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Date:   Sat, 9 Oct 2021 21:44:34 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     linux-cxl@...r.kernel.org, Ben Widawsky <ben.widawsky@...el.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org, hch@....de
Subject: Re: [PATCH v3 07/10] cxl/pci: Split cxl_pci_setup_regs()

On Sat, Oct 09, 2021 at 09:44:34AM -0700, Dan Williams wrote:
> From: Ben Widawsky <ben.widawsky@...el.com>
> 
> In preparation for moving parts of register mapping to cxl_core, split
> cxl_pci_setup_regs() into a helper that finds register blocks,
> (cxl_find_regblock()), and a generic wrapper that probes the precise
> register sets within a block (cxl_setup_regs()).
> 
> Move the actual mapping (cxl_map_regs()) of the only register-set that
> cxl_pci cares about (memory device registers) up a level from the former
> cxl_pci_setup_regs() into cxl_pci_probe().
> 
> With this change the unused component registers are no longer mapped,
> but the helpers are primed to move into the core.
> 
> Signed-off-by: Ben Widawsky <ben.widawsky@...el.com>
> [djbw: rebase on the cxl_register_map refactor]
> [djbw: drop cxl_map_regs() for component registers]

Reviewed-by: Ira Weiny <ira.weiny@...el.com>

> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> ---
>  drivers/cxl/pci.c |   73 +++++++++++++++++++++++++++--------------------------
>  1 file changed, 37 insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index b42407d067ac..b6bc8e5ca028 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -433,72 +433,69 @@ static void cxl_decode_regblock(u32 reg_lo, u32 reg_hi,
>  }
>  
>  /**
> - * cxl_pci_setup_regs() - Setup necessary MMIO.
> - * @cxlm: The CXL memory device to communicate with.
> + * cxl_find_regblock() - Locate register blocks by type
> + * @pdev: The CXL PCI device to enumerate.
> + * @type: Register Block Indicator id
> + * @map: Enumeration output, clobbered on error
>   *
> - * Return: 0 if all necessary registers mapped.
> + * Return: 0 if register block enumerated, negative error code otherwise
>   *
> - * A memory device is required by spec to implement a certain set of MMIO
> - * regions. The purpose of this function is to enumerate and map those
> - * registers.
> + * A CXL DVSEC may additional point one or more register blocks, search
> + * for them by @type.
>   */
> -static int cxl_pci_setup_regs(struct cxl_mem *cxlm)
> +static int cxl_find_regblock(struct pci_dev *pdev, enum cxl_regloc_type type,
> +			     struct cxl_register_map *map)
>  {
>  	u32 regloc_size, regblocks;
> -	int regloc, i, n_maps, ret = 0;
> -	struct device *dev = cxlm->dev;
> -	struct pci_dev *pdev = to_pci_dev(dev);
> -	struct cxl_register_map *map, maps[CXL_REGLOC_RBI_TYPES];
> +	int regloc, i;
>  
>  	regloc = cxl_pci_dvsec(pdev, PCI_DVSEC_ID_CXL_REGLOC_DVSEC_ID);
> -	if (!regloc) {
> -		dev_err(dev, "register location dvsec not found\n");
> +	if (!regloc)
>  		return -ENXIO;
> -	}
>  
> -	/* Get the size of the Register Locator DVSEC */
>  	pci_read_config_dword(pdev, regloc + PCI_DVSEC_HEADER1, &regloc_size);
>  	regloc_size = FIELD_GET(PCI_DVSEC_HEADER1_LENGTH_MASK, regloc_size);
>  
>  	regloc += PCI_DVSEC_ID_CXL_REGLOC_BLOCK1_OFFSET;
>  	regblocks = (regloc_size - PCI_DVSEC_ID_CXL_REGLOC_BLOCK1_OFFSET) / 8;
>  
> -	for (i = 0, n_maps = 0; i < regblocks; i++, regloc += 8) {
> +	for (i = 0; i < regblocks; i++, regloc += 8) {
>  		u32 reg_lo, reg_hi;
>  
>  		pci_read_config_dword(pdev, regloc, &reg_lo);
>  		pci_read_config_dword(pdev, regloc + 4, &reg_hi);
>  
> -		map = &maps[n_maps];
>  		cxl_decode_regblock(reg_lo, reg_hi, map);
>  
> -		/* Ignore unknown register block types */
> -		if (map->reg_type > CXL_REGLOC_RBI_MEMDEV)
> -			continue;
> +		if (map->reg_type == type)
> +			return 0;
> +	}
>  
> -		ret = cxl_map_regblock(pdev, map);
> -		if (ret)
> -			return ret;
> +	return -ENODEV;
> +}
>  
> -		ret = cxl_probe_regs(pdev, map);
> -		cxl_unmap_regblock(pdev, map);
> -		if (ret)
> -			return ret;
> +static int cxl_setup_regs(struct pci_dev *pdev, enum cxl_regloc_type type,
> +			  struct cxl_register_map *map)
> +{
> +	int rc;
>  
> -		n_maps++;
> -	}
> +	rc = cxl_find_regblock(pdev, type, map);
> +	if (rc)
> +		return rc;
>  
> -	for (i = 0; i < n_maps; i++) {
> -		ret = cxl_map_regs(cxlm, &maps[i]);
> -		if (ret)
> -			break;
> -	}
> +	rc = cxl_map_regblock(pdev, map);
> +	if (rc)
> +		return rc;
> +
> +	rc = cxl_probe_regs(pdev, map);
> +	cxl_unmap_regblock(pdev, map);
>  
> -	return ret;
> +	return rc;
>  }
>  
>  static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  {
> +	struct cxl_register_map map;
>  	struct cxl_memdev *cxlmd;
>  	struct cxl_mem *cxlm;
>  	int rc;
> @@ -518,7 +515,11 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  	if (IS_ERR(cxlm))
>  		return PTR_ERR(cxlm);
>  
> -	rc = cxl_pci_setup_regs(cxlm);
> +	rc = cxl_setup_regs(pdev, CXL_REGLOC_RBI_MEMDEV, &map);
> +	if (rc)
> +		return rc;
> +
> +	rc = cxl_map_regs(cxlm, &map);
>  	if (rc)
>  		return rc;
>  
> 

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