1 files changed, 133 insertions, 0 deletions
diff --git a/drivers/video/fbdev/core/fb_io_fops.c b/drivers/video/fbdev/core/fb_io_fops.c
new file mode 100644
index 000000000000..f5299d50f33b
--- /dev/null
+++ b/drivers/video/fbdev/core/fb_io_fops.c
@@ -0,0 +1,133 @@
+// 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_fromfb(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_tofb(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);