2 * CMOS/NV-RAM driver for Linux
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)
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).
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
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!)
24 * 1.1 Cesar Barros: SMP locking fixes
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
31 #define NVRAM_VERSION "1.3"
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>
47 #include <linux/uaccess.h>
48 #include <linux/mutex.h>
49 #include <linux/pagemap.h>
52 #include <asm/nvram.h>
55 static DEFINE_MUTEX(nvram_mutex
);
56 static DEFINE_SPINLOCK(nvram_state_lock
);
57 static int nvram_open_cnt
; /* #times opened */
58 static int nvram_open_mode
; /* special open modes */
59 static ssize_t nvram_size
;
60 #define NVRAM_WRITE 1 /* opened for writing (exclusive) */
61 #define NVRAM_EXCL 2 /* opened with O_EXCL */
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).
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.
75 #define NVRAM_BYTES (128 - NVRAM_FIRST_BYTE)
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.)
83 static unsigned char __nvram_read_byte(int i
)
85 return CMOS_READ(NVRAM_FIRST_BYTE
+ i
);
88 static unsigned char pc_nvram_read_byte(int i
)
93 spin_lock_irqsave(&rtc_lock
, flags
);
94 c
= __nvram_read_byte(i
);
95 spin_unlock_irqrestore(&rtc_lock
, flags
);
99 /* This races nicely with trying to read with checksum checking (nvram_read) */
100 static void __nvram_write_byte(unsigned char c
, int i
)
102 CMOS_WRITE(c
, NVRAM_FIRST_BYTE
+ i
);
105 static void pc_nvram_write_byte(unsigned char c
, int i
)
109 spin_lock_irqsave(&rtc_lock
, flags
);
110 __nvram_write_byte(c
, i
);
111 spin_unlock_irqrestore(&rtc_lock
, flags
);
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
119 static int __nvram_check_checksum(void)
122 unsigned short sum
= 0;
123 unsigned short expect
;
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
;
132 static void __nvram_set_checksum(void)
135 unsigned short sum
= 0;
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);
143 static long pc_nvram_set_checksum(void)
145 spin_lock_irq(&rtc_lock
);
146 __nvram_set_checksum();
147 spin_unlock_irq(&rtc_lock
);
151 static long pc_nvram_initialize(void)
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
);
163 static ssize_t
pc_nvram_get_size(void)
168 static ssize_t
pc_nvram_read(char *buf
, size_t count
, loff_t
*ppos
)
173 spin_lock_irq(&rtc_lock
);
174 if (!__nvram_check_checksum()) {
175 spin_unlock_irq(&rtc_lock
);
178 for (i
= *ppos
; count
> 0 && i
< NVRAM_BYTES
; --count
, ++i
, ++p
)
179 *p
= __nvram_read_byte(i
);
180 spin_unlock_irq(&rtc_lock
);
186 static ssize_t
pc_nvram_write(char *buf
, size_t count
, loff_t
*ppos
)
191 spin_lock_irq(&rtc_lock
);
192 if (!__nvram_check_checksum()) {
193 spin_unlock_irq(&rtc_lock
);
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
);
205 const 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
,
214 EXPORT_SYMBOL(arch_nvram_ops
);
215 #endif /* CONFIG_X86 */
218 * The are the file operation function for user access to /dev/nvram
221 static loff_t
nvram_misc_llseek(struct file
*file
, loff_t offset
, int origin
)
223 return generic_file_llseek_size(file
, offset
, origin
, MAX_LFS_FILESIZE
,
227 static ssize_t
nvram_misc_read(struct file
*file
, char __user
*buf
,
228 size_t count
, loff_t
*ppos
)
234 if (!access_ok(buf
, count
))
236 if (*ppos
>= nvram_size
)
239 count
= min_t(size_t, count
, nvram_size
- *ppos
);
240 count
= min_t(size_t, count
, PAGE_SIZE
);
242 tmp
= kmalloc(count
, GFP_KERNEL
);
246 ret
= nvram_read(tmp
, count
, ppos
);
250 if (copy_to_user(buf
, tmp
, ret
)) {
260 static ssize_t
nvram_misc_write(struct file
*file
, const char __user
*buf
,
261 size_t count
, loff_t
*ppos
)
266 if (!access_ok(buf
, count
))
268 if (*ppos
>= nvram_size
)
271 count
= min_t(size_t, count
, nvram_size
- *ppos
);
272 count
= min_t(size_t, count
, PAGE_SIZE
);
274 tmp
= memdup_user(buf
