Re: [PATCH v3 06/11] coresight-tpdm: Add node to set dsb programming mode

[Tao Zhang <quic_taozha@quicinc.com>]

Hi Suzuki,

On 3/23/2023 10:55 PM, Suzuki K Poulose wrote:
> On 23/03/2023 06:04, 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>
>> ---
>>   .../ABI/testing/sysfs-bus-coresight-devices-tpdm   | 10 ++++
>>   drivers/hwtracing/coresight/coresight-tpdm.c       | 62 
>> ++++++++++++++++++++++
>>   drivers/hwtracing/coresight/coresight-tpdm.h       | 13 +++++
>>   3 files changed, 85 insertions(+)
>>
>> diff --git 
>> a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm 
>> b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
>> index 27ce681..f13e282 100644
>> --- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
>> +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
>> @@ -35,3 +35,13 @@ Description:
>>           Accepts only one of the 2 values -  0 or 1.
>>           0 : Set the DSB trigger type to false
>>           1 : Set the DSB trigger type to true
>> +
>> +What: /sys/bus/coresight/devices/<tpdm-name>/dsb_mode
>> +Date:        March 2023
>> +KernelVersion    6.3
>> +Contact:    Jinlong Mao (QUIC) <quic_jinlmao@quicinc.com>, Tao Zhang 
>> (QUIC) <quic_taozha@quicinc.com>
>> +Description:
>> +        (Write) Set the mode of DSB tpdm. Read the mode of DSB
>> +        tpdm.
>> +
>> +        Accepts the value needs to be greater than 0.
>
> Please could you document the values ?
I will update this in the next patch series.
>
>> diff --git a/drivers/hwtracing/coresight/coresight-tpdm.c 
>> b/drivers/hwtracing/coresight/coresight-tpdm.c
>> index e28cf10..8cd822f 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>
>> @@ -51,6 +52,32 @@ static int tpdm_init_datasets(struct tpdm_drvdata 
>> *drvdata)
>>       return 0;
>>   }
>>   +static void set_dsb_cycacc_mode(struct tpdm_drvdata *drvdata, u32 
>> *val)
>> +{
>> +    u32 mode;
>> +
>> +    mode = TPDM_DSB_MODE_CYCACC(drvdata->dsb->mode);
>> +    *val &= ~TPDM_DSB_TEST_MODE;
>> +    *val |= FIELD_PREP(TPDM_DSB_TEST_MODE, mode);
>> +}
>> +
>> +static void set_dsb_hpsel_mode(struct tpdm_drvdata *drvdata, u32 *val)
>> +{
>> +    u32 mode;
>> +
>> +    mode = TPDM_DSB_MODE_HPBYTESEL(drvdata->dsb->mode);
>> +    *val &= ~TPDM_DSB_HPSEL;
>> +    *val |= FIELD_PREP(TPDM_DSB_HPSEL, mode);
>> +}
>> +
>> +static void set_dsb_perf_mode(struct tpdm_drvdata *drvdata, u32 *val)
>> +{
>> +    if (drvdata->dsb->mode & TPDM_DSB_MODE_PERF)
>> +        *val |= TPDM_DSB_CR_MODE;
>> +    else
>> +        *val &= ~TPDM_DSB_CR_MODE;
>> +}
>> +
>>   static void set_trigger_type(struct tpdm_drvdata *drvdata, u32 *val)
>>   {
>>       if (drvdata->dsb->trig_type)
>> @@ -72,6 +99,12 @@ static void tpdm_enable_dsb(struct tpdm_drvdata 
>> *drvdata)
>>       writel_relaxed(val, drvdata->base + TPDM_DSB_TIER);
>>         val = readl_relaxed(drvdata->base + TPDM_DSB_CR);
>> +    /* Set the cycle accurate mode */
>> +    set_dsb_cycacc_mode(drvdata, &val);
>> +    /* Set the byte lane for high-performance mode */
>> +    set_dsb_hpsel_mode(drvdata, &val);
>> +    /* Set the performance mode */
>> +    set_dsb_perf_mode(drvdata, &val);
>>       /* Set trigger type */
>>       set_trigger_type(drvdata, &val);
>>       /* Set the enable bit of DSB control register to 1 */
>> @@ -250,6 +283,34 @@ 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)
>> @@ -321,6 +382,7 @@ 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 68f33bd..8fee562 100644
>> --- a/drivers/hwtracing/coresight/coresight-tpdm.h
>> +++ b/drivers/hwtracing/coresight/coresight-tpdm.h
>> @@ -15,11 +15,22 @@
>>     /* Enable bit for DSB subunit */
>>   #define TPDM_DSB_CR_ENA        BIT(0)
>> +/* Enable bit for DSB subunit perfmance mode */
>> +#define TPDM_DSB_CR_MODE        BIT(1)
>>   /* Enable bit for DSB subunit trigger type */
>>   #define TPDM_DSB_CR_TRIG_TYPE        BIT(12)
>> +
>>   /* Enable bit for DSB subunit trigger timestamp */
>>   #define TPDM_DSB_TIER_XTRIG_TSENAB        BIT(1)
>>   +/* DSB programming modes */
>> +#define TPDM_DSB_MODE_CYCACC(val)    (val & GENMASK(2, 0))
>
> What do the values for the CYCACC mode mean ?

It means cycle accurate mode.  The targets may no longer have that mode. 
I will

make a final check and update this in the next patch series.

>
>> +#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)
>
> Again what do the values mean ? Even if the kernel doesn't use them
> it would be good to document it.

I will update this in the next patch series.


Tao

>
> Suzuki
>
>> +
>>   /* TPDM integration test registers */
>>   #define TPDM_ITATBCNTRL        (0xEF0)
>>   #define TPDM_ITCNTRL        (0xF00)
>> @@ -48,10 +59,12 @@
>>     /**
>>    * 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;
>>   };
>
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