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Message-ID: <CANLsYky8MKh_7ZgSiqekAxXmMm5t4mEAy=mAEtAiXTiqHcgynA@mail.gmail.com>
Date:	Thu, 4 Aug 2016 11:15:49 -0600
From:	Mathieu Poirier <mathieu.poirier@...aro.org>
To:	Sudeep Holla <sudeep.holla@....com>
Cc:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] coresight: fix handling of ETM trace register
 access via sysfs

On 4 August 2016 at 10:22, Sudeep Holla <sudeep.holla@....com> wrote:
> The ETM registers are classified into 2 categories: trace and management.
> The core power domain contains most of the trace unit logic including
> all(except TRCOSLAR and TRCOSLSR) the trace registers. The debug power
> domain contains the external debugger interface including all management
> registers.
>
> This patch adds coresight unit specific function coresight_simple_func
> which can be used for ETM trace registers by providing a ETM specific
> read function which does smp cross call to ensure the trace core is
> powered up before the register is accessed.
>
> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> ---
>  drivers/hwtracing/coresight/coresight-etb10.c      |  2 +-
>  .../hwtracing/coresight/coresight-etm3x-sysfs.c    |  2 +-
>  .../hwtracing/coresight/coresight-etm4x-sysfs.c    | 62 ++++++++++++++++------
>  drivers/hwtracing/coresight/coresight-priv.h       |  9 +++-
>  drivers/hwtracing/coresight/coresight-stm.c        |  2 +-
>  drivers/hwtracing/coresight/coresight-tmc.c        |  2 +-
>  6 files changed, 57 insertions(+), 22 deletions(-)
>
> Changes v1->v2:
>         - s/etmv4_reg/etmv4_reg/
>         - s/etmv4_chk_trace_reg_access/etmv4_cross_read/
>         - s/coresight_etm4x_trace_reg_func/coresight_etm4x_cross_read/
>         - Removed stale macro defination
>         - Added a comment mentioning that the smp cross reading of the
>           trace registers guarantees the core power domain is enabled.
>
> diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
> index 8a4927ca9181..d7325c6534ad 100644
> --- a/drivers/hwtracing/coresight/coresight-etb10.c
> +++ b/drivers/hwtracing/coresight/coresight-etb10.c
> @@ -559,7 +559,7 @@ static const struct file_operations etb_fops = {
>  };
>
>  #define coresight_etb10_simple_func(name, offset)                       \
> -       coresight_simple_func(struct etb_drvdata, name, offset)
> +       coresight_simple_func(struct etb_drvdata, NULL, name, offset)
>
>  coresight_etb10_simple_func(rdp, ETB_RAM_DEPTH_REG);
>  coresight_etb10_simple_func(sts, ETB_STATUS_REG);
> diff --git a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> index 02d4b629891f..4856c8098416 100644
> --- a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> +++ b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> @@ -1222,7 +1222,7 @@ static struct attribute *coresight_etm_attrs[] = {
>  };
>
>  #define coresight_etm3x_simple_func(name, offset)                      \
> -       coresight_simple_func(struct etm_drvdata, name, offset)
> +       coresight_simple_func(struct etm_drvdata, NULL, name, offset)
>
>  coresight_etm3x_simple_func(etmccr, ETMCCR);
>  coresight_etm3x_simple_func(etmccer, ETMCCER);
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> index 7c84308c5564..fd7ff613db17 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> @@ -2039,15 +2039,42 @@ static struct attribute *coresight_etmv4_attrs[] = {
>         NULL,
>  };
>
> +struct etmv4_reg {
> +       void __iomem *addr;
> +       u32 data;
> +};
> +
> +static void do_smp_cross_read(void *data)
> +{
> +       struct etmv4_reg *reg = data;
> +
> +       reg->data = readl_relaxed(reg->addr);
> +}
> +
> +static u32 etmv4_cross_read(const struct device *dev, u32 offset)
> +{
> +       struct etmv4_drvdata *drvdata = dev_get_drvdata(dev);
> +       struct etmv4_reg reg;
> +
> +       reg.addr = drvdata->base + offset;
> +       /*
> +        * smp cross call ensures the CPU will be powered up before
> +        * accessing the ETMv4 trace core registers
> +        */
> +       smp_call_function_single(drvdata->cpu, do_smp_cross_read, &reg, 1);
> +       return reg.data;
> +}
> +
>  #define coresight_etm4x_simple_func(name, offset)                      \
> -       coresight_simple_func(struct etmv4_drvdata, name, offset)
> +       coresight_simple_func(struct etmv4_drvdata, NULL, name, offset)
> +
> +#define coresight_etm4x_cross_read(name, offset)                       \
> +       coresight_simple_func(struct etmv4_drvdata, etmv4_cross_read,   \
> +                             name, offset)
>
> -coresight_etm4x_simple_func(trcoslsr, TRCOSLSR);
>  coresight_etm4x_simple_func(trcpdcr, TRCPDCR);
>  coresight_etm4x_simple_func(trcpdsr, TRCPDSR);
>  coresight_etm4x_simple_func(trclsr, TRCLSR);
> -coresight_etm4x_simple_func(trcconfig, TRCCONFIGR);
> -coresight_etm4x_simple_func(trctraceid, TRCTRACEIDR);
>  coresight_etm4x_simple_func(trcauthstatus, TRCAUTHSTATUS);
>  coresight_etm4x_simple_func(trcdevid, TRCDEVID);
>  coresight_etm4x_simple_func(trcdevtype, TRCDEVTYPE);
