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