1/*
2 * CMOS/NV-RAM driver for Linux
3 *
4 * Copyright (C) 1997 Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de>
5 * idea by and with help from Richard Jelinek <rj@suse.de>
6 * Portions copyright (c) 2001,2002 Sun Microsystems (thockin@sun.com)
7 *
8 * This driver allows you to access the contents of the non-volatile memory in
9 * the mc146818rtc.h real-time clock. This chip is built into all PCs and into
10 * many Atari machines. In the former it's called "CMOS-RAM", in the latter
11 * "NVRAM" (NV stands for non-volatile).
12 *
13 * The data are supplied as a (seekable) character device, /dev/nvram. The
14 * size of this file is dependent on the controller. The usual size is 114,
15 * the number of freely available bytes in the memory (i.e., not used by the
16 * RTC itself).
17 *
18 * Checksums over the NVRAM contents are managed by this driver. In case of a
19 * bad checksum, reads and writes return -EIO. The checksum can be initialized
20 * to a sane state either by ioctl(NVRAM_INIT) (clear whole NVRAM) or
21 * ioctl(NVRAM_SETCKS) (doesn't change contents, just makes checksum valid
22 * again; use with care!)
23 *
24 * 1.1 Cesar Barros: SMP locking fixes
25 * added changelog
26 * 1.2 Erik Gilling: Cobalt Networks support
27 * Tim Hockin: general cleanup, Cobalt support
28 * 1.3 Wim Van Sebroeck: convert PRINT_PROC to seq_file
29 */
30
31#define NVRAM_VERSION "1.3"
32
33#include <linux/module.h>
34#include <linux/nvram.h>
35#include <linux/types.h>
36#include <linux/errno.h>
37#include <linux/miscdevice.h>
38#include <linux/ioport.h>
39#include <linux/fcntl.h>
40#include <linux/mc146818rtc.h>
41#include <linux/init.h>
42#include <linux/proc_fs.h>
43#include <linux/seq_file.h>
44#include <linux/slab.h>
45#include <linux/spinlock.h>
46#include <linux/io.h>
47#include <linux/uaccess.h>
48#include <linux/mutex.h>
49#include <linux/pagemap.h>
50
51#ifdef CONFIG_PPC
52#include <asm/nvram.h>
53#endif
54
55static DEFINE_MUTEX(nvram_mutex);
56static DEFINE_SPINLOCK(nvram_state_lock);
57static int nvram_open_cnt; /* #times opened */
58static int nvram_open_mode; /* special open modes */
59static ssize_t nvram_size;
60#define NVRAM_WRITE 1 /* opened for writing (exclusive) */
61#define NVRAM_EXCL 2 /* opened with O_EXCL */
62
63#ifdef CONFIG_X86
64/*
65 * These functions are provided to be called internally or by other parts of
66 * the kernel. It's up to the caller to ensure correct checksum before reading
67 * or after writing (needs to be done only once).
68 *
69 * It is worth noting that these functions all access bytes of general
70 * purpose memory in the NVRAM - that is to say, they all add the
71 * NVRAM_FIRST_BYTE offset. Pass them offsets into NVRAM as if you did not
72 * know about the RTC cruft.
73 */
74
75#define NVRAM_BYTES (128 - NVRAM_FIRST_BYTE)
76
77/* Note that *all* calls to CMOS_READ and CMOS_WRITE must be done with
78 * rtc_lock held. Due to the index-port/data-port design of the RTC, we
79 * don't want two different things trying to get to it at once. (e.g. the
80 * periodic 11 min sync from kernel/time/ntp.c vs. this driver.)
