drivers/gpu/drm/i915/intel_ringbuffer.h - kernel/msm-4.19 - Gitiles

 #ifndef _INTEL_RINGBUFFER_H_
 #define _INTEL_RINGBUFFER_H_

 #include <linux/hashtable.h>

 #define I915_CMD_HASH_ORDER 9

 /* Early gen2 devices have a cacheline of just 32 bytes, using 64 is overkill,
  * but keeps the logic simple. Indeed, the whole purpose of this macro is just
  * to give some inclination as to some of the magic values used in the various
  * workarounds!
  */
 #define CACHELINE_BYTES 64

 /*
  * Gen2 BSpec "1. Programming Environment" / 1.4.4.6 "Ring Buffer Use"
  * Gen3 BSpec "vol1c Memory Interface Functions" / 2.3.4.5 "Ring Buffer Use"
  * Gen4+ BSpec "vol1c Memory Interface and Command Stream" / 5.3.4.5 "Ring Buffer Use"
  *
  * "If the Ring Buffer Head Pointer and the Tail Pointer are on the same
  * cacheline, the Head Pointer must not be greater than the Tail
  * Pointer."
  */
 #define I915_RING_FREE_SPACE 64

 struct  intel_hw_status_page {
 	u32		*page_addr;
 	unsigned int	gfx_addr;
 	struct		drm_i915_gem_object *obj;
 };

 #define I915_READ_TAIL(ring) I915_READ(RING_TAIL((ring)->mmio_base))
 #define I915_WRITE_TAIL(ring, val) I915_WRITE(RING_TAIL((ring)->mmio_base), val)

 #define I915_READ_START(ring) I915_READ(RING_START((ring)->mmio_base))
 #define I915_WRITE_START(ring, val) I915_WRITE(RING_START((ring)->mmio_base), val)

 #define I915_READ_HEAD(ring)  I915_READ(RING_HEAD((ring)->mmio_base))
 #define I915_WRITE_HEAD(ring, val) I915_WRITE(RING_HEAD((ring)->mmio_base), val)

 #define I915_READ_CTL(ring) I915_READ(RING_CTL((ring)->mmio_base))
 #define I915_WRITE_CTL(ring, val) I915_WRITE(RING_CTL((ring)->mmio_base), val)

 #define I915_READ_IMR(ring) I915_READ(RING_IMR((ring)->mmio_base))
 #define I915_WRITE_IMR(ring, val) I915_WRITE(RING_IMR((ring)->mmio_base), val)

 #define I915_READ_MODE(ring) I915_READ(RING_MI_MODE((ring)->mmio_base))
 #define I915_WRITE_MODE(ring, val) I915_WRITE(RING_MI_MODE((ring)->mmio_base), val)

 /* seqno size is actually only a uint32, but since we plan to use MI_FLUSH_DW to
  * do the writes, and that must have qw aligned offsets, simply pretend it's 8b.
  */
 #define i915_semaphore_seqno_size sizeof(uint64_t)
 #define GEN8_SIGNAL_OFFSET(__ring, to)			     \
 	(i915_gem_obj_ggtt_offset(dev_priv->semaphore_obj) + \
 	((__ring)->id * I915_NUM_RINGS * i915_semaphore_seqno_size) +	\
 	(i915_semaphore_seqno_size * (to)))

 #define GEN8_WAIT_OFFSET(__ring, from)			     \
 	(i915_gem_obj_ggtt_offset(dev_priv->semaphore_obj) + \
 	((from) * I915_NUM_RINGS * i915_semaphore_seqno_size) + \
 	(i915_semaphore_seqno_size * (__ring)->id))

 #define GEN8_RING_SEMAPHORE_INIT do { \
 	if (!dev_priv->semaphore_obj) { \
 		break; \
 	} \
 	ring->semaphore.signal_ggtt[RCS] = GEN8_SIGNAL_OFFSET(ring, RCS); \
 	ring->semaphore.signal_ggtt[VCS] = GEN8_SIGNAL_OFFSET(ring, VCS); \
 	ring->semaphore.signal_ggtt[BCS] = GEN8_SIGNAL_OFFSET(ring, BCS); \
 	ring->semaphore.signal_ggtt[VECS] = GEN8_SIGNAL_OFFSET(ring, VECS); \
 	ring->semaphore.signal_ggtt[VCS2] = GEN8_SIGNAL_OFFSET(ring, VCS2); \
 	ring->semaphore.signal_ggtt[ring->id] = MI_SEMAPHORE_SYNC_INVALID; \
 	} while(0)

 enum intel_ring_hangcheck_action {
 	HANGCHECK_IDLE = 0,
 	HANGCHECK_WAIT,
 	HANGCHECK_ACTIVE,
 	HANGCHECK_ACTIVE_LOOP,
 	HANGCHECK_KICK,
 	HANGCHECK_HUNG,
 };

