[PATCH 08/13] coresight: etm: retrieve and handle atclk

[Ulf Hansson]

On 17 April 2015 at 10:58, Linus Walleij <linus.walleij at linaro.org> wrote:
> 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.
>
> Signed-off-by: Linus Walleij <linus.walleij at linaro.org>
> ---
>  drivers/coresight/coresight-etm.h   |  2 ++
>  drivers/coresight/coresight-etm3x.c | 38 ++++++++++++++++++++++++++++++++++++-
>  2 files changed, 39 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/coresight/coresight-etm.h b/drivers/coresight/coresight-etm.h
> index d1421e1f8b8a..098ffbec0a44 100644
> --- a/drivers/coresight/coresight-etm.h
> +++ b/drivers/coresight/coresight-etm.h
> @@ -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;
> diff --git a/drivers/coresight/coresight-etm3x.c b/drivers/coresight/coresight-etm3x.c
> index f0be12bd79e0..25f49b84a6d2 100644
> --- a/drivers/coresight/coresight-etm3x.c
> +++ b/drivers/coresight/coresight-etm3x.c
> @@ -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 +1865,34 @@ static int etm_remove(struct amba_device *adev)
>         return 0;
>  }
>
> +#ifdef CONFIG_PM
> +static int etm_runtime_suspend(struct device *dev)
> +{
> +       struct amba_device *adev = to_amba_device(dev);
> +       struct etm_drvdata *drvdata = amba_get_drvdata(adev);

I think you could replace the above two lines with:

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 amba_device *adev = to_amba_device(dev);
> +       struct etm_drvdata *drvdata = amba_get_drvdata(adev);

I think you could replace the above two lines with:

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 +1921,7 @@ static struct amba_driver etm_driver = {
>         .drv = {
>                 .name   = "coresight-etm3x",
>                 .owner  = THIS_MODULE,
> +               .pm     = &etm_dev_pm_ops,
>         },
>         .probe          = etm_probe,
>         .remove         = etm_remove,
> --
> 1.9.3
>

With the minor changes suggested.

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