81 */
82
83static unsigned char __nvram_read_byte(int i)
84{
85 return CMOS_READ(NVRAM_FIRST_BYTE + i);
86}
87
88static unsigned char pc_nvram_read_byte(int i)
89{
90 unsigned long flags;
91 unsigned char c;
92
93 spin_lock_irqsave(&rtc_lock, flags);
94 c = __nvram_read_byte(i);
95 spin_unlock_irqrestore(&rtc_lock, flags);
96 return c;
97}
98
99/* This races nicely with trying to read with checksum checking (nvram_read) */
100static void __nvram_write_byte(unsigned char c, int i)
101{
102 CMOS_WRITE(c, NVRAM_FIRST_BYTE + i);
103}
104
105static void pc_nvram_write_byte(unsigned char c, int i)
106{
107 unsigned long flags;
108
109 spin_lock_irqsave(&rtc_lock, flags);
110 __nvram_write_byte(c, i);
111 spin_unlock_irqrestore(&rtc_lock, flags);
112}
113
114/* On PCs, the checksum is built only over bytes 2..31 */
115#define PC_CKS_RANGE_START 2
116#define PC_CKS_RANGE_END 31
117#define PC_CKS_LOC 32
118
119static int __nvram_check_checksum(void)
120{
121 int i;
122 unsigned short sum = 0;
123 unsigned short expect;
124
125 for (i = PC_CKS_RANGE_START; i <= PC_CKS_RANGE_END; ++i)
126 sum += __nvram_read_byte(i);
127 expect = __nvram_read_byte(PC_CKS_LOC)<<8 |
128 __nvram_read_byte(PC_CKS_LOC+1);
129 return (sum & 0xffff) == expect;
130}
131
132static void __nvram_set_checksum(void)
133{
134 int i;
135 unsigned short sum = 0;
136
137 for (i = PC_CKS_RANGE_START; i <= PC_CKS_RANGE_END; ++i)
138 sum += __nvram_read_byte(i);
139 __nvram_write_byte(sum >> 8, PC_CKS_LOC);
140 __nvram_write_byte(sum & 0xff, PC_CKS_LOC + 1);
141}
142
143static long pc_nvram_set_checksum(void)
144{
145 spin_lock_irq(&rtc_lock);
146 __nvram_set_checksum();
147 spin_unlock_irq(&rtc_lock);
148 return 0;
149}
150
151static long pc_nvram_initialize(void)
152{
153 ssize_t i;
154
155 spin_lock_irq(&rtc_lock);
156 for (i = 0; i < NVRAM_BYTES; ++i)
157 __nvram_write_byte(0, i);
158 __nvram_set_checksum();
159 spin_unlock_irq(&rtc_lock);
160 return 0;
161}
162
163static ssize_t pc_nvram_get_size(void)
164{
165 return NVRAM_BYTES;
166}
167
168static ssize_t pc_nvram_read(char *buf, size_t count, loff_t *ppos)
169{
170 char *p = buf;
171 loff_t i;
172
173 spin_lock_irq(&rtc_lock);
174 if (!__nvram_check_checksum()) {
175 spin_unlock_irq(&rtc_lock);
176 return -EIO;
177 }
178 for (i = *ppos; count > 0 && i < NVRAM_BYTES; --count, ++i, ++p)
179 *p = __nvram_read_byte(i);
180 spin_unlock_irq(&rtc_lock);
181
182 *ppos = i;
183 return p - buf;
184}
185
186static ssize_t pc_nvram_write(char *buf, size_t count, loff_t *ppos)
187{
188 char *p = buf;
189 loff_t i;
190
191 spin_lock_irq(&rtc_lock);
192 if (!__nvram_check_checksum()) {
193 spin_unlock_irq(&rtc_lock);
194 return -EIO;
195 }
196 for (i = *ppos; count > 0 && i < NVRAM_BYTES; --count, ++i, ++p)
197 __nvram_write_byte(*p, i);
198 __nvram_set_checksum();
199 spin_unlock_irq(&rtc_lock);
200
201 *ppos = i;
202 return p - buf;
203}
204
205const struct nvram_ops arch_nvram_ops = {
206 .read = pc_nvram_read,
207 .write = pc_nvram_write,
