drivers/char/nvram.c

/*
 * 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>
 *
 * 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 50, 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
 */

#define NVRAM_VERSION		"1.1"

#include <linux/module.h>
#include <linux/config.h>
#include <linux/sched.h>
#include <linux/smp_lock.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 others?? */
#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	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))

/* 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/slab.h>
#include <linux/ioport.h>
#include <linux/fcntl.h>
#include <linux/mc146818rtc.h>
#include <linux/nvram.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/spinlock.h>

#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/system.h>

static int nvram_open_cnt;	/* #times opened */
static int nvram_open_mode;	/* special open modes */
static spinlock_t nvram_open_lock = SPIN_LOCK_UNLOCKED;
                               /* guards nvram_open_cnt and
                                         nvram_open_mode */
#define	NVRAM_WRITE		1		/* opened for writing (exclusive) */
#define	NVRAM_EXCL		2		/* opened with O_EXCL */

#define	RTC_FIRST_BYTE		14	/* RTC register number of first NVRAM byte */
#define	NVRAM_BYTES			128-RTC_FIRST_BYTE	/* number of NVRAM bytes */


static int mach_check_checksum( void );
static void mach_set_checksum( void );
#ifdef CONFIG_PROC_FS
static int mach_proc_infos( unsigned char *contents, char *buffer, int *len,
							off_t *begin, off_t offset, int size );
#endif


/*
 * These are the internal NVRAM access functions, which do NOT disable
 * interrupts and do not check the checksum. Both tasks are left to higher
 * level function, so they need to be done only once per syscall.
 */

static __inline__ unsigned char nvram_read_int( int i )
{
	return( CMOS_READ( RTC_FIRST_BYTE+i ) );
}

static __inline__ void nvram_write_int( unsigned char c, int i )
{
	CMOS_WRITE( c, RTC_FIRST_BYTE+i );
}

static __inline__ int nvram_check_checksum_int( void )
{
	return( mach_check_checksum() );
}

static __inline__ void nvram_set_checksum_int( void )
{
	mach_set_checksum();
}

#if MACH == ATARI

/*
 * These non-internal functions are provided to be called 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).
 *
 * They're only built if CONFIG_ATARI is defined, because Atari drivers use
 * them. For other configurations (PC), the rest of the kernel can't rely on
 * them being present (this driver may not be configured at all, or as a
 * module), so they access config information themselves.
 */

unsigned char nvram_read_byte( int i )
{
	unsigned long flags;
	unsigned char c;

	spin_lock_irqsave (&rtc_lock, flags);
	c = nvram_read_int( i );
	spin_unlock_irqrestore (&rtc_lock, flags);
	return( c );
}

/* This races nicely with trying to read with checksum checking (nvram_read) */
void nvram_write_byte( unsigned char c, int i )
{
	unsigned long flags;

	spin_lock_irqsave (&rtc_lock, flags);
	nvram_write_int( c, i );
	spin_unlock_irqrestore (&rtc_lock, flags);
}

int nvram_check_checksum( void )
{
	unsigned long flags;
	int rv;

	spin_lock_irqsave (&rtc_lock, flags);
	rv = nvram_check_checksum_int();
	spin_unlock_irqrestore (&rtc_lock, flags);
	return( rv );
}

void nvram_set_checksum( void )
{
	unsigned long flags;

	spin_lock_irqsave (&rtc_lock, flags);
	nvram_set_checksum_int();
	spin_unlock_irqrestore (&rtc_lock, flags);
}

