Re: [PATCH 2/3] soc: qcom: smem: Support dynamic item limit

[Bjorn Andersson]

On Thu 17 Aug 18:15 PDT 2017, Chris Lew wrote:

> In V12 SMEM, SBL writes SMEM parameter information
> after the TOC. Use the SBL provided item count
> as the max item number.
> 
> Signed-off-by: Chris Lew <clew@xxxxxxxxxxxxxx>
> ---
>  drivers/soc/qcom/smem.c | 41 +++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 39 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/soc/qcom/smem.c b/drivers/soc/qcom/smem.c
> index fed2934d6bda..a51f4ba42173 100644
> --- a/drivers/soc/qcom/smem.c
> +++ b/drivers/soc/qcom/smem.c
> @@ -225,6 +225,24 @@ struct smem_private_entry {
>  #define SMEM_PRIVATE_CANARY	0xa5a5
>  
>  /**
> + * struct smem_info - smem region info located after the table of contents
> + * @magic:	magic number, must be SMEM_INFO_MAGIC
> + * @size:	size of the smem region
> + * @base_addr:	base address of the smem region
> + * @reserved: for now reserved entry
> + * @num_items: highest accepted item number

Try to make the indentation of the descriptions a little bit more
consistent.

> + */
> +struct smem_info {
> +	u8 magic[4];
> +	__le32 size;
> +	__le32 base_addr;

May I ask why you keep the size and address of SMEM here? Didn't we just
use that information to find this item?

> +	__le32 reserved;
> +	__le32 num_items;
> +};
> +
> +static const u8 SMEM_INFO_MAGIC[] = { 0x53, 0x49, 0x49, 0x49 }; /* SIII */
> +
> +/**
>   * struct smem_region - representation of a chunk of memory used for smem
>   * @aux_base:	identifier of aux_mem base
>   * @virt_base:	virtual base address of memory with this aux_mem identifier
> @@ -245,6 +263,7 @@ struct smem_region {
>   * @partitions:	list of pointers to partitions affecting the current
>   *		processor/host
>   * @cacheline:	list of cacheline sizes for each host
> + * @item_count: max accepted item number
>   * @num_regions: number of @regions
>   * @regions:	list of the memory regions defining the shared memory
>   */
> @@ -257,6 +276,7 @@ struct qcom_smem {
>  	size_t global_cacheline;
>  	struct smem_partition_header *partitions[SMEM_HOST_COUNT];
>  	size_t cacheline[SMEM_HOST_COUNT];
> +	u32 item_count;
>  
>  	unsigned num_regions;
>  	struct smem_region regions[0];
> @@ -388,7 +408,7 @@ static int qcom_smem_alloc_global(struct qcom_smem *smem,
>  	struct smem_header *header;
>  	struct smem_global_entry *entry;
>  
> -	if (WARN_ON(item >= SMEM_ITEM_COUNT))
> +	if (WARN_ON(item >= smem->item_count))
>  		return -EINVAL;
>  
>  	header = smem->regions[0].virt_base;
> @@ -473,7 +493,7 @@ static void *qcom_smem_get_global(struct qcom_smem *smem,
>  	u32 aux_base;
>  	unsigned i;
>  
> -	if (WARN_ON(item >= SMEM_ITEM_COUNT))
> +	if (WARN_ON(item >= smem->item_count))
>  		return ERR_PTR(-EINVAL);
>  
>  	header = smem->regions[0].virt_base;
> @@ -640,6 +660,19 @@ static int qcom_smem_get_sbl_version(struct qcom_smem *smem)
>  	return le32_to_cpu(versions[SMEM_MASTER_SBL_VERSION_INDEX]);
>  }
>  
> +static u32 qcom_smem_get_dynamic_item(struct qcom_smem *smem)
> +{
> +	struct smem_ptable *ptable;
> +	struct smem_info *info;
> +
> +	ptable = smem->regions[0].virt_base + smem->regions[0].size - SZ_4K;

This should be expanded to check the magic and version of the ptable,
but per my suggestion of duplicating this logic in patch 1 this should
likely just be broken out into a "get pointer to valid ptable"-function.

> +	info = (struct smem_info *)&ptable->entry[ptable->num_entries];
> +	if (memcmp(info->magic, SMEM_INFO_MAGIC, sizeof(info->magic)))
> +		return SMEM_ITEM_COUNT;
> +
> +	return le32_to_cpu(info->num_items);
> +}

Other than that this looks good.

Regards,
Bjorn