 #define HANGCHECK_SCORE_RING_HUNG 31

 struct intel_ring_hangcheck {
 	u64 acthd;
 	u64 max_acthd;
 	u32 seqno;
 	int score;
 	enum intel_ring_hangcheck_action action;
 	int deadlock;
 };

 struct intel_ringbuffer {
 	struct drm_i915_gem_object *obj;
 	void __iomem *virtual_start;

 	struct intel_engine_cs *ring;

 	/*
 	 * FIXME: This backpointer is an artifact of the history of how the
 	 * execlist patches came into being. It will get removed once the basic
 	 * code has landed.
 	 */
 	struct intel_context *FIXME_lrc_ctx;

 	u32 head;
 	u32 tail;
 	int space;
 	int size;
 	int effective_size;

 	/** We track the position of the requests in the ring buffer, and
 	 * when each is retired we increment last_retired_head as the GPU
 	 * must have finished processing the request and so we know we
 	 * can advance the ringbuffer up to that position.
 	 *
 	 * last_retired_head is set to -1 after the value is consumed so
 	 * we can detect new retirements.
 	 */
 	u32 last_retired_head;
 };

 struct  intel_engine_cs {
 	const char	*name;
 	enum intel_ring_id {
 		RCS = 0x0,
 		VCS,
 		BCS,
 		VECS,
 		VCS2
 	} id;
 #define I915_NUM_RINGS 5
 #define LAST_USER_RING (VECS + 1)
 	u32		mmio_base;
 	struct		drm_device *dev;
 	struct intel_ringbuffer *buffer;

 	struct intel_hw_status_page status_page;

 	unsigned irq_refcount; /* protected by dev_priv->irq_lock */
 	u32		irq_enable_mask;	/* bitmask to enable ring interrupt */
 	u32		trace_irq_seqno;
 	bool __must_check (*irq_get)(struct intel_engine_cs *ring);
 	void		(*irq_put)(struct intel_engine_cs *ring);

 	int		(*init)(struct intel_engine_cs *ring);

 	int		(*init_context)(struct intel_engine_cs *ring);

 	void		(*write_tail)(struct intel_engine_cs *ring,
 				      u32 value);
 	int __must_check (*flush)(struct intel_engine_cs *ring,
 				  u32	invalidate_domains,
 				  u32	flush_domains);
 	int		(*add_request)(struct intel_engine_cs *ring);
 	/* Some chipsets are not quite as coherent as advertised and need
 	 * an expensive kick to force a true read of the up-to-date seqno.
 	 * However, the up-to-date seqno is not always required and the last
 	 * seen value is good enough. Note that the seqno will always be
 	 * monotonic, even if not coherent.
 	 */
 	u32		(*get_seqno)(struct intel_engine_cs *ring,
 				     bool lazy_coherency);
 	void		(*set_seqno)(struct intel_engine_cs *ring,
 				     u32 seqno);
 	int		(*dispatch_execbuffer)(struct intel_engine_cs *ring,
 					       u64 offset, u32 length,
 					       unsigned flags);
 #define I915_DISPATCH_SECURE 0x1
 #define I915_DISPATCH_PINNED 0x2
 	void		(*cleanup)(struct intel_engine_cs *ring);

 	/* GEN8 signal/wait table - never trust comments!
 	 *	  signal to	signal to    signal to   signal to      signal to
 	 *	    RCS		   VCS          BCS        VECS		 VCS2
 	 *      --------------------------------------------------------------------
 	 *  RCS | NOP (0x00) | VCS (0x08) | BCS (0x10) | VECS (0x18) | VCS2 (0x20) |
 	 *	|-------------------------------------------------------------------
 	 *  VCS | RCS (0x28) | NOP (0x30) | BCS (0x38) | VECS (0x40) | VCS2 (0x48) |
 	 *	|-------------------------------------------------------------------
 	 *  BCS | RCS (0x50) | VCS (0x58) | NOP (0x60) | VECS (0x68) | VCS2 (0x70) |
 	 *	|-------------------------------------------------------------------
 	 * VECS | RCS (0x78) | VCS (0x80) | BCS (0x88) |  NOP (0x90) | VCS2 (0x98) |
 	 *	|-------------------------------------------------------------------
 	 * VCS2 | RCS (0xa0) | VCS (0xa8) | BCS (0xb0) | VECS (0xb8) | NOP  (0xc0) |
 	 *	|-------------------------------------------------------------------
 	 *
 	 * Generalization:
 	 *  f(x, y) := (x->id * NUM_RINGS * seqno_size) + (seqno_size * y->id)
 	 *  ie. transpose of g(x, y)
 	 *
 	 *	 sync from	sync from    sync from    sync from	sync from
 	 *	    RCS		   VCS          BCS        VECS		 VCS2
 	 *      --------------------------------------------------------------------
 	 *  RCS | NOP (0x00) | VCS (0x28) | BCS (0x50) | VECS (0x78) | VCS2 (0xa0) |
 	 *	|-------------------------------------------------------------------
 	 *  VCS | RCS (0x08) | NOP (0x30) | BCS (0x58) | VECS (0x80) | VCS2 (0xa8) |
 	 *	|-------------------------------------------------------------------
 	 *  BCS | RCS (0x10) | VCS (0x38) | NOP (0x60) | VECS (0x88) | VCS2 (0xb0) |
 	 *	|-------------------------------------------------------------------
 	 * VECS | RCS (0x18) | VCS (0x40) | BCS (0x68) |  NOP (0x90) | VCS2 (0xb8) |
 	 *	|-------------------------------------------------------------------
 	 * VCS2 | RCS (0x20) | VCS (0x48) | BCS (0x70) | VECS (0x98) |  NOP (0xc0) |
 	 *	|-------------------------------------------------------------------
 	 *
 	 * Generalization:
 	 *  g(x, y) := (y->id * NUM_RINGS * seqno_size) + (seqno_size * x->id)
 	 *  ie. transpose of f(x, y)
 	 */
 	struct {
 		u32	sync_seqno[I915_NUM_RINGS-1];

