Re: [PATCH 2/2] coresight: tmc: Add shutdown callback for TMC ETR/ETF

[Mike Leach <mike.leach@linaro.org>]

Hi,

On Mon, 1 Jun 2020 at 09:02, Sai Prakash Ranjan
<saiprakash.ranjan@codeaurora.org> wrote:
>
> Implement a shutdown callback to ensure ETR/ETF hardware is
> properly shutdown in reboot/shutdown path. This is required
> for ETR/ETF which has SMMU address translation enabled like
> on SC7180 SoC and few others. If the hardware is still accessing
> memory after SMMU translation is disabled as part of SMMU
> shutdown callback in system reboot or shutdown path, then
> IOVAs(I/O virtual address) which it was using will go on the bus
> as the physical addresses which might result in unknown crashes
> (NoC/interconnect errors). So we make sure from this shutdown
> callback that the ETR/ETF is shutdown before SMMU translation is
> disabled and device_link in SMMU driver will take care of ordering
> of shutdown callbacks such that SMMU shutdown callback is not
> called before any of its consumer shutdown callbacks.
>
> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
> ---
>  .../hwtracing/coresight/coresight-tmc-etf.c   |  4 +--
>  .../hwtracing/coresight/coresight-tmc-etr.c   |  2 +-
>  drivers/hwtracing/coresight/coresight-tmc.c   | 29 +++++++++++++++++++
>  drivers/hwtracing/coresight/coresight-tmc.h   |  3 ++
>  4 files changed, 35 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> index 36cce2bfb744..cba3e7592820 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> @@ -85,7 +85,7 @@ static void __tmc_etb_disable_hw(struct tmc_drvdata *drvdata)
>         CS_LOCK(drvdata->base);
>  }
>
> -static void tmc_etb_disable_hw(struct tmc_drvdata *drvdata)
> +void tmc_etb_disable_hw(struct tmc_drvdata *drvdata)
>  {
>         __tmc_etb_disable_hw(drvdata);
>         coresight_disclaim_device(drvdata->base);
> @@ -118,7 +118,7 @@ static int tmc_etf_enable_hw(struct tmc_drvdata *drvdata)
>         return 0;
>  }
>
> -static void tmc_etf_disable_hw(struct tmc_drvdata *drvdata)
> +void tmc_etf_disable_hw(struct tmc_drvdata *drvdata)
>  {
>         CS_UNLOCK(drvdata->base);
>
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index 625882bc8b08..b29c2db94d96 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> @@ -1110,7 +1110,7 @@ static void __tmc_etr_disable_hw(struct tmc_drvdata *drvdata)
>
>  }
>
> -static void tmc_etr_disable_hw(struct tmc_drvdata *drvdata)
> +void tmc_etr_disable_hw(struct tmc_drvdata *drvdata)
>  {
>         __tmc_etr_disable_hw(drvdata);
>         /* Disable CATU device if this ETR is connected to one */
> diff --git a/drivers/hwtracing/coresight/coresight-tmc.c b/drivers/hwtracing/coresight/coresight-tmc.c
> index 5a271ebc4585..7e687a356fe0 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc.c
> @@ -540,6 +540,34 @@ static int tmc_probe(struct amba_device *adev, const struct amba_id *id)
>         return ret;
>  }
>
> +static void tmc_shutdown(struct amba_device *adev)
> +{
> +       struct tmc_drvdata *drvdata = amba_get_drvdata(adev);
> +

Take drvdata->spinlock here? The tmc_xxx_disable_hw functions are
normally called with the spinlock claimed.

> +       if (!drvdata->enable)

As per previous patch drvdata->mode can be used here.

Regards

Mike

> +               goto out;
> +
> +       /*
> +        * We do not care about the active trace sessions here
> +        * since the system is going down unlike remove callback,
> +        * just make sure that the hardware is shutdown.
> +        */
> +       switch (drvdata->config_type) {
> +       case TMC_CONFIG_TYPE_ETB:
> +               tmc_etb_disable_hw(drvdata);
> +               break;
> +       case TMC_CONFIG_TYPE_ETF:
> +               tmc_etf_disable_hw(drvdata);
> +               break;
> +       case TMC_CONFIG_TYPE_ETR:
> +               tmc_etr_disable_hw(drvdata);
> +       }
> +
> +out:
> +       misc_deregister(&drvdata->miscdev);
> +       coresight_unregister(drvdata->csdev);
> +}
> +
>  static const struct amba_id tmc_ids[] = {
>         CS_AMBA_ID(0x000bb961),
>         /* Coresight SoC 600 TMC-ETR/ETS */
> @@ -558,6 +586,7 @@ static struct amba_driver tmc_driver = {
>                 .suppress_bind_attrs = true,
>         },
>         .probe          = tmc_probe,
> +       .shutdown       = tmc_shutdown,
>         .id_table       = tmc_ids,
>  };
>  builtin_amba_driver(tmc_driver);
> diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
> index d156860495c7..f4f56c474e58 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc.h
> +++ b/drivers/hwtracing/coresight/coresight-tmc.h
> @@ -262,6 +262,8 @@ u32 tmc_get_memwidth_mask(struct tmc_drvdata *drvdata);
>  /* ETB/ETF functions */
>  int tmc_read_prepare_etb(struct tmc_drvdata *drvdata);
>  int tmc_read_unprepare_etb(struct tmc_drvdata *drvdata);
> +void tmc_etb_disable_hw(struct tmc_drvdata *drvdata);
> +void tmc_etf_disable_hw(struct tmc_drvdata *drvdata);
>  extern const struct coresight_ops tmc_etb_cs_ops;
>  extern const struct coresight_ops tmc_etf_cs_ops;
>
> @@ -270,6 +272,7 @@ ssize_t tmc_etb_get_sysfs_trace(struct tmc_drvdata *drvdata,
>  /* ETR functions */
>  int tmc_read_prepare_etr(struct tmc_drvdata *drvdata);
>  int tmc_read_unprepare_etr(struct tmc_drvdata *drvdata);
> +void tmc_etr_disable_hw(struct tmc_drvdata *drvdata);
>  extern const struct coresight_ops tmc_etr_cs_ops;
>  ssize_t tmc_etr_get_sysfs_trace(struct tmc_drvdata *drvdata,
>                                 loff_t pos, size_t len, char **bufpp);
> --
> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
> of Code Aurora Forum, hosted by The Linux Foundation
>


-- 
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK