intel_th: Add runtime power management handling

Currently, an Intel TH (pci) device will be always active, because the
devices on the 'intel_th' bus don't implement runtime pm to track their
usage.

To address this, this patch adds runtime pm support to the 'intel_th'
bus and some additional bits for the hub. The 'output' type device is
in use while a capture is active; the 'source' type device (STH) relies
on its child stm class device for runtime pm tracking.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>

drivers/hwtracing/intel_th/core.c

@@ -23,6 +23,7 @@
 #include <linux/debugfs.h>
 #include <linux/idr.h>
 #include <linux/pci.h>
+#include <linux/pm_runtime.h>
 #include <linux/dma-mapping.h>
 
 #include "intel_th.h"
@@ -67,23 +68,33 @@ static int intel_th_probe(struct device *dev)
 
 	hubdrv = to_intel_th_driver(hub->dev.driver);
 
+	pm_runtime_set_active(dev);
+	pm_runtime_no_callbacks(dev);
+	pm_runtime_enable(dev);
+
 	ret = thdrv->probe(to_intel_th_device(dev));
 	if (ret)
-		return ret;
+		goto out_pm;
 
 	if (thdrv->attr_group) {
 		ret = sysfs_create_group(&thdev->dev.kobj, thdrv->attr_group);
-		if (ret) {
-			thdrv->remove(thdev);
-
-			return ret;
-		}
+		if (ret)
+			goto out;
 	}
 
 	if (thdev->type == INTEL_TH_OUTPUT &&
 	    !intel_th_output_assigned(thdev))
+		/* does not talk to hardware */
 		ret = hubdrv->assign(hub, thdev);
 
+out:
+	if (ret)
+		thdrv->remove(thdev);
+
+out_pm:
+	if (ret)
+		pm_runtime_disable(dev);
+
 	return ret;
 }
 
@@ -103,6 +114,8 @@ static int intel_th_remove(struct device *dev)
 	if (thdrv->attr_group)
 		sysfs_remove_group(&thdev->dev.kobj, thdrv->attr_group);
 
+	pm_runtime_get_sync(dev);
+
 	thdrv->remove(thdev);
 
 	if (intel_th_output_assigned(thdev)) {
@@ -110,9 +123,14 @@ static int intel_th_remove(struct device *dev)
 			to_intel_th_driver(dev->parent->driver);
 
 		if (hub->dev.driver)
+			/* does not talk to hardware */
 			hubdrv->unassign(hub, thdev);
 	}
 
+	pm_runtime_disable(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+
 	return 0;
 }
 
@@ -185,6 +203,7 @@ 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);
+	int ret = 0;
 
 	if (!thdrv)
 		return -ENODEV;
@@ -192,12 +211,17 @@ static int intel_th_output_activate(struct intel_th_device *thdev)
 	if (!try_module_get(thdrv->driver.owner))
 		return -ENODEV;
 
-	if (thdrv->activate)
-		return thdrv->activate(thdev);
+	pm_runtime_get_sync(&thdev->dev);
 
+	if (thdrv->activate)
+		ret = thdrv->activate(thdev);
+	else
 		intel_th_trace_enable(thdev);
 
-	return 0;
+	if (ret)
+		pm_runtime_put(&thdev->dev);
+
+	return ret;
 }
 
 static void intel_th_output_deactivate(struct intel_th_device *thdev)
@@ -213,6 +237,7 @@ static void intel_th_output_deactivate(struct intel_th_device *thdev)
 	else
 		intel_th_trace_disable(thdev);
 
+	pm_runtime_put(&thdev->dev);
 	module_put(thdrv->driver.owner);
 }
 
@@ -628,6 +653,10 @@ intel_th_alloc(struct device *dev, struct resource *devres,
 
 	dev_set_drvdata(dev, th);
 
+	pm_runtime_no_callbacks(dev);
+	pm_runtime_put(dev);
+	pm_runtime_allow(dev);
+
 	err = intel_th_populate(th, devres, ndevres, irq);
 	if (err)
 		goto err_chrdev;
@@ -635,6 +664,8 @@ intel_th_alloc(struct device *dev, struct resource *devres,
 	return th;
 
 err_chrdev:
+	pm_runtime_forbid(dev);
+
 	__unregister_chrdev(th->major, 0, TH_POSSIBLE_OUTPUTS,
 			    "intel_th/output");
 
@@ -658,6 +689,9 @@ void intel_th_free(struct intel_th *th)
 
 	intel_th_device_remove(th->hub);
 
+	pm_runtime_get_sync(th->dev);
+	pm_runtime_forbid(th->dev);
+
 	__unregister_chrdev(th->major, 0, TH_POSSIBLE_OUTPUTS,
 			    "intel_th/output");
 
@@ -682,6 +716,7 @@ int intel_th_trace_enable(struct intel_th_device *thdev)
 	if (WARN_ON_ONCE(thdev->type != INTEL_TH_OUTPUT))
 		return -EINVAL;
 
+	pm_runtime_get_sync(&thdev->dev);
 	hubdrv->enable(hub, &thdev->output);
 
 	return 0;
@@ -702,6 +737,7 @@ int intel_th_trace_disable(struct intel_th_device *thdev)
 		return -EINVAL;
 
 	hubdrv->disable(hub, &thdev->output);
+	pm_runtime_put(&thdev->dev);
 
 	return 0;
 }

drivers/hwtracing/intel_th/gth.c

@@ -22,6 +22,7 @@
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/bitmap.h>
+#include <linux/pm_runtime.h>
 
 #include "intel_th.h"
 #include "gth.h"
@@ -190,6 +191,11 @@ static ssize_t master_attr_store(struct device *dev,
 	if (old_port >= 0) {
 		gth->master[ma->master] = -1;
 		clear_bit(ma->master, gth->output[old_port].master);
+
+		/*
+		 * if the port is active, program this setting,
+		 * implies that runtime PM is on
+		 */
 		if (gth->output[old_port].output->active)
 			gth_master_set(gth, ma->master, -1);
 	}
@@ -204,7 +210,7 @@ static ssize_t master_attr_store(struct device *dev,
 
 		set_bit(ma->master, gth->output[port].master);
 
-		/* if the port is active, program this setting */
+		/* if the port is active, program this setting, see above */
 		if (gth->output[port].output->active)
 			gth_master_set(gth, ma->master, port);
 	}
@@ -326,11 +332,15 @@ static ssize_t output_attr_show(struct device *dev,
 	struct gth_device *gth = oa->gth;
 	size_t count;
 
+	pm_runtime_get_sync(dev);
+
 	spin_lock(&gth->gth_lock);
 	count = snprintf(buf, PAGE_SIZE, "%x\n",
 			 gth_output_parm_get(gth, oa->port, oa->parm));
 	spin_unlock(&gth->gth_lock);
 
+	pm_runtime_put(dev);
+
 	return count;
 }
 
@@ -346,10 +356,14 @@ static ssize_t output_attr_store(struct device *dev,
 	if (kstrtouint(buf, 16, &config) < 0)
 		return -EINVAL;
 
+	pm_runtime_get_sync(dev);
+
 	spin_lock(&gth->gth_lock);
 	gth_output_parm_set(gth, oa->port, oa->parm, config);
 	spin_unlock(&gth->gth_lock);
 
+	pm_runtime_put(dev);
+
 	return count;
 }