[PATCH 02/13] drm/i915/guc: Update MMIO based communication

[Matthew Brost <matthew.brost@intel.com>]

From: Michal Wajdeczko <michal.wajdeczko@intel.com>

The MMIO based Host-to-GuC communication protocol has been
updated to use unified HXG messages.

Update our intel_guc_send_mmio() function by correctly handle
BUSY, RETRY and FAILURE replies. Also update our documentation.

Since some of the new MMIO actions may use DATA0 from MMIO HXG
response, we must update intel_guc_send_mmio() to copy full response,
including HXG header. There will be no impact to existing users as all
of them are only relying just on return code.

v2:
 (Daniele)
  - preffered -> preferred
  - Max MMIO DW set to 4
  - Update commit message

GuC: 55.0.0
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Piotr Piórkowski <piotr.piorkowski@intel.com>
Cc: Michal Winiarski <michal.winiarski@intel.com> #v3
---
 .../gt/uc/abi/guc_communication_mmio_abi.h    | 65 +++++++------
 drivers/gpu/drm/i915/gt/uc/intel_guc.c        | 92 ++++++++++++++-----
 2 files changed, 98 insertions(+), 59 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/abi/guc_communication_mmio_abi.h b/drivers/gpu/drm/i915/gt/uc/abi/guc_communication_mmio_abi.h
index be066a62e9e0..bbf1ddb77434 100644
--- a/drivers/gpu/drm/i915/gt/uc/abi/guc_communication_mmio_abi.h
+++ b/drivers/gpu/drm/i915/gt/uc/abi/guc_communication_mmio_abi.h
@@ -7,46 +7,43 @@
 #define _ABI_GUC_COMMUNICATION_MMIO_ABI_H
 
 /**
- * DOC: MMIO based communication
+ * DOC: GuC MMIO based communication
  *
- * The MMIO based communication between Host and GuC uses software scratch
- * registers, where first register holds data treated as message header,
- * and other registers are used to hold message payload.
+ * The MMIO based communication between Host and GuC relies on special
+ * hardware registers which format could be defined by the software
+ * (so called scratch registers).
  *
- * For Gen9+, GuC uses software scratch registers 0xC180-0xC1B8,
- * but no H2G command takes more than 8 parameters and the GuC FW
- * itself uses an 8-element array to store the H2G message.
+ * Each MMIO based message, both Host to GuC (H2G) and GuC to Host (G2H)
+ * messages, which maximum length depends on number of available scratch
+ * registers, is directly written into those scratch registers.
  *
- *      +-----------+---------+---------+---------+
- *      |  MMIO[0]  | MMIO[1] |   ...   | MMIO[n] |
- *      +-----------+---------+---------+---------+
- *      | header    |      optional payload       |
- *      +======+====+=========+=========+=========+
- *      | 31:28|type|         |         |         |
- *      +------+----+         |         |         |
- *      | 27:16|data|         |         |         |
- *      +------+----+         |         |         |
- *      |  15:0|code|         |         |         |
- *      +------+----+---------+---------+---------+
+ * For Gen9+, there are 16 software scratch registers 0xC180-0xC1B8,
+ * but no H2G command takes more than 4 parameters and the GuC firmware
+ * itself uses an 4-element array to store the H2G message.
  *
- * The message header consists of:
+ * For Gen11+, there are additional 4 registers 0x190240-0x19024C, which
+ * are, regardless on lower count, preferred over legacy ones.
  *
- * - **type**, indicates message type
- * - **code**, indicates message code, is specific for **type**
- * - **data**, indicates message data, optional, depends on **code**
- *
- * The following message **types** are supported:
- *
- * - **REQUEST**, indicates Host-to-GuC request, requested GuC action code
- *   must be priovided in **code** field. Optional action specific parameters
- *   can be provided in remaining payload registers or **data** field.
- *
- * - **RESPONSE**, indicates GuC-to-Host response from earlier GuC request,
- *   action response status will be provided in **code** field. Optional
- *   response data can be returned in remaining payload registers or **data**
- *   field.
+ * The MMIO based communication is mainly used during driver initialization
+ * phase to setup the `CTB based communication`_ that will be used afterwards.
  */
 
