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