> @@ -2055,6 +2082,9 @@ coresight_etm4x_simple_func(trcpidr0, TRCPIDR0);
>  coresight_etm4x_simple_func(trcpidr1, TRCPIDR1);
>  coresight_etm4x_simple_func(trcpidr2, TRCPIDR2);
>  coresight_etm4x_simple_func(trcpidr3, TRCPIDR3);
> +coresight_etm4x_cross_read(trcoslsr, TRCOSLSR);
> +coresight_etm4x_cross_read(trcconfig, TRCCONFIGR);
> +coresight_etm4x_cross_read(trctraceid, TRCTRACEIDR);
>
>  static struct attribute *coresight_etmv4_mgmt_attrs[] = {
>         &dev_attr_trcoslsr.attr,
> @@ -2073,19 +2103,19 @@ static struct attribute *coresight_etmv4_mgmt_attrs[] = {
>         NULL,
>  };
>
> -coresight_etm4x_simple_func(trcidr0, TRCIDR0);
> -coresight_etm4x_simple_func(trcidr1, TRCIDR1);
> -coresight_etm4x_simple_func(trcidr2, TRCIDR2);
> -coresight_etm4x_simple_func(trcidr3, TRCIDR3);
> -coresight_etm4x_simple_func(trcidr4, TRCIDR4);
> -coresight_etm4x_simple_func(trcidr5, TRCIDR5);
> +coresight_etm4x_cross_read(trcidr0, TRCIDR0);
> +coresight_etm4x_cross_read(trcidr1, TRCIDR1);
> +coresight_etm4x_cross_read(trcidr2, TRCIDR2);
> +coresight_etm4x_cross_read(trcidr3, TRCIDR3);
> +coresight_etm4x_cross_read(trcidr4, TRCIDR4);
> +coresight_etm4x_cross_read(trcidr5, TRCIDR5);
>  /* trcidr[6,7] are reserved */
> -coresight_etm4x_simple_func(trcidr8, TRCIDR8);
> -coresight_etm4x_simple_func(trcidr9, TRCIDR9);
> -coresight_etm4x_simple_func(trcidr10, TRCIDR10);
> -coresight_etm4x_simple_func(trcidr11, TRCIDR11);
> -coresight_etm4x_simple_func(trcidr12, TRCIDR12);
> -coresight_etm4x_simple_func(trcidr13, TRCIDR13);
> +coresight_etm4x_cross_read(trcidr8, TRCIDR8);
> +coresight_etm4x_cross_read(trcidr9, TRCIDR9);
> +coresight_etm4x_cross_read(trcidr10, TRCIDR10);
> +coresight_etm4x_cross_read(trcidr11, TRCIDR11);
> +coresight_etm4x_cross_read(trcidr12, TRCIDR12);
> +coresight_etm4x_cross_read(trcidr13, TRCIDR13);
>
>  static struct attribute *coresight_etmv4_trcidr_attrs[] = {
>         &dev_attr_trcidr0.attr,
> diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
> index decfd52b5dc3..39841d1f58e0 100644
> --- a/drivers/hwtracing/coresight/coresight-priv.h
> +++ b/drivers/hwtracing/coresight/coresight-priv.h
> @@ -38,14 +38,19 @@
>  #define ETM_MODE_EXCL_KERN     BIT(30)
>  #define ETM_MODE_EXCL_USER     BIT(31)
>
> -#define coresight_simple_func(type, name, offset)                      \
> +typedef u32 (*coresight_read_fn)(const struct device *, u32 offset);
> +#define coresight_simple_func(type, func, name, offset)                        \
>  static ssize_t name##_show(struct device *_dev,                                \
>                            struct device_attribute *attr, char *buf)    \
>  {                                                                      \
>         type *drvdata = dev_get_drvdata(_dev->parent);                  \
> +       coresight_read_fn fn = func;                                    \
>         u32 val;                                                        \
>         pm_runtime_get_sync(_dev->parent);                              \
> -       val = readl_relaxed(drvdata->base + offset);                    \
> +       if (fn)                                                         \
> +               val = fn(_dev->parent, offset);                         \
> +       else                                                            \
> +               val = readl_relaxed(drvdata->base + offset);            \
>         pm_runtime_put_sync(_dev->parent);                              \
>         return scnprintf(buf, PAGE_SIZE, "0x%x\n", val);                \
>  }                                                                      \
> diff --git a/drivers/hwtracing/coresight/coresight-stm.c b/drivers/hwtracing/coresight/coresight-stm.c
> index 819629aed2f7..7949f0f6744a 100644
> --- a/drivers/hwtracing/coresight/coresight-stm.c
> +++ b/drivers/hwtracing/coresight/coresight-stm.c
> @@ -635,7 +635,7 @@ static ssize_t traceid_store(struct device *dev,
>  static DEVICE_ATTR_RW(traceid);
>
>  #define coresight_stm_simple_func(name, offset)        \
> -       coresight_simple_func(struct stm_drvdata, name, offset)
> +       coresight_simple_func(struct stm_drvdata, NULL, name, offset)
>
>  coresight_stm_simple_func(tcsr, STMTCSR);
>  coresight_stm_simple_func(tsfreqr, STMTSFREQR);
> diff --git a/drivers/hwtracing/coresight/coresight-tmc.c b/drivers/hwtracing/coresight/coresight-tmc.c
> index 4cbcaf93c9d9..a4748630f5d6 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc.c
> @@ -218,7 +218,7 @@ static enum tmc_mem_intf_width tmc_get_memwidth(u32 devid)
>  }
>
>  #define coresight_tmc_simple_func(name, offset)                        \
> -       coresight_simple_func(struct tmc_drvdata, name, offset)
> +       coresight_simple_func(struct tmc_drvdata, NULL, name, offset)
>
>  coresight_tmc_simple_func(rsz, TMC_RSZ);
>  coresight_tmc_simple_func(sts, TMC_STS);
> --
> 2.7.4
>

Applied - thanks.
Mathieu

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