-#define GUC_MAX_MMIO_MSG_LEN		8
+#define GUC_MAX_MMIO_MSG_LEN		4
+
+/**
+ * DOC: MMIO HXG Message
+ *
+ * Format of the MMIO messages follows definitions of `HXG Message`_.
+ *
+ *  +---+-------+--------------------------------------------------------------+
+ *  |   | Bits  | Description                                                  |
+ *  +===+=======+==============================================================+
+ *  | 0 |  31:0 |  +--------------------------------------------------------+  |
+ *  +---+-------+  |                                                        |  |
+ *  |...|       |  |  Embedded `HXG Message`_                               |  |
+ *  +---+-------+  |                                                        |  |
+ *  | n |  31:0 |  +--------------------------------------------------------+  |
+ *  +---+-------+--------------------------------------------------------------+
+ */
 
 #endif /* _ABI_GUC_COMMUNICATION_MMIO_ABI_H */
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
index f147cb389a20..b773567cb080 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
@@ -376,29 +376,27 @@ void intel_guc_fini(struct intel_guc *guc)
 /*
  * This function implements the MMIO based host to GuC interface.
  */
-int intel_guc_send_mmio(struct intel_guc *guc, const u32 *action, u32 len,
+int intel_guc_send_mmio(struct intel_guc *guc, const u32 *request, u32 len,
 			u32 *response_buf, u32 response_buf_size)
 {
+	struct drm_i915_private *i915 = guc_to_gt(guc)->i915;
 	struct intel_uncore *uncore = guc_to_gt(guc)->uncore;
-	u32 status;
+	u32 header;
 	int i;
 	int ret;
 
 	GEM_BUG_ON(!len);
 	GEM_BUG_ON(len > guc->send_regs.count);
 
-	/* We expect only action code */
-	GEM_BUG_ON(*action & ~INTEL_GUC_MSG_CODE_MASK);
-
-	/* If CT is available, we expect to use MMIO only during init/fini */
-	GEM_BUG_ON(*action != INTEL_GUC_ACTION_REGISTER_COMMAND_TRANSPORT_BUFFER &&
-		   *action != INTEL_GUC_ACTION_DEREGISTER_COMMAND_TRANSPORT_BUFFER);
+	GEM_BUG_ON(FIELD_GET(GUC_HXG_MSG_0_ORIGIN, request[0]) != GUC_HXG_ORIGIN_HOST);
+	GEM_BUG_ON(FIELD_GET(GUC_HXG_MSG_0_TYPE, request[0]) != GUC_HXG_TYPE_REQUEST);
 
 	mutex_lock(&guc->send_mutex);
 	intel_uncore_forcewake_get(uncore, guc->send_regs.fw_domains);
 
+retry:
 	for (i = 0; i < len; i++)
-		intel_uncore_write(uncore, guc_send_reg(guc, i), action[i]);
+		intel_uncore_write(uncore, guc_send_reg(guc, i), request[i]);
 
 	intel_uncore_posting_read(uncore, guc_send_reg(guc, i - 1));
 
@@ -410,30 +408,74 @@ int intel_guc_send_mmio(struct intel_guc *guc, const u32 *action, u32 len,
 	 */
 	ret = __intel_wait_for_register_fw(uncore,
 					   guc_send_reg(guc, 0),
-					   INTEL_GUC_MSG_TYPE_MASK,
-					   INTEL_GUC_MSG_TYPE_RESPONSE <<
-					   INTEL_GUC_MSG_TYPE_SHIFT,
-					   10, 10, &status);
-	/* If GuC explicitly returned an error, convert it to -EIO */
-	if (!ret && !INTEL_GUC_MSG_IS_RESPONSE_SUCCESS(status))
-		ret = -EIO;
+					   GUC_HXG_MSG_0_ORIGIN,
+					   FIELD_PREP(GUC_HXG_MSG_0_ORIGIN,
+						      GUC_HXG_ORIGIN_GUC),
+					   10, 10, &header);
+	if (unlikely(ret)) {
+timeout:
+		drm_err(&i915->drm, "mmio request %#x: no reply %x\n",
+			request[0], header);
+		goto out;
+	}
 
