nvram.c

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/*
 * /dev/nvram driver for Power Macintosh.
 */

#define NVRAM_VERSION "1.0"

#include <linux/module.h>

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/fcntl.h>
#include <linux/nvram.h>
#include <linux/init.h>
#include <asm/uaccess.h>
#include <asm/nvram.h>

#define NVRAM_SIZE  8192

static loff_t nvram_llseek(struct file *file, loff_t offset, int origin)
{
    switch (origin) {
    case 0:
        break;
    case 1:
        offset += file->f_pos;
        break;
    case 2:
        offset += NVRAM_SIZE;
        break;
    default:
        offset = -1;
    }
    if (offset < 0)
        return -EINVAL;

    file->f_pos = offset;
    return file->f_pos;
}

static ssize_t read_nvram(struct file *file, char __user *buf,
              size_t count, loff_t *ppos)
{
    unsigned int i;
    char __user *p = buf;

    if (!access_ok(VERIFY_WRITE, buf, count))
        return -EFAULT;
    if (*ppos >= NVRAM_SIZE)
        return 0;
    for (i = *ppos; count > 0 && i < NVRAM_SIZE; ++i, ++p, --count)
        if (__put_user(nvram_read_byte(i), p))
            return -EFAULT;
    *ppos = i;
    return p - buf;
}

static ssize_t write_nvram(struct file *file, const char __user *buf,
               size_t count, loff_t *ppos)
{
    unsigned int i;
    const char __user *p = buf;
    char c;

    if (!access_ok(VERIFY_READ, buf, count))
        return -EFAULT;
    if (*ppos >= NVRAM_SIZE)
        return 0;
    for (i = *ppos; count > 0 && i < NVRAM_SIZE; ++i, ++p, --count) {
        if (__get_user(c, p))
            return -EFAULT;
        nvram_write_byte(c, i);
    }
    *ppos = i;
    return p - buf;
}

static long nvram_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    switch(cmd) {
        case PMAC_NVRAM_GET_OFFSET:
        {
            int part, offset;
            if (copy_from_user(&part, (void __user*)arg, sizeof(part)) != 0)
                return -EFAULT;
            if (part < pmac_nvram_OF || part > pmac_nvram_NR)
                return -EINVAL;
            offset = pmac_get_partition(part);
            if (copy_to_user((void __user*)arg, &offset, sizeof(offset)) != 0)
                return -EFAULT;
            break;
        }

        default:
            return -EINVAL;
    }

    return 0;
}

const struct file_operations nvram_fops = {
    .owner      = THIS_MODULE,
    .llseek     = nvram_llseek,
    .read       = read_nvram,
    .write      = write_nvram,
    .unlocked_ioctl = nvram_ioctl,
};

static struct miscdevice nvram_dev = {
    NVRAM_MINOR,
    "nvram",
    &nvram_fops
};

int __init nvram_init(void)
{
    printk(KERN_INFO "Macintosh non-volatile memory driver v%s\n",
        NVRAM_VERSION);
    return misc_register(&nvram_dev);
}

void __exit nvram_cleanup(void)
{
        misc_deregister( &nvram_dev );
}

module_init(nvram_init);
module_exit(nvram_cleanup);
MODULE_LICENSE("GPL");