/*
   * 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/mutex.h>

  #include <asm/system.h>

  static DEFINE_MUTEX(nvram_mutex);

  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;

  	default:
  		return -EINVAL;

  	}

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

  		mutex_lock(&nvram_mutex);

  		spin_lock_irq(&rtc_lock);
  
  		for (i = 0; i < NVRAM_BYTES; ++i)
  			__nvram_write_byte(0, i);
  		__nvram_set_checksum();
  
  		spin_unlock_irq(&rtc_lock);

  		mutex_unlock(&nvram_mutex);

  		return 0;
  
  	case NVRAM_SETCKS:

  		/* just set checksum, contents unchanged (maybe useful after

  		 * checksum garbaged somehow...) */
  		if (!capable(CAP_SYS_ADMIN))
  			return -EACCES;

  		mutex_lock(&nvram_mutex);

  		spin_lock_irq(&rtc_lock);
  		__nvram_set_checksum();
  		spin_unlock_irq(&rtc_lock);

  		mutex_unlock(&nvram_mutex);

  		return 0;
  
  	default:
  		return -ENOTTY;
  	}
  }

  static int nvram_open(struct inode *inode, struct file *file)

  {
  	spin_lock(&nvram_state_lock);
  
  	if ((nvram_open_cnt && (file->f_flags & O_EXCL)) ||
  	    (nvram_open_mode & NVRAM_EXCL) ||

  	    ((file->f_mode & FMODE_WRITE) && (nvram_open_mode & NVRAM_WRITE))) {

  		spin_unlock(&nvram_state_lock);
  		return -EBUSY;
  	}
  
  	if (file->f_flags & O_EXCL)
  		nvram_open_mode |= NVRAM_EXCL;

  	if (file->f_mode & FMODE_WRITE)

  		nvram_open_mode |= NVRAM_WRITE;
  	nvram_open_cnt++;
  
  	spin_unlock(&nvram_state_lock);
  
  	return 0;
  }

  static int nvram_release(struct inode *inode, struct file *file)

  {
  	spin_lock(&nvram_state_lock);
  
  	nvram_open_cnt--;
  
  	/* if only one instance is open, clear the EXCL bit */
  	if (nvram_open_mode & NVRAM_EXCL)
  		nvram_open_mode &= ~NVRAM_EXCL;

  	if (file->f_mode & FMODE_WRITE)

  		nvram_open_mode &= ~NVRAM_WRITE;
  
  	spin_unlock(&nvram_state_lock);
  
  	return 0;
  }
  
  #ifndef CONFIG_PROC_FS

  static int nvram_add_proc_fs(void)

  {
  	return 0;
  }

  #else

  static int nvram_proc_read(struct seq_file *seq, void *offset)

  {
  	unsigned char contents[NVRAM_BYTES];

  	int i = 0;

  
  	spin_lock_irq(&rtc_lock);
  	for (i = 0; i < NVRAM_BYTES; ++i)
  		contents[i] = __nvram_read_byte(i);
  	spin_unlock_irq(&rtc_lock);

  	mach_proc_infos(contents, seq, offset);

  	return 0;
  }

  static int nvram_proc_open(struct inode *inode, struct file *file)
  {
  	return single_open(file, nvram_proc_read, NULL);

  }

  static const struct file_operations nvram_proc_fops = {
  	.owner		= THIS_MODULE,
  	.open		= nvram_proc_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= single_release,
  };
  
  static int nvram_add_proc_fs(void)
  {
  	if (!proc_create("driver/nvram", 0, NULL, &nvram_proc_fops))
  		return -ENOMEM;
  	return 0;
  }

  
  #endif /* CONFIG_PROC_FS */

  static const struct file_operations nvram_fops = {

  	.owner		= THIS_MODULE,
  	.llseek		= nvram_llseek,
  	.read		= nvram_read,
  	.write		= nvram_write,