 		union {
 			struct {
 				/* our mbox written by others */
 				u32		wait[I915_NUM_RINGS];
 				/* mboxes this ring signals to */
 				u32		signal[I915_NUM_RINGS];
 			} mbox;
 			u64		signal_ggtt[I915_NUM_RINGS];
 		};

 		/* AKA wait() */
 		int	(*sync_to)(struct intel_engine_cs *ring,
 				   struct intel_engine_cs *to,
 				   u32 seqno);
 		int	(*signal)(struct intel_engine_cs *signaller,
 				  /* num_dwords needed by caller */
 				  unsigned int num_dwords);
 	} semaphore;

 	/* Execlists */
 	spinlock_t execlist_lock;
 	struct list_head execlist_queue;
 	u8 next_context_status_buffer;
 	u32             irq_keep_mask; /* bitmask for interrupts that should not be masked */
 	int		(*emit_request)(struct intel_ringbuffer *ringbuf);
 	int		(*emit_flush)(struct intel_ringbuffer *ringbuf,
 				      u32 invalidate_domains,
 				      u32 flush_domains);
 	int		(*emit_bb_start)(struct intel_ringbuffer *ringbuf,
 					 u64 offset, unsigned flags);

 	/**
 	 * List of objects currently involved in rendering from the
 	 * ringbuffer.
 	 *
 	 * Includes buffers having the contents of their GPU caches
 	 * flushed, not necessarily primitives.  last_rendering_seqno
 	 * represents when the rendering involved will be completed.
 	 *
 	 * A reference is held on the buffer while on this list.
 	 */
 	struct list_head active_list;

 	/**
 	 * List of breadcrumbs associated with GPU requests currently
 	 * outstanding.
 	 */
 	struct list_head request_list;

 	/**
 	 * Do we have some not yet emitted requests outstanding?
 	 */
 	struct drm_i915_gem_request *preallocated_lazy_request;
 	u32 outstanding_lazy_seqno;
 	bool gpu_caches_dirty;
 	bool fbc_dirty;

 	wait_queue_head_t irq_queue;

 	struct intel_context *default_context;
 	struct intel_context *last_context;

 	struct intel_ring_hangcheck hangcheck;

 	struct {
 		struct drm_i915_gem_object *obj;
 		u32 gtt_offset;
 		volatile u32 *cpu_page;
 	} scratch;

 	bool needs_cmd_parser;

 	/*
 	 * Table of commands the command parser needs to know about
 	 * for this ring.
 	 */
 	DECLARE_HASHTABLE(cmd_hash, I915_CMD_HASH_ORDER);

 	/*
 	 * Table of registers allowed in commands that read/write registers.
 	 */
 	const u32 *reg_table;
 	int reg_count;

 	/*
 	 * Table of registers allowed in commands that read/write registers, but
 	 * only from the DRM master.
 	 */
 	const u32 *master_reg_table;
 	int master_reg_count;

 	/*
 	 * Returns the bitmask for the length field of the specified command.
 	 * Return 0 for an unrecognized/invalid command.
 	 *
 	 * If the command parser finds an entry for a command in the ring's
 	 * cmd_tables, it gets the command's length based on the table entry.
 	 * If not, it calls this function to determine the per-ring length field
 	 * encoding for the command (i.e. certain opcode ranges use certain bits
 	 * to encode the command length in the header).
 	 */
 	u32 (*get_cmd_length_mask)(u32 cmd_header);
 };

 bool intel_ring_initialized(struct intel_engine_cs *ring);

 static inline unsigned
 intel_ring_flag(struct intel_engine_cs *ring)
 {
 	return 1 << ring->id;
 }

 static inline u32
 intel_ring_sync_index(struct intel_engine_cs *ring,
 		      struct intel_engine_cs *other)
 {
 	int idx;

