linux-kernel - Re: [PATCH] soc: qcom: smem: introduce qcom_smem_virt_to

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Date:   Wed, 25 Apr 2018 20:22:06 -0500
From:   Alex Elder <elder@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     andy.gross@...aro.org, clew@...eaurora.org, aneela@...eaurora.org,
        david.brown@...aro.org, linux-arm-msm@...r.kernel.org,
        linux-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] soc: qcom: smem: introduce qcom_smem_virt_to_phys()

On 04/25/2018 06:14 PM, Bjorn Andersson wrote:
> On Wed 25 Apr 08:18 PDT 2018, Alex Elder wrote:
> 
>> Create function qcom_smem_virt_to_phys(), which returns the physical
>> address corresponding to a given SMEM item's virtual address.  This
>> feature is required for a driver that will soon be out for review.
>>
> 
> It might be wise to turn the aux_base in smem_region into a phys_addr_t
> and then mask that with AUX_BASE_MASK before comparing with the entry's
> aux_base in qcom_smem_get_global(). But this will work fine until the
> day someone places smem above 4GB.

I thought of that but went for this for now, because it made for a
nice, concise change.  I agree with you though.

Thanks a lot for the quick review.

					-Alex

> Reviewed-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> 
> Regards,
> Bjorn
> 
>> Signed-off-by: Alex Elder <elder@...aro.org>
>> ---
>>  drivers/soc/qcom/smem.c       | 27 +++++++++++++++++++++++++++
>>  include/linux/soc/qcom/smem.h |  2 ++
>>  2 files changed, 29 insertions(+)
>>
>> diff --git a/drivers/soc/qcom/smem.c b/drivers/soc/qcom/smem.c
>> index 7d9a43da5084..70b2ee80d6bd 100644
>> --- a/drivers/soc/qcom/smem.c
>> +++ b/drivers/soc/qcom/smem.c
>> @@ -655,6 +655,33 @@ int qcom_smem_get_free_space(unsigned host)
>>  }
>>  EXPORT_SYMBOL(qcom_smem_get_free_space);
>>  
>> +/**
>> + * qcom_smem_virt_to_phys() - return the physical address associated
>> + * with an smem item pointer (previously returned by qcom_smem_get()
>> + * @p:	the virtual address to convert
>> + *
>> + * Returns 0 if the pointer provided is not within any smem region.
>> + */
>> +phys_addr_t qcom_smem_virt_to_phys(void *p)
>> +{
>> +	unsigned i;
>> +
>> +	for (i = 0; i < __smem->num_regions; i++) {
>> +		struct smem_region *region = &__smem->regions[i];
>> +
>> +		if (p < region->virt_base)
>> +			continue;
>> +		if (p < region->virt_base + region->size) {
>> +			u64 offset = p - region->virt_base;
>> +
>> +			return (phys_addr_t)region->aux_base + offset;
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL(qcom_smem_virt_to_phys);
>> +
>>  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 c1657ed27b30..86e1b358688a 100644
>> --- a/include/linux/soc/qcom/smem.h
>> +++ b/include/linux/soc/qcom/smem.h
>> @@ -9,4 +9,6 @@ void *qcom_smem_get(unsigned host, unsigned item, size_t *size);
>>  
>>  int qcom_smem_get_free_space(unsigned host);
>>  
>> +phys_addr_t qcom_smem_virt_to_phys(void *p);
>> +
>>  #endif
>> -- 
>> 2.14.1
>>
>> --
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