#endif /* MACH == ATARI */


/*
 * The are the file operation function for user access to /dev/nvram
 */

static long long nvram_llseek(struct file *file,loff_t offset, int origin )
{
	lock_kernel();
	switch( origin ) {
	  case 0:
		/* nothing to do */
		break;
	  case 1:
		offset += file->f_pos;
		break;
	  case 2:
		offset += NVRAM_BYTES;
		break;
	}
	unlock_kernel();
	return( (offset >= 0) ? (file->f_pos = offset) : -EINVAL );
}

static ssize_t nvram_read(struct file * file,
	char * buf, size_t count, loff_t *ppos )
{
	char contents [NVRAM_BYTES];
	unsigned i = *ppos;
	char *tmp;

	spin_lock_irq (&rtc_lock);
	
	if (!nvram_check_checksum_int())
		goto checksum_err;

	for (tmp = contents; count-- > 0 && i < NVRAM_BYTES; ++i, ++tmp)
		*tmp = nvram_read_int(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 * buf, size_t count, loff_t *ppos )
{
	char contents [NVRAM_BYTES];
	unsigned i = *ppos;
	char * tmp;

	if (copy_from_user (contents, buf, (NVRAM_BYTES - i) < count ?
						(NVRAM_BYTES - i) : count))
		return -EFAULT;

	spin_lock_irq (&rtc_lock);

	if (!nvram_check_checksum_int())
		goto checksum_err;

	for (tmp = contents; count-- > 0 && i < NVRAM_BYTES; ++i, ++tmp)
		nvram_write_int (*tmp, i);

	nvram_set_checksum_int();

	spin_unlock_irq (&rtc_lock);

	*ppos = i;

	return (tmp - contents);

checksum_err:
	spin_unlock_irq (&rtc_lock);
	return -EIO;
}

static int nvram_ioctl( struct inode *inode, struct file *file,
						unsigned int cmd, unsigned long arg )
{
	int i;
	
	switch( cmd ) {

	  case NVRAM_INIT:			/* initialize NVRAM contents and checksum */
		if (!capable(CAP_SYS_ADMIN))
			return( -EACCES );

		spin_lock_irq (&rtc_lock);

		for( i = 0; i < NVRAM_BYTES; ++i )
			nvram_write_int( 0, i );
		nvram_set_checksum_int();
		
		spin_unlock_irq (&rtc_lock);
		return( 0 );
	  
	  case NVRAM_SETCKS:		/* just set checksum, contents unchanged
								 * (maybe useful after checksum garbaged
								 * somehow...) */
		if (!capable(CAP_SYS_ADMIN))
			return( -EACCES );

		spin_lock_irq (&rtc_lock);
		nvram_set_checksum_int();
		spin_unlock_irq (&rtc_lock);
		return( 0 );

	  default:
		return( -EINVAL );
	}
}

static int nvram_open( struct inode *inode, struct file *file )
{
	spin_lock( &nvram_open_lock );
	if ((nvram_open_cnt && (file->f_flags & O_EXCL)) ||
		(nvram_open_mode & NVRAM_EXCL) ||
		((file->f_mode & 2) && (nvram_open_mode & NVRAM_WRITE)))
	{	
		spin_unlock( &nvram_open_lock );
		return( -EBUSY );
	}

	if (file->f_flags & O_EXCL)
		nvram_open_mode |= NVRAM_EXCL;
	if (file->f_mode & 2)
		nvram_open_mode |= NVRAM_WRITE;
	nvram_open_cnt++;
	spin_unlock( &nvram_open_lock );
	return( 0 );
}

static int nvram_release( struct inode *inode, struct file *file )
{
	spin_lock( &nvram_open_lock );
	nvram_open_cnt--;
	if (file->f_flags & O_EXCL)
		nvram_open_mode &= ~NVRAM_EXCL;
	if (file->f_mode & 2)
		nvram_open_mode &= ~NVRAM_WRITE;
	spin_unlock( &nvram_open_lock );
	return( 0 );
}


#ifndef CONFIG_PROC_FS
static int nvram_read_proc( char *buffer, char **start, off_t offset,
			    int size, int *eof, void *data) { return 0; }
#else

static int nvram_read_proc( char *buffer, char **start, off_t offset,
							int size, int *eof, void *data )
{
	unsigned char contents[NVRAM_BYTES];
    int i, len = 0;
    off_t begin = 0;

	spin_lock_irq (&rtc_lock);
	for( i = 0; i < NVRAM_BYTES; ++i )
		contents[i] = nvram_read_int( i );
	spin_unlock_irq (&rtc_lock);
	
