ppdev: add support for compat ioctl

The arg of ioctl in ppdev is the pointer of integer except the
timeval in PPSETTIME, PPGETTIME. Different size of timeval
is already supported by the previous patches. So, it is safe
to add compat support.

Signed-off-by: Bamvor Jian Zhang <[e-mail]>
Reviewed-by: Arnd Bergmann <[e-mail]>
Tested-by: Sudip Mukherjee <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/char/ppdev.c

···
 #include <linux/ppdev.h>
 #include <linux/mutex.h>
 #include <linux/uaccess.h>
+#include <linux/compat.h>
 
 #define PP_VERSION "ppdev: user-space parallel port driver"
 #define CHRDEV "ppdev"
···
 	return ret;
 }
 
+#ifdef CONFIG_COMPAT
+static long pp_compat_ioctl(struct file *file, unsigned int cmd,
+		unsigned long arg)
+{
+	return pp_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
+}
+#endif
+
 static int pp_open (struct inode * inode, struct file * file)
 {
 	unsigned int minor = iminor(inode);
···
 	.write		= pp_write,
 	.poll		= pp_poll,
 	.unlocked_ioctl	= pp_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl   = pp_compat_ioctl,
+#endif
 	.open		= pp_open,
 	.release	= pp_release,
 };