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

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Date:   Wed, 25 Apr 2018 16:14:24 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Alex Elder <elder@...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 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.

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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