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 <asm/uaccess.h>
  23 #include <asm/nvram.h>
  24 #ifdef CONFIG_PPC_PMAC
  25 #include <asm/machdep.h>
  26 #endif
  27
  28 #define NVRAM_SIZE      8192
  29
  30 static ssize_t nvram_len;
  31
  32 static loff_t nvram_llseek(struct file *file, loff_t offset, int origin)
  33 {
  34         switch (origin) {
  35         case 1:
  36                 offset += file->f_pos;
  37                 break;
  38         case 2:
  39                 offset += nvram_len;
  40                 break;
  41         }
  42         if (offset < 0)
  43                 return -EINVAL;
  44
  45         file->f_pos = offset;
  46
  47         return file->f_pos;
  48 }
  49
  50 static ssize_t read_nvram(struct file *file, char __user *buf,
  51                           size_t count, loff_t *ppos)
  52 {
  53         unsigned int i;
  54         char __user *p = buf;
  55
  56         if (!access_ok(VERIFY_WRITE, buf, count))
  57                 return -EFAULT;
  58         if (*ppos >= nvram_len)
  59                 return 0;
  60         for (i = *ppos; count > 0 && i < nvram_len; ++i, ++p, --count)
  61                 if (__put_user(nvram_read_byte(i), p))
  62                         return -EFAULT;
  63         *ppos = i;
  64         return p - buf;
  65 }
  66
  67 static ssize_t write_nvram(struct file *file, const char __user *buf,
  68                            size_t count, loff_t *ppos)
  69 {
  70         unsigned int i;
  71         const char __user *p = buf;
  72         char c;
  73
  74         if (!access_ok(VERIFY_READ, buf, count))
  75                 return -EFAULT;
  76         if (*ppos >= nvram_len)
  77                 return 0;
  78         for (i = *ppos; count > 0 && i < nvram_len; ++i, ++p, --count) {
  79                 if (__get_user(c, p))
  80                         return -EFAULT;
  81                 nvram_write_byte(c, i);
  82         }
  83         *ppos = i;
  84         return p - buf;
  85 }
  86
  87 static int nvram_ioctl(struct inode *inode, struct file *file,
  88         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 const struct file_operations nvram_fops = {
 120         .owner          = THIS_MODULE,
 121         .llseek         = nvram_llseek,
 122         .read           = read_nvram,
 123         .write          = write_nvram,
 124         .ioctl          = nvram_ioctl,
 125 };
 126
 127 static struct miscdevice nvram_dev = {
 128         NVRAM_MINOR,
 129         "nvram",
 130         &nvram_fops
 131 };
 132
 133 int __init nvram_init(void)
 134 {
 135         int ret = 0;
 136
 137         printk(KERN_INFO "Generic non-volatile memory driver v%s\n",
 138                 NVRAM_VERSION);
 139         ret = misc_register(&nvram_dev);
 140         if (ret != 0)
 141                 goto out;
 142
 143         nvram_len = nvram_get_size();
 144         if (nvram_len < 0)
 145                 nvram_len = NVRAM_SIZE;
 146
 147 out:
 148         return ret;
 149 }
 150
 151 void __exit nvram_cleanup(void)
 152 {
 153         misc_deregister( &nvram_dev );
 154 }
 155
 156 module_init(nvram_init);
 157 module_exit(nvram_cleanup);
 158 MODULE_LICENSE("GPL");