linux-kernel - Re: [PATCH v4 3/5] soc: qcom: smem: introduce qcom_smem_get_soc

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Date:   Thu, 25 May 2023 19:33:25 -0700
From:   Bjorn Andersson <andersson@...nel.org>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>
Cc:     Robert Marko <robimarko@...il.com>, agross@...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 v4 3/5] soc: qcom: smem: introduce qcom_smem_get_soc_id()

On Fri, May 26, 2023 at 01:18:17AM +0200, Konrad Dybcio wrote:
> 
> 
> On 25.05.2023 23:02, 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 v4:
> > * Change helper name to qcom_smem_get_soc_id()
> > * Remove len and just pass NULL, that is sufficient here
> > 
> > Changes in v3:
> > * Change export to EXPORT_SYMBOL_GPL
> > * Use an argument for returning SoC ID
> > * Update kerneldoc
> > ---
> >  drivers/soc/qcom/smem.c       | 23 +++++++++++++++++++++++
> >  include/linux/soc/qcom/smem.h |  2 ++
> >  2 files changed, 25 insertions(+)
> > 
> > diff --git a/drivers/soc/qcom/smem.c b/drivers/soc/qcom/smem.c
> > index bc98520c4969..78cf79ea4924 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 +773,28 @@ phys_addr_t qcom_smem_virt_to_phys(void *p)
> >  }
> >  EXPORT_SYMBOL_GPL(qcom_smem_virt_to_phys);
> >  
> > +/**
> > + * qcom_smem_get_soc_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_soc_id(u32 *id)
> __le32 *id
> 

Why do you want this passed back to the user in little endian? When is
it not going to be compared to a cpu-endian constant?

> LGTM otherwise!
> 
> Konrad
> > +{
> > +	struct socinfo *info;
> > +
> > +	info = qcom_smem_get(QCOM_SMEM_HOST_ANY, SMEM_HW_SW_BUILD_ID, NULL);
> > +	if (IS_ERR(info))
> > +		return PTR_ERR(info);
> > +
> > +	*id = info->id;

This should be __le32_to_cpu() though...

Regards,
Bjorn

> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(qcom_smem_get_soc_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..223db6a9c733 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_soc_id(u32 *id);
> > +
> >  #endif