v4.19.13 snapshot.
diff --git a/include/drm/drm_os_linux.h b/include/drm/drm_os_linux.h
new file mode 100644
index 0000000..ee8d61b
--- /dev/null
+++ b/include/drm/drm_os_linux.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/**
+ * \file drm_os_linux.h
+ * OS abstraction macros.
+ */
+
+#include <linux/interrupt.h> /* For task queue support */
+#include <linux/sched/signal.h>
+#include <linux/delay.h>
+#include <linux/io-64-nonatomic-lo-hi.h>
+
+/** Current process ID */
+#define DRM_CURRENTPID task_pid_nr(current)
+#define DRM_UDELAY(d) udelay(d)
+/** Read a byte from a MMIO region */
+#define DRM_READ8(map, offset) readb(((void __iomem *)(map)->handle) + (offset))
+/** Read a word from a MMIO region */
+#define DRM_READ16(map, offset) readw(((void __iomem *)(map)->handle) + (offset))
+/** Read a dword from a MMIO region */
+#define DRM_READ32(map, offset) readl(((void __iomem *)(map)->handle) + (offset))
+/** Write a byte into a MMIO region */
+#define DRM_WRITE8(map, offset, val) writeb(val, ((void __iomem *)(map)->handle) + (offset))
+/** Write a word into a MMIO region */
+#define DRM_WRITE16(map, offset, val) writew(val, ((void __iomem *)(map)->handle) + (offset))
+/** Write a dword into a MMIO region */
+#define DRM_WRITE32(map, offset, val) writel(val, ((void __iomem *)(map)->handle) + (offset))
+
+/** Read a qword from a MMIO region - be careful using these unless you really understand them */
+#define DRM_READ64(map, offset) readq(((void __iomem *)(map)->handle) + (offset))
+/** Write a qword into a MMIO region */
+#define DRM_WRITE64(map, offset, val) writeq(val, ((void __iomem *)(map)->handle) + (offset))
+
+#define DRM_WAIT_ON( ret, queue, timeout, condition ) \
+do { \
+ DECLARE_WAITQUEUE(entry, current); \
+ unsigned long end = jiffies + (timeout); \
+ add_wait_queue(&(queue), &entry); \
+ \
+ for (;;) { \
+ __set_current_state(TASK_INTERRUPTIBLE); \
+ if (condition) \
+ break; \
+ if (time_after_eq(jiffies, end)) { \
+ ret = -EBUSY; \
+ break; \
+ } \
+ schedule_timeout((HZ/100 > 1) ? HZ/100 : 1); \
+ if (signal_pending(current)) { \
+ ret = -EINTR; \
+ break; \
+ } \
+ } \
+ __set_current_state(TASK_RUNNING); \
+ remove_wait_queue(&(queue), &entry); \
+} while (0)