drm/i915/guc: Introduce buffer based cmd transport

Buffer based command transport can replace MMIO based mechanism.
It may be used to perform host-2-guc and guc-to-host communication.

Portions of this patch are based on work by:
 Michel Thierry <michel.thierry@intel.com>
 Robert Beckett <robert.beckett@intel.com>
 Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>

v2: use gem_object_pin_map (Chris)
    don't use DEBUG_RATELIMITED (Chris)
    don't track action stats (Chris)
    simplify next fence (Chris)
    use READ_ONCE (Chris)
    move blob allocation to new function (Chris)

v3: use static owner id (Daniele)
v4: but keep channel initialization generic (Daniele)
    and introduce owner_sub_id (Daniele)
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Oscar Mateo <oscar.mateo@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170526111326.87280-3-michal.wajdeczko@intel.com

drivers/gpu/drm/i915/Makefile

@@ -58,6 +58,7 @@ i915-y += i915_cmd_parser.o \
 
 # general-purpose microcontroller (GuC) support
 i915-y += intel_uc.o \
+	  intel_guc_ct.o \
 	  intel_guc_log.o \
 	  intel_guc_loader.o \
 	  intel_huc.o \

drivers/gpu/drm/i915/i915_drv.h

@@ -760,6 +760,7 @@ struct intel_csr {
 	func(has_gmbus_irq); \
 	func(has_gmch_display); \
 	func(has_guc); \
+	func(has_guc_ct); \
 	func(has_hotplug); \
 	func(has_l3_dpf); \
 	func(has_llc); \
@@ -2947,6 +2948,7 @@ intel_info(const struct drm_i915_private *dev_priv)
  * properties, so we have separate macros to test them.
  */
 #define HAS_GUC(dev_priv)	((dev_priv)->info.has_guc)
+#define HAS_GUC_CT(dev_priv)	((dev_priv)->info.has_guc_ct)
 #define HAS_GUC_UCODE(dev_priv)	(HAS_GUC(dev_priv))
 #define HAS_GUC_SCHED(dev_priv)	(HAS_GUC(dev_priv))
 #define HAS_HUC_UCODE(dev_priv)	(HAS_GUC(dev_priv))

drivers/gpu/drm/i915/intel_guc_ct.h

+/*
+ * Copyright © 2016-2017 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#ifndef _INTEL_GUC_CT_H_
+#define _INTEL_GUC_CT_H_
+
+struct intel_guc;
+struct i915_vma;
+
+#include "intel_guc_fwif.h"
+
+/**
+ * DOC: Command Transport (CT).
+ *
+ * Buffer based command transport is a replacement for MMIO based mechanism.
+ * It can be used to perform both host-2-guc and guc-to-host communication.
+ */
+
+/** Represents single command transport buffer.
+ *
+ * A single command transport buffer consists of two parts, the header
+ * record (command transport buffer descriptor) and the actual buffer which
+ * holds the commands.
+ *
+ * @desc: pointer to the buffer descriptor
+ * @cmds: pointer to the commands buffer
+ */
+struct intel_guc_ct_buffer {
+	struct guc_ct_buffer_desc *desc;
+	u32 *cmds;
+};
+
+/** Represents pair of command transport buffers.
+ *
+ * Buffers go in pairs to allow bi-directional communication.
+ * To simplify the code we place both of them in the same vma.
+ * Buffers from the same pair must share unique owner id.
+ *
+ * @vma: pointer to the vma with pair of CT buffers
+ * @ctbs: buffers for sending(0) and receiving(1) commands
+ * @owner: unique identifier
+ * @next_fence: fence to be used with next send command
+ */
+struct intel_guc_ct_channel {
+	struct i915_vma *vma;
+	struct intel_guc_ct_buffer ctbs[2];
+	u32 owner;
+	u32 next_fence;
+};
+
+/** Holds all command transport channels.
+ *
+ * @host_channel: main channel used by the host
+ */
+struct intel_guc_ct {
+	struct intel_guc_ct_channel host_channel;
+	/* other channels are tbd */
+};
+
+void intel_guc_ct_init_early(struct intel_guc_ct *ct);
+
+/* XXX: move to intel_uc.h ? don't fit there either */
+int intel_guc_enable_ct(struct intel_guc *guc);
+void intel_guc_disable_ct(struct intel_guc *guc);
+
+#endif /* _INTEL_GUC_CT_H_ */

drivers/gpu/drm/i915/intel_guc_fwif.h

@@ -331,6 +331,47 @@ struct guc_stage_desc {
 	u64 desc_private;
 } __packed;
 
