by Anshuman Khandual

[permalink] [raw]

Subject: Re: [PATCH V2 3/5] coresight: etm4x: Drop pid argument from etm4_probe()

On 3/31/23 16:36, Suzuki K Poulose wrote:
> On 27/03/2023 06:05, Anshuman Khandual wrote:
>> Coresight device pid can be retrieved from its iomem base address, which is
>> stored in 'struct etm4x_drvdata'. This drops pid argument from etm4_probe()
>> and 'struct etm4_init_arg'. Instead etm4_check_arch_features() derives the
>> coresight device pid with a new helper coresight_get_pid(), right before it
>> is consumed in etm4_hisi_match_pid().
>>
>> Cc: Mathieu Poirier <[email protected]>
>> Cc: Suzuki K Poulose <[email protected]>
>> Cc: Mike Leach <[email protected]>
>> Cc: Leo Yan <[email protected]>
>> Cc: [email protected]
>> Cc: [email protected]
>> Cc: [email protected]
>> Signed-off-by: Anshuman Khandual <[email protected]>
>> ---
>> .../coresight/coresight-etm4x-core.c          | 21 +++++++------------
>> include/linux/coresight.h                     | 12 +++++++++++
>> 2 files changed, 20 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> index 5d77571a8df9..3521838ab4fb 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> @@ -66,7 +66,6 @@ static u64 etm4_get_access_type(struct etmv4_config *config);
>> static enum cpuhp_state hp_online;
>> struct etm4_init_arg {
>> -    unsigned int        pid;
>>       struct device        *dev;
>>       struct csdev_access    *csa;
>> };
>> @@ -370,8 +369,10 @@ static void etm4_disable_arch_specific(struct etmv4_drvdata *drvdata)
>> }
>> static void etm4_check_arch_features(struct etmv4_drvdata *drvdata,
>> -                      unsigned int id)
>> +                     struct csdev_access *csa)
>> {
>> +    unsigned int id = coresight_get_pid(csa);
>> +
>
> This throws up the following error on an ETE.
>
> ete: trying to read unsupported register @fe0
>
> So, I guess this must be performed only for iomem based
> devices. System instruction based device must be identified
> by MIDR_EL1/REVIDR_EL1 if needed for specific erratum.
> This is not required now. So, we could bail out early
> if we are system instruction based device.

Will bail out on non iomem devices via drvdata->base address switch.

--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -373,9 +373,10 @@ static void etm4_disable_arch_specific(struct etmv4_drvdata *drvdata)
static void etm4_check_arch_features(struct etmv4_drvdata *drvdata,
struct csdev_access *csa)
{
- unsigned int id = coresight_get_pid(csa);
+ if (!drvdata->base)
+ return;

- if (etm4_hisi_match_pid(id))
+ if (etm4_hisi_match_pid(coresight_get_pid(csa)))
set_bit(ETM4_IMPDEF_HISI_CORE_COMMIT, drvdata->arch_features);
}
#else

>
>
>>       if (etm4_hisi_match_pid(id))
>>           set_bit(ETM4_IMPDEF_HISI_CORE_COMMIT, drvdata->arch_features);
>> }
>> @@ -385,7 +386,7 @@ static void etm4_disable_arch_specific(struct etmv4_drvdata *drvdata)
>> }
>> static void etm4_check_arch_features(struct etmv4_drvdata *drvdata,
>> -                     unsigned int id)
>> +                     struct csdev_access *csa)
>> {
>> }
>> #endif /* CONFIG_ETM4X_IMPDEF_FEATURE */
>> @@ -1165,7 +1166,7 @@ static void etm4_init_arch_data(void *info)
>>       etm4_os_unlock_csa(drvdata, csa);
>>       etm4_cs_unlock(drvdata, csa);
>> -    etm4_check_arch_features(drvdata, init_arg->pid);
>> +    etm4_check_arch_features(drvdata, csa);
>>       /* find all capabilities of the tracing unit */
>>       etmidr0 = etm4x_relaxed_read32(csa, TRCIDR0);
>> @@ -2048,7 +2049,7 @@ static int etm4_add_coresight_dev(struct etm4_init_arg *init_arg)
>>       return 0;
>> }
>> -static int etm4_probe(struct device *dev, u32 etm_pid)
>> +static int etm4_probe(struct device *dev)
>> {
>>       struct etmv4_drvdata *drvdata = dev_get_drvdata(dev);
>>       struct csdev_access access = { 0 };
>> @@ -2077,7 +2078,6 @@ static int etm4_probe(struct device *dev, u32 etm_pid)
>>       init_arg.dev = dev;
>>       init_arg.csa = &access;
>> -    init_arg.pid = etm_pid;
>>       /*
>>        * Serialize against CPUHP callbacks to avoid race condition
>> @@ -2124,7 +2124,7 @@ static int etm4_probe_amba(struct amba_device *adev, const struct amba_id *id)
>>       drvdata->base = base;
>>       dev_set_drvdata(dev, drvdata);
>> -    ret = etm4_probe(dev, id->id);
>> +    ret = etm4_probe(dev);
>>       if (!ret)
>>           pm_runtime_put(&adev->dev);
>> @@ -2146,12 +2146,7 @@ static int etm4_probe_platform_dev(struct platform_device *pdev)
>>       pm_runtime_set_active(&pdev->dev);
>>       pm_runtime_enable(&pdev->dev);
>> -    /*
>> -     * System register based devices could match the
>> -     * HW by reading appropriate registers on the HW
>> -     * and thus we could skip the PID.
>> -     */
>> -    ret = etm4_probe(&pdev->dev, 0);
>> +    ret = etm4_probe(&pdev->dev);
>>       pm_runtime_put(&pdev->dev);
>>       return ret;
>> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
>> index f19a47b9bb5a..f85b041ea475 100644
>> --- a/include/linux/coresight.h
>> +++ b/include/linux/coresight.h
>> @@ -370,6 +370,18 @@ static inline u32 csdev_access_relaxed_read32(struct csdev_access *csa,
>>       return csa->read(offset, true, false);
>> }
>> +#define CORESIGHT_PIDRn(i)    (0xFE0 + ((i) * 4))
>> +
>> +static inline u32 coresight_get_pid(struct csdev_access *csa)
>> +{
>> +    u32 i, pid = 0;
>> +
>> +    for (i = 0; i < 4; i++)
>> +        pid |= csdev_access_relaxed_read32(csa, CORESIGHT_PIDRn(i)) << (i * 8);
>
> Given the above, we could make this iomem specific.