  	.unlocked_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 -ENODEV;

  
  	ret = misc_register(&nvram_dev);
  	if (ret) {
  		printk(KERN_ERR "nvram: can't misc_register on minor=%d
  ",
  		    NVRAM_MINOR);
  		goto out;
  	}

  	ret = nvram_add_proc_fs();
  	if (ret) {

  		printk(KERN_ERR "nvram: can't create /proc/driver/nvram
  ");

  		goto outmisc;
  	}
  	ret = 0;
  	printk(KERN_INFO "Non-volatile memory driver v" NVRAM_VERSION "
  ");

  out:

  	return ret;

  outmisc:

  	misc_deregister(&nvram_dev);
  	goto out;
  }

  static void __exit nvram_cleanup_module(void)

  {
  	remove_proc_entry("driver/nvram", NULL);
  	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;
  	unsigned short expect;
  
  	for (i = PC_CKS_RANGE_START; i <= PC_CKS_RANGE_END; ++i)
  		sum += __nvram_read_byte(i);
  	expect = __nvram_read_byte(PC_CKS_LOC)<<8 |
  	    __nvram_read_byte(PC_CKS_LOC+1);

  	return (sum & 0xffff) == expect;

  }

  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_byte(i);
  	__nvram_write_byte(sum >> 8, PC_CKS_LOC);
  	__nvram_write_byte(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 void pc_proc_infos(unsigned char *nvram, struct seq_file *seq,
  								void *offset)

  {
  	int checksum;
  	int type;
  
  	spin_lock_irq(&rtc_lock);
  	checksum = __nvram_check_checksum();
  	spin_unlock_irq(&rtc_lock);

  	seq_printf(seq, "Checksum status: %svalid
  ", checksum ? "" : "not ");

  	seq_printf(seq, "# floppies     : %d
  ",

  	    (nvram[6] & 1) ? (nvram[6] >> 6) + 1 : 0);

  	seq_printf(seq, "Floppy 0 type  : ");

  	type = nvram[2] >> 4;

  	if (type < ARRAY_SIZE(floppy_types))

  		seq_printf(seq, "%s
  ", floppy_types[type]);

  	else

  		seq_printf(seq, "%d (unknown)
  ", type);
  	seq_printf(seq, "Floppy 1 type  : ");

  	type = nvram[2] & 0x0f;

  	if (type < ARRAY_SIZE(floppy_types))

  		seq_printf(seq, "%s
  ", floppy_types[type]);

  	else

  		seq_printf(seq, "%d (unknown)
  ", type);

  	seq_printf(seq, "HD 0 type      : ");

  	type = nvram[4] >> 4;
  	if (type)

  		seq_printf(seq, "%02x
  ", type == 0x0f ? nvram[11] : type);

  	else

  		seq_printf(seq, "none
  ");

  	seq_printf(seq, "HD 1 type      : ");

  	type = nvram[4] & 0x0f;
  	if (type)

  		seq_printf(seq, "%02x
  ", type == 0x0f ? nvram[12] : type);

  	else

  		seq_printf(seq, "none
  ");

  	seq_printf(seq, "HD type 48 data: %d/%d/%d C/H/S, precomp %d, lz %d
  ",

  	    nvram[18] | (nvram[19] << 8),
  	    nvram[20], nvram[25],
  	    nvram[21] | (nvram[22] << 8), nvram[23] | (nvram[24] << 8));

  	seq_printf(seq, "HD type 49 data: %d/%d/%d C/H/S, precomp %d, lz %d
  ",

  	    nvram[39] | (nvram[40] << 8),
  	    nvram[41], nvram[46],
  	    nvram[42] | (nvram[43] << 8), nvram[44] | (nvram[45] << 8));

  	seq_printf(seq, "DOS base memory: %d kB
  ", nvram[7] | (nvram[8] << 8));
  	seq_printf(seq, "Extended memory: %d kB (configured), %d kB (tested)
  ",

  	    nvram[9] | (nvram[10] << 8), nvram[34] | (nvram[35] << 8));

  	seq_printf(seq, "Gfx adapter    : %s
  ",
  	    gfx_types[(nvram[6] >> 4) & 3]);

  	seq_printf(seq, "FPU            : %sinstalled
  ",

  	    (nvram[6] & 2) ? "" : "not ");

  	return;