, count
);
278 ret
= nvram_write(tmp
, count
, ppos
);
283 static long nvram_misc_ioctl(struct file
*file
, unsigned int cmd
,
290 case OBSOLETE_PMAC_NVRAM_GET_OFFSET
:
291 pr_warn("nvram: Using obsolete PMAC_NVRAM_GET_OFFSET ioctl\n");
293 case IOC_NVRAM_GET_OFFSET
:
295 #ifdef CONFIG_PPC_PMAC
296 if (machine_is(powermac
)) {
299 if (copy_from_user(&part
, (void __user
*)arg
,
302 if (part
< pmac_nvram_OF
|| part
> pmac_nvram_NR
)
304 offset
= pmac_get_partition(part
);
307 if (copy_to_user((void __user
*)arg
,
308 &offset
, sizeof(offset
)) != 0)
316 if (ppc_md
.nvram_sync
!= NULL
) {
317 mutex_lock(&nvram_mutex
);
319 mutex_unlock(&nvram_mutex
);
324 #elif defined(CONFIG_X86) || defined(CONFIG_M68K)
326 /* initialize NVRAM contents and checksum */
327 if (!capable(CAP_SYS_ADMIN
))
330 if (arch_nvram_ops
.initialize
!= NULL
) {
331 mutex_lock(&nvram_mutex
);
332 ret
= arch_nvram_ops
.initialize();
333 mutex_unlock(&nvram_mutex
);
337 /* just set checksum, contents unchanged (maybe useful after
338 * checksum garbaged somehow...) */
339 if (!capable(CAP_SYS_ADMIN
))
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
);
348 #endif /* CONFIG_X86 || CONFIG_M68K */
353 static int nvram_misc_open(struct inode
*inode
, struct file
*file
)
355 spin_lock(&nvram_state_lock
);
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
);
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
);
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
;
379 spin_unlock(&nvram_state_lock
);
384 static int nvram_misc_release(struct inode
*inode
, struct file
*file
)
386 spin_lock(&nvram_state_lock
);
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
;
396 spin_unlock(&nvram_state_lock
);
401 #if defined(CONFIG_X86) && defined(CONFIG_PROC_FS)
402 static 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"
407 static const char * const gfx_types
[] = {
408 "EGA, VGA, ... (with BIOS)",
414 static void pc_nvram_proc_read(unsigned char *nvram
, struct seq_file
*seq
,
420 spin_lock_irq(&rtc_lock
);
421 checksum
= __nvram_check_checksum();
422 spin_unlock_irq(&rtc_lock
);
424 seq_printf(seq
, "Checksum status: %svalid\n", checksum
? "" : "not ");
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
]);
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
]);
439 seq_printf(seq
, "%d (unknown)\n", type
);
441 seq_printf(seq
, "HD 0 type : ");
442 type
= nvram
[4] >> 4;
444 seq_printf(seq
, "%02x\n", type
== 0x0f ? nvram
[11] : type
);
446 seq_printf(seq
, "none\n");
448 seq_printf(seq
, "HD 1 type : ");
449 type
= nvram
[4] & 0x0f;
451 seq_printf(seq
, "%02x\n", type
== 0x0f ? nvram
[12] : type
);
453 seq_printf(seq
, "none\n");
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));
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));
468 seq_printf(seq
, "Gfx adapter : %s\n",
469 gfx_types
[(nvram
[6] >> 4) & 3]);
471 seq_printf(seq
, "FPU : %sinstalled\n",
472 (nvram
[6] & 2) ? "" : "not ");
477 static int nvram_proc_read(struct seq_file
*seq
, void *offset
)
479 unsigned char contents
[NVRAM_BYTES
];
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
);
487 pc_nvram_proc_read(contents
, seq
, offset
);
491 #endif /* CONFIG_X86 && CONFIG_PROC_FS */
493 static 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
,
503 static struct miscdevice nvram_misc
= {
509 static int __init
nvram_module_init(void)
513 nvram_size
= nvram_get_size();
517 ret
= misc_register(&nvram_misc
);
519 pr_err("nvram: can't misc_register on minor=%d\n", NVRAM_MINOR
);
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
);
531 pr_info("Non-volatile memory driver v" NVRAM_VERSION
"\n");
535 static void __exit
nvram_module_exit(void)
537 #if defined(CONFIG_X86) && defined(CONFIG_PROC_FS)
538 remove_proc_entry("driver/nvram", NULL
);
540 misc_deregister(&nvram_misc
);
543 module_init(nvram_module_init
);
544 module_exit(nvram_module_exit
);
546 MODULE_LICENSE("GPL");
547 MODULE_ALIAS_MISCDEV(NVRAM_MINOR
);
548 MODULE_ALIAS("devname:nvram");