coresight: replicator: retrieve and handle atclk

As can be seen from the datasheet of the CoreSight
Components, DDI0314 table A-4 the funnel has a clock signal
apart from the AHB interconnect ("amba_pclk", that we're
already handling) called ATCLK, ARM Trace Clock, that SoC
implementers may provide from an entirely different clock
source. So to model this correctly create an optional
path for handling ATCLK alongside the PCLK so we don't
break old platforms that only define PCLK ("amba_pclk") but
still makes it possible for SoCs that have both clock signals
(such as the DB8500) to fetch and prepare/enable/disable/
unprepare both clocks.

The ATCLK is enabled and disabled using the runtime PM
callbacks. As the replicator is a platform device, the
code is a bit different from the other CoreSight components
and the bus core does not activate runtime PM by default,
so we need a few extra calls.

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hwtracing/coresight/coresight-replicator.c

@@ -18,6 +18,7 @@
 #include <linux/io.h>
 #include <linux/err.h>
 #include <linux/slab.h>
+#include <linux/pm_runtime.h>
 #include <linux/clk.h>
 #include <linux/of.h>
 #include <linux/coresight.h>
@@ -27,10 +28,12 @@
 /**
  * struct replicator_drvdata - specifics associated to a replicator component
  * @dev:	the device entity associated with this component
+ * @atclk:	optional clock for the core parts of the replicator.
  * @csdev:	component vitals needed by the framework
  */
 struct replicator_drvdata {
 	struct device		*dev;
+	struct clk		*atclk;
 	struct coresight_device	*csdev;
 };
 
@@ -39,6 +42,7 @@ static int replicator_enable(struct coresight_device *csdev, int inport,
 {
 	struct replicator_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 
+	pm_runtime_get_sync(drvdata->dev);
 	dev_info(drvdata->dev, "REPLICATOR enabled\n");
 	return 0;
 }
@@ -48,6 +52,7 @@ static void replicator_disable(struct coresight_device *csdev, int inport,
 {
 	struct replicator_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 
+	pm_runtime_put(drvdata->dev);
 	dev_info(drvdata->dev, "REPLICATOR disabled\n");
 }
 
@@ -62,6 +67,7 @@ static const struct coresight_ops replicator_cs_ops = {
 
 static int replicator_probe(struct platform_device *pdev)
 {
+	int ret;
 	struct device *dev = &pdev->dev;
 	struct coresight_platform_data *pdata = NULL;
 	struct replicator_drvdata *drvdata;
@@ -80,11 +86,22 @@ static int replicator_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	drvdata->dev = &pdev->dev;
+	drvdata->atclk = devm_clk_get(&pdev->dev, "atclk"); /* optional */
+	if (!IS_ERR(drvdata->atclk)) {
+		ret = clk_prepare_enable(drvdata->atclk);
+		if (ret)
+			return ret;
+	}
+	pm_runtime_get_noresume(&pdev->dev);
+	pm_runtime_set_active(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
 	platform_set_drvdata(pdev, drvdata);
 
 	desc = devm_kzalloc(dev, sizeof(*desc), GFP_KERNEL);
-	if (!desc)
-		return -ENOMEM;
+	if (!desc) {
+		ret = -ENOMEM;
+		goto out_disable_pm;
+	}
 
 	desc->type = CORESIGHT_DEV_TYPE_LINK;
 	desc->subtype.link_subtype = CORESIGHT_DEV_SUBTYPE_LINK_SPLIT;
@@ -92,11 +109,23 @@ static int replicator_probe(struct platform_device *pdev)
 	desc->pdata = pdev->dev.platform_data;
 	desc->dev = &pdev->dev;
 	drvdata->csdev = coresight_register(desc);
-	if (IS_ERR(drvdata->csdev))
-		return PTR_ERR(drvdata->csdev);
+	if (IS_ERR(drvdata->csdev)) {
+		ret = PTR_ERR(drvdata->csdev);
+		goto out_disable_pm;
+	}
+
+	pm_runtime_put(&pdev->dev);
 
 	dev_info(dev, "REPLICATOR initialized\n");
 	return 0;
+
+out_disable_pm:
+	if (!IS_ERR(drvdata->atclk))
+		clk_disable_unprepare(drvdata->atclk);
+	pm_runtime_put_noidle(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+
+	return ret;
 }
 
 static int replicator_remove(struct platform_device *pdev)
@@ -104,9 +133,42 @@ static int replicator_remove(struct platform_device *pdev)
 	struct replicator_drvdata *drvdata = platform_get_drvdata(pdev);
 
 	coresight_unregister(drvdata->csdev);
+	pm_runtime_get_sync(&pdev->dev);
+	if (!IS_ERR(drvdata->atclk))
+		clk_disable_unprepare(drvdata->atclk);
+	pm_runtime_put_noidle(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+
 	return 0;
 }
 
+#ifdef CONFIG_PM
+static int replicator_runtime_suspend(struct device *dev)
+{
+	struct replicator_drvdata *drvdata = dev_get_drvdata(dev);
+
+	if (drvdata && !IS_ERR(drvdata->atclk))
+		clk_disable_unprepare(drvdata->atclk);
+
+	return 0;
+}
+
+static int replicator_runtime_resume(struct device *dev)
+{
+	struct replicator_drvdata *drvdata = dev_get_drvdata(dev);
+
+	if (drvdata && !IS_ERR(drvdata->atclk))
+		clk_prepare_enable(drvdata->atclk);
+
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops replicator_dev_pm_ops = {
+	SET_RUNTIME_PM_OPS(replicator_runtime_suspend,
+			   replicator_runtime_resume, NULL)
+};
+
 static const struct of_device_id replicator_match[] = {
 	{.compatible = "arm,coresight-replicator"},
 	{}
@@ -118,6 +180,7 @@ static struct platform_driver replicator_driver = {
 	.driver         = {
 		.name   = "coresight-replicator",
 		.of_match_table = replicator_match,
+		.pm	= &replicator_dev_pm_ops,
 	},
 };