 	/*
 	 * rcs -> 0 = vcs, 1 = bcs, 2 = vecs, 3 = vcs2;
 	 * vcs -> 0 = bcs, 1 = vecs, 2 = vcs2, 3 = rcs;
 	 * bcs -> 0 = vecs, 1 = vcs2. 2 = rcs, 3 = vcs;
 	 * vecs -> 0 = vcs2, 1 = rcs, 2 = vcs, 3 = bcs;
 	 * vcs2 -> 0 = rcs, 1 = vcs, 2 = bcs, 3 = vecs;
 	 */

 	idx = (other - ring) - 1;
 	if (idx < 0)
 		idx += I915_NUM_RINGS;

 	return idx;
 }

 static inline u32
 intel_read_status_page(struct intel_engine_cs *ring,
 		       int reg)
 {
 	/* Ensure that the compiler doesn't optimize away the load. */
 	barrier();
 	return ring->status_page.page_addr[reg];
 }

 static inline void
 intel_write_status_page(struct intel_engine_cs *ring,
 			int reg, u32 value)
 {
 	ring->status_page.page_addr[reg] = value;
 }

 /**
  * Reads a dword out of the status page, which is written to from the command
  * queue by automatic updates, MI_REPORT_HEAD, MI_STORE_DATA_INDEX, or
  * MI_STORE_DATA_IMM.
  *
  * The following dwords have a reserved meaning:
  * 0x00: ISR copy, updated when an ISR bit not set in the HWSTAM changes.
  * 0x04: ring 0 head pointer
  * 0x05: ring 1 head pointer (915-class)
  * 0x06: ring 2 head pointer (915-class)
  * 0x10-0x1b: Context status DWords (GM45)
  * 0x1f: Last written status offset. (GM45)
  *
  * The area from dword 0x20 to 0x3ff is available for driver usage.
  */
 #define I915_GEM_HWS_INDEX		0x20
 #define I915_GEM_HWS_SCRATCH_INDEX	0x30
 #define I915_GEM_HWS_SCRATCH_ADDR (I915_GEM_HWS_SCRATCH_INDEX << MI_STORE_DWORD_INDEX_SHIFT)

 void intel_destroy_ringbuffer_obj(struct intel_ringbuffer *ringbuf);
 int intel_alloc_ringbuffer_obj(struct drm_device *dev,
 			       struct intel_ringbuffer *ringbuf);

 void intel_stop_ring_buffer(struct intel_engine_cs *ring);
 void intel_cleanup_ring_buffer(struct intel_engine_cs *ring);

 int __must_check intel_ring_begin(struct intel_engine_cs *ring, int n);
 int __must_check intel_ring_cacheline_align(struct intel_engine_cs *ring);
 static inline void intel_ring_emit(struct intel_engine_cs *ring,
 				   u32 data)
 {
 	struct intel_ringbuffer *ringbuf = ring->buffer;
 	iowrite32(data, ringbuf->virtual_start + ringbuf->tail);
 	ringbuf->tail += 4;
 }
 static inline void intel_ring_advance(struct intel_engine_cs *ring)
 {
 	struct intel_ringbuffer *ringbuf = ring->buffer;
 	ringbuf->tail &= ringbuf->size - 1;
 }
 int __intel_ring_space(int head, int tail, int size);
 int intel_ring_space(struct intel_ringbuffer *ringbuf);
 bool intel_ring_stopped(struct intel_engine_cs *ring);
 void __intel_ring_advance(struct intel_engine_cs *ring);

 int __must_check intel_ring_idle(struct intel_engine_cs *ring);
 void intel_ring_init_seqno(struct intel_engine_cs *ring, u32 seqno);
 int intel_ring_flush_all_caches(struct intel_engine_cs *ring);
 int intel_ring_invalidate_all_caches(struct intel_engine_cs *ring);

 void intel_fini_pipe_control(struct intel_engine_cs *ring);
 int intel_init_pipe_control(struct intel_engine_cs *ring);

 int intel_init_render_ring_buffer(struct drm_device *dev);
 int intel_init_bsd_ring_buffer(struct drm_device *dev);
 int intel_init_bsd2_ring_buffer(struct drm_device *dev);
 int intel_init_blt_ring_buffer(struct drm_device *dev);
 int intel_init_vebox_ring_buffer(struct drm_device *dev);

 u64 intel_ring_get_active_head(struct intel_engine_cs *ring);
 void intel_ring_setup_status_page(struct intel_engine_cs *ring);

 static inline u32 intel_ring_get_tail(struct intel_ringbuffer *ringbuf)
 {
 	return ringbuf->tail;
 }

 static inline u32 intel_ring_get_seqno(struct intel_engine_cs *ring)
 {
 	BUG_ON(ring->outstanding_lazy_seqno == 0);
 	return ring->outstanding_lazy_seqno;
 }

 static inline void i915_trace_irq_get(struct intel_engine_cs *ring, u32 seqno)
 {
 	if (ring->trace_irq_seqno == 0 && ring->irq_get(ring))
 		ring->trace_irq_seqno = seqno;
 }

