panfrost: Add backend targeting the DRM driver

This backend interacts with the new DRM driver for Midgard GPUs which is
currently in development.

When using this backend, Panfrost has roughly on-par functionality as
when using the non-DRM driver from Arm.

Alyssa Rosenzweig: To do so, we implement additional routines for
runtime GPU version detection and fencing. We cleanup some duplicate
code interfering with the new driver. We fix a long-standing memory leak
which is aggravated on the new driver. Finally, we implement BO
import/export in a way compatible with the new driver. These changes are
squashed to preserve bisectability given the hard-to-track ABI shifts in
the nondrm module

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>

include/drm-uapi/panfrost_drm.h

@@ -0,0 +1,141 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2014-2018 Broadcom
+ * Copyright © 2019 Collabora ltd.
+ */
+#ifndef _PANFROST_DRM_H_
+#define _PANFROST_DRM_H_
+
+#include "drm.h"
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+#define DRM_PANFROST_SUBMIT			0x00
+#define DRM_PANFROST_WAIT_BO			0x01
+#define DRM_PANFROST_CREATE_BO			0x02
+#define DRM_PANFROST_MMAP_BO			0x03
+#define DRM_PANFROST_GET_PARAM			0x04
+#define DRM_PANFROST_GET_BO_OFFSET		0x05
+
+#define DRM_IOCTL_PANFROST_SUBMIT		DRM_IOWR(DRM_COMMAND_BASE + DRM_PANFROST_SUBMIT, struct drm_panfrost_submit)
+#define DRM_IOCTL_PANFROST_WAIT_BO		DRM_IOWR(DRM_COMMAND_BASE + DRM_PANFROST_WAIT_BO, struct drm_panfrost_wait_bo)
+#define DRM_IOCTL_PANFROST_CREATE_BO		DRM_IOWR(DRM_COMMAND_BASE + DRM_PANFROST_CREATE_BO, struct drm_panfrost_create_bo)
+#define DRM_IOCTL_PANFROST_MMAP_BO		DRM_IOWR(DRM_COMMAND_BASE + DRM_PANFROST_MMAP_BO, struct drm_panfrost_mmap_bo)
+#define DRM_IOCTL_PANFROST_GET_PARAM		DRM_IOWR(DRM_COMMAND_BASE + DRM_PANFROST_GET_PARAM, struct drm_panfrost_get_param)
+#define DRM_IOCTL_PANFROST_GET_BO_OFFSET	DRM_IOWR(DRM_COMMAND_BASE + DRM_PANFROST_GET_BO_OFFSET, struct drm_panfrost_get_bo_offset)
+
+#define PANFROST_JD_REQ_FS (1 << 0)
+
+/**
+ * struct drm_panfrost_submit - ioctl argument for submitting commands to the 3D
+ * engine.
+ *
+ * This asks the kernel to have the GPU execute a render command list.
+ */
+struct drm_panfrost_submit {
+
+	/** Address to GPU mapping of job descriptor */
+	__u64 jc;
+
+	/** An optional array of sync objects to wait on before starting this job. */
+	__u64 in_syncs;
+
+	/** Number of sync objects to wait on before starting this job. */
+	__u32 in_sync_count;
+
+	/** An optional sync object to place the completion fence in. */
+	__u32 out_sync;
+
+	/** Pointer to a u32 array of the BOs that are referenced by the job. */
+	__u64 bo_handles;
+
+	/** Number of BO handles passed in (size is that times 4). */
+	__u32 bo_handle_count;
+
+	/** A combination of PANFROST_JD_REQ_* */
+	__u32 requirements;
+};
+
+/**
+ * struct drm_panfrost_wait_bo - ioctl argument for waiting for
+ * completion of the last DRM_PANFROST_SUBMIT_CL on a BO.
+ *
+ * This is useful for cases where multiple processes might be
+ * rendering to a BO and you want to wait for all rendering to be
+ * completed.
+ */
+struct drm_panfrost_wait_bo {
+	__u32 handle;
+	__u32 pad;
+	__s64 timeout_ns;	/* absolute */
+};
+
+/**
+ * struct drm_panfrost_create_bo - ioctl argument for creating Panfrost BOs.
+ *
+ * There are currently no values for the flags argument, but it may be
+ * used in a future extension.
+ */
+struct drm_panfrost_create_bo {
+	__u32 size;
+	__u32 flags;
+	/** Returned GEM handle for the BO. */
+	__u32 handle;
+	/**
+	 * Returned offset for the BO in the GPU address space.  This offset
+	 * is private to the DRM fd and is valid for the lifetime of the GEM
+	 * handle.
+	 *
+	 * This offset value will always be nonzero, since various HW
+	 * units treat 0 specially.
+	 */
+	__u64 offset;
+};
+
+/**
+ * struct drm_panfrost_mmap_bo - ioctl argument for mapping Panfrost BOs.
+ *
+ * This doesn't actually perform an mmap.  Instead, it returns the
+ * offset you need to use in an mmap on the DRM device node.  This
+ * means that tools like valgrind end up knowing about the mapped
+ * memory.
+ *
+ * There are currently no values for the flags argument, but it may be
+ * used in a future extension.
+ */
+struct drm_panfrost_mmap_bo {
+	/** Handle for the object being mapped. */
+	__u32 handle;
+	__u32 flags;
+	/** offset into the drm node to use for subsequent mmap call. */
+	__u64 offset;
+};
+
+enum drm_panfrost_param {
+	DRM_PANFROST_PARAM_GPU_ID,
+};
+
+struct drm_panfrost_get_param {
+	__u32 param;
+	__u32 pad;
+	__u64 value;
+};
+
+/**
+ * Returns the offset for the BO in the GPU address space for this DRM fd.
+ * This is the same value returned by drm_panfrost_create_bo, if that was called
+ * from this DRM fd.
+ */
+struct drm_panfrost_get_bo_offset {
+	__u32 handle;
+	__u32 pad;
+	__u64 offset;
+};
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif /* _PANFROST_DRM_H_ */