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Commit b5ea95b9 authored by Linus Walleij's avatar Linus Walleij Committed by Shashank Mittal
Browse files

coresight: etm: retrieve and handle atclk 



As can be seen from the datasheet of the CoreSight
Components, DDI0401C A.1.1 the ETM 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.

Change-Id: I7f4e6c3db8ff58d9b6cb3e6727ce006547e3cf36
Reviewed-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarMathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Git-commit: d1839e68777316cc607d1d3f82579046ca945958
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: default avatarShashank Mittal <mittals@codeaurora.org>
parent a0043d95

drivers/hwtracing/coresight/coresight-etm.h

+2 −0
Original line number Diff line number Diff line
@@ -140,6 +140,7 @@ 
 * struct etm_drvdata - specifics associated to an ETM component

 * @base:	memory mapped base address for this component.

 * @dev:	the device entity associated to this component.

 * @atclk:	optional clock for the core parts of the ETM.

 * @csdev:	component vitals needed by the framework.

 * @spinlock:	only one at a time pls.

 * @cpu:	the cpu this component is affined to.
@@ -191,6 +192,7 @@ 
struct etm_drvdata {

	void __iomem			*base;

	struct device			*dev;

	struct clk			*atclk;

	struct coresight_device		*csdev;

	spinlock_t			spinlock;

	int				cpu;

drivers/hwtracing/coresight/coresight-etm3x.c

+35 −1
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ 
#include <linux/amba/bus.h>

#include <linux/seq_file.h>

#include <linux/uaccess.h>

#include <linux/clk.h>

#include <asm/sections.h>



#include "coresight-etm.h"
@@ -1315,7 +1316,6 @@ static ssize_t seq_curr_state_show(struct device *dev, 
	}



	pm_runtime_get_sync(drvdata->dev);



	spin_lock_irqsave(&drvdata->spinlock, flags);



	CS_UNLOCK(drvdata->base);
@@ -1796,6 +1796,13 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id) 


	spin_lock_init(&drvdata->spinlock);



	drvdata->atclk = devm_clk_get(&adev->dev, "atclk"); /* optional */

	if (!IS_ERR(drvdata->atclk)) {

		ret = clk_prepare_enable(drvdata->atclk);

		if (ret)

			return ret;

	}



	drvdata->cpu = pdata ? pdata->cpu : 0;



	get_online_cpus();
@@ -1858,6 +1865,32 @@ static int etm_remove(struct amba_device *adev) 
	return 0;

}



#ifdef CONFIG_PM

static int etm_runtime_suspend(struct device *dev)

{

	struct etm_drvdata *drvdata = dev_get_drvdata(dev);



	if (drvdata && !IS_ERR(drvdata->atclk))

		clk_disable_unprepare(drvdata->atclk);



	return 0;

}



static int etm_runtime_resume(struct device *dev)

{

	struct etm_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 etm_dev_pm_ops = {

	SET_RUNTIME_PM_OPS(etm_runtime_suspend, etm_runtime_resume, NULL)

};



static struct amba_id etm_ids[] = {

	{	/* ETM 3.3 */

		.id	= 0x0003b921,
@@ -1886,6 +1919,7 @@ static struct amba_driver etm_driver = { 
	.drv = {

		.name	= "coresight-etm3x",

		.owner	= THIS_MODULE,

		.pm	= &etm_dev_pm_ops,

	},

	.probe		= etm_probe,

	.remove		= etm_remove,