208 .read_byte = pc_nvram_read_byte,
209 .write_byte = pc_nvram_write_byte,
210 .get_size = pc_nvram_get_size,
211 .set_checksum = pc_nvram_set_checksum,
212 .initialize = pc_nvram_initialize,
213};
214EXPORT_SYMBOL(arch_nvram_ops);
215#endif /* CONFIG_X86 */
216
217/*
218 * The are the file operation function for user access to /dev/nvram
219 */
220
221static loff_t nvram_misc_llseek(struct file *file, loff_t offset, int origin)
222{
223 return generic_file_llseek_size(file, offset, origin, MAX_LFS_FILESIZE,
224 nvram_size);
225}
226
227static ssize_t nvram_misc_read(struct file *file, char __user *buf,
228 size_t count, loff_t *ppos)
229{
230 char *tmp;
231 ssize_t ret;
232
233
234 if (!access_ok(buf, count))
235 return -EFAULT;
236 if (*ppos >= nvram_size)
237 return 0;
238
239 count = min_t(size_t, count, nvram_size - *ppos);
240 count = min_t(size_t, count, PAGE_SIZE);
241
242 tmp = kmalloc(count, GFP_KERNEL);
243 if (!tmp)
244 return -ENOMEM;
245
246 ret = nvram_read(tmp, count, ppos);
247 if (ret <= 0)
248 goto out;
249
250 if (copy_to_user(buf, tmp, ret)) {
251 *ppos -= ret;
252 ret = -EFAULT;
253 }
254
255out:
256 kfree(tmp);
257 return ret;
258}
259
260static ssize_t nvram_misc_write(struct file *file, const char __user *buf,
261 size_t count, loff_t *ppos)
262{
263 char *tmp;
264 ssize_t ret;
265
266 if (!access_ok(buf, count))
267 return -EFAULT;
268 if (*ppos >= nvram_size)
269 return 0;
270
271 count = min_t(size_t, count, nvram_size - *ppos);
272 count = min_t(size_t, count, PAGE_SIZE);
273
274 tmp = memdup_user(buf, count);
275 if (IS_ERR(tmp))
276 return PTR_ERR(tmp);
277
278 ret = nvram_write(tmp, count, ppos);
279 kfree(tmp);
280 return ret;
281}
282
283static long nvram_misc_ioctl(struct file *file, unsigned int cmd,
284 unsigned long arg)
285{
286 long ret = -ENOTTY;
287
288 switch (cmd) {
289#ifdef CONFIG_PPC
290 case OBSOLETE_PMAC_NVRAM_GET_OFFSET:
291 pr_warn("nvram: Using obsolete PMAC_NVRAM_GET_OFFSET ioctl\n");
292 /* fall through */
293 case IOC_NVRAM_GET_OFFSET:
294 ret = -EINVAL;
295#ifdef CONFIG_PPC_PMAC
296 if (machine_is(powermac)) {
297 int part, offset;
298
299 if (copy_from_user(&part, (void __user *)arg,
300 sizeof(part)) != 0)
301 return -EFAULT;
302 if (part < pmac_nvram_OF || part > pmac_nvram_NR)
303 return -EINVAL;
304 offset = pmac_get_partition(part);
305 if (offset < 0)
306 return -EINVAL;
307 if (copy_to_user((void __user *)arg,
308 &offset, sizeof(offset)) != 0)
309 return -EFAULT;
310 ret = 0;
311 }
312#endif
313 break;
314#ifdef CONFIG_PPC32
315 case IOC_NVRAM_SYNC:
316 if (ppc_md.nvram_sync != NULL) {
317 mutex_lock(&nvram_mutex);
318 ppc_md.nvram_sync();
319 mutex_unlock(&nvram_mutex);
320 }
321 ret = 0;
322 break;
323#endif
324#elif defined(CONFIG_X86) || defined(CONFIG_M68K)
325 case NVRAM_INIT:
326 /* initialize NVRAM contents and checksum */
327 if (!capable(CAP_SYS_ADMIN))
328 return -EACCES;
329
330 if (arch_nvram_ops.initialize != NULL) {
331 mutex_lock(&nvram_mutex);
