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

[Tao Zhang <quic_taozha@quicinc.com>]

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@quicinc.com>
>> Signed-off-by: Tao Zhang <taozha@qti.qualcomm.com>
>> ---
>>   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;
>>   };
>