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// SPDX-License-Identifier: GPL-2.0
#include <linux/fb.h>
#include <linux/module.h>
#include <linux/uaccess.h>
ssize_t fb_io_read(struct fb_info *info, char __user *buf, size_t count, loff_t *ppos)
{
unsigned long p = *ppos;
u8 *buffer, *dst;
u8 __iomem *src;
int c, cnt = 0, err = 0;
unsigned long total_size, trailing;
if (!info->screen_base)
return -ENODEV;
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;
buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count,
GFP_KERNEL);
if (!buffer)
return -ENOMEM;
src = (u8 __iomem *) (info->screen_base + p);
if (info->fbops->fb_sync)
info->fbops->fb_sync(info);
while (count) {
c = (count > PAGE_SIZE) ? PAGE_SIZE : count;
dst = buffer;
fb_memcpy_fromio(dst, src, c);
dst += c;
src += c;
trailing = copy_to_user(buf, buffer, c);
if (trailing == c) {
err = -EFAULT;
break;
}
c -= trailing;
*ppos += c;
buf += c;
cnt += c;
count -= c;
}
kfree(buffer);
return cnt ? cnt : err;
}
EXPORT_SYMBOL(fb_io_read);
ssize_t fb_io_write(struct fb_info *info, const char __user *buf, size_t count, loff_t *ppos)
{
unsigned long p = *ppos;
u8 *buffer, *src;
u8 __iomem *dst;
int c, cnt = 0, err = 0;
unsigned long total_size, trailing;
if (!info->screen_base)
return -ENODEV;
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;
}
buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count,
GFP_KERNEL);
if (!buffer)
return -ENOMEM;
dst = (u8 __iomem *) (info->screen_base + p);
if (info->fbops->fb_sync)
info->fbops->fb_sync(info);
while (count) {
c = (count > PAGE_SIZE) ? PAGE_SIZE : count;
src = buffer;
trailing = copy_from_user(src, buf, c);
if (trailing == c) {
err = -EFAULT;
break;
}
c -= trailing;
fb_memcpy_toio(dst, src, c);
dst += c;
src += c;
*ppos += c;
buf += c;
cnt += c;
count -= c;
}
kfree(buffer);
return (cnt) ? cnt : err;
}
EXPORT_SYMBOL(fb_io_write);
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