  }
  #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_byte(i);

  	return (__nvram_read_byte(ATARI_CKS_LOC) == (~sum & 0xff)) &&
  	    (__nvram_read_byte(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_byte(i);
  	__nvram_write_byte(~sum, ATARI_CKS_LOC);
  	__nvram_write_byte(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", "??", "??", "??"
  };

  static void atari_proc_infos(unsigned char *nvram, struct seq_file *seq,
  								void *offset)

  {
  	int checksum = nvram_check_checksum();
  	int i;
  	unsigned vmode;

  	seq_printf(seq, "Checksum status  : %svalid
  ", checksum ? "" : "not ");

  	seq_printf(seq, "Boot preference  : ");

  	for (i = ARRAY_SIZE(boot_prefs) - 1; i >= 0; --i) {

  		if (nvram[1] == boot_prefs[i].val) {

  			seq_printf(seq, "%s
  ", boot_prefs[i].name);

  			break;
  		}
  	}
  	if (i < 0)

  		seq_printf(seq, "0x%02x (undefined)
  ", nvram[1]);

  	seq_printf(seq, "SCSI arbitration : %s
  ",

  	    (nvram[16] & 0x80) ? "on" : "off");

  	seq_printf(seq, "SCSI host ID     : ");

  	if (nvram[16] & 0x80)

  		seq_printf(seq, "%d
  ", nvram[16] & 7);

  	else

  		seq_printf(seq, "n/a
  ");

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

  		return;

  	seq_printf(seq, "OS language      : ");

  	if (nvram[6] < ARRAY_SIZE(languages))

  		seq_printf(seq, "%s
  ", languages[nvram[6]]);

  	else

  		seq_printf(seq, "%u (undefined)
  ", nvram[6]);
  	seq_printf(seq, "Keyboard language: ");

  	if (nvram[7] < ARRAY_SIZE(languages))

  		seq_printf(seq, "%s
  ", languages[nvram[7]]);

  	else

  		seq_printf(seq, "%u (undefined)
  ", nvram[7]);
  	seq_printf(seq, "Date format      : ");
  	seq_printf(seq, dateformat[nvram[8] & 7],

  	    nvram[9] ? nvram[9] : '/', nvram[9] ? nvram[9] : '/');

  	seq_printf(seq, ", %dh clock
  ", nvram[8] & 16 ? 24 : 12);
  	seq_printf(seq, "Boot delay       : ");

  	if (nvram[10] == 0)

  		seq_printf(seq, "default");

  	else

  		seq_printf(seq, "%ds%s
  ", nvram[10],

  		    nvram[10] < 8 ? ", no memory test" : "");
  
  	vmode = (nvram[14] << 8) || nvram[15];

  	seq_printf(seq,
  	    "Video mode       : %s colors, %d columns, %s %s monitor
  ",

  	    colors[vmode & 7],
  	    vmode & 8 ? 80 : 40,
  	    vmode & 16 ? "VGA" : "TV", vmode & 32 ? "PAL" : "NTSC");

  	seq_printf(seq, "                   %soverscan, compat. mode %s%s
  ",

  	    vmode & 64 ? "" : "no ",
  	    vmode & 128 ? "on" : "off",
  	    vmode & 256 ?
  	    (vmode & 16 ? ", line doubling" : ", half screen") : "");

  	return;

  }
  #endif
  
  #endif /* MACH == ATARI */
  
  MODULE_LICENSE("GPL");

  MODULE_ALIAS_MISCDEV(NVRAM_MINOR);