fb_sys_fops.c

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/*
 * linux/drivers/video/fb_sys_read.c - Generic file operations where
 * framebuffer is in system RAM
 *
 * Copyright (C) 2007 Antonino Daplas <[email protected]>
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive
 * for more details.
 *
 */
#include <linux/fb.h>
#include <linux/module.h>
#include <linux/uaccess.h>

ssize_t fb_sys_read(struct fb_info *info, char __user *buf, size_t count,
            loff_t *ppos)
{
    unsigned long p = *ppos;
    void *src;
    int err = 0;
    unsigned long total_size;

    if (info->state != FBINFO_STATE_RUNNING)
        return -EPERM;

    total_size = info->screen_size;

    if (total_size == 0)
        total_size = info->fix.smem_len;

    if (p >= total_size)
        return 0;

    if (count >= total_size)
        count = total_size;

    if (count + p > total_size)
        count = total_size - p;

    src = (void __force *)(info->screen_base + p);

    if (info->fbops->fb_sync)
        info->fbops->fb_sync(info);

    if (copy_to_user(buf, src, count))
        err = -EFAULT;

    if  (!err)
        *ppos += count;

    return (err) ? err : count;
}
EXPORT_SYMBOL_GPL(fb_sys_read);

ssize_t fb_sys_write(struct fb_info *info, const char __user *buf,
             size_t count, loff_t *ppos)
{
    unsigned long p = *ppos;
    void *dst;
    int err = 0;
    unsigned long total_size;

    if (info->state != FBINFO_STATE_RUNNING)
        return -EPERM;

    total_size = info->screen_size;

    if (total_size == 0)
        total_size = info->fix.smem_len;

    if (p > total_size)
        return -EFBIG;

    if (count > total_size) {
        err = -EFBIG;
        count = total_size;
    }

    if (count + p > total_size) {
        if (!err)
            err = -ENOSPC;

        count = total_size - p;
    }

    dst = (void __force *) (info->screen_base + p);

    if (info->fbops->fb_sync)
        info->fbops->fb_sync(info);

    if (copy_from_user(dst, buf, count))
        err = -EFAULT;

    if  (!err)
        *ppos += count;

    return (err) ? err : count;
}
EXPORT_SYMBOL_GPL(fb_sys_write);

MODULE_AUTHOR("Antonino Daplas <[email protected]>");
MODULE_DESCRIPTION("Generic file read (fb in system RAM)");
MODULE_LICENSE("GPL");