Implement surface read

1 files changed, 17 insertions, 1 deletions

diff --git a/surface.c b/surface.c
index 4020a31..fd5d37b 100644
--- a/surface.c
+++ b/surface.c
@@ -3,6 +3,7 @@
 #include <linux/fs.h>
 #include <linux/dma-mapping.h>
 #include <linux/slab.h>
+#include <asm/uaccess.h>
 
 #include "private_data.h"
 #include "harddoom.h"
@@ -17,7 +18,22 @@ long surface_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 ssize_t surface_read(struct file *filp, char __user *buf, size_t count,
 		loff_t *offset)
 {
-	return -1;
+	struct surface_data *surface_data;
+	unsigned long not_written;
+
+	surface_data = filp->private_data;
+	if (*offset >= surface_data->surface_size) {
+		return 0;
+	}
+
+	if (*offset + count > surface_data->surface_size) {
+		count = surface_data->surface_size - *offset;
+	}
+
+	not_written = copy_to_user(buf, surface_data->surface_cpu + *offset,
+			count);
+
+	return count - not_written;
 }
 
 loff_t surface_llseek(struct file *filp, loff_t offset, int origin)