Re: [PATCH v2 6/9] coresight-tpdm: Add node to set dsb programming mode

[Tao Zhang]

Hi Suzuki,

在 2/28/2023 7:35 PM, Suzuki K Poulose 写道:
> On 19/01/2023 07:41, Tao Zhang wrote:
> > Add node to set and show programming mode for TPDM DSB subunit.
> > Once the DSB programming mode is set, it will be written to the
> > register DSB_CR. Bit[10:9] of the DSB_CR register is used to set
> > the DSB test mode.
> >
> > Signed-off-by: Tao Zhang <quic_taozha@xxxxxxxxxxx>
> > Signed-off-by: Tao Zhang <taozha@xxxxxxxxxxxxxxxx>
> > ---
> >   drivers/hwtracing/coresight/coresight-tpdm.c | 45 
> > +++++++++++++++++++++++++++-
> >   drivers/hwtracing/coresight/coresight-tpdm.h | 12 ++++++++
> >   2 files changed, 56 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-tpdm.c 
> > b/drivers/hwtracing/coresight/coresight-tpdm.c
> > index 1dbb6c4..9126a37 100644
> > --- a/drivers/hwtracing/coresight/coresight-tpdm.c
> > +++ b/drivers/hwtracing/coresight/coresight-tpdm.c
> > @@ -4,6 +4,7 @@
> >    */
> >     #include <linux/amba/bus.h>
> > +#include <linux/bitfield.h>
> >   #include <linux/bitmap.h>
> >   #include <linux/coresight.h>
> >   #include <linux/coresight-pmu.h>
> > @@ -38,7 +39,7 @@ static umode_t tpdm_dsb_is_visible(struct kobject 
> > *kobj,
> >     static void tpdm_enable_dsb(struct tpdm_drvdata *drvdata)
> >   {
> > -    u32 val;
> > +    u32 val, mode;
> >         val = readl_relaxed(drvdata->base + TPDM_DSB_TIER);
> >       /* Set trigger timestamp */
> > @@ -58,6 +59,19 @@ static void tpdm_enable_dsb(struct tpdm_drvdata 
> > *drvdata)
> >         /* Set the enable bit of DSB control register to 1 */
> >       val = readl_relaxed(drvdata->base + TPDM_DSB_CR);
> > +    /* Set the cycle accurate mode */
> > +    mode = TPDM_DSB_MODE_CYCACC(drvdata->dsb->mode);
> > +    val &= ~TPDM_DSB_TEST_MODE;
> > +    val |= FIELD_PREP(TPDM_DSB_TEST_MODE, mode);
> > +    /* Set the byte lane for high-performance mode */
> > +    mode = TPDM_DSB_MODE_HPBYTESEL(drvdata->dsb->mode);
> > +    val &= ~TPDM_DSB_HPSEL;
> > +    val |= FIELD_PREP(TPDM_DSB_HPSEL, mode);
> > +    /* Set the performance mode */
> > +    if (drvdata->dsb->mode & TPDM_DSB_MODE_PERF)
> > +        val |= TPDM_DSB_MODE;
> > +    else
> > +        val &= ~TPDM_DSB_MODE;
>
> This looks a bit tricky to me. Please could you add documentation of
> the values supported under Documentation/ABI/testing/sysfs-....-
>
> Couldn't we provide separate handles for these "mode bits" ?
>
> cycacc
> perf
> hpsel

Sure, I will update this according to your advice in the next version of 
the patch.

Tao

> Suzuki
>
>
> >       val |= TPDM_DSB_CR_ENA;
> >       writel_relaxed(val, drvdata->base + TPDM_DSB_CR);
> >   }
> > @@ -257,6 +271,34 @@ static struct attribute_group tpdm_attr_grp = {
> >       .attrs = tpdm_attrs,
> >   };
> >   +static ssize_t dsb_mode_show(struct device *dev,
> > +                  struct device_attribute *attr,
> > +                  char *buf)
> > +{
> > +    struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
> > +
> > +    return sysfs_emit(buf, "%lx\n",
> > +             (unsigned long)drvdata->dsb->mode);
> > +}
> > +
> > +static ssize_t dsb_mode_store(struct device *dev,
> > +                   struct device_attribute *attr,
> > +                   const char *buf,
> > +                   size_t size)
> > +{
> > +    struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
> > +    unsigned long val;
> > +
> > +    if ((kstrtoul(buf, 0, &val)) || val < 0)
> > +        return -EINVAL;
> > +
> > +    spin_lock(&drvdata->spinlock);
> > +    drvdata->dsb->mode = val & TPDM_MODE_ALL;
> > +    spin_unlock(&drvdata->spinlock);
> > +    return size;
> > +}
> > +static DEVICE_ATTR_RW(dsb_mode);
> > +
> >   static ssize_t dsb_trig_type_show(struct device *dev,
> >                        struct device_attribute *attr,
> >                        char *buf)
> > @@ -327,6 +369,7 @@ static ssize_t dsb_trig_ts_store(struct device *dev,
> >   }
> >   static DEVICE_ATTR_RW(dsb_trig_ts);
> >   static struct attribute *tpdm_dsb_attrs[] = {
> > +    &dev_attr_dsb_mode.attr,
> >       &dev_attr_dsb_trig_ts.attr,
> >       &dev_attr_dsb_trig_type.attr,
> >       NULL,
> > diff --git a/drivers/hwtracing/coresight/coresight-tpdm.h 
> > b/drivers/hwtracing/coresight/coresight-tpdm.h
> > index 3ad1be5..b3ecb9f 100644
> > --- a/drivers/hwtracing/coresight/coresight-tpdm.h
> > +++ b/drivers/hwtracing/coresight/coresight-tpdm.h
> > @@ -19,6 +19,16 @@
> >   #define TPDM_DSB_XTRIG_TSENAB        BIT(1)
> >   /* Enable bit for DSB subunit trigger type */
> >   #define TPDM_DSB_TRIG_TYPE        BIT(12)
> > +/* Enable bit for DSB subunit perfmance mode */
> > +#define TPDM_DSB_MODE        BIT(1)
> > +
> > +/* DSB programming modes */
> > +#define TPDM_DSB_MODE_CYCACC(val)    (val & GENMASK(2, 0))
> > +#define TPDM_DSB_MODE_PERF        BIT(3)
> > +#define TPDM_DSB_MODE_HPBYTESEL(val)    (val & GENMASK(8, 4))
> > +#define TPDM_MODE_ALL            (0xFFFFFFF)
> > +#define TPDM_DSB_TEST_MODE        GENMASK(11, 9)
> > +#define TPDM_DSB_HPSEL        GENMASK(6, 2)
> >     /* TPDM integration test registers */
> >   #define TPDM_ITATBCNTRL        (0xEF0)
> > @@ -48,10 +58,12 @@
> >     /**
> >    * struct dsb_dataset - specifics associated to dsb dataset
> > + * @mode:             DSB programming mode
> >    * @trig_ts:          Enable/Disable trigger timestamp.
> >    * @trig_type:        Enable/Disable trigger type.
> >    */
> >   struct dsb_dataset {
> > +    u32                mode;
> >       bool            trig_ts;
> >       bool            trig_type;
> >   };