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|
/*
* CMOS/NV-RAM driver for Linux
*
* Copyright (C) 1997 Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de>
* idea by and with help from Richard Jelinek <rj@suse.de>
* Portions copyright (c) 2001,2002 Sun Microsystems (thockin@sun.com)
*
* This driver allows you to access the contents of the non-volatile memory in
* the mc146818rtc.h real-time clock. This chip is built into all PCs and into
* many Atari machines. In the former it's called "CMOS-RAM", in the latter
* "NVRAM" (NV stands for non-volatile).
*
* The data are supplied as a (seekable) character device, /dev/nvram. The
* size of this file is dependent on the controller. The usual size is 114,
* the number of freely available bytes in the memory (i.e., not used by the
* RTC itself).
*
* Checksums over the NVRAM contents are managed by this driver. In case of a
* bad checksum, reads and writes return -EIO. The checksum can be initialized
* to a sane state either by ioctl(NVRAM_INIT) (clear whole NVRAM) or
* ioctl(NVRAM_SETCKS) (doesn't change contents, just makes checksum valid
* again; use with care!)
*
* This file also provides some functions for other parts of the kernel that
* want to access the NVRAM: nvram_{read,write,check_checksum,set_checksum}.
* Obviously this can be used only if this driver is always configured into
* the kernel and is not a module. Since the functions are used by some Atari
* drivers, this is the case on the Atari.
*
*
* 1.1 Cesar Barros: SMP locking fixes
* added changelog
* 1.2 Erik Gilling: Cobalt Networks support
* Tim Hockin: general cleanup, Cobalt support
* 1.3 Wim Van Sebroeck: convert PRINT_PROC to seq_file
*/
#define NVRAM_VERSION "1.3"
#include <linux/module.h>
#include <linux/nvram.h>
#define PC 1
#define ATARI 2
/* select machine configuration */
#if defined(CONFIG_ATARI)
# define MACH ATARI
#elif defined(__i386__) || defined(__x86_64__) || defined(__arm__) /* and ?? */
# define MACH PC
#else
# error Cannot build nvram driver for this machine configuration.
#endif
#if MACH == PC
/* RTC in a PC */
#define CHECK_DRIVER_INIT() 1
/* On PCs, the checksum is built only over bytes 2..31 */
#define PC_CKS_RANGE_START 2
#define PC_CKS_RANGE_END 31
#define PC_CKS_LOC 32
#define NVRAM_BYTES (128-NVRAM_FIRST_BYTE)
#define mach_check_checksum pc_check_checksum
#define mach_set_checksum pc_set_checksum
#define mach_proc_infos pc_proc_infos
#endif
#if MACH == ATARI
/* Special parameters for RTC in Atari machines */
#include <asm/atarihw.h>
#include <asm/atariints.h>
#define RTC_PORT(x) (TT_RTC_BAS + 2*(x))
#define CHECK_DRIVER_INIT() (MACH_IS_ATARI && ATARIHW_PRESENT(TT_CLK))
#define NVRAM_BYTES 50
/* On Ataris, the checksum is over all bytes except the checksum bytes
* themselves; these are at the very end */
#define ATARI_CKS_RANGE_START 0
#define ATARI_CKS_RANGE_END 47
#define ATARI_CKS_LOC 48
#define mach_check_checksum atari_check_checksum
#define mach_set_checksum atari_set_checksum
#define mach_proc_infos atari_proc_infos
#endif
/* Note that *all* calls to CMOS_READ and CMOS_WRITE must be done with
* rtc_lock held. Due to the index-port/data-port design of the RTC, we
* don't want two different things trying to get to it at once. (e.g. the
* periodic 11 min sync from time.c vs. this driver.)
*/
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/ioport.h>
#include <linux/fcntl.h>
#include <linux/mc146818rtc.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/spinlock.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/smp_lock.h>
#include <asm/system.h>
static DEFINE_SPINLOCK(nvram_state_lock);
static int nvram_open_cnt; /* #times opened */
static int nvram_open_mode; /* special open modes */
#define NVRAM_WRITE 1 /* opened for writing (exclusive) */
#define NVRAM_EXCL 2 /* opened with O_EXCL */
static int mach_check_checksum(void);
static void mach_set_checksum(void);
#ifdef CONFIG_PROC_FS
static void mach_proc_infos(unsigned char *contents, struct seq_file *seq,
void *offset);
#endif
/*
* These functions are provided to be called internally or by other parts of
* the kernel. It's up to the caller to ensure correct checksum before reading
* or after writing (needs to be done only once).
