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, nvram_get_size
   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 ssize_t nvram_len;
  32
  33 static loff_t nvram_llseek(struct file *file, loff_t offset, int origin)
  34 {
  35         switch (origin) {
  36         case 1:
  37                 offset += file->f_pos;
  38                 break;
  39         case 2:
  40                 offset += nvram_len;
  41                 break;
  42         }
  43         if (offset < 0)
  44                 return -EINVAL;
  45
  46         file->f_pos = offset;
  47
  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_len)
  60                 return 0;
  61         for (i = *ppos; count > 0 && i < nvram_len; ++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_len)
  78                 return 0;
  79         for (i = *ppos; count > 0 && i < nvram_len; ++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 file *file, unsigned int cmd, unsigned long arg)
  89 {
  90         switch(cmd) {
  91 #ifdef CONFIG_PPC_PMAC
  92         case OBSOLETE_PMAC_NVRAM_GET_OFFSET:
  93                 printk(KERN_WARNING "nvram: Using obsolete PMAC_NVRAM_GET_OFFSET ioctl\n");
  94         case IOC_NVRAM_GET_OFFSET: {
  95                 int part, offset;
  96
  97                 if (!machine_is(powermac))
  98                         return -EINVAL;
  99                 if (copy_from_user(&part, (void __user*)arg, sizeof(part)) != 0)
 100                         return -EFAULT;
 101                 if (part < pmac_nvram_OF || part > pmac_nvram_NR)
 102                         return -EINVAL;
 103                 offset = pmac_get_partition(part);
 104                 if (copy_to_user((void __user*)arg, &offset, sizeof(offset)) != 0)
 105                         return -EFAULT;
 106                 break;
 107         }
 108 #endif /* CONFIG_PPC_PMAC */
 109         case IOC_NVRAM_SYNC:
 110                 nvram_sync();
 111                 break;
 112         default:
 113                 return -EINVAL;
 114         }
 115
 116         return 0;
 117 }
 118
 119 static long nvram_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 120 {
 121         int ret;
 122
 123         lock_kernel();
 124         ret = nvram_ioctl(file, cmd, arg);
 125         unlock_kernel();
 126
 127         return ret;
 128 }
 129
 130 const struct file_operations nvram_fops = {
 131         .owner          = THIS_MODULE,
 132         .llseek         = nvram_llseek,
 133         .read           = read_nvram,
 134         .write          = write_nvram,
 135         .unlocked_ioctl = nvram_unlocked_ioctl,
 136 };
 137
 138 static struct miscdevice nvram_dev = {
 139         NVRAM_MINOR,
 140         "nvram",
 141         &nvram_fops
 142 };
 143
 144 int __init nvram_init(void)
 145 {
 146         int ret = 0;
 147
 148         printk(KERN_INFO "Generic non-volatile memory driver v%s\n",
 149                 NVRAM_VERSION);
 150         ret = misc_register(&nvram_dev);
 151         if (ret != 0)
 152                 goto out;
 153
 154         nvram_len = nvram_get_size();
 155         if (nvram_len < 0)
 156                 nvram_len = NVRAM_SIZE;
 157
 158 out:
 159         return ret;
 160 }
 161
 162 void __exit nvram_cleanup(void)
 163 {
 164         misc_deregister( &nvram_dev );
 165 }
 166
 167 module_init(nvram_init);
 168 module_exit(nvram_cleanup);
 169 MODULE_LICENSE("GPL");