	*eof = mach_proc_infos( contents, buffer, &len, &begin, offset, size );

    if (offset >= begin + len)
		return( 0 );
    *start = buffer + (offset - begin);
    return( size < begin + len - offset ? size : begin + len - offset );
	
}

/* This macro frees the machine specific function from bounds checking and
 * this like that... */
#define	PRINT_PROC(fmt,args...)							\
	do {												\
		*len += sprintf( buffer+*len, fmt, ##args );	\
		if (*begin + *len > offset + size)				\
			return( 0 );								\
		if (*begin + *len < offset) {					\
			*begin += *len;								\
			*len = 0;									\
		}												\
	} while(0)

#endif /* CONFIG_PROC_FS */

static struct file_operations nvram_fops = {
	owner:		THIS_MODULE,
	llseek:		nvram_llseek,
	read:		nvram_read,
	write:		nvram_write,
	ioctl:		nvram_ioctl,
	open:		nvram_open,
	release:	nvram_release,
};

static struct miscdevice nvram_dev = {
	NVRAM_MINOR,
	"nvram",
	&nvram_fops
};


static int __init nvram_init(void)
{
	int ret;

	/* First test whether the driver should init at all */
	if (!CHECK_DRIVER_INIT())
	    return( -ENXIO );

	ret = misc_register( &nvram_dev );
	if (ret) {
		printk(KERN_ERR "nvram: can't misc_register on minor=%d\n", NVRAM_MINOR);
		goto out;
	}
	if (!create_proc_read_entry("driver/nvram",0,0,nvram_read_proc,NULL)) {
		printk(KERN_ERR "nvram: can't create /proc/driver/nvram\n");
		ret = -ENOMEM;
		goto outmisc;
	}
	ret = 0;
	printk(KERN_INFO "Non-volatile memory driver v" NVRAM_VERSION "\n");
out:
	return( ret );
outmisc:
	misc_deregister( &nvram_dev );
	goto out;
}

static void __exit nvram_cleanup_module (void)
{
	remove_proc_entry( "driver/nvram", 0 );
	misc_deregister( &nvram_dev );
}

module_init(nvram_init);
module_exit(nvram_cleanup_module);


/*
 * Machine specific functions
 */


#if MACH == PC

static int pc_check_checksum( void )
{
	int i;
	unsigned short sum = 0;
	
	for( i = PC_CKS_RANGE_START; i <= PC_CKS_RANGE_END; ++i )
		sum += nvram_read_int( i );
	return( (sum & 0xffff) ==
			((nvram_read_int(PC_CKS_LOC) << 8) |
			 nvram_read_int(PC_CKS_LOC+1)) );
}

static void pc_set_checksum( void )
{
	int i;
	unsigned short sum = 0;
	
	for( i = PC_CKS_RANGE_START; i <= PC_CKS_RANGE_END; ++i )
		sum += nvram_read_int( i );
	nvram_write_int( sum >> 8, PC_CKS_LOC );
	nvram_write_int( sum & 0xff, PC_CKS_LOC+1 );
}

#ifdef CONFIG_PROC_FS

static char *floppy_types[] = {
	"none", "5.25'' 360k", "5.25'' 1.2M", "3.5'' 720k", "3.5'' 1.44M",
	"3.5'' 2.88M", "3.5'' 2.88M"
};

static char *gfx_types[] = {
	"EGA, VGA, ... (with BIOS)",
	"CGA (40 cols)",
	"CGA (80 cols)",
	"monochrome",
};

static int pc_proc_infos( unsigned char *nvram, char *buffer, int *len,
						  off_t *begin, off_t offset, int size )
{
	int checksum;
	int type;

	spin_lock_irq (&rtc_lock);
	checksum = nvram_check_checksum_int();
	spin_unlock_irq (&rtc_lock);

