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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>
 * 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
 */

#define NVRAM_VERSION   "1.2"

#include <linux/module.h>
#include <linux/smp_lock.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 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 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/slab.h>
#include <linux/ioport.h>
#include <linux/fcntl.h>
#include <linux/mc146818rtc.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 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 int mach_proc_infos(unsigned char *contents, char *buffer, int *len,
    off_t *begin, off_t offset, int size);
#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);
}

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;
}

/* 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);
}

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);
}

int
__nvram_check_checksum(void)
{
      return mach_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;
}

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 )
{
      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 __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;
      int len;

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

      spin_lock_irq(&rtc_lock);

      if (!__nvram_check_checksum())
            goto checksum_err;

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

            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();
            spin_unlock_irq(&rtc_lock);
            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 & 2) && (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 & 2)
            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 & 2)
            nvram_open_mode &= ~NVRAM_WRITE;

      spin_unlock(&nvram_state_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_byte(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 const 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, NULL, 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", 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 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();
      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 < ARRAY_SIZE(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 < ARRAY_SIZE(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_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 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 = ARRAY_SIZE(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] < ARRAY_SIZE(languages))
            PRINT_PROC("%s\n", languages[nvram[6]]);
      else
            PRINT_PROC("%u (undefined)\n", nvram[6]);
      PRINT_PROC("Keyboard language: ");
      if (nvram[7] < ARRAY_SIZE(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_SYMBOL(__nvram_read_byte);
EXPORT_SYMBOL(nvram_read_byte);
EXPORT_SYMBOL(__nvram_write_byte);
EXPORT_SYMBOL(nvram_write_byte);
EXPORT_SYMBOL(__nvram_check_checksum);
EXPORT_SYMBOL(nvram_check_checksum);
MODULE_ALIAS_MISCDEV(NVRAM_MINOR);

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