 /* DRI warts */
 int intel_render_ring_init_dri(struct drm_device *dev, u64 start, u32 size);

 #endif /* _INTEL_RINGBUFFER_H_ */
	#ifndef _INTEL_RINGBUFFER_H_
	#define _INTEL_RINGBUFFER_H_

	#include <linux/hashtable.h>

	#define I915_CMD_HASH_ORDER 9

	/* Early gen2 devices have a cacheline of just 32 bytes, using 64 is overkill,
	* but keeps the logic simple. Indeed, the whole purpose of this macro is just
	* to give some inclination as to some of the magic values used in the various
	* workarounds!
	*/
	#define CACHELINE_BYTES 64

	/*
	* Gen2 BSpec "1. Programming Environment" / 1.4.4.6 "Ring Buffer Use"
	* Gen3 BSpec "vol1c Memory Interface Functions" / 2.3.4.5 "Ring Buffer Use"
	* Gen4+ BSpec "vol1c Memory Interface and Command Stream" / 5.3.4.5 "Ring Buffer Use"
	*
	* "If the Ring Buffer Head Pointer and the Tail Pointer are on the same
	* cacheline, the Head Pointer must not be greater than the Tail
	* Pointer."
	*/
	#define I915_RING_FREE_SPACE 64

	struct intel_hw_status_page {
	u32 *page_addr;
	unsigned int gfx_addr;
	struct drm_i915_gem_object *obj;
	};

	#define I915_READ_TAIL(ring) I915_READ(RING_TAIL((ring)->mmio_base))
	#define I915_WRITE_TAIL(ring, val) I915_WRITE(RING_TAIL((ring)->mmio_base), val)

	#define I915_READ_START(ring) I915_READ(RING_START((ring)->mmio_base))
	#define I915_WRITE_START(ring, val) I915_WRITE(RING_START((ring)->mmio_base), val)

	#define I915_READ_HEAD(ring) I915_READ(RING_HEAD((ring)->mmio_base))
	#define I915_WRITE_HEAD(ring, val) I915_WRITE(RING_HEAD((ring)->mmio_base), val)

	#define I915_READ_CTL(ring) I915_READ(RING_CTL((ring)->mmio_base))
	#define I915_WRITE_CTL(ring, val) I915_WRITE(RING_CTL((ring)->mmio_base), val)

	#define I915_READ_IMR(ring) I915_READ(RING_IMR((ring)->mmio_base))
	#define I915_WRITE_IMR(ring, val) I915_WRITE(RING_IMR((ring)->mmio_base), val)

	#define I915_READ_MODE(ring) I915_READ(RING_MI_MODE((ring)->mmio_base))
	#define I915_WRITE_MODE(ring, val) I915_WRITE(RING_MI_MODE((ring)->mmio_base), val)

	/* seqno size is actually only a uint32, but since we plan to use MI_FLUSH_DW to
	* do the writes, and that must have qw aligned offsets, simply pretend it's 8b.
	*/
	#define i915_semaphore_seqno_size sizeof(uint64_t)
	#define GEN8_SIGNAL_OFFSET(__ring, to) \
	(i915_gem_obj_ggtt_offset(dev_priv->semaphore_obj) + \
	((__ring)->id * I915_NUM_RINGS * i915_semaphore_seqno_size) + \
	(i915_semaphore_seqno_size * (to)))

	#define GEN8_WAIT_OFFSET(__ring, from) \
	(i915_gem_obj_ggtt_offset(dev_priv->semaphore_obj) + \
	((from) * I915_NUM_RINGS * i915_semaphore_seqno_size) + \
	(i915_semaphore_seqno_size * (__ring)->id))

	#define GEN8_RING_SEMAPHORE_INIT do { \
	if (!dev_priv->semaphore_obj) { \
	break; \
	} \
	ring->semaphore.signal_ggtt[RCS] = GEN8_SIGNAL_OFFSET(ring, RCS); \
	ring->semaphore.signal_ggtt[VCS] = GEN8_SIGNAL_OFFSET(ring, VCS); \
	ring->semaphore.signal_ggtt[BCS] = GEN8_SIGNAL_OFFSET(ring, BCS); \
	ring->semaphore.signal_ggtt[VECS] = GEN8_SIGNAL_OFFSET(ring, VECS); \
	ring->semaphore.signal_ggtt[VCS2] = GEN8_SIGNAL_OFFSET(ring, VCS2); \
	ring->semaphore.signal_ggtt[ring->id] = MI_SEMAPHORE_SYNC_INVALID; \
	} while(0)

	enum intel_ring_hangcheck_action {
	HANGCHECK_IDLE = 0,
	HANGCHECK_WAIT,
	HANGCHECK_ACTIVE,
	HANGCHECK_ACTIVE_LOOP,
	HANGCHECK_KICK,
	HANGCHECK_HUNG,
	};

