drm/amd/display: Support for DMUB HPD interrupt handling

[WHY]
To add support for HPD interrupt handling from DMUB.
HPD interrupt could be triggered from outbox1 from DMUB

[HOW]
1) Use queue_work to handle hpd task from outbox1

2) Add handle_hpd_irq_helper to share interrupt handling code
between legacy and DMUB HPD from outbox1

3) Added DMUB HPD handling in dmub_srv_stat_get_notification().
HPD handling callback function and wake up the DMUB thread.

Reviewed-by: Nicholas Kazlauskas <[e-mail]>
Acked-by: Qingqing Zhuo <[e-mail]>
Signed-off-by: Jude Shih <[e-mail]>
Tested-by: Daniel Wheeler <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

···
 static const struct drm_format_info *
 amd_get_format_info(const struct drm_mode_fb_cmd2 *cmd);
 
+static void handle_hpd_irq_helper(struct amdgpu_dm_connector *aconnector);
+
 static bool
 is_timing_unchanged_for_freesync(struct drm_crtc_state *old_crtc_state,
 				 struct drm_crtc_state *new_crtc_state);
···
 }
 #endif
 
+/**
+ * dmub_aux_setconfig_reply_callback - Callback for AUX or SET_CONFIG command.
+ * @adev: amdgpu_device pointer
+ * @notify: dmub notification structure
+ *
+ * Dmub AUX or SET_CONFIG command completion processing callback
+ * Copies dmub notification to DM which is to be read by AUX command.
+ * issuing thread and also signals the event to wake up the thread.
+ */
+void dmub_aux_setconfig_callback(struct amdgpu_device *adev, struct dmub_notification *notify)
+{
+	if (adev->dm.dmub_notify)
+		memcpy(adev->dm.dmub_notify, notify, sizeof(struct dmub_notification));
+	if (notify->type == DMUB_NOTIFICATION_AUX_REPLY)
+		complete(&adev->dm.dmub_aux_transfer_done);
+}
+
+/**
+ * dmub_hpd_callback - DMUB HPD interrupt processing callback.
+ * @adev: amdgpu_device pointer
+ * @notify: dmub notification structure
+ *
+ * Dmub Hpd interrupt processing callback. Gets displayindex through the
+ * ink index and calls helper to do the processing.
+ */
+void dmub_hpd_callback(struct amdgpu_device *adev, struct dmub_notification *notify)
+{
+	struct amdgpu_dm_connector *aconnector;
+	struct drm_connector *connector;
+	struct drm_connector_list_iter iter;
+	struct dc_link *link;
+	uint8_t link_index = 0;
+	struct drm_device *dev = adev->dm.ddev;
+
+	if (adev == NULL)
+		return;
+
+	if (notify == NULL) {
+		DRM_ERROR("DMUB HPD callback notification was NULL");
+		return;
+	}
+
+	if (notify->link_index > adev->dm.dc->link_count) {
+		DRM_ERROR("DMUB HPD index (%u)is abnormal", notify->link_index);
+		return;
+	}
+
+	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
+
+	link_index = notify->link_index;
+
+	link = adev->dm.dc->links[link_index];
+
+	drm_connector_list_iter_begin(dev, &iter);
+	drm_for_each_connector_iter(connector, &iter) {
+		aconnector = to_amdgpu_dm_connector(connector);
+		if (link && aconnector->dc_link == link) {
+			DRM_INFO("DMUB HPD callback: link_index=%u\n", link_index);
+			handle_hpd_irq_helper(aconnector);
+			break;
+		}
+	}
+	drm_connector_list_iter_end(&iter);
+	drm_modeset_unlock(&dev->mode_config.connection_mutex);
+
+}
+
+/**
+ * register_dmub_notify_callback - Sets callback for DMUB notify
+ * @adev: amdgpu_device pointer
+ * @type: Type of dmub notification
+ * @callback: Dmub interrupt callback function
+ * @dmub_int_thread_offload: offload indicator
+ *
+ * API to register a dmub callback handler for a dmub notification
+ * Also sets indicator whether callback processing to be offloaded.
+ * to dmub interrupt handling thread
+ * Return: true if successfully registered, false if there is existing registration
+ */
+bool register_dmub_notify_callback(struct amdgpu_device *adev, enum dmub_notification_type type,
+dmub_notify_interrupt_callback_t callback, bool dmub_int_thread_offload)
+{
+	if (callback != NULL && type < ARRAY_SIZE(adev->dm.dmub_thread_offload)) {
+		adev->dm.dmub_callback[type] = callback;
+		adev->dm.dmub_thread_offload[type] = dmub_int_thread_offload;
+	} else
+		return false;
+
+	return true;
+}
+
+static void dm_handle_hpd_work(struct work_struct *work)
+{
+	struct dmub_hpd_work *dmub_hpd_wrk;
+
+	dmub_hpd_wrk = container_of(work, struct dmub_hpd_work, handle_hpd_work);
+
+	if (!dmub_hpd_wrk->dmub_notify) {
+		DRM_ERROR("dmub_hpd_wrk dmub_notify is NULL");
+		return;
+	}
+
+	if (dmub_hpd_wrk->dmub_notify->type < ARRAY_SIZE(dmub_hpd_wrk->adev->dm.dmub_callback)) {
+		dmub_hpd_wrk->adev->dm.dmub_callback[dmub_hpd_wrk->dmub_notify->type](dmub_hpd_wrk->adev,
+		dmub_hpd_wrk->dmub_notify);
+	}
+	kfree(dmub_hpd_wrk);
+
+}
+
 #define DMUB_TRACE_MAX_READ 64
 /**
  * dm_dmub_outbox1_low_irq() - Handles Outbox interrupt
···
 	struct amdgpu_display_manager *dm = &adev->dm;
 	struct dmcub_trace_buf_entry entry = { 0 };
 	uint32_t count = 0;
+	struct dmub_hpd_work *dmub_hpd_wrk;
 
