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