LXR linux/drivers/char/generic

   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 <linux/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
  32static DEFINE_MUTEX(nvram_mutex);
  33static ssize_t nvram_len;
  34
  35static 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
  41static 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
  58static 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
  78static 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
 109static 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
 120const 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
 128static struct miscdevice nvram_dev = {
 129        NVRAM_MINOR,
 130        "nvram",
 131        &nvram_fops
 132};
 133
 134int __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
 148out:
 149        return ret;
 150}
 151
 152void __exit nvram_cleanup(void)
 153{
 154        misc_deregister( &nvram_dev );
 155}
 156
 157module_init(nvram_init);
 158module_exit(nvram_cleanup);
 159MODULE_LICENSE("GPL");
 160