332 ret = arch_nvram_ops.initialize();
333 mutex_unlock(&nvram_mutex);
334 }
335 break;
336 case NVRAM_SETCKS:
337 /* just set checksum, contents unchanged (maybe useful after
338 * checksum garbaged somehow...) */
339 if (!capable(CAP_SYS_ADMIN))
340 return -EACCES;
341
342 if (arch_nvram_ops.set_checksum != NULL) {
343 mutex_lock(&nvram_mutex);
344 ret = arch_nvram_ops.set_checksum();
345 mutex_unlock(&nvram_mutex);
346 }
347 break;
348#endif /* CONFIG_X86 || CONFIG_M68K */
349 }
350 return ret;
351}
352
353static int nvram_misc_open(struct inode *inode, struct file *file)
354{
355 spin_lock(&nvram_state_lock);
356
357 /* Prevent multiple readers/writers if desired. */
358 if ((nvram_open_cnt && (file->f_flags & O_EXCL)) ||
359 (nvram_open_mode & NVRAM_EXCL)) {
360 spin_unlock(&nvram_state_lock);
361 return -EBUSY;
362 }
363
364#if defined(CONFIG_X86) || defined(CONFIG_M68K)
365 /* Prevent multiple writers if the set_checksum ioctl is implemented. */
366 if ((arch_nvram_ops.set_checksum != NULL) &&
367 (file->f_mode & FMODE_WRITE) && (nvram_open_mode & NVRAM_WRITE)) {
368 spin_unlock(&nvram_state_lock);
369 return -EBUSY;
370 }
371#endif
372
373 if (file->f_flags & O_EXCL)
374 nvram_open_mode |= NVRAM_EXCL;
375 if (file->f_mode & FMODE_WRITE)
376 nvram_open_mode |= NVRAM_WRITE;
377 nvram_open_cnt++;
378
379 spin_unlock(&nvram_state_lock);
380
381 return 0;
382}
383
384static int nvram_misc_release(struct inode *inode, struct file *file)
385{
386 spin_lock(&nvram_state_lock);
387
388 nvram_open_cnt--;
389
390 /* if only one instance is open, clear the EXCL bit */
391 if (nvram_open_mode & NVRAM_EXCL)
392 nvram_open_mode &= ~NVRAM_EXCL;
393 if (file->f_mode & FMODE_WRITE)
394 nvram_open_mode &= ~NVRAM_WRITE;
395
396 spin_unlock(&nvram_state_lock);
397
398 return 0;
399}
400
401#if defined(CONFIG_X86) && defined(CONFIG_PROC_FS)
402static const char * const floppy_types[] = {
403 "none", "5.25'' 360k", "5.25'' 1.2M", "3.5'' 720k", "3.5'' 1.44M",
404 "3.5'' 2.88M", "3.5'' 2.88M"
405};
406
407static const char * const gfx_types[] = {
408 "EGA, VGA, ... (with BIOS)",
409 "CGA (40 cols)",
410 "CGA (80 cols)",
411 "monochrome",
412};
413
414static void pc_nvram_proc_read(unsigned char *nvram, struct seq_file *seq,
415 void *offset)
416{
417 int checksum;
418 int type;
419
420 spin_lock_irq(&rtc_lock);
421 checksum = __nvram_check_checksum();
422 spin_unlock_irq(&rtc_lock);
423
424 seq_printf(seq, "Checksum status: %svalid\n", checksum ? "" : "not ");
425
426 seq_printf(seq, "# floppies : %d\n",
427 (nvram[6] & 1) ? (nvram[6] >> 6) + 1 : 0);
428 seq_printf(seq, "Floppy 0 type : ");
429 type = nvram[2] >> 4;
430 if (type < ARRAY_SIZE(floppy_types))
431 seq_printf(seq, "%s\n", floppy_types[type]);
432 else
433 seq_printf(seq, "%d (unknown)\n", type);
434 seq_printf(seq, "Floppy 1 type : ");
435 type = nvram[2] & 0x0f;
436 if (type < ARRAY_SIZE(floppy_types))
437 seq_printf(seq, "%s\n", floppy_types[type]);
438 else
439 seq_printf(seq, "%d (unknown)\n", type);
440