	PRINT_PROC( "Checksum status: %svalid\n", checksum ? "" : "not " );

	PRINT_PROC( "# floppies     : %d\n",
				(nvram[6] & 1) ? (nvram[6] >> 6) + 1 : 0 );
	PRINT_PROC( "Floppy 0 type  : " );
	type = nvram[2] >> 4;
	if (type < sizeof(floppy_types)/sizeof(*floppy_types))
		PRINT_PROC( "%s\n", floppy_types[type] );
	else
		PRINT_PROC( "%d (unknown)\n", type );
	PRINT_PROC( "Floppy 1 type  : " );
	type = nvram[2] & 0x0f;
	if (type < sizeof(floppy_types)/sizeof(*floppy_types))
		PRINT_PROC( "%s\n", floppy_types[type] );
	else
		PRINT_PROC( "%d (unknown)\n", type );

	PRINT_PROC( "HD 0 type      : " );
	type = nvram[4] >> 4;
	if (type)
		PRINT_PROC( "%02x\n", type == 0x0f ? nvram[11] : type );
	else
		PRINT_PROC( "none\n" );

	PRINT_PROC( "HD 1 type      : " );
	type = nvram[4] & 0x0f;
	if (type)
		PRINT_PROC( "%02x\n", type == 0x0f ? nvram[12] : type );
	else
		PRINT_PROC( "none\n" );

	PRINT_PROC( "HD type 48 data: %d/%d/%d C/H/S, precomp %d, lz %d\n",
				nvram[18] | (nvram[19] << 8),
				nvram[20], nvram[25],
				nvram[21] | (nvram[22] << 8),
				nvram[23] | (nvram[24] << 8) );
	PRINT_PROC( "HD type 49 data: %d/%d/%d C/H/S, precomp %d, lz %d\n",
				nvram[39] | (nvram[40] << 8),
				nvram[41], nvram[46],
				nvram[42] | (nvram[43] << 8),
				nvram[44] | (nvram[45] << 8) );

	PRINT_PROC( "DOS base memory: %d kB\n", nvram[7] | (nvram[8] << 8) );
	PRINT_PROC( "Extended memory: %d kB (configured), %d kB (tested)\n",
				nvram[9] | (nvram[10] << 8),
				nvram[34] | (nvram[35] << 8) );

	PRINT_PROC( "Gfx adapter    : %s\n", gfx_types[ (nvram[6] >> 4)&3 ] );

	PRINT_PROC( "FPU            : %sinstalled\n",
				(nvram[6] & 2) ? "" : "not " );
	
	return( 1 );
}
#endif

#endif /* MACH == PC */

#if MACH == ATARI

static int atari_check_checksum( void )
{
	int i;
	unsigned char sum = 0;
	
	for( i = ATARI_CKS_RANGE_START; i <= ATARI_CKS_RANGE_END; ++i )
		sum += nvram_read_int( i );
	return( nvram_read_int( ATARI_CKS_LOC ) == (~sum & 0xff) &&
			nvram_read_int( ATARI_CKS_LOC+1 ) == (sum & 0xff) );
}

static void atari_set_checksum( void )
{
	int i;
	unsigned char sum = 0;
	
	for( i = ATARI_CKS_RANGE_START; i <= ATARI_CKS_RANGE_END; ++i )
		sum += nvram_read_int( i );
	nvram_write_int( ~sum, ATARI_CKS_LOC );
	nvram_write_int( sum, ATARI_CKS_LOC+1 );
}

