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 <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 DEFINE_MUTEX(nvram_mutex);
  32 static ssize_t nvram_len;
  33
  34 static loff_t nvram_llseek(struct file *file, loff_t offset, int origin)
  35 {
  36         switch (origin) {
  37         case 0:
  38                 break;
  39         case 1:
  40                 offset += file->f_pos;
  41                 break;
  42         case 2:
  43                 offset += nvram_len;
  44                 break;
  45         default:
  46                 offset = -1;
  47         }
  48         if (offset < 0)
  49                 return -EINVAL;
  50
  51         file->f_pos = offset;
  52
  53         return file->f_pos;
  54 }
  55
  56 static ssize_t read_nvram(struct file *file, char __user *buf,
  57                           size_t count, loff_t *ppos)
  58 {
  59         unsigned int i;
  60         char __user *p = buf;
  61
  62         if (!access_ok(VERIFY_WRITE, buf, count))
  63                 return -EFAULT;
  64         if (*ppos >= nvram_len)
  65                 return 0;
  66         for (i = *ppos; count > 0 && i < nvram_len; ++i, ++p, --count)
  67                 if (__put_user(nvram_read_byte(i), p))
  68                         return -EFAULT;
  69         *ppos = i;
  70         return p - buf;
  71 }
  72
  73 static ssize_t write_nvram(struct file *file, const char __user *buf,
  74                            size_t count, loff_t *ppos)
  75 {
  76         unsigned int i;
  77         const char __user *p = buf;
  78         char c;
  79
  80         if (!access_ok(VERIFY_READ, buf, count))
  81                 return -EFAULT;
  82         if (*ppos >= nvram_len)
  83                 return 0;
  84         for (i = *ppos; count > 0 && i < nvram_len; ++i, ++p, --count) {
  85                 if (__get_user(c, p))
  86                         return -EFAULT;
  87                 nvram_write_byte(c, i);
  88         }
  89         *ppos = i;
  90         return p - buf;
  91 }
  92
  93 static int nvram_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  94 {
  95         switch(cmd) {
  96 #ifdef CONFIG_PPC_PMAC
  97         case OBSOLETE_PMAC_NVRAM_GET_OFFSET:
  98                 printk(KERN_WARNING "nvram: Using obsolete PMAC_NVRAM_GET_OFFSET ioctl\n");
  99         case IOC_NVRAM_GET_OFFSET: {
 100                 int part, offset;
 101
 102                 if (!machine_is(powermac))
 103                         return -EINVAL;
 104                 if (copy_from_user(&part, (void __user*)arg, sizeof(part)) != 0)
 105                         return -EFAULT;
 106                 if (part < pmac_nvram_OF || part > pmac_nvram_NR)
 107                         return -EINVAL;
 108                 offset = pmac_get_partition(part);
 109                 if (copy_to_user((void __user*)arg, &offset, sizeof(offset)) != 0)
 110                         return -EFAULT;
 111                 break;
 112         }
 113 #endif /* CONFIG_PPC_PMAC */
 114         case IOC_NVRAM_SYNC:
 115                 nvram_sync();
 116                 break;
 117         default:
 118                 return -EINVAL;
 119         }
 120
 121         return 0;
 122 }
 123
 124 static long nvram_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 125 {
 126         int ret;
 127
 128         mutex_lock(&nvram_mutex);
 129         ret = nvram_ioctl(file, cmd, arg);
 130         mutex_unlock(&nvram_mutex);
 131
 132         return ret;
 133 }
 134
 135 const struct file_operations nvram_fops = {
 136         .owner          = THIS_MODULE,
 137         .llseek         = nvram_llseek,
 138         .read           = read_nvram,
 139         .write          = write_nvram,
 140         .unlocked_ioctl = nvram_unlocked_ioctl,
 141 };
 142
 143 static struct miscdevice nvram_dev = {
 144         NVRAM_MINOR,
 145         "nvram",
 146         &nvram_fops
 147 };
 148
 149 int __init nvram_init(void)
 150 {
 151         int ret = 0;
 152
 153         printk(KERN_INFO "Generic non-volatile memory driver v%s\n",
 154                 NVRAM_VERSION);
 155         ret = misc_register(&nvram_dev);
 156         if (ret != 0)
 157                 goto out;
 158
 159         nvram_len = nvram_get_size();
 160         if (nvram_len < 0)
 161                 nvram_len = NVRAM_SIZE;
 162
 163 out:
 164         return ret;
 165 }
 166
 167 void __exit nvram_cleanup(void)
 168 {
 169         misc_deregister( &nvram_dev );
 170 }
 171
 172 module_init(nvram_init);
 173 module_exit(nvram_cleanup);
 174 MODULE_LICENSE("GPL");