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/mutex.h>
  23 #include <linux/pagemap.h>
  24 #include <asm/uaccess.h>
  25 #include <asm/nvram.h>
  26 #ifdef CONFIG_PPC_PMAC
  27 #include <asm/machdep.h>
  28 #endif
  29
  30 #define NVRAM_SIZE      8192
  31
  32 static DEFINE_MUTEX(nvram_mutex);
  33 static ssize_t nvram_len;
  34
  35 static loff_t nvram_llseek(struct file *file, loff_t offset, int origin)
  36 {
  37         return generic_file_llseek_size(file, offset, origin,
  38                                         MAX_LFS_FILESIZE, nvram_len);
  39 }
  40
  41 static ssize_t read_nvram(struct file *file, char __user *buf,
  42                           size_t count, loff_t *ppos)
  43 {
  44         unsigned int i;
  45         char __user *p = buf;
  46
  47         if (!access_ok(VERIFY_WRITE, buf, count))
  48                 return -EFAULT;
  49         if (*ppos >= nvram_len)
  50                 return 0;
  51         for (i = *ppos; count > 0 && i < nvram_len; ++i, ++p, --count)
  52                 if (__put_user(nvram_read_byte(i), p))
  53                         return -EFAULT;
  54         *ppos = i;
  55         return p - buf;
  56 }
  57
  58 static ssize_t write_nvram(struct file *file, const char __user *buf,
  59                            size_t count, loff_t *ppos)
  60 {
  61         unsigned int i;
  62         const char __user *p = buf;
  63         char c;
  64
  65         if (!access_ok(VERIFY_READ, buf, count))
  66                 return -EFAULT;
  67         if (*ppos >= nvram_len)
  68                 return 0;
  69         for (i = *ppos; count > 0 && i < nvram_len; ++i, ++p, --count) {
  70                 if (__get_user(c, p))
  71                         return -EFAULT;
  72                 nvram_write_byte(c, i);
  73         }
  74         *ppos = i;
  75         return p - buf;
  76 }
  77
  78 static int nvram_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  79 {
  80         switch(cmd) {
  81 #ifdef CONFIG_PPC_PMAC
  82         case OBSOLETE_PMAC_NVRAM_GET_OFFSET:
  83                 printk(KERN_WARNING "nvram: Using obsolete PMAC_NVRAM_GET_OFFSET ioctl\n");
  84         case IOC_NVRAM_GET_OFFSET: {
  85                 int part, offset;
  86
  87                 if (!machine_is(powermac))
  88                         return -EINVAL;
  89                 if (copy_from_user(&part, (void __user*)arg, sizeof(part)) != 0)
  90                         return -EFAULT;
  91                 if (part < pmac_nvram_OF || part > pmac_nvram_NR)
  92                         return -EINVAL;
  93                 offset = pmac_get_partition(part);
  94                 if (copy_to_user((void __user*)arg, &offset, sizeof(offset)) != 0)
  95                         return -EFAULT;
  96                 break;
  97         }
  98 #endif /* CONFIG_PPC_PMAC */
  99         case IOC_NVRAM_SYNC:
 100                 nvram_sync();
 101                 break;
 102         default:
 103                 return -EINVAL;
 104         }
 105
 106         return 0;
 107 }
 108
 109 static long nvram_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 110 {
 111         int ret;
 112
 113         mutex_lock(&nvram_mutex);
 114         ret = nvram_ioctl(file, cmd, arg);
 115         mutex_unlock(&nvram_mutex);
 116
 117         return ret;
 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         .unlocked_ioctl = nvram_unlocked_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         int ret = 0;
 137
 138         printk(KERN_INFO "Generic non-volatile memory driver v%s\n",
 139                 NVRAM_VERSION);
 140         ret = misc_register(&nvram_dev);
 141         if (ret != 0)
 142                 goto out;
 143
 144         nvram_len = nvram_get_size();
 145         if (nvram_len < 0)
 146                 nvram_len = NVRAM_SIZE;
 147
 148 out:
 149         return ret;
 150 }
 151
 152 void __exit nvram_cleanup(void)
 153 {
 154         misc_deregister( &nvram_dev );
 155 }
 156
 157 module_init(nvram_init);
 158 module_exit(nvram_cleanup);
 159 MODULE_LICENSE("GPL");