#ifdef CONFIG_PROC_FS

static struct {
	unsigned char val;
	char *name;
} boot_prefs[] = {
	{ 0x80, "TOS" },
	{ 0x40, "ASV" },
	{ 0x20, "NetBSD (?)" },
	{ 0x10, "Linux" },
	{ 0x00, "unspecified" }
};

static char *languages[] = {
	"English (US)",
	"German",
	"French",
	"English (UK)",
	"Spanish",
	"Italian",
	"6 (undefined)",
	"Swiss (French)",
	"Swiss (German)"
};

static char *dateformat[] = {
	"MM%cDD%cYY",
	"DD%cMM%cYY",
	"YY%cMM%cDD",
	"YY%cDD%cMM",
	"4 (undefined)",
	"5 (undefined)",
	"6 (undefined)",
	"7 (undefined)"
};

static char *colors[] = {
	"2", "4", "16", "256", "65536", "??", "??", "??"
};

#define fieldsize(a)	(sizeof(a)/sizeof(*a))

static int atari_proc_infos( unsigned char *nvram, char *buffer, int *len,
			    off_t *begin, off_t offset, int size )
{
	int checksum = nvram_check_checksum();
	int i;
	unsigned vmode;
	
	PRINT_PROC( "Checksum status  : %svalid\n", checksum ? "" : "not " );

	PRINT_PROC( "Boot preference  : " );
	for( i = fieldsize(boot_prefs)-1; i >= 0; --i ) {
		if (nvram[1] == boot_prefs[i].val) {
			PRINT_PROC( "%s\n", boot_prefs[i].name );
			break;
		}
	}
	if (i < 0)
		PRINT_PROC( "0x%02x (undefined)\n", nvram[1] );

	PRINT_PROC( "SCSI arbitration : %s\n", (nvram[16] & 0x80) ? "on" : "off" );
	PRINT_PROC( "SCSI host ID     : " );
	if (nvram[16] & 0x80)
		PRINT_PROC( "%d\n", nvram[16] & 7 );
	else
		PRINT_PROC( "n/a\n" );

	/* the following entries are defined only for the Falcon */
	if ((atari_mch_cookie >> 16) != ATARI_MCH_FALCON)
		return 1;

	PRINT_PROC( "OS language      : " );
	if (nvram[6] < fieldsize(languages))
		PRINT_PROC( "%s\n", languages[nvram[6]] );
	else
		PRINT_PROC( "%u (undefined)\n", nvram[6] );
	PRINT_PROC( "Keyboard language: " );
	if (nvram[7] < fieldsize(languages))
		PRINT_PROC( "%s\n", languages[nvram[7]] );
	else
		PRINT_PROC( "%u (undefined)\n", nvram[7] );
	PRINT_PROC( "Date format      : " );
	PRINT_PROC( dateformat[nvram[8]&7],
				nvram[9] ? nvram[9] : '/', nvram[9] ? nvram[9] : '/' );
	PRINT_PROC( ", %dh clock\n", nvram[8] & 16 ? 24 : 12 );
	PRINT_PROC( "Boot delay       : " );
	if (nvram[10] == 0)
		PRINT_PROC( "default" );
	else
		PRINT_PROC( "%ds%s\n", nvram[10],
					nvram[10] < 8 ? ", no memory test" : "" );

	vmode = (nvram[14] << 8) || nvram[15];
	PRINT_PROC( "Video mode       : %s colors, %d columns, %s %s monitor\n",
				colors[vmode & 7],
				vmode & 8 ? 80 : 40,
				vmode & 16 ? "VGA" : "TV",
				vmode & 32 ? "PAL" : "NTSC" );
	PRINT_PROC( "                   %soverscan, compat. mode %s%s\n",
				vmode & 64 ? "" : "no ",
				vmode & 128 ? "on" : "off",
				vmode & 256 ?
				  (vmode & 16 ? ", line doubling" : ", half screen") : "" );
		
	return( 1 );
}
#endif

#endif /* MACH == ATARI */

MODULE_LICENSE("GPL");

EXPORT_NO_SYMBOLS;

/*
 * Local variables:
 *  c-indent-level: 4
 *  tab-width: 4
 * End:
 */