Re: [RFC PATCH v2 1/4] cxl: Add function to count regblocks of a given type.

[Dave Jiang <dave.jiang@intel.com>]

On 8/24/2022 3:36 AM, Jonathan Cameron wrote:
> Until the recently release CXL 3.0 specification, there
> was only ever one instance of any given register block pointed
> to by the Register Block Locator DVSEC. Now, the specification allows
> for multiple CXL PMU instances, each with their own register block.
>
> To enable this add an index parameter to cxl_find_regblock()
> and use that to implement cxl_count_regblock().
>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> ---
>   drivers/cxl/core/pci.c  |  2 +-
>   drivers/cxl/core/port.c |  2 +-
>   drivers/cxl/core/regs.c | 35 ++++++++++++++++++++++++++++++++---
>   drivers/cxl/cxl.h       |  3 ++-
>   drivers/cxl/pci.c       |  2 +-
>   5 files changed, 37 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
> index 9240df53ed87..f29cdc9df330 100644
> --- a/drivers/cxl/core/pci.c
> +++ b/drivers/cxl/core/pci.c
> @@ -49,7 +49,7 @@ static int match_add_dports(struct pci_dev *pdev, void *data)
>   				  &lnkcap))
>   		return 0;
>   
> -	rc = cxl_find_regblock(pdev, CXL_REGLOC_RBI_COMPONENT, &map);
> +	rc = cxl_find_regblock(pdev, CXL_REGLOC_RBI_COMPONENT, &map, 0);
>   	if (rc)
>   		dev_dbg(&port->dev, "failed to find component registers\n");
>   
> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> index bffde862de0b..1629c7a4033f 100644
> --- a/drivers/cxl/core/port.c
> +++ b/drivers/cxl/core/port.c
> @@ -1235,7 +1235,7 @@ static resource_size_t find_component_registers(struct device *dev)
>   
>   	pdev = to_pci_dev(dev);
>   
> -	cxl_find_regblock(pdev, CXL_REGLOC_RBI_COMPONENT, &map);
> +	cxl_find_regblock(pdev, CXL_REGLOC_RBI_COMPONENT, &map, 0);
>   	return cxl_regmap_to_base(pdev, &map);
>   }
>   
> diff --git a/drivers/cxl/core/regs.c b/drivers/cxl/core/regs.c
> index 39a129c57d40..2f651211d120 100644
> --- a/drivers/cxl/core/regs.c
> +++ b/drivers/cxl/core/regs.c
> @@ -262,6 +262,7 @@ static void cxl_decode_regblock(u32 reg_lo, u32 reg_hi,
>    * @pdev: The CXL PCI device to enumerate.
>    * @type: Register Block Indicator id
>    * @map: Enumeration output, clobbered on error
> + * @index: Index into which particular instance of a regblock we want.
>    *
>    * Return: 0 if register block enumerated, negative error code otherwise
>    *
> @@ -269,9 +270,10 @@ static void cxl_decode_regblock(u32 reg_lo, u32 reg_hi,
>    * by @type.
>    */
>   int cxl_find_regblock(struct pci_dev *pdev, enum cxl_regloc_type type,
> -		      struct cxl_register_map *map)
> +		      struct cxl_register_map *map, int index)
>   {
>   	u32 regloc_size, regblocks;
> +	int instance = 0;
>   	int regloc, i;
>   
>   	map->block_offset = U64_MAX;
> @@ -294,11 +296,38 @@ int cxl_find_regblock(struct pci_dev *pdev, enum cxl_regloc_type type,
>   
>   		cxl_decode_regblock(reg_lo, reg_hi, map);
>   
> -		if (map->reg_type == type)
> -			return 0;
> +		if (map->reg_type == type) {
> +			if (index == instance)
> +				return 0;
> +			instance++;
> +		}
>   	}
>   
>   	map->block_offset = U64_MAX;
>   	return -ENODEV;
>   }
>   EXPORT_SYMBOL_NS_GPL(cxl_find_regblock, CXL);
> +
> +/**
> + * cxl_count_regblock() - Count instances of a given regblock type.
> + * @pdev: The CXL PCI device to enumerate.
> + * @type: Register Block Indicator id
> + *
> + * Some regblocks may be repeated. Count how many instances.
> + *
> + * Return: count of matching regblocks.
> + */
> +int cxl_count_regblock(struct pci_dev *pdev, enum cxl_regloc_type type)
> +{
> +	struct cxl_register_map map;
> +	int rc, count = 0;
> +
> +	while (1) {
> +		rc = cxl_find_regblock(pdev, type, &map, count);
> +		if (rc)
> +			return count;
> +		count++;
> +	}
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_count_regblock, CXL);
> +
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index f680450f0b16..5a1bcdbda654 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -216,8 +216,9 @@ int cxl_map_device_regs(struct pci_dev *pdev,
>   			struct cxl_register_map *map);
>   
>   enum cxl_regloc_type;
> +int cxl_count_regblock(struct pci_dev *pdev, enum cxl_regloc_type type);
>   int cxl_find_regblock(struct pci_dev *pdev, enum cxl_regloc_type type,
> -		      struct cxl_register_map *map);
> +		      struct cxl_register_map *map, int index);
>   void __iomem *devm_cxl_iomap_block(struct device *dev, resource_size_t addr,
>   				   resource_size_t length);
>   
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index faeb5d9d7a7a..1758380247ec 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -373,7 +373,7 @@ static int cxl_setup_regs(struct pci_dev *pdev, enum cxl_regloc_type type,
>   {
>   	int rc;
>   
> -	rc = cxl_find_regblock(pdev, type, map);
> +	rc = cxl_find_regblock(pdev, type, map, 0);
>   	if (rc)
>   		return rc;
>