drm: add helpers for fence and reservation based dma-buf sync

BUG=chromium:395901
TEST=emerge-veyron chromeos-kernel-3_14, deploy and boot kernel

Change-Id: I0cdf6d23e9f4924128d4de77c0f3ed7589766bb8
Signed-off-by: Dominik Behr <dbehr@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/218381
[mszyprow: ported to v4.1 kernel]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

1 files changed, 156 insertions, 0 deletions

diff --git a/include/drm/drm_sync_helper.h b/include/drm/drm_sync_helper.h
new file mode 100644
index 000000000000..a5586c674fec
--- /dev/null
+++ b/include/drm/drm_sync_helper.h
@@ -0,0 +1,156 @@
+/*
+ * drm_sync_helper.h: software fence and helper functions for fences and
+ * reservations used for dma buffer access synchronization between drivers.
+ *
+ * Copyright 2014 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _DRM_SYNC_HELPER_H_
+#define _DRM_SYNC_HELPER_H_
+
+#include <linux/fence.h>
+#include <linux/reservation.h>
+#include <linux/atomic.h>
+#include <linux/workqueue.h>
+
+/**
+ * Create software fence
+ * @context: execution context
+ * @seqno: the sequence number of this fence inside the execution context
+ */
+struct fence *drm_sw_fence_new(unsigned int context,
+			unsigned seqno);
+
+/**
+ * Signal and decrease reference count for a fence if it exists
+ * @fence: fence to signal
+ *
+ * Utility function called when owner access to object associated with fence is
+ * finished (e.g. GPU done with rendering).
+ */
+static inline void drm_fence_signal_and_put(struct fence **fence)
+{
+	if (*fence) {
+		fence_signal(*fence);
+		fence_put(*fence);
+		*fence = NULL;
+	}
+}
+
+struct drm_reservation_cb;
+
+struct drm_reservation_fence_cb {
+	struct fence_cb base;
+	struct drm_reservation_cb *parent;
+	struct fence *fence;
+};
+
+/**
+ * Callback executed when all fences in reservation callback are signaled
+ * @rcb: reservation callback structure
+ * @context: context provided by user at init time
+ */
+typedef void (*drm_reservation_cb_func_t)(struct drm_reservation_cb *rcb,
+					  void *context);
+
+/**
+ * Reservation callback structure
+ * @work: work context in which func is executed
+ * @fence_cbs: fence callbacks array
+ * @num_fence_cbs: number of fence callbacks
+ * @count: count of signaled fences, when it drops to 0 func is called
+ * @func: callback to execute when all fences are signaled
+ * @context: context provided by user during initialization
+ *
+ * It is safe and expected that func will destroy this structure before
+ * returning.
+ */
+struct drm_reservation_cb {
+	struct work_struct work;
+	struct drm_reservation_fence_cb **fence_cbs;
+	unsigned num_fence_cbs;
+	atomic_t count;
+	void *context;
+	drm_reservation_cb_func_t func;
+};
+
+/**
+ * Initialize reservation callback
+ * @rcb: reservation callback structure to initialize
+ * @func: function to call when all fences are signaled
+ * @context: parameter to call func with
+ */
+void drm_reservation_cb_init(struct drm_reservation_cb *rcb,
+			     drm_reservation_cb_func_t func,
+			     void *context);
+
+/**
+ * Add fences from reservation object to callback
+ * @rcb: reservation callback structure
+ * @resv: reservation object
+ * @exclusive: (for exclusive wait) when true add all fences, otherwise only
+ *    exclusive fence
+ */
+int drm_reservation_cb_add(struct drm_reservation_cb *rcb,
+			   struct reservation_object *resv,
+			   bool exclusive);
+
+/**
+ * Finish adding fences
+ * @rcb: reservation callback structure
+ *
+ * It will trigger callback worker if all fences were signaled before.
+ */
+void drm_reservation_cb_done(struct drm_reservation_cb *rcb);
+
+/**
+ * Cleanup reservation callback structure
+ * @rcb: reservation callback structure
+ *
+ * Can be called to cancel primed reservation callback.
+ */
+void drm_reservation_cb_fini(struct drm_reservation_cb *rcb);
+
+/**
+ * Add reservation to array of reservations
+ * @resv: reservation to add
+ * @resvs: array of reservations
+ * @excl_resvs_bitmap: bitmap for exclusive reservations
+ * @num_resvs: number of reservations in array
+ * @exclusive: bool to store in excl_resvs_bitmap
+ */
+void
+drm_add_reservation(struct reservation_object *resv,
+			struct reservation_object **resvs,
+			unsigned long *excl_resvs_bitmap,
+			unsigned int *num_resvs, bool exclusive);
+
+/**
+ * Acquire ww_mutex lock on all reservations in the array
+ * @resvs: array of reservations
+ * @num_resvs: number of reservations in the array
+ * @ctx: ww mutex context
+ */
+int drm_lock_reservations(struct reservation_object **resvs,
+			unsigned int num_resvs, struct ww_acquire_ctx *ctx);
+
+/**
+ * Release ww_mutex lock on all reservations in the array
+ * @resvs: array of reservations
+ * @num_resvs: number of reservations in the array
+ * @ctx: ww mutex context
+ */
+void drm_unlock_reservations(struct reservation_object **resvs,
+				unsigned int num_resvs,
+				struct ww_acquire_ctx *ctx);
+
+#endif