[10/13] coresight: etb: retrieve and handle atclk

Message ID 1429261140-13910-11-git-send-email-linus.walleij@linaro.org
State New
Headers show

Commit Message

Linus Walleij April 17, 2015, 8:58 a.m.
As can be seen from the datasheet of the CoreSight
Components, DDI0314 table A-8 the ETB 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.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/coresight/coresight-etb10.c | 39 +++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

Comments

Ulf Hansson April 17, 2015, 9:21 a.m. | #1
On 17 April 2015 at 10:58, Linus Walleij <linus.walleij@linaro.org> wrote:
> As can be seen from the datasheet of the CoreSight
> Components, DDI0314 table A-8 the ETB 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.
>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
>  drivers/coresight/coresight-etb10.c | 39 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 39 insertions(+)
>
> diff --git a/drivers/coresight/coresight-etb10.c b/drivers/coresight/coresight-etb10.c
> index c4587510a826..7d751a39d959 100644
> --- a/drivers/coresight/coresight-etb10.c
> +++ b/drivers/coresight/coresight-etb10.c
> @@ -26,6 +26,7 @@
>  #include <linux/seq_file.h>
>  #include <linux/coresight.h>
>  #include <linux/amba/bus.h>
> +#include <linux/clk.h>
>
>  #include "coresight-priv.h"
>
> @@ -66,6 +67,7 @@
>   * struct etb_drvdata - specifics associated to an ETB 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 ETB.
>   * @csdev:     component vitals needed by the framework.
>   * @miscdev:   specifics to handle "/dev/xyz.etb" entry.
>   * @spinlock:  only one at a time pls.
> @@ -78,6 +80,7 @@
>  struct etb_drvdata {
>         void __iomem            *base;
>         struct device           *dev;
> +       struct clk              *atclk;
>         struct coresight_device *csdev;
>         struct miscdevice       miscdev;
>         spinlock_t              spinlock;
> @@ -426,6 +429,12 @@ static int etb_probe(struct amba_device *adev, const struct amba_id *id)
>                 return -ENOMEM;
>
>         drvdata->dev = &adev->dev;
> +       drvdata->atclk = devm_clk_get(&adev->dev, "atclk"); /* optional */
> +       if (!IS_ERR(drvdata->atclk)) {
> +               ret = clk_prepare_enable(drvdata->atclk);
> +               if (ret)
> +                       return ret;
> +       }
>         dev_set_drvdata(dev, drvdata);
>
>         /* validity for the resource is already checked by the AMBA core */
> @@ -486,6 +495,34 @@ static int etb_remove(struct amba_device *adev)
>         return 0;
>  }
>
> +#ifdef CONFIG_PM
> +static int etb_runtime_suspend(struct device *dev)
> +{
> +       struct amba_device *adev = to_amba_device(dev);
> +       struct etb_drvdata *drvdata = amba_get_drvdata(adev);
> +
> +       if (drvdata && !IS_ERR(drvdata->atclk))
> +               clk_disable_unprepare(drvdata->atclk);
> +
> +       return 0;
> +}
> +
> +static int etb_runtime_resume(struct device *dev)
> +{
> +       struct amba_device *adev = to_amba_device(dev);
> +       struct etb_drvdata *drvdata = amba_get_drvdata(adev);
> +
> +       if (drvdata && !IS_ERR(drvdata->atclk))
> +               clk_prepare_enable(drvdata->atclk);
> +
> +       return 0;
> +}
> +#endif
> +
> +static const struct dev_pm_ops etb_dev_pm_ops = {
> +       SET_RUNTIME_PM_OPS(etb_runtime_suspend, etb_runtime_resume, NULL)
> +};
> +
>  static struct amba_id etb_ids[] = {
>         {
>                 .id     = 0x0003b907,
> @@ -498,6 +535,8 @@ static struct amba_driver etb_driver = {
>         .drv = {
>                 .name   = "coresight-etb10",
>                 .owner  = THIS_MODULE,
> +               .pm     = &etb_dev_pm_ops,
> +
>         },
>         .probe          = etb_probe,
>         .remove         = etb_remove,
> --
> 1.9.3
>

With the same comment as I had to previous patchnumber.

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

Patch

diff --git a/drivers/coresight/coresight-etb10.c b/drivers/coresight/coresight-etb10.c
index c4587510a826..7d751a39d959 100644
--- a/drivers/coresight/coresight-etb10.c
+++ b/drivers/coresight/coresight-etb10.c
@@ -26,6 +26,7 @@ 
 #include <linux/seq_file.h>
 #include <linux/coresight.h>
 #include <linux/amba/bus.h>
+#include <linux/clk.h>
 
 #include "coresight-priv.h"
 
@@ -66,6 +67,7 @@ 
  * struct etb_drvdata - specifics associated to an ETB 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 ETB.
  * @csdev:	component vitals needed by the framework.
  * @miscdev:	specifics to handle "/dev/xyz.etb" entry.
  * @spinlock:	only one at a time pls.
@@ -78,6 +80,7 @@ 
 struct etb_drvdata {
 	void __iomem		*base;
 	struct device		*dev;
+	struct clk		*atclk;
 	struct coresight_device	*csdev;
 	struct miscdevice	miscdev;
 	spinlock_t		spinlock;
@@ -426,6 +429,12 @@  static int etb_probe(struct amba_device *adev, const struct amba_id *id)
 		return -ENOMEM;
 
 	drvdata->dev = &adev->dev;
+	drvdata->atclk = devm_clk_get(&adev->dev, "atclk"); /* optional */
+	if (!IS_ERR(drvdata->atclk)) {
+		ret = clk_prepare_enable(drvdata->atclk);
+		if (ret)
+			return ret;
+	}
 	dev_set_drvdata(dev, drvdata);
 
 	/* validity for the resource is already checked by the AMBA core */
@@ -486,6 +495,34 @@  static int etb_remove(struct amba_device *adev)
 	return 0;
 }
 
+#ifdef CONFIG_PM
+static int etb_runtime_suspend(struct device *dev)
+{
+	struct amba_device *adev = to_amba_device(dev);
+	struct etb_drvdata *drvdata = amba_get_drvdata(adev);
+
+	if (drvdata && !IS_ERR(drvdata->atclk))
+		clk_disable_unprepare(drvdata->atclk);
+
+	return 0;
+}
+
+static int etb_runtime_resume(struct device *dev)
+{
+	struct amba_device *adev = to_amba_device(dev);
+	struct etb_drvdata *drvdata = amba_get_drvdata(adev);
+
+	if (drvdata && !IS_ERR(drvdata->atclk))
+		clk_prepare_enable(drvdata->atclk);
+
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops etb_dev_pm_ops = {
+	SET_RUNTIME_PM_OPS(etb_runtime_suspend, etb_runtime_resume, NULL)
+};
+
 static struct amba_id etb_ids[] = {
 	{
 		.id	= 0x0003b907,
@@ -498,6 +535,8 @@  static struct amba_driver etb_driver = {
 	.drv = {
 		.name	= "coresight-etb10",
 		.owner	= THIS_MODULE,
+		.pm	= &etb_dev_pm_ops,
+
 	},
 	.probe		= etb_probe,
 	.remove		= etb_remove,