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/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
  31static ssize_t nvram_len;
  32
  33static 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
  53static 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
  70static 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
  90static 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
 122const 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
 130static struct miscdevice nvram_dev = {
 131        NVRAM_MINOR,
 132        "nvram",
 133        &nvram_fops
 134};
 135
 136int __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
 150out:
 151        return ret;
 152}
 153
 154void __exit nvram_cleanup(void)
 155{
 156        misc_deregister( &nvram_dev );
 157}
 158
 159module_init(nvram_init);
 160module_exit(nvram_cleanup);
 161MODULE_LICENSE("GPL");
 162