drivers/char/generic_nvram.c

   1 /*
   2  * Generic /dev/nvram driver for architectures providing some
   3  * "generic" hooks, that is :
   4  *
   5  * nvram_read_byte, nvram_write_byte, nvram_sync
   6  *
   7  * Note that an additional hook is supported for PowerMac only
   8  * for getting the nvram "partition" informations
   9  *
  10  */
  11
  12 #define NVRAM_VERSION "1.1"
  13
  14 #include <linux/module.h>
  15
  16 #include <linux/types.h>
  17 #include <linux/errno.h>
  18 #include <linux/fs.h>
  19 #include <linux/miscdevice.h>
  20 #include <linux/fcntl.h>
  21 #include <linux/init.h>
  22 #include <linux/smp_lock.h>
  23 #include <asm/uaccess.h>
  24 #include <asm/nvram.h>
  25
  26 #define NVRAM_SIZE      8192
  27
  28 static loff_t nvram_llseek(struct file *file, loff_t offset, int origin)
  29 {
  30         lock_kernel();
  31         switch (origin) {
  32         case 1:
  33                 offset += file->f_pos;
  34                 break;
  35         case 2:
  36                 offset += NVRAM_SIZE;
  37                 break;
  38         }
  39         if (offset < 0) {
  40                 unlock_kernel();
  41                 return -EINVAL;
  42         }
  43         file->f_pos = offset;
  44         unlock_kernel();
  45         return file->f_pos;
  46 }
  47
  48 static ssize_t read_nvram(struct file *file, char __user *buf,
  49                           size_t count, loff_t *ppos)
  50 {
  51         unsigned int i;
  52         char __user *p = buf;
  53
  54         if (!access_ok(VERIFY_WRITE, buf, count))
  55                 return -EFAULT;
  56         if (*ppos >= NVRAM_SIZE)
  57                 return 0;
  58         for (i = *ppos; count > 0 && i < NVRAM_SIZE; ++i, ++p, --count)
  59                 if (__put_user(nvram_read_byte(i), p))
  60                         return -EFAULT;
  61         *ppos = i;
  62         return p - buf;
  63 }
  64
  65 static ssize_t write_nvram(struct file *file, const char __user *buf,
  66                            size_t count, loff_t *ppos)
  67 {
  68         unsigned int i;
  69         const char __user *p = buf;
  70         char c;
  71
  72         if (!access_ok(VERIFY_READ, buf, count))
  73                 return -EFAULT;
  74         if (*ppos >= NVRAM_SIZE)
  75                 return 0;
  76         for (i = *ppos; count > 0 && i < NVRAM_SIZE; ++i, ++p, --count) {
  77                 if (__get_user(c, p))
  78                         return -EFAULT;
  79                 nvram_write_byte(c, i);
  80         }
  81         *ppos = i;
  82         return p - buf;
  83 }
  84
  85 static int nvram_ioctl(struct inode *inode, struct file *file,
  86         unsigned int cmd, unsigned long arg)
  87 {
  88         switch(cmd) {
  89 #ifdef CONFIG_PPC_PMAC
  90         case OBSOLETE_PMAC_NVRAM_GET_OFFSET:
  91                 printk(KERN_WARNING "nvram: Using obsolete PMAC_NVRAM_GET_OFFSET ioctl\n");
  92         case IOC_NVRAM_GET_OFFSET: {
  93                 int part, offset;
  94
  95                 if (_machine != _MACH_Pmac)
  96                         return -EINVAL;
  97                 if (copy_from_user(&part, (void __user*)arg, sizeof(part)) != 0)
  98                         return -EFAULT;
  99                 if (part < pmac_nvram_OF || part > pmac_nvram_NR)
 100                         return -EINVAL;
 101                 offset = pmac_get_partition(part);
 102                 if (copy_to_user((void __user*)arg, &offset, sizeof(offset)) != 0)
 103                         return -EFAULT;
 104                 break;
 105         }
 106 #endif /* CONFIG_PPC_PMAC */
 107         case IOC_NVRAM_SYNC:
 108                 nvram_sync();
 109                 break;
 110         default:
 111                 return -EINVAL;
 112         }
 113
 114         return 0;
 115 }
 116
 117 struct file_operations nvram_fops = {
 118         .owner          = THIS_MODULE,
 119         .llseek         = nvram_llseek,
 120         .read           = read_nvram,
 121         .write          = write_nvram,
 122         .ioctl          = nvram_ioctl,
 123 };
 124
 125 static struct miscdevice nvram_dev = {
 126         NVRAM_MINOR,
 127         "nvram",
 128         &nvram_fops
 129 };
 130
 131 int __init nvram_init(void)
 132 {
 133         printk(KERN_INFO "Macintosh non-volatile memory driver v%s\n",
 134                 NVRAM_VERSION);
 135         return misc_register(&nvram_dev);
 136 }
 137
 138 void __exit nvram_cleanup(void)
 139 {
 140         misc_deregister( &nvram_dev );
 141 }
 142
 143 module_init(nvram_init);
 144 module_exit(nvram_cleanup);
 145 MODULE_LICENSE("GPL");