441 seq_printf(seq, "HD 0 type : ");
442 type = nvram[4] >> 4;
443 if (type)
444 seq_printf(seq, "%02x\n", type == 0x0f ? nvram[11] : type);
445 else
446 seq_printf(seq, "none\n");
447
448 seq_printf(seq, "HD 1 type : ");
449 type = nvram[4] & 0x0f;
450 if (type)
451 seq_printf(seq, "%02x\n", type == 0x0f ? nvram[12] : type);
452 else
453 seq_printf(seq, "none\n");
454
455 seq_printf(seq, "HD type 48 data: %d/%d/%d C/H/S, precomp %d, lz %d\n",
456 nvram[18] | (nvram[19] << 8),
457 nvram[20], nvram[25],
458 nvram[21] | (nvram[22] << 8), nvram[23] | (nvram[24] << 8));
459 seq_printf(seq, "HD type 49 data: %d/%d/%d C/H/S, precomp %d, lz %d\n",
460 nvram[39] | (nvram[40] << 8),
461 nvram[41], nvram[46],
462 nvram[42] | (nvram[43] << 8), nvram[44] | (nvram[45] << 8));
463
464 seq_printf(seq, "DOS base memory: %d kB\n", nvram[7] | (nvram[8] << 8));
465 seq_printf(seq, "Extended memory: %d kB (configured), %d kB (tested)\n",
466 nvram[9] | (nvram[10] << 8), nvram[34] | (nvram[35] << 8));
467
468 seq_printf(seq, "Gfx adapter : %s\n",
469 gfx_types[(nvram[6] >> 4) & 3]);
470
471 seq_printf(seq, "FPU : %sinstalled\n",
472 (nvram[6] & 2) ? "" : "not ");
473
474 return;
475}
476
477static int nvram_proc_read(struct seq_file *seq, void *offset)
478{
479 unsigned char contents[NVRAM_BYTES];
480 int i = 0;
481
482 spin_lock_irq(&rtc_lock);
483 for (i = 0; i < NVRAM_BYTES; ++i)
484 contents[i] = __nvram_read_byte(i);
485 spin_unlock_irq(&rtc_lock);
486
487 pc_nvram_proc_read(contents, seq, offset);
488
489 return 0;
490}
491#endif /* CONFIG_X86 && CONFIG_PROC_FS */
492
493static const struct file_operations nvram_misc_fops = {
494 .owner = THIS_MODULE,
495 .llseek = nvram_misc_llseek,
496 .read = nvram_misc_read,
497 .write = nvram_misc_write,
498 .unlocked_ioctl = nvram_misc_ioctl,
499 .open = nvram_misc_open,
500 .release = nvram_misc_release,
501};
502
503static struct miscdevice nvram_misc = {
504 NVRAM_MINOR,
505 "nvram",
506 &nvram_misc_fops,
507};
508
509static int __init nvram_module_init(void)
510{
511 int ret;
512
513 nvram_size = nvram_get_size();
514 if (nvram_size < 0)
515 return nvram_size;
516
517 ret = misc_register(&nvram_misc);
518 if (ret) {
519 pr_err("nvram: can't misc_register on minor=%d\n", NVRAM_MINOR);
520 return ret;
521 }
522
523#if defined(CONFIG_X86) && defined(CONFIG_PROC_FS)
524 if (!proc_create_single("driver/nvram", 0, NULL, nvram_proc_read)) {
525 pr_err("nvram: can't create /proc/driver/nvram\n");
526 misc_deregister(&nvram_misc);
527 return -ENOMEM;
528 }
529#endif
530
531 pr_info("Non-volatile memory driver v" NVRAM_VERSION "\n");
532 return 0;
533}
534
535static void __exit nvram_module_exit(void)
536{
537#if defined(CONFIG_X86) && defined(CONFIG_PROC_FS)
538 remove_proc_entry("driver/nvram", NULL);
539#endif
540 misc_deregister(&nvram_misc);
541}
542
543module_init(nvram_module_init);
544module_exit(nvram_module_exit);
545
546MODULE_LICENSE("GPL");
547MODULE_ALIAS_MISCDEV(NVRAM_MINOR);
548MODULE_ALIAS("devname:nvram");
549