linux-kernel - Re: [PATCH v3 06/10] cxl/pci: Add @base to cxl_register

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Date:   Sat, 9 Oct 2021 21:20:56 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     linux-cxl@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, hch@....de
Subject: Re: [PATCH v3 06/10] cxl/pci: Add @base to cxl_register_map

On Sat, Oct 09, 2021 at 09:44:29AM -0700, Dan Williams wrote:
> In addition to carrying @barno, @block_offset, and @reg_type, add @base
> to keep all map/unmap parameters in one object. The helpers
> cxl_{map,unmap}_regblock() handle adjusting @base to the @block_offset
> at map and unmap time.
> 
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> ---
>  drivers/cxl/cxl.h |    1 +
>  drivers/cxl/pci.c |   31 ++++++++++++++++---------------
>  2 files changed, 17 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index a6687e7fd598..7cd16ef144dd 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -140,6 +140,7 @@ struct cxl_device_reg_map {
>  };
>  
>  struct cxl_register_map {
> +	void __iomem *base;
>  	u64 block_offset;
>  	u8 reg_type;
>  	u8 barno;
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index 9f006299a0e3..b42407d067ac 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -306,8 +306,7 @@ static int cxl_pci_setup_mailbox(struct cxl_mem *cxlm)
>  	return 0;
>  }
>  
> -static void __iomem *cxl_pci_map_regblock(struct pci_dev *pdev,
> -					  struct cxl_register_map *map)
> +static int cxl_map_regblock(struct pci_dev *pdev, struct cxl_register_map *map)
>  {
>  	void __iomem *addr;
>  	int bar = map->barno;
> @@ -318,24 +317,27 @@ static void __iomem *cxl_pci_map_regblock(struct pci_dev *pdev,
>  	if (pci_resource_len(pdev, bar) < offset) {
>  		dev_err(dev, "BAR%d: %pr: too small (offset: %#llx)\n", bar,
>  			&pdev->resource[bar], (unsigned long long)offset);
> -		return NULL;
> +		return -ENXIO;
>  	}
>  
>  	addr = pci_iomap(pdev, bar, 0);
>  	if (!addr) {
>  		dev_err(dev, "failed to map registers\n");
> -		return addr;
> +		return -ENOMEM;
>  	}
>  
>  	dev_dbg(dev, "Mapped CXL Memory Device resource bar %u @ %#llx\n",
>  		bar, offset);
>  
> -	return addr;
> +	map->base = addr + map->block_offset;
> +	return 0;
>  }
>  
> -static void cxl_pci_unmap_regblock(struct pci_dev *pdev, void __iomem *base)
> +static void cxl_unmap_regblock(struct pci_dev *pdev,
> +			       struct cxl_register_map *map)
>  {
> -	pci_iounmap(pdev, base);
> +	pci_iounmap(pdev, map->base - map->block_offset);

I know we need to get these in soon.  But I think map->base should be 'base'
and map->block_offset should be handled in cxl_probe_regs() rather than
subtract it here..

Either way this is cleaner than what it was.

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

> +	map->base = NULL;
>  }
>  
>  static int cxl_pci_dvsec(struct pci_dev *pdev, int dvsec)
> @@ -361,12 +363,12 @@ static int cxl_pci_dvsec(struct pci_dev *pdev, int dvsec)
>  	return 0;
>  }
>  
> -static int cxl_probe_regs(struct pci_dev *pdev, void __iomem *base,
> -			  struct cxl_register_map *map)
> +static int cxl_probe_regs(struct pci_dev *pdev, struct cxl_register_map *map)
>  {
>  	struct cxl_component_reg_map *comp_map;
>  	struct cxl_device_reg_map *dev_map;
>  	struct device *dev = &pdev->dev;
> +	void __iomem *base = map->base;
>  
>  	switch (map->reg_type) {
>  	case CXL_REGLOC_RBI_COMPONENT:
> @@ -442,7 +444,6 @@ static void cxl_decode_regblock(u32 reg_lo, u32 reg_hi,
>   */
>  static int cxl_pci_setup_regs(struct cxl_mem *cxlm)
>  {
> -	void __iomem *base;
>  	u32 regloc_size, regblocks;
>  	int regloc, i, n_maps, ret = 0;
>  	struct device *dev = cxlm->dev;
> @@ -475,12 +476,12 @@ static int cxl_pci_setup_regs(struct cxl_mem *cxlm)
>  		if (map->reg_type > CXL_REGLOC_RBI_MEMDEV)
>  			continue;
>  
> -		base = cxl_pci_map_regblock(pdev, map);
> -		if (!base)
> -			return -ENOMEM;
> +		ret = cxl_map_regblock(pdev, map);
> +		if (ret)
> +			return ret;
>  
> -		ret = cxl_probe_regs(pdev, base + map->block_offset, map);
> -		cxl_pci_unmap_regblock(pdev, base);
> +		ret = cxl_probe_regs(pdev, map);
> +		cxl_unmap_regblock(pdev, map);
>  		if (ret)
>  			return ret;
>  
>