summaryrefslogtreecommitdiffstats
path: root/probe_roms.c
blob: 7ea04c7ade280ba54b30769d0a86be3307a5bbcd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
/*
 * probe_roms - scan for Adapter ROMS
 *
 * (based on linux-2.6:arch/x86/kernel/probe_roms_32.c)
 *
 * Copyright (C) 2008 Intel Corporation
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "probe_roms.h"
#include "mdadm.h"
#include <unistd.h>
#include <signal.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <asm/types.h>

static void *rom_mem = MAP_FAILED;
static int rom_fd = -1;
static const int rom_len = 0xf0000 - 0xc0000; /* option-rom memory region */
static int _sigbus;
static unsigned long rom_align;

static void roms_deinit(void);
static int roms_init(void);

static void sigbus(int sig)
{
	_sigbus = 1;
}

static int probe_address8(const __u8 *ptr, __u8 *val)
{
	int rc = 0;

	*val = *ptr;
	if (_sigbus)
		rc = -1;
	_sigbus = 0;

	return rc;
}

static int probe_address16(const __u16 *ptr, __u16 *val)
{
	int rc = 0;

	*val = *ptr;
	if (_sigbus)
		rc = -1;
	_sigbus = 0;

	return rc;
}

void probe_roms_exit(void)
{
	signal(SIGBUS, SIG_DFL);
	if (rom_fd >= 0) {
		close(rom_fd);
		rom_fd = -1;
	}
	if (rom_mem != MAP_FAILED) {
		munmap(rom_mem, rom_len);
		rom_mem = MAP_FAILED;
	}
	roms_deinit();
}

int probe_roms_init(unsigned long align)
{
	int fd = -1;
	int rc = 0;

	/* valid values are 2048 and 512.  512 is for PCI-3.0 compliant
	 * systems, or systems that do not have dangerous/legacy ISA
	 * devices.  2048 should always be safe
	 */
	if (align == 512 || align == 2048)
		rom_align = align;
	else
		return -1;

	if (roms_init())
		return -1;

	if (signal(SIGBUS, sigbus) == SIG_ERR)
		rc = -1;
	if (rc == 0) {
		fd = open("/dev/mem", O_RDONLY);
		if (fd < 0)
			rc = -1;
	}
	if (rc == 0) {
		rom_mem = mmap(NULL, rom_len, PROT_READ, MAP_PRIVATE, fd, 0xc0000);
		if (rom_mem == MAP_FAILED)
			rc = -1;
	}

	if (rc == 0)
		rom_fd = fd;
	else {
		if (fd >= 0)
			close(fd);
		probe_roms_exit();
	}
	return rc;
}

/**
 * isa_bus_to_virt - convert physical address to mmap'd region
 * @addr - address to convert
 *
 * Only valid between a successful call to probe_roms_init and the
 * corresponding probe_roms_exit
 */
static void *isa_bus_to_virt(unsigned long addr)
{
	return rom_mem + (addr - 0xc0000);
}

struct resource {
	unsigned long start;
	unsigned long end;
	unsigned long data;
	const char *name;
	struct resource *next;
};

static struct resource system_rom_resource = {
	.name	= "System ROM",
	.start	= 0xf0000,
	.data   = 0,
	.end	= 0xfffff,
};

static struct resource extension_rom_resource = {
	.name	= "Extension ROM",
	.start	= 0xe0000,
	.data   = 0,
	.end	= 0xeffff,
};

static struct resource *adapter_rom_resources;

static struct resource video_rom_resource = {
	.name	= "Video ROM",
	.start	= 0xc0000,
	.data   = 0,
	.end	= 0xc7fff,
};

static int roms_init(void)
{
	adapter_rom_resources = malloc(sizeof(struct resource));
	if (adapter_rom_resources == NULL)
		return 1;
	adapter_rom_resources->name = "Adapter ROM";
	adapter_rom_resources->start = 0xc8000;
	adapter_rom_resources->data = 0;
	adapter_rom_resources->end = 0;
	adapter_rom_resources->next = NULL;
	return 0;
}