 	if (dc_enable_dmub_notifications(adev->dm.dc)) {
+		dmub_hpd_wrk = kzalloc(sizeof(*dmub_hpd_wrk), GFP_ATOMIC);
+		if (!dmub_hpd_wrk) {
+			DRM_ERROR("Failed to allocate dmub_hpd_wrk");
+			return;
+		}
+		INIT_WORK(&dmub_hpd_wrk->handle_hpd_work, dm_handle_hpd_work);
+
 		if (irq_params->irq_src == DC_IRQ_SOURCE_DMCUB_OUTBOX) {
 			do {
 				dc_stat_get_dmub_notification(adev->dm.dc, &notify);
-			} while (notify.pending_notification);
+				if (notify.type > ARRAY_SIZE(dm->dmub_thread_offload)) {
+					DRM_ERROR("DM: notify type %d larger than the array size %ld !", notify.type,
+					ARRAY_SIZE(dm->dmub_thread_offload));
+					continue;
+				}
+				if (dm->dmub_thread_offload[notify.type] == true) {
+					dmub_hpd_wrk->dmub_notify = &notify;
+					dmub_hpd_wrk->adev = adev;
+					queue_work(adev->dm.delayed_hpd_wq, &dmub_hpd_wrk->handle_hpd_work);
+				} else {
+					dm->dmub_callback[notify.type](adev, &notify);
+				}
 
-			if (adev->dm.dmub_notify)
-				memcpy(adev->dm.dmub_notify, &notify, sizeof(struct dmub_notification));
-			if (notify.type == DMUB_NOTIFICATION_AUX_REPLY)
-				complete(&adev->dm.dmub_aux_transfer_done);
-			// TODO : HPD Implementation
+			} while (notify.pending_notification);
 