*
* It is worth noting that these functions all access bytes of general
* purpose memory in the NVRAM - that is to say, they all add the
* NVRAM_FIRST_BYTE offset. Pass them offsets into NVRAM as if you did not
* know about the RTC cruft.
*/
unsigned char __nvram_read_byte(int i)
{
return CMOS_READ(NVRAM_FIRST_BYTE + i);
}
EXPORT_SYMBOL(__nvram_read_byte);
unsigned char nvram_read_byte(int i)
{
unsigned long flags;
unsigned char c;
spin_lock_irqsave(&rtc_lock, flags);
c = __nvram_read_byte(i);
spin_unlock_irqrestore(&rtc_lock, flags);
return c;
}
EXPORT_SYMBOL(nvram_read_byte);
/* This races nicely with trying to read with checksum checking (nvram_read) */
void __nvram_write_byte(unsigned char c, int i)
{
CMOS_WRITE(c, NVRAM_FIRST_BYTE + i);
}
EXPORT_SYMBOL(__nvram_write_byte);
void nvram_write_byte(unsigned char c, int i)
{
unsigned long flags;
spin_lock_irqsave(&rtc_lock, flags);
__nvram_write_byte(c, i);
spin_unlock_irqrestore(&rtc_lock, flags);
}
EXPORT_SYMBOL(nvram_write_byte);
int __nvram_check_checksum(void)
{
return mach_check_checksum();
}
EXPORT_SYMBOL(__nvram_check_checksum);
int nvram_check_checksum(void)
{
unsigned long flags;
int rv;
spin_lock_irqsave(&rtc_lock, flags);
rv = __nvram_check_checksum();
spin_unlock_irqrestore(&rtc_lock, flags);
return rv;
}
EXPORT_SYMBOL(nvram_check_checksum);
static void __nvram_set_checksum(void)
{
mach_set_checksum();
}
#if 0
void nvram_set_checksum(void)
{
unsigned long flags;
spin_lock_irqsave(&rtc_lock, flags);
__nvram_set_checksum();
spin_unlock_irqrestore(&rtc_lock, flags);
}
#endif /* 0 */
/*
* The are the file operation function for user access to /dev/nvram
*/
static loff_t nvram_llseek(struct file *file, loff_t offset, int origin)
{
switch (origin) {
case 0:
/* nothing to do */
break;
case 1:
offset += file->f_pos;
break;
case 2:
offset += NVRAM_BYTES;
break;
}
return (offset >= 0) ? (file->f_pos = offset) : -EINVAL;
}
static ssize_t nvram_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
unsigned char contents[NVRAM_BYTES];
unsigned i = *ppos;
unsigned char *tmp;
spin_lock_irq(&rtc_lock);
if (!__nvram_check_checksum())
goto checksum_err;
for (tmp = contents; count-- > 0 && i < NVRAM_BYTES; ++i, ++tmp)
*tmp = __nvram_read_byte(i);
spin_unlock_irq(&rtc_lock);
if (copy_to_user(buf, contents, tmp - contents))
return -EFAULT;
*ppos = i;
return tmp - contents;
checksum_err:
spin_unlock_irq(&rtc_lock);
return -EIO;
}
static ssize_t nvram_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
unsigned char contents[NVRAM_BYTES];
unsigned i = *ppos;
unsigned char *tmp;
if (i >= NVRAM_BYTES)
return 0; /* Past EOF */
if (count > NVRAM_BYTES - i)
count = NVRAM_BYTES - i;
if (count > NVRAM_BYTES)
return -EFAULT; /* Can't happen, but prove it to gcc */
if (copy_from_user(contents, buf, count))
return -EFAULT;
spin_lock_irq(&rtc_lock);
if (!__nvram_check_checksum())
goto checksum_err;
for (tmp = contents; count--; ++i, ++tmp)
__nvram_write_byte(*tmp, i);
__nvram_set_checksum();
spin_unlock_irq(&rtc_lock);
*ppos = i;
return tmp - contents;
checksum_err:
spin_unlock_irq(&rtc_lock);
return -EIO;
}
static long nvram_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
int i;
switch (cmd) {
case NVRAM_INIT:
|