static void roms_deinit(void)
{
	struct resource *res;

	res = adapter_rom_resources;
	while (res) {
		struct resource *tmp = res;

		res = res->next;
		free(tmp);
	}
}

#define ROMSIGNATURE 0xaa55


static int romsignature(const unsigned char *rom)
{
	const unsigned short * const ptr = (const unsigned short *)rom;
	unsigned short sig = 0;

	return probe_address16(ptr, &sig) == 0 && sig == ROMSIGNATURE;
}

static int romchecksum(const unsigned char *rom, unsigned long length)
{
	unsigned char sum, c;

	for (sum = 0; length && probe_address8(rom++, &c) == 0; length--)
		sum += c;
	return !length && !sum;
}

int scan_adapter_roms(scan_fn fn)
{
	/* let scan_fn examing each of the adapter roms found by probe_roms */
	struct resource *res = adapter_rom_resources;
	int found;

	if (rom_fd < 0)
		return 0;

	found = 0;
	while (res) {
		if (res->start) {
			found = fn(isa_bus_to_virt(res->start),
				   isa_bus_to_virt(res->end),
				   isa_bus_to_virt(res->data));
			if (found)
				break;
		} else
			break;
		res = res->next;
	}

	return found;
}

static unsigned long align(unsigned long addr, unsigned long alignment)
{
	return (addr + alignment - 1) & ~(alignment - 1);
}

void probe_roms(void)
{
	const void *rom;
	unsigned long start, length, upper;
	unsigned char c;
	struct resource *res = adapter_rom_resources;
	__u16 val=0;

	if (rom_fd < 0)
		return;

	/* video rom */
	upper = res->start;
	for (start = video_rom_resource.start; start < upper; start += rom_align) {
		rom = isa_bus_to_virt(start);
		if (!romsignature(rom))
			continue;

		video_rom_resource.start = start;

		if (probe_address8(rom + 2, &c) != 0)
			continue;

		/* 0 < length <= 0x7f * 512, historically */
		length = c * 512;

		/* if checksum okay, trust length byte */
		if (length && romchecksum(rom, length))
			video_rom_resource.end = start + length - 1;
		break;
	}

	start = align(video_rom_resource.end + 1, rom_align);
	if (start < upper)
		start = upper;

	/* system rom */
	upper = system_rom_resource.start;

	/* check for extension rom (ignore length byte!) */
	rom = isa_bus_to_virt(extension_rom_resource.start);
	if (romsignature(rom)) {
		length = extension_rom_resource.end - extension_rom_resource.start + 1;
		if (romchecksum(rom, length))
			upper = extension_rom_resource.start;
	}

	struct resource *prev_res = res;
	/* check for adapter roms on 2k boundaries */
	for (; start < upper; start += rom_align) {
		rom = isa_bus_to_virt(start);
		if (!romsignature(rom))
			continue;

		if (probe_address8(rom + 2, &c) != 0)
			continue;

		/* 0 < length <= 0x7f * 512, historically */
		length = c * 512;

		/* Retrieve 16-bit pointer to PCI Data Structure (offset 18h-19h)
		 * The data can be within 64KB forward of the first location
		 * of this code image. The pointer is in little-endian order
		 */

		if (probe_address16(rom + 0x18, &val) != 0)
			continue;
		val = __le16_to_cpu(val);

		/* but accept any length that fits if checksum okay */
		if (!length || start + length > upper || !romchecksum(rom, length))
			continue;

		if (res == NULL) {
			res = calloc(1, sizeof(struct resource));
			if (res == NULL)
				return;
			prev_res->next = res;
		}

		res->start = start;
		res->data = start + (unsigned long)val;
		res->end = start + length - 1;

		start = res->end & ~(rom_align - 1);
		prev_res = res;
		res = res->next;
	}
}