+/*
+ * Describes single command transport buffer.
+ * Used by both guc-master and clients.
+ */
+struct guc_ct_buffer_desc {
+	u32 addr;		/* gfx address */
+	u64 host_private;	/* host private data */
+	u32 size;		/* size in bytes */
+	u32 head;		/* offset updated by GuC*/
+	u32 tail;		/* offset updated by owner */
+	u32 is_in_error;	/* error indicator */
+	u32 fence;		/* fence updated by GuC */
+	u32 status;		/* status updated by GuC */
+	u32 owner;		/* id of the channel owner */
+	u32 owner_sub_id;	/* owner-defined field for extra tracking */
+	u32 reserved[5];
+} __packed;
+
+/* Type of command transport buffer */
+#define INTEL_GUC_CT_BUFFER_TYPE_SEND	0x0u
+#define INTEL_GUC_CT_BUFFER_TYPE_RECV	0x1u
+
+/*
+ * Definition of the command transport message header (DW0)
+ *
+ * bit[4..0]	message len (in dwords)
+ * bit[7..5]	reserved
+ * bit[8]	write fence to desc
+ * bit[9]	write status to H2G buff
+ * bit[10]	send status (via G2H)
+ * bit[15..11]	reserved
+ * bit[31..16]	action code
+ */
+#define GUC_CT_MSG_LEN_SHIFT			0
+#define GUC_CT_MSG_LEN_MASK			0x1F
+#define GUC_CT_MSG_WRITE_FENCE_TO_DESC		(1 << 8)
+#define GUC_CT_MSG_WRITE_STATUS_TO_BUFF		(1 << 9)
+#define GUC_CT_MSG_SEND_STATUS			(1 << 10)
+#define GUC_CT_MSG_ACTION_SHIFT			16
+#define GUC_CT_MSG_ACTION_MASK			0xFFFF
+
 #define GUC_FORCEWAKE_RENDER	(1 << 0)
 #define GUC_FORCEWAKE_MEDIA	(1 << 1)
 
@@ -515,6 +556,8 @@ enum intel_guc_action {
 	INTEL_GUC_ACTION_EXIT_S_STATE = 0x502,
 	INTEL_GUC_ACTION_SLPC_REQUEST = 0x3003,
 	INTEL_GUC_ACTION_AUTHENTICATE_HUC = 0x4000,
+	INTEL_GUC_ACTION_REGISTER_COMMAND_TRANSPORT_BUFFER = 0x4505,
+	INTEL_GUC_ACTION_DEREGISTER_COMMAND_TRANSPORT_BUFFER = 0x4506,
 	INTEL_GUC_ACTION_UK_LOG_ENABLE_LOGGING = 0x0E000,
 	INTEL_GUC_ACTION_LIMIT
 };

drivers/gpu/drm/i915/intel_uc.c

@@ -105,6 +105,8 @@ void intel_uc_init_early(struct drm_i915_private *dev_priv)
 {
 	struct intel_guc *guc = &dev_priv->guc;
 
+	intel_guc_ct_init_early(&guc->ct);
+
 	mutex_init(&guc->send_mutex);
 	guc->send = intel_guc_send_nop;
 	guc->notify = guc_write_irq_trigger;
@@ -288,14 +290,24 @@ static void guc_init_send_regs(struct intel_guc *guc)
 
 static int guc_enable_communication(struct intel_guc *guc)
 {
-	/* XXX: placeholder for alternate setup */
+	struct drm_i915_private *dev_priv = guc_to_i915(guc);
+
 	guc_init_send_regs(guc);
+
+	if (HAS_GUC_CT(dev_priv))
+		return intel_guc_enable_ct(guc);
+
 	guc->send = intel_guc_send_mmio;
 	return 0;
 }
 
 static void guc_disable_communication(struct intel_guc *guc)
 {
+	struct drm_i915_private *dev_priv = guc_to_i915(guc);
+
+	if (HAS_GUC_CT(dev_priv))
+		intel_guc_disable_ct(guc);
+
 	guc->send = intel_guc_send_nop;
 }
 
@@ -442,6 +454,11 @@ int intel_guc_send_mmio(struct intel_guc *guc, const u32 *action, u32 len)
 	GEM_BUG_ON(!len);
 	GEM_BUG_ON(len > guc->send_regs.count);
 
+	/* If CT is available, we expect to use MMIO only during init/fini */
+	GEM_BUG_ON(HAS_GUC_CT(dev_priv) &&
+		*action != INTEL_GUC_ACTION_REGISTER_COMMAND_TRANSPORT_BUFFER &&
+		*action != INTEL_GUC_ACTION_DEREGISTER_COMMAND_TRANSPORT_BUFFER);
+
 	mutex_lock(&guc->send_mutex);
 	intel_uncore_forcewake_get(dev_priv, guc->send_regs.fw_domains);
 

drivers/gpu/drm/i915/intel_uc.h

@@ -27,7 +27,7 @@
 #include "intel_guc_fwif.h"
 #include "i915_guc_reg.h"
 #include "intel_ringbuffer.h"
-
+#include "intel_guc_ct.h"
 #include "i915_vma.h"
 
 struct drm_i915_gem_request;
@@ -173,6 +173,7 @@ struct intel_guc_log {
 struct intel_guc {
 	struct intel_uc_fw fw;
 	struct intel_guc_log log;
+	struct intel_guc_ct ct;
 
 	/* intel_guc_recv interrupt related state */
 	bool interrupts_enabled;