	#define HANGCHECK_SCORE_RING_HUNG 31

	struct intel_ring_hangcheck {
	u64 acthd;
	u64 max_acthd;
	u32 seqno;
	int score;
	enum intel_ring_hangcheck_action action;
	int deadlock;
	};

	struct intel_ringbuffer {
	struct drm_i915_gem_object *obj;
	void __iomem *virtual_start;

	struct intel_engine_cs *ring;

	/*
	* FIXME: This backpointer is an artifact of the history of how the
	* execlist patches came into being. It will get removed once the basic
	* code has landed.
	*/
	struct intel_context *FIXME_lrc_ctx;

	u32 head;
	u32 tail;
	int space;
	int size;
	int effective_size;

	/** We track the position of the requests in the ring buffer, and
	* when each is retired we increment last_retired_head as the GPU
	* must have finished processing the request and so we know we
	* can advance the ringbuffer up to that position.
	*
	* last_retired_head is set to -1 after the value is consumed so
	* we can detect new retirements.
	*/
	u32 last_retired_head;
	};

	struct intel_engine_cs {
	const char *name;
	enum intel_ring_id {
	RCS = 0x0,
	VCS,
	BCS,
	VECS,
	VCS2
	} id;
	#define I915_NUM_RINGS 5
	#define LAST_USER_RING (VECS + 1)
	u32 mmio_base;
	struct drm_device *dev;
	struct intel_ringbuffer *buffer;

	struct intel_hw_status_page status_page;

	unsigned irq_refcount; /* protected by dev_priv->irq_lock */
	u32 irq_enable_mask; /* bitmask to enable ring interrupt */
	u32 trace_irq_seqno;
	bool __must_check (irq_get)(struct intel_engine_cs ring);
	void (irq_put)(struct intel_engine_cs ring);

	int (init)(struct intel_engine_cs ring);

	int (init_context)(struct intel_engine_cs ring);

	void (write_tail)(struct intel_engine_cs ring,
	u32 value);
	int __must_check (flush)(struct intel_engine_cs ring,
	u32 invalidate_domains,
	u32 flush_domains);
	int (add_request)(struct intel_engine_cs ring);
	/* Some chipsets are not quite as coherent as advertised and need
	* an expensive kick to force a true read of the up-to-date seqno.
	* However, the up-to-date seqno is not always required and the last
	* seen value is good enough. Note that the seqno will always be
	* monotonic, even if not coherent.
	*/
	u32 (get_seqno)(struct intel_engine_cs ring,
	bool lazy_coherency);
	void (set_seqno)(struct intel_engine_cs ring,
	u32 seqno);
	int (dispatch_execbuffer)(struct intel_engine_cs ring,
	u64 offset, u32 length,
	unsigned flags);
	#define I915_DISPATCH_SECURE 0x1
	#define I915_DISPATCH_PINNED 0x2
	void (cleanup)(struct intel_engine_cs ring);

	/* GEN8 signal/wait table - never trust comments!
	* signal to signal to signal to signal to signal to
	* RCS VCS BCS VECS VCS2
	* --------------------------------------------------------------------
	* RCS \| NOP (0x00) \| VCS (0x08) \| BCS (0x10) \| VECS (0x18) \| VCS2 (0x20) \|
	* \|-------------------------------------------------------------------
	* VCS \| RCS (0x28) \| NOP (0x30) \| BCS (0x38) \| VECS (0x40) \| VCS2 (0x48) \|
	* \|-------------------------------------------------------------------
	* BCS \| RCS (0x50) \| VCS (0x58) \| NOP (0x60) \| VECS (0x68) \| VCS2 (0x70) \|
	* \|-------------------------------------------------------------------
	* VECS \| RCS (0x78) \| VCS (0x80) \| BCS (0x88) \| NOP (0x90) \| VCS2 (0x98) \|
	* \|-------------------------------------------------------------------
	* VCS2 \| RCS (0xa0) \| VCS (0xa8) \| BCS (0xb0) \| VECS (0xb8) \| NOP (0xc0) \|
	* \|-------------------------------------------------------------------
	*
	* Generalization:
	* f(x, y) := (x->id * NUM_RINGS * seqno_size) + (seqno_size * y->id)
	* ie. transpose of g(x, y)
	*
	* sync from sync from sync from sync from sync from
	* RCS VCS BCS VECS VCS2
	* --------------------------------------------------------------------
	* RCS \| NOP (0x00) \| VCS (0x28) \| BCS (0x50) \| VECS (0x78) \| VCS2 (0xa0) \|
	* \|-------------------------------------------------------------------
	* VCS \| RCS (0x08) \| NOP (0x30) \| BCS (0x58) \| VECS (0x80) \| VCS2 (0xa8) \|
	* \|-------------------------------------------------------------------
	* BCS \| RCS (0x10) \| VCS (0x38) \| NOP (0x60) \| VECS (0x88) \| VCS2 (0xb0) \|
	* \|-------------------------------------------------------------------
	* VECS \| RCS (0x18) \| VCS (0x40) \| BCS (0x68) \| NOP (0x90) \| VCS2 (0xb8) \|
	* \|-------------------------------------------------------------------
	* VCS2 \| RCS (0x20) \| VCS (0x48) \| BCS (0x70) \| VECS (0x98) \| NOP (0xc0) \|
	* \|-------------------------------------------------------------------
	*
	* Generalization:
	* g(x, y) := (y->id * NUM_RINGS * seqno_size) + (seqno_size * x->id)
	* ie. transpose of f(x, y)
	*/
	struct {
	u32 sync_seqno[I915_NUM_RINGS-1];