-	if (ret) {
-		DRM_ERROR("MMIO: GuC action %#x failed with error %d %#x\n",
-			  action[0], ret, status);
+	if (FIELD_GET(GUC_HXG_MSG_0_TYPE, header) == GUC_HXG_TYPE_NO_RESPONSE_BUSY) {
+#define done ({ header = intel_uncore_read(uncore, guc_send_reg(guc, 0)); \
+		FIELD_GET(GUC_HXG_MSG_0_ORIGIN, header) != GUC_HXG_ORIGIN_GUC || \
+		FIELD_GET(GUC_HXG_MSG_0_TYPE, header) != GUC_HXG_TYPE_NO_RESPONSE_BUSY; })
+
+		ret = wait_for(done, 1000);
+		if (unlikely(ret))
+			goto timeout;
+		if (unlikely(FIELD_GET(GUC_HXG_MSG_0_ORIGIN, header) !=
+				       GUC_HXG_ORIGIN_GUC))
+			goto proto;
+#undef done
+	}
+
+	if (FIELD_GET(GUC_HXG_MSG_0_TYPE, header) == GUC_HXG_TYPE_NO_RESPONSE_RETRY) {
+		u32 reason = FIELD_GET(GUC_HXG_RETRY_MSG_0_REASON, header);
+
+		drm_dbg(&i915->drm, "mmio request %#x: retrying, reason %u\n",
+			request[0], reason);
+		goto retry;
+	}
+
+	if (FIELD_GET(GUC_HXG_MSG_0_TYPE, header) == GUC_HXG_TYPE_RESPONSE_FAILURE) {
+		u32 hint = FIELD_GET(GUC_HXG_FAILURE_MSG_0_HINT, header);
+		u32 error = FIELD_GET(GUC_HXG_FAILURE_MSG_0_ERROR, header);
+
+		drm_err(&i915->drm, "mmio request %#x: failure %x/%u\n",
+			request[0], error, hint);
+		ret = -ENXIO;
+		goto out;
+	}
+
+	if (FIELD_GET(GUC_HXG_MSG_0_TYPE, header) != GUC_HXG_TYPE_RESPONSE_SUCCESS) {
+proto:
+		drm_err(&i915->drm, "mmio request %#x: unexpected reply %#x\n",
+			request[0], header);
+		ret = -EPROTO;
 		goto out;
 	}
 
 	if (response_buf) {
-		int count = min(response_buf_size, guc->send_regs.count - 1);
+		int count = min(response_buf_size, guc->send_regs.count);
 
-		for (i = 0; i < count; i++)
+		GEM_BUG_ON(!count);
+
+		response_buf[0] = header;
+
+		for (i = 1; i < count; i++)
 			response_buf[i] = intel_uncore_read(uncore,
-							    guc_send_reg(guc, i + 1));
-	}
+							    guc_send_reg(guc, i));
 
-	/* Use data from the GuC response as our return value */
-	ret = INTEL_GUC_MSG_TO_DATA(status);
+		/* Use number of copied dwords as our return value */
+		ret = count;
+	} else {
+		/* Use data from the GuC response as our return value */
+		ret = FIELD_GET(GUC_HXG_RESPONSE_MSG_0_DATA0, header);
+	}
 
 out:
 	intel_uncore_forcewake_put(uncore, guc->send_regs.fw_domains);
-- 
2.28.0