We could change coresight_get_pid() to take iomem base address instead
and fetch the pid. But is not the existing csdev_access based approach
better and more generic ?

#define CORESIGHT_PIDRn(i) (0xFE0 + ((i) * 4))

static inline u32 coresight_get_pid(void __iomem *base)
{
u32 i, pid = 0;

for (i = 0; i < 4; i++)
pid |= readl(base + CORESIGHT_PIDRn(i)) << (i * 8);

return pid;
}

2023-05-17 09:43:46

by Suzuki K Poulose

[permalink] [raw]

Subject: Re: [PATCH V2 3/5] coresight: etm4x: Drop pid argument from etm4_probe()

On 17/05/2023 05:32, Anshuman Khandual wrote:
>
>
> On 3/31/23 16:36, Suzuki K Poulose wrote:
>> On 27/03/2023 06:05, Anshuman Khandual wrote:
>>> Coresight device pid can be retrieved from its iomem base address, which is
>>> stored in 'struct etm4x_drvdata'. This drops pid argument from etm4_probe()
>>> and 'struct etm4_init_arg'. Instead etm4_check_arch_features() derives the
>>> coresight device pid with a new helper coresight_get_pid(), right before it
>>> is consumed in etm4_hisi_match_pid().
>>>
>>> Cc: Mathieu Poirier <[email protected]>
>>> Cc: Suzuki K Poulose <[email protected]>
>>> Cc: Mike Leach <[email protected]>
>>> Cc: Leo Yan <[email protected]>
>>> Cc: [email protected]
>>> Cc: [email protected]
>>> Cc: [email protected]
>>> Signed-off-by: Anshuman Khandual <[email protected]>
>>> ---
>>> .../coresight/coresight-etm4x-core.c          | 21 +++++++------------
>>> include/linux/coresight.h                     | 12 +++++++++++
>>> 2 files changed, 20 insertions(+), 13 deletions(-)
>>>
>>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>> index 5d77571a8df9..3521838ab4fb 100644
>>> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>>> @@ -66,7 +66,6 @@ static u64 etm4_get_access_type(struct etmv4_config *config);
>>> static enum cpuhp_state hp_online;
>>> struct etm4_init_arg {
>>> -    unsigned int        pid;
>>>       struct device        *dev;
>>>       struct csdev_access    *csa;
>>> };
>>> @@ -370,8 +369,10 @@ static void etm4_disable_arch_specific(struct etmv4_drvdata *drvdata)
>>> }
>>> static void etm4_check_arch_features(struct etmv4_drvdata *drvdata,
>>> -                      unsigned int id)
>>> +                     struct csdev_access *csa)
>>> {
>>> +    unsigned int id = coresight_get_pid(csa);
>>> +
>>
>> This throws up the following error on an ETE.
>>
>> ete: trying to read unsupported register @fe0
>>
>> So, I guess this must be performed only for iomem based
>> devices. System instruction based device must be identified
>> by MIDR_EL1/REVIDR_EL1 if needed for specific erratum.
>> This is not required now. So, we could bail out early
>> if we are system instruction based device.
>
> Will bail out on non iomem devices via drvdata->base address switch.
>
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -373,9 +373,10 @@ static void etm4_disable_arch_specific(struct etmv4_drvdata *drvdata)
> static void etm4_check_arch_features(struct etmv4_drvdata *drvdata,
> struct csdev_access *csa)
> {
> - unsigned int id = coresight_get_pid(csa);
> + if (!drvdata->base)
> + return;

I would use !csa->io_mem to be more readerf friendly.