 		} else {
 			DRM_ERROR("DM: Failed to receive correct outbox IRQ !");
···
 			DRM_INFO("amdgpu: fail to allocate adev->dm.dmub_notify");
 			goto error;
 		}
+
+		adev->dm.delayed_hpd_wq = create_singlethread_workqueue("amdgpu_dm_hpd_wq");
+		if (!adev->dm.delayed_hpd_wq) {
+			DRM_ERROR("amdgpu: failed to create hpd offload workqueue.\n");
+			goto error;
+		}
+
 		amdgpu_dm_outbox_init(adev);
+#if defined(CONFIG_DRM_AMD_DC_DCN)
+		if (!register_dmub_notify_callback(adev, DMUB_NOTIFICATION_AUX_REPLY,
+			dmub_aux_setconfig_callback, false)) {
+			DRM_ERROR("amdgpu: fail to register dmub aux callback");
+			goto error;
+		}
+		if (!register_dmub_notify_callback(adev, DMUB_NOTIFICATION_HPD, dmub_hpd_callback, true)) {
+			DRM_ERROR("amdgpu: fail to register dmub hpd callback");
+			goto error;
+		}
+#endif
 	}
 
 	if (amdgpu_dm_initialize_drm_device(adev)) {
···
 	if (dc_enable_dmub_notifications(adev->dm.dc)) {
 		kfree(adev->dm.dmub_notify);
 		adev->dm.dmub_notify = NULL;
+		destroy_workqueue(adev->dm.delayed_hpd_wq);
+		adev->dm.delayed_hpd_wq = NULL;
 	}
 
 	if (adev->dm.dmub_bo)
···
 		dc_sink_release(sink);
 }
 
-static void handle_hpd_irq(void *param)
+static void handle_hpd_irq_helper(struct amdgpu_dm_connector *aconnector)
 {
-	struct amdgpu_dm_connector *aconnector = (struct amdgpu_dm_connector *)param;
 	struct drm_connector *connector = &aconnector->base;
 	struct drm_device *dev = connector->dev;
 	enum dc_connection_type new_connection_type = dc_connection_none;
···
 	mutex_unlock(&aconnector->hpd_lock);
 
 }
+
+static void handle_hpd_irq(void *param)
+{
+	struct amdgpu_dm_connector *aconnector = (struct amdgpu_dm_connector *)param;
+
+	handle_hpd_irq_helper(aconnector);
+
+}
+
 
 static void dm_handle_hpd_rx_irq(struct amdgpu_dm_connector *aconnector)
 {

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h

···
 #define AMDGPU_DM_MAX_CRTC 6
 
 #define AMDGPU_DM_MAX_NUM_EDP 2
+
+#define AMDGPU_DMUB_NOTIFICATION_MAX 5
 /*
 #include "include/amdgpu_dal_power_if.h"
 #include "amdgpu_dm_irq.h"
···
 	void *cpu_addr;
 	struct amdgpu_bo *bo_ptr;
 	uint64_t gpu_addr;
+};
+
+typedef void (*dmub_notify_interrupt_callback_t)(struct amdgpu_device *adev, struct dmub_notification *notify);
+
+/**
+ * struct dmub_hpd_work - Handle time consuming work in low priority outbox IRQ
+ *
+ * @handle_hpd_work: Work to be executed in a separate thread to handle hpd_low_irq
+ * @dmub_notify:  notification for callback function
+ * @adev: amdgpu_device pointer
+ */
+struct dmub_hpd_work {
+	struct work_struct handle_hpd_work;
+	struct dmub_notification *dmub_notify;
+	struct amdgpu_device *adev;
 };
 
 /**
···
 	 */
 	struct dmub_srv *dmub_srv;
 
+	/**
+	 * @dmub_notify:
+	 *
+	 * Notification from DMUB.
+	 */
+
 	struct dmub_notification *dmub_notify;
+
+	/**
+	 * @dmub_callback:
+	 *
+	 * Callback functions to handle notification from DMUB.
+	 */
+
+	dmub_notify_interrupt_callback_t dmub_callback[AMDGPU_DMUB_NOTIFICATION_MAX];
+
+	/**
+	 * @dmub_thread_offload:
+	 *
+	 * Flag to indicate if callback is offload.
+	 */
+
+	bool dmub_thread_offload[AMDGPU_DMUB_NOTIFICATION_MAX];
 
 	/**
 	 * @dmub_fb_info:
···
 	 */
 	struct list_head da_list;
 	struct completion dmub_aux_transfer_done;
+	struct workqueue_struct *delayed_hpd_wq;
 
 	/**
 	 * @brightness: