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nvram.c

/*
 * /dev/nvram driver for Power Macintosh.
 */

#define NVRAM_VERSION "1.0"

#include <linux/module.h>

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/fcntl.h>
#include <linux/nvram.h>
#include <linux/init.h>
#include <linux/smp_lock.h>
#include <asm/uaccess.h>
#include <asm/nvram.h>

#define NVRAM_SIZE      8192

static loff_t nvram_llseek(struct file *file, loff_t offset, int origin)
{
      lock_kernel();
      switch (origin) {
      case 1:
            offset += file->f_pos;
            break;
      case 2:
            offset += NVRAM_SIZE;
            break;
      }
      if (offset < 0) {
            unlock_kernel();
            return -EINVAL;
      }
      file->f_pos = offset;
      unlock_kernel();
      return file->f_pos;
}

static ssize_t read_nvram(struct file *file, char __user *buf,
                    size_t count, loff_t *ppos)
{
      unsigned int i;
      char __user *p = buf;

      if (!access_ok(VERIFY_WRITE, buf, count))
            return -EFAULT;
      if (*ppos >= NVRAM_SIZE)
            return 0;
      for (i = *ppos; count > 0 && i < NVRAM_SIZE; ++i, ++p, --count)
            if (__put_user(nvram_read_byte(i), p))
                  return -EFAULT;
      *ppos = i;
      return p - buf;
}

static ssize_t write_nvram(struct file *file, const char __user *buf,
                     size_t count, loff_t *ppos)
{
      unsigned int i;
      const char __user *p = buf;
      char c;

      if (!access_ok(VERIFY_READ, buf, count))
            return -EFAULT;
      if (*ppos >= NVRAM_SIZE)
            return 0;
      for (i = *ppos; count > 0 && i < NVRAM_SIZE; ++i, ++p, --count) {
            if (__get_user(c, p))
                  return -EFAULT;
            nvram_write_byte(c, i);
      }
      *ppos = i;
      return p - buf;
}

static int nvram_ioctl(struct inode *inode, struct file *file,
      unsigned int cmd, unsigned long arg)
{
      switch(cmd) {
            case PMAC_NVRAM_GET_OFFSET:
            {
                  int part, offset;
                  if (copy_from_user(&part, (void __user*)arg, sizeof(part)) != 0)
                        return -EFAULT;
                  if (part < pmac_nvram_OF || part > pmac_nvram_NR)
                        return -EINVAL;
                  offset = pmac_get_partition(part);
                  if (copy_to_user((void __user*)arg, &offset, sizeof(offset)) != 0)
                        return -EFAULT;
                  break;
            }

            default:
                  return -EINVAL;
      }

      return 0;
}

const struct file_operations nvram_fops = {
      .owner            = THIS_MODULE,
      .llseek           = nvram_llseek,
      .read       = read_nvram,
      .write            = write_nvram,
      .ioctl            = nvram_ioctl,
};

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

int __init nvram_init(void)
{
      printk(KERN_INFO "Macintosh non-volatile memory driver v%s\n",
            NVRAM_VERSION);
      return misc_register(&nvram_dev);
}

void __exit nvram_cleanup(void)
{
        misc_deregister( &nvram_dev );
}

module_init(nvram_init);
module_exit(nvram_cleanup);
MODULE_LICENSE("GPL");

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