>
> - if (etm4_hisi_match_pid(id))
> + if (etm4_hisi_match_pid(coresight_get_pid(csa)))
> set_bit(ETM4_IMPDEF_HISI_CORE_COMMIT, drvdata->arch_features);
> }
> #else
>
>>
>>
>>>       if (etm4_hisi_match_pid(id))
>>>           set_bit(ETM4_IMPDEF_HISI_CORE_COMMIT, drvdata->arch_features);
>>> }
>>> @@ -385,7 +386,7 @@ static void etm4_disable_arch_specific(struct etmv4_drvdata *drvdata)
>>> }
>>> static void etm4_check_arch_features(struct etmv4_drvdata *drvdata,
>>> -                     unsigned int id)
>>> +                     struct csdev_access *csa)
>>> {
>>> }
>>> #endif /* CONFIG_ETM4X_IMPDEF_FEATURE */
>>> @@ -1165,7 +1166,7 @@ static void etm4_init_arch_data(void *info)
>>>       etm4_os_unlock_csa(drvdata, csa);
>>>       etm4_cs_unlock(drvdata, csa);
>>> -    etm4_check_arch_features(drvdata, init_arg->pid);
>>> +    etm4_check_arch_features(drvdata, csa);
>>>       /* find all capabilities of the tracing unit */
>>>       etmidr0 = etm4x_relaxed_read32(csa, TRCIDR0);
>>> @@ -2048,7 +2049,7 @@ static int etm4_add_coresight_dev(struct etm4_init_arg *init_arg)
>>>       return 0;
>>> }
>>> -static int etm4_probe(struct device *dev, u32 etm_pid)
>>> +static int etm4_probe(struct device *dev)
>>> {
>>>       struct etmv4_drvdata *drvdata = dev_get_drvdata(dev);
>>>       struct csdev_access access = { 0 };
>>> @@ -2077,7 +2078,6 @@ static int etm4_probe(struct device *dev, u32 etm_pid)
>>>       init_arg.dev = dev;
>>>       init_arg.csa = &access;
>>> -    init_arg.pid = etm_pid;
>>>       /*
>>>        * Serialize against CPUHP callbacks to avoid race condition
>>> @@ -2124,7 +2124,7 @@ static int etm4_probe_amba(struct amba_device *adev, const struct amba_id *id)
>>>       drvdata->base = base;
>>>       dev_set_drvdata(dev, drvdata);
>>> -    ret = etm4_probe(dev, id->id);
>>> +    ret = etm4_probe(dev);
>>>       if (!ret)
>>>           pm_runtime_put(&adev->dev);
>>> @@ -2146,12 +2146,7 @@ static int etm4_probe_platform_dev(struct platform_device *pdev)
>>>       pm_runtime_set_active(&pdev->dev);
>>>       pm_runtime_enable(&pdev->dev);
>>> -    /*
>>> -     * System register based devices could match the
>>> -     * HW by reading appropriate registers on the HW
>>> -     * and thus we could skip the PID.
>>> -     */
>>> -    ret = etm4_probe(&pdev->dev, 0);
>>> +    ret = etm4_probe(&pdev->dev);
>>>       pm_runtime_put(&pdev->dev);
>>>       return ret;
>>> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
>>> index f19a47b9bb5a..f85b041ea475 100644
>>> --- a/include/linux/coresight.h
>>> +++ b/include/linux/coresight.h
>>> @@ -370,6 +370,18 @@ static inline u32 csdev_access_relaxed_read32(struct csdev_access *csa,
>>>       return csa->read(offset, true, false);
>>> }
>>> +#define CORESIGHT_PIDRn(i)    (0xFE0 + ((i) * 4))
>>> +
>>> +static inline u32 coresight_get_pid(struct csdev_access *csa)
>>> +{
>>> +    u32 i, pid = 0;
>>> +
>>> +    for (i = 0; i < 4; i++)
>>> +        pid |= csdev_access_relaxed_read32(csa, CORESIGHT_PIDRn(i)) << (i * 8);
>>
>> Given the above, we could make this iomem specific.
>
> We could change coresight_get_pid() to take iomem base address instead
> and fetch the pid. But is not the existing csdev_access based approach
> better and more generic ?

Yes, true, lets leave it with csdev_access, as it is coresight specific
and not ETMv4.

Cheers
Suzuki