[PATCH 07/13] coresight: tmc: let runtime PM handle core clock

[Ulf Hansson]

On 17 April 2015 at 10:58, Linus Walleij <linus.walleij at linaro.org> wrote:
> This uses runtime PM to manage the PCLK ("amba_pclk") instead
> of screwing around with the framework by going in and taking
> a copy from the amba device. The amba bus core will uprepare
> and disable the clock when the device is unused when
> CONFIG_PM is selected, else the clock will be always on.
>
> Prior to this patch, as the AMBA primecell bus code enables
> the PCLK, it would be left on after probe as
> the clk_prepare_enable() and clk_disable_unprepare() was
> called and thus just increase and decreas the refcount by
> one, without it reaching zero and actually disabling the
> clock. Now the runtime PM callbacks will make sure the PCLK
> is properly disabled after probe.
>
> Signed-off-by: Linus Walleij <linus.walleij at linaro.org>

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

> ---
>  drivers/coresight/coresight-tmc.c | 20 +++++---------------
>  1 file changed, 5 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/coresight/coresight-tmc.c b/drivers/coresight/coresight-tmc.c
> index 3ff232f9ddf7..db917c70d2b3 100644
> --- a/drivers/coresight/coresight-tmc.c
> +++ b/drivers/coresight/coresight-tmc.c
> @@ -23,7 +23,7 @@
>  #include <linux/slab.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/spinlock.h>
> -#include <linux/clk.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/of.h>
>  #include <linux/coresight.h>
>  #include <linux/amba/bus.h>
> @@ -104,7 +104,6 @@ enum tmc_mem_intf_width {
>   * @dev:       the device entity associated to this component.
>   * @csdev:     component vitals needed by the framework.
>   * @miscdev:   specifics to handle "/dev/xyz.tmc" entry.
> - * @clk:       the clock this component is associated to.
>   * @spinlock:  only one at a time pls.
>   * @read_count:        manages preparation of buffer for reading.
>   * @buf:       area of memory where trace data get sent.
> @@ -120,7 +119,6 @@ struct tmc_drvdata {
>         struct device           *dev;
>         struct coresight_device *csdev;
>         struct miscdevice       miscdev;
> -       struct clk              *clk;
>         spinlock_t              spinlock;
>         int                     read_count;
>         bool                    reading;
> @@ -242,17 +240,14 @@ static void tmc_etf_enable_hw(struct tmc_drvdata *drvdata)
>
>  static int tmc_enable(struct tmc_drvdata *drvdata, enum tmc_mode mode)
>  {
> -       int ret;
>         unsigned long flags;
>
> -       ret = clk_prepare_enable(drvdata->clk);
> -       if (ret)
> -               return ret;
> +       pm_runtime_get_sync(drvdata->dev);
>
>         spin_lock_irqsave(&drvdata->spinlock, flags);
>         if (drvdata->reading) {
>                 spin_unlock_irqrestore(&drvdata->spinlock, flags);
> -               clk_disable_unprepare(drvdata->clk);
> +               pm_runtime_put(drvdata->dev);
>                 return -EBUSY;
>         }
>
> @@ -386,7 +381,7 @@ out:
>         drvdata->enable = false;
>         spin_unlock_irqrestore(&drvdata->spinlock, flags);
>
> -       clk_disable_unprepare(drvdata->clk);
> +       pm_runtime_put(drvdata->dev);
>
>         dev_info(drvdata->dev, "TMC disabled\n");
>  }
> @@ -644,11 +639,6 @@ static int tmc_probe(struct amba_device *adev, const struct amba_id *id)
>
>         spin_lock_init(&drvdata->spinlock);
>
> -       drvdata->clk = adev->pclk;
> -       ret = clk_prepare_enable(drvdata->clk);
> -       if (ret)
> -               return ret;
> -
>         devid = readl_relaxed(drvdata->base + CORESIGHT_DEVID);
>         drvdata->config_type = BMVAL(devid, 6, 7);
>
> @@ -663,7 +653,7 @@ static int tmc_probe(struct amba_device *adev, const struct amba_id *id)
>                 drvdata->size = readl_relaxed(drvdata->base + TMC_RSZ) * 4;
>         }
>
> -       clk_disable_unprepare(drvdata->clk);
> +       pm_runtime_put(&adev->dev);
>
>         if (drvdata->config_type == TMC_CONFIG_TYPE_ETR) {
>                 drvdata->vaddr = dma_alloc_coherent(dev, drvdata->size,
> --
> 1.9.3
>