Re: [PATCH v5 3/3] coresight: tpda: add sysfs node to flush specific port

[Jie Gan <jie.gan@oss.qualcomm.com>]

On 12/19/2025 6:33 PM, Suzuki K Poulose wrote:
> On 19/12/2025 10:04, Jie Gan wrote:
>> From: Tao Zhang <tao.zhang@oss.qualcomm.com>
>>
>> Setting bit i in the TPDA_FLUSH_CR register initiates a flush request
>> for port i, forcing the data to synchronize and be transmitted to the
>> sink device.
>>
>> Signed-off-by: Tao Zhang <tao.zhang@oss.qualcomm.com>
>> Reviewed-by: James Clark <james.clark@linaro.org>
>> Co-developed-by: Jie Gan <jie.gan@oss.qualcomm.com>
>> Signed-off-by: Jie Gan <jie.gan@oss.qualcomm.com>
>> ---
>>   .../ABI/testing/sysfs-bus-coresight-devices-tpda   |  7 ++++
>>   drivers/hwtracing/coresight/coresight-tpda.c       | 49 ++++++++++++ 
>> ++++++++++
>>   drivers/hwtracing/coresight/coresight-tpda.h       |  1 +
>>   3 files changed, 57 insertions(+)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices- 
>> tpda b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpda
>> index a7855922328e..ef2804f87d1e 100644
>> --- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpda
>> +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpda
>> @@ -41,3 +41,10 @@ Contact:    Jinlong Mao 
>> <jinlong.mao@oss.qualcomm.com>, Tao Zhang <tao.zhang@oss.qu
>>   Description:
>>           (RW) Configure the CMB/MCMB channel mode for all enabled ports.
>>           Value 0 means raw channel mapping mode. Value 1 means 
>> channel pair marking mode.
>> +
>> +What:        /sys/bus/coresight/devices/<tpda-name>/port_flush_req
>> +Date:        December 2025
>> +KernelVersion:    6.19
>> +Contact:    Jinlong Mao <jinlong.mao@oss.qualcomm.com>, Tao Zhang 
>> <tao.zhang@oss.qualcomm.com>, Jie Gan <jie.gan@oss.qualcomm.com>
>> +Description:
>> +        (RW) Configure the bit i to requests a flush operation of 
>> port i on the TPDA.
>> diff --git a/drivers/hwtracing/coresight/coresight-tpda.c b/drivers/ 
>> hwtracing/coresight/coresight-tpda.c
>> index d378ff8ad77d..5b4a9e41b067 100644
>> --- a/drivers/hwtracing/coresight/coresight-tpda.c
>> +++ b/drivers/hwtracing/coresight/coresight-tpda.c
>> @@ -375,6 +375,45 @@ static ssize_t tpda_trig_sysfs_store(struct 
>> device *dev,
>>       return ret;
>>   }
>> +static ssize_t port_flush_req_show(struct device *dev,
>> +                   struct device_attribute *attr,
>> +                   char *buf)
>> +{
>> +    struct tpda_drvdata *drvdata = dev_get_drvdata(dev->parent);
>> +    unsigned long val;
>> +
>> +    if (!drvdata->csdev->refcnt)
>> +        return -EINVAL;
>> +
>> +    guard(spinlock)(&drvdata->spinlock);
>> +    val = readl_relaxed(drvdata->base + TPDA_FLUSH_CR);
>> +
>> +    return sysfs_emit(buf, "0x%lx\n", val);
>> +}
>> +
>> +static ssize_t port_flush_req_store(struct device *dev,
>> +                    struct device_attribute *attr,
>> +                    const char *buf,
>> +                    size_t size)
>> +{
>> +    struct tpda_drvdata *drvdata = dev_get_drvdata(dev->parent);
>> +    u32 val;
>> +
>> +    if (kstrtou32(buf, 0, &val))
>> +        return -EINVAL;
>> +
>> +    if (!drvdata->csdev->refcnt || !val)
>> +        return -EINVAL;
>> +
>> +    guard(spinlock)(&drvdata->spinlock);
>> +    CS_UNLOCK(drvdata->base);
>> +    writel_relaxed(val, drvdata->base + TPDA_FLUSH_CR);
>> +    CS_LOCK(drvdata->base);
>> +
>> +    return size;
>> +}
>> +static DEVICE_ATTR_RW(port_flush_req);
>> +
>>   static struct attribute *tpda_global_cr_attrs[] = {
>>       tpda_trig_sysfs_rw(global_flush_req, FLREQ),
>>       tpda_trig_sysfs_rw(freq_ts_enable, FREQTS),
>> @@ -385,13 +424,23 @@ static struct attribute *tpda_global_cr_attrs[] = {
>>       NULL,
>>   };
>> +static struct attribute *tpda_attrs[] = {
>> +    &dev_attr_port_flush_req.attr,
>> +    NULL,
>> +};
>> +
> 
> But why ? Why can't this be a part of the tpda_global_cr_attrs[] ?
> For that matter, why is tpda_global_cr_attrs named as such and why not
> tpda_attrs ?
> 

will move all attributes to tpda_attrs[].

Thanks,
Jie

> Suzuki
> 
>>   static struct attribute_group tpda_global_cr_attr_grp = {
>>       .attrs    = tpda_global_cr_attrs,
>>       .name    = "global_cr",
>>   };
>> +static struct attribute_group tpda_attr_grp = {
>> +    .attrs    = tpda_attrs,
>> +};
>> +
>>   static const struct attribute_group *tpda_attr_grps[] = {
>>       &tpda_global_cr_attr_grp,
>> +    &tpda_attr_grp,
>>       NULL,
>>   };
>> diff --git a/drivers/hwtracing/coresight/coresight-tpda.h b/drivers/ 
>> hwtracing/coresight/coresight-tpda.h
>> index 97e2729c15c9..ec93f9cb9648 100644
>> --- a/drivers/hwtracing/coresight/coresight-tpda.h
>> +++ b/drivers/hwtracing/coresight/coresight-tpda.h
>> @@ -10,6 +10,7 @@
>>   #define TPDA_Pn_CR(n)        (0x004 + (n * 4))
>>   #define TPDA_FPID_CR        (0x084)
>>   #define TPDA_SYNCR        (0x08C)
>> +#define TPDA_FLUSH_CR        (0x090)
>>   /* Cross trigger Global (all ports) flush request bit */
>>   #define TPDA_CR_FLREQ        BIT(0)
>>
>