linux-kernel - Re: [PATCH v3 3/5] soc: qcom: smem: introduce qcom_smem_get_msm

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Date:   Thu, 25 May 2023 23:21:50 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Robert Marko <robimarko@...il.com>,
        Kathiravan T <quic_kathirav@...cinc.com>
Cc:     agross@...nel.org, andersson@...nel.org, ilia.lin@...nel.org,
        rafael@...nel.org, viresh.kumar@...aro.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-pm@...r.kernel.org, ansuelsmth@...il.com
Subject: Re: [PATCH v3 3/5] soc: qcom: smem: introduce qcom_smem_get_msm_id()



On 25.05.2023 17:03, Robert Marko wrote:
> On Thu, 25 May 2023 at 14:59, Kathiravan T <quic_kathirav@...cinc.com> wrote:
>>
>>
>> On 5/25/2023 5:39 PM, Robert Marko wrote:
>>> Introduce a helper to return the SoC SMEM ID, which is used to identify the
>>> exact SoC model as there may be differences in the same SoC family.
>>>
>>> Currently, cpufreq-nvmem does this completely in the driver and there has
>>> been more interest expresed for other drivers to use this information so
>>> lets expose a common helper to prevent redoing it in individual drivers
>>> since this field is present on every SMEM table version.
>>>
>>> Signed-off-by: Robert Marko <robimarko@...il.com>
>>> ---
>>> Changes in v3:
>>> * Change export to EXPORT_SYMBOL_GPL
>>> * Use an argument for returning SoC ID
>>> * Update kerneldoc
>>> ---
>>>   drivers/soc/qcom/smem.c       | 24 ++++++++++++++++++++++++
>>>   include/linux/soc/qcom/smem.h |  2 ++
>>>   2 files changed, 26 insertions(+)
>>>
>>> diff --git a/drivers/soc/qcom/smem.c b/drivers/soc/qcom/smem.c
>>> index bc98520c4969..185ed0da11a1 100644
>>> --- a/drivers/soc/qcom/smem.c
>>> +++ b/drivers/soc/qcom/smem.c
>>> @@ -14,6 +14,7 @@
>>>   #include <linux/sizes.h>
>>>   #include <linux/slab.h>
>>>   #include <linux/soc/qcom/smem.h>
>>> +#include <linux/soc/qcom/socinfo.h>
>>>
>>>   /*
>>>    * The Qualcomm shared memory system is a allocate only heap structure that
>>> @@ -772,6 +773,29 @@ phys_addr_t qcom_smem_virt_to_phys(void *p)
>>>   }
>>>   EXPORT_SYMBOL_GPL(qcom_smem_virt_to_phys);
>>>
>>> +/**
>>> + * qcom_smem_get_msm_id() - return the SoC ID
>>> + * @id:      On success, we return the SoC ID here.
>>> + *
>>> + * Look up SoC ID from HW/SW build ID and return it.
>>> + *
>>> + * Return: 0 on success, negative errno on failure.
>>> + */
>>> +int qcom_smem_get_msm_id(u32 *id)
>>
>>
>> I think, MSM  is not the only platform which will leverage this API.
>> qcom_smem_get_soc_id() / qcom_smem_get_cpu_id() would make more sense
>> than qcom_smem_get_msm_id() ?
> 
> I agree, qcom_smem_get_soc_id() sounds better to me as its not just MSM parts.
>>
>>
>>> +{
>>> +     size_t len;
>>> +     struct socinfo *info;
>>> +
>>> +     info = qcom_smem_get(QCOM_SMEM_HOST_ANY, SMEM_HW_SW_BUILD_ID, &len);
>>
>>
>> len is unused after this, can we just pass NULL? Did a quick check on
>> the code, if we pass the address, size of the item will be updated, else no.
> 
> Yes, indeed passing NULL works here for the simple case this helper is handling.
> Will address in v4.
Please also consider Bjorn's suggestion of using PTR_ERR

Konrad
> 
> Regards,
> Robert
>>
>>
>>> +     if (IS_ERR(info))
>>> +             return PTR_ERR(info);
>>> +
>>> +     *id = info->id;
>>> +
>>> +     return 0;
>>> +}
>>> +EXPORT_SYMBOL_GPL(qcom_smem_get_msm_id);
>>> +
>>>   static int qcom_smem_get_sbl_version(struct qcom_smem *smem)
>>>   {
>>>       struct smem_header *header;
>>> diff --git a/include/linux/soc/qcom/smem.h b/include/linux/soc/qcom/smem.h
>>> index 86e1b358688a..cb204ad6373c 100644
>>> --- a/include/linux/soc/qcom/smem.h
>>> +++ b/include/linux/soc/qcom/smem.h
>>> @@ -11,4 +11,6 @@ int qcom_smem_get_free_space(unsigned host);
>>>
>>>   phys_addr_t qcom_smem_virt_to_phys(void *p);
>>>
>>> +int qcom_smem_get_msm_id(u32 *id);
>>> +
>>>   #endif