	union {
	struct {
	/* our mbox written by others */
	u32 wait[I915_NUM_RINGS];
	/* mboxes this ring signals to */
	u32 signal[I915_NUM_RINGS];
	} mbox;
	u64 signal_ggtt[I915_NUM_RINGS];
	};

	/* AKA wait() */
	int (sync_to)(struct intel_engine_cs ring,
	struct intel_engine_cs *to,
	u32 seqno);
	int (signal)(struct intel_engine_cs signaller,
	/* num_dwords needed by caller */
	unsigned int num_dwords);
	} semaphore;

	/* Execlists */
	spinlock_t execlist_lock;
	struct list_head execlist_queue;
	u8 next_context_status_buffer;
	u32 irq_keep_mask; /* bitmask for interrupts that should not be masked */
	int (emit_request)(struct intel_ringbuffer ringbuf);
	int (emit_flush)(struct intel_ringbuffer ringbuf,
	u32 invalidate_domains,
	u32 flush_domains);
	int (emit_bb_start)(struct intel_ringbuffer ringbuf,
	u64 offset, unsigned flags);

	/**
	* List of objects currently involved in rendering from the
	* ringbuffer.
	*
	* Includes buffers having the contents of their GPU caches
	* flushed, not necessarily primitives. last_rendering_seqno
	* represents when the rendering involved will be completed.
	*
	* A reference is held on the buffer while on this list.
	*/
	struct list_head active_list;

	/**
	* List of breadcrumbs associated with GPU requests currently
	* outstanding.
	*/
	struct list_head request_list;

	/**
	* Do we have some not yet emitted requests outstanding?
	*/
	struct drm_i915_gem_request *preallocated_lazy_request;
	u32 outstanding_lazy_seqno;
	bool gpu_caches_dirty;
	bool fbc_dirty;

	wait_queue_head_t irq_queue;

	struct intel_context *default_context;
	struct intel_context *last_context;

	struct intel_ring_hangcheck hangcheck;

	struct {
	struct drm_i915_gem_object *obj;
	u32 gtt_offset;
	volatile u32 *cpu_page;
	} scratch;

	bool needs_cmd_parser;

	/*
	* Table of commands the command parser needs to know about
	* for this ring.
	*/
	DECLARE_HASHTABLE(cmd_hash, I915_CMD_HASH_ORDER);

	/*
	* Table of registers allowed in commands that read/write registers.
	*/
	const u32 *reg_table;
	int reg_count;

	/*
	* Table of registers allowed in commands that read/write registers, but
	* only from the DRM master.
	*/
	const u32 *master_reg_table;
	int master_reg_count;

	/*
	* Returns the bitmask for the length field of the specified command.
	* Return 0 for an unrecognized/invalid command.
	*
	* If the command parser finds an entry for a command in the ring's
	* cmd_tables, it gets the command's length based on the table entry.
	* If not, it calls this function to determine the per-ring length field
	* encoding for the command (i.e. certain opcode ranges use certain bits
	* to encode the command length in the header).
	*/
	u32 (*get_cmd_length_mask)(u32 cmd_header);
	};

	bool intel_ring_initialized(struct intel_engine_cs *ring);

	static inline unsigned
	intel_ring_flag(struct intel_engine_cs *ring)
	{
	return 1 << ring->id;
	}

	static inline u32
	intel_ring_sync_index(struct intel_engine_cs *ring,
	struct intel_engine_cs *other)
	{
	int idx;

