drivers/macintosh/nvram.c

   1 /*
   2  * /dev/nvram driver for Power Macintosh.
   3  */
   4 #include <linux/types.h>
   5 #include <linux/errno.h>
   6 #include <linux/fs.h>
   7 #include <linux/miscdevice.h>
   8 #include <linux/fcntl.h>
   9 #include <linux/nvram.h>
  10 #include <linux/init.h>
  11 #include <asm/uaccess.h>
  12 #include <asm/init.h>
  13
  14 #define NVRAM_SIZE      8192
  15
  16 __openfirmware
  17
  18 static long long nvram_llseek(struct file *file, loff_t offset, int origin)
  19 {
  20         switch (origin) {
  21         case 1:
  22                 offset += file->f_pos;
  23                 break;
  24         case 2:
  25                 offset += NVRAM_SIZE;
  26                 break;
  27         }
  28         if (offset < 0)
  29                 return -EINVAL;
  30         file->f_pos = offset;
  31         return file->f_pos;
  32 }
  33
  34 static ssize_t read_nvram(struct file *file, char *buf,
  35                           size_t count, loff_t *ppos)
  36 {
  37         unsigned int i;
  38         char *p = buf;
  39
  40         if (verify_area(VERIFY_WRITE, buf, count))
  41                 return -EFAULT;
  42         if (*ppos >= NVRAM_SIZE)
  43                 return 0;
  44         for (i = *ppos; count > 0 && i < NVRAM_SIZE; ++i, ++p, --count)
  45                 if (__put_user(nvram_read_byte(i), p))
  46                         return -EFAULT;
  47         *ppos = i;
  48         return p - buf;
  49 }
  50
  51 static ssize_t write_nvram(struct file *file, const char *buf,
  52                            size_t count, loff_t *ppos)
  53 {
  54         unsigned int i;
  55         const char *p = buf;
  56         char c;
  57
  58         if (verify_area(VERIFY_READ, buf, count))
  59                 return -EFAULT;
  60         if (*ppos >= NVRAM_SIZE)
  61                 return 0;
  62         for (i = *ppos; count > 0 && i < NVRAM_SIZE; ++i, ++p, --count) {
  63                 if (__get_user(c, p))
  64                         return -EFAULT;
  65                 nvram_write_byte(c, i);
  66         }
  67         *ppos = i;
  68         return p - buf;
  69 }
  70
  71 static int nvram_open(struct inode *inode, struct file *file)
  72 {
  73         return 0;
  74 }
  75
  76 struct file_operations nvram_fops = {
  77         nvram_llseek,
  78         read_nvram,
  79         write_nvram,
  80         NULL,           /* nvram_readdir */
  81         NULL,           /* nvram_select */
  82         NULL,           /* nvram_ioctl */
  83         NULL,           /* nvram_mmap */
  84         nvram_open,
  85         NULL,           /* flush */
  86         NULL,           /* no special release code */
  87         NULL            /* fsync */
  88 };
  89
  90 static struct miscdevice nvram_dev = {
  91         NVRAM_MINOR,
  92         "nvram",
  93         &nvram_fops
  94 };
  95
  96 __initfunc(int nvram_init(void))
  97 {
  98         misc_register(&nvram_dev);
  99         return 0;
 100 }