[PATCH] soc: qcom: smem: introduce qcom_smem_virt_to_phys()

[PATCH] soc: qcom: smem: introduce qcom_smem_virt_to_phys()

[Alex Elder]

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.

Signed-off-by: Alex Elder <elder@linaro.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

Re: [PATCH] soc: qcom: smem: introduce qcom_smem_virt_to_phys()

[Bjorn Andersson]

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@linaro.org>

Regards,
Bjorn

> Signed-off-by: Alex Elder <elder@linaro.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
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH] soc: qcom: smem: introduce qcom_smem_virt_to_phys()

[Alex Elder]

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@linaro.org>
> 
> Regards,
> Bjorn
> 
>> Signed-off-by: Alex Elder <elder@linaro.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
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH] soc: qcom: smem: introduce qcom_smem_virt_to_phys()

[Chris Lew]

Hi Alex,

Minor comment.

On 4/25/2018 8:18 AM, 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.
> 
> Signed-off-by: Alex Elder <elder@linaro.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;
> +

We have a null pointer check for __smem here since it is called by 
external clients. This case should probably never happen though.

> +	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);

Thanks,
Chris

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH] soc: qcom: smem: introduce qcom_smem_virt_to_phys()

[Alex Elder]

On 04/25/2018 06:29 PM, Chris Lew wrote:
> Hi Alex,
> 
> Minor comment.
> 
> On 4/25/2018 8:18 AM, 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.
>>
>> Signed-off-by: Alex Elder <elder@linaro.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;
>> +
> 
> We have a null pointer check for __smem here since it is called by
> external clients. This case should probably never happen though.

I think you're suggesting that we should verify __smem is non-null first?

I'll make a few statements about that.
- This function can only be called with a pointer that was returned by
  qcom_smem_get().  That function won't return a valid pointer unless
  __smem was non-null.
- The only other way __smem would be null is if this were called after
  qcom_smem_remove(), which is erroneous.
- I think putting a null pointer check suggests that it's a condition
  that might be expected to occur.  If anything, I'd put an assertion
  in there (e.g. BUG_ON(!__smem)) but I don't think it's warranted.

I do understand why you suggest this--and it's a relatively harmless
check.   But I think it's better without it.

					-Alex


>> +    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);
> 
> Thanks,
> Chris
>