	/*
	* rcs -> 0 = vcs, 1 = bcs, 2 = vecs, 3 = vcs2;
	* vcs -> 0 = bcs, 1 = vecs, 2 = vcs2, 3 = rcs;
	* bcs -> 0 = vecs, 1 = vcs2. 2 = rcs, 3 = vcs;
	* vecs -> 0 = vcs2, 1 = rcs, 2 = vcs, 3 = bcs;
	* vcs2 -> 0 = rcs, 1 = vcs, 2 = bcs, 3 = vecs;
	*/

	idx = (other - ring) - 1;
	if (idx < 0)
	idx += I915_NUM_RINGS;

	return idx;
	}

	static inline u32
	intel_read_status_page(struct intel_engine_cs *ring,
	int reg)
	{
	/* Ensure that the compiler doesn't optimize away the load. */
	barrier();
	return ring->status_page.page_addr[reg];
	}

	static inline void
	intel_write_status_page(struct intel_engine_cs *ring,
	int reg, u32 value)
	{
	ring->status_page.page_addr[reg] = value;
	}

	/**
	* Reads a dword out of the status page, which is written to from the command
	* queue by automatic updates, MI_REPORT_HEAD, MI_STORE_DATA_INDEX, or
	* MI_STORE_DATA_IMM.
	*
	* The following dwords have a reserved meaning:
	* 0x00: ISR copy, updated when an ISR bit not set in the HWSTAM changes.
	* 0x04: ring 0 head pointer
	* 0x05: ring 1 head pointer (915-class)
	* 0x06: ring 2 head pointer (915-class)
	* 0x10-0x1b: Context status DWords (GM45)
	* 0x1f: Last written status offset. (GM45)
	*
	* The area from dword 0x20 to 0x3ff is available for driver usage.
	*/
	#define I915_GEM_HWS_INDEX 0x20
	#define I915_GEM_HWS_SCRATCH_INDEX 0x30
	#define I915_GEM_HWS_SCRATCH_ADDR (I915_GEM_HWS_SCRATCH_INDEX << MI_STORE_DWORD_INDEX_SHIFT)

	void intel_destroy_ringbuffer_obj(struct intel_ringbuffer *ringbuf);
	int intel_alloc_ringbuffer_obj(struct drm_device *dev,
	struct intel_ringbuffer *ringbuf);

	void intel_stop_ring_buffer(struct intel_engine_cs *ring);
	void intel_cleanup_ring_buffer(struct intel_engine_cs *ring);

	int __must_check intel_ring_begin(struct intel_engine_cs *ring, int n);
	int __must_check intel_ring_cacheline_align(struct intel_engine_cs *ring);
	static inline void intel_ring_emit(struct intel_engine_cs *ring,
	u32 data)
	{
	struct intel_ringbuffer *ringbuf = ring->buffer;
	iowrite32(data, ringbuf->virtual_start + ringbuf->tail);
	ringbuf->tail += 4;
	}
	static inline void intel_ring_advance(struct intel_engine_cs *ring)
	{
	struct intel_ringbuffer *ringbuf = ring->buffer;
	ringbuf->tail &= ringbuf->size - 1;
	}
	int __intel_ring_space(int head, int tail, int size);
	int intel_ring_space(struct intel_ringbuffer *ringbuf);
	bool intel_ring_stopped(struct intel_engine_cs *ring);
	void __intel_ring_advance(struct intel_engine_cs *ring);

	int __must_check intel_ring_idle(struct intel_engine_cs *ring);
	void intel_ring_init_seqno(struct intel_engine_cs *ring, u32 seqno);
	int intel_ring_flush_all_caches(struct intel_engine_cs *ring);
	int intel_ring_invalidate_all_caches(struct intel_engine_cs *ring);

	void intel_fini_pipe_control(struct intel_engine_cs *ring);
	int intel_init_pipe_control(struct intel_engine_cs *ring);

	int intel_init_render_ring_buffer(struct drm_device *dev);
	int intel_init_bsd_ring_buffer(struct drm_device *dev);
	int intel_init_bsd2_ring_buffer(struct drm_device *dev);
	int intel_init_blt_ring_buffer(struct drm_device *dev);
	int intel_init_vebox_ring_buffer(struct drm_device *dev);

	u64 intel_ring_get_active_head(struct intel_engine_cs *ring);
	void intel_ring_setup_status_page(struct intel_engine_cs *ring);

	static inline u32 intel_ring_get_tail(struct intel_ringbuffer *ringbuf)
	{
	return ringbuf->tail;
	}

	static inline u32 intel_ring_get_seqno(struct intel_engine_cs *ring)
	{
	BUG_ON(ring->outstanding_lazy_seqno == 0);
	return ring->outstanding_lazy_seqno;
	}

	static inline void i915_trace_irq_get(struct intel_engine_cs *ring, u32 seqno)
	{
	if (ring->trace_irq_seqno == 0 && ring->irq_get(ring))
	ring->trace_irq_seqno = seqno;
	}

	/* DRI warts */
	int intel_render_ring_init_dri(struct drm_device *dev, u64 start, u32 size);

	#endif /* _INTEL_RINGBUFFER_H_ */