeof(offset));
45 checksum = hgsmi_hash_process(checksum, (u8 *)header, sizeof(*header));
46 /* 4 -> Do not checksum the checksum itself */
47 checksum = hgsmi_hash_process(checksum, (u8 *)tail, 4);
48
49 return hgsmi_hash_end(checksum);
50 }
51
hgsmi_buffer_alloc(struct gen_pool * guest_pool,size_t size,u8 channel,u16 channel_info)52 void *hgsmi_buffer_alloc(struct gen_pool *guest_pool, size_t size,
53 u8 channel, u16 channel_info)
54 {
55 struct hgsmi_buffer_header *h;
56 struct hgsmi_buffer_tail *t;
57 size_t total_size;
58 dma_addr_t offset;
59
60 total_size = size + sizeof(*h) + sizeof(*t);
61 h = gen_pool_dma_alloc(guest_pool, total_size, &offset);
62 if (!h)
63 return NULL;
64
65 t = (struct hgsmi_buffer_tail *)((u8 *)h + sizeof(*h) + size);
66
67 h->flags = HGSMI_BUFFER_HEADER_F_SEQ_SINGLE;
68 h->data_size = size;
69 h->channel = channel;
70 h->channel_info = channel_info;
71 memset(&h->u.header_data, 0, sizeof(h->u.header_data));
72
73 t->reserved = 0;
74 t->checksum = hgsmi_checksum(offset, h, t);
75
76 return (u8 *)h + sizeof(*h);
77 }
78
hgsmi_buffer_free(struct gen_pool * guest_pool,void * buf)79 void hgsmi_buffer_free(struct gen_pool *guest_pool, void *buf)
80 {
81 struct hgsmi_buffer_header *h =
82 (struct hgsmi_buffer_header *)((u8 *)buf - sizeof(*h));
83 size_t total_size = h->data_size + sizeof(*h) +
84 sizeof(struct hgsmi_buffer_tail);
85
86 gen_pool_free(guest_pool, (unsigned long)h, total_size);
87 }
88
hgsmi_buffer_submit(struct gen_pool * guest_pool,void * buf)89 int hgsmi_buffer_submit(struct gen_pool *guest_pool, void *buf)
90 {
91 phys_addr_t offset;
92
93 offset = gen_pool_virt_to_phys(guest_pool, (unsigned long)buf -
94 sizeof(struct hgsmi_buffer_header));
95 outl(offset, VGA_PORT_HGSMI_GUEST);
96 /* Make the compiler aware that the host has changed memory. */
97 mb();
98
99 return 0;
100 }
101