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

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Date:   Thu, 25 May 2023 23:36:11 +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 23:21, Konrad Dybcio wrote:
> 
> 
> 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
Nevermind, brain too laggy ;)

Konrad
> 
> 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