intel_th: Add global activate/deactivate callbacks for the glue layers

A glue layer may want to install its own hooks into trace capture start
and stop paths to apply workarounds. This adds optional callbacks.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>

drivers/hwtracing/intel_th/core.c

@@ -226,6 +226,7 @@ static int intel_th_output_activate(struct intel_th_device *thdev)
 {
 	struct intel_th_driver *thdrv =
 		to_intel_th_driver_or_null(thdev->dev.driver);
+	struct intel_th *th = to_intel_th(thdev);
 	int ret = 0;
 
 	if (!thdrv)
@@ -236,15 +237,28 @@ static int intel_th_output_activate(struct intel_th_device *thdev)
 
 	pm_runtime_get_sync(&thdev->dev);
 
+	if (th->activate)
+		ret = th->activate(th);
+	if (ret)
+		goto fail_put;
+
 	if (thdrv->activate)
 		ret = thdrv->activate(thdev);
 	else
 		intel_th_trace_enable(thdev);
 
-	if (ret) {
-		pm_runtime_put(&thdev->dev);
-		module_put(thdrv->driver.owner);
-	}
+	if (ret)
+		goto fail_deactivate;
+
+	return 0;
+
+fail_deactivate:
+	if (th->deactivate)
+		th->deactivate(th);
+
+fail_put:
+	pm_runtime_put(&thdev->dev);
+	module_put(thdrv->driver.owner);
 
 	return ret;
 }
@@ -253,6 +267,7 @@ static void intel_th_output_deactivate(struct intel_th_device *thdev)
 {
 	struct intel_th_driver *thdrv =
 		to_intel_th_driver_or_null(thdev->dev.driver);
+	struct intel_th *th = to_intel_th(thdev);
 
 	if (!thdrv)
 		return;
@@ -262,6 +277,9 @@ static void intel_th_output_deactivate(struct intel_th_device *thdev)
 	else
 		intel_th_trace_disable(thdev);
 
+	if (th->deactivate)
+		th->deactivate(th);
+
 	pm_runtime_put(&thdev->dev);
 	module_put(thdrv->driver.owner);
 }

drivers/hwtracing/intel_th/intel_th.h

@@ -263,6 +263,8 @@ struct intel_th {
 	struct intel_th_drvdata	*drvdata;
 
 	struct resource		*resource;
+	int			(*activate)(struct intel_th *);
+	void			(*deactivate)(struct intel_th *);
 	unsigned int		num_thdevs;
 	unsigned int		num_resources;
 	int			irq;