linux-kernel - Re: [PATCH v4 05/10] cxl/pci: Make more use of cxl_register

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Date:   Sat, 9 Oct 2021 21:03:49 -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>,
        kernel test robot <lkp@...el.com>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 05/10] cxl/pci: Make more use of cxl_register_map

On Sat, Oct 09, 2021 at 01:51:13PM -0700, Dan Williams wrote:
> From: Ben Widawsky <ben.widawsky@...el.com>
> 
> The structure exists to pass around information about register mapping.
> Use it for passing @barno and @block_offset, and eliminate duplicate
> local variables.
> 
> The helpers that use @map do not care about @cxlm, so just pass them a
> pdev instead.
> 
> Signed-off-by: Ben Widawsky <ben.widawsky@...el.com>
> Reported-by: kernel test robot <lkp@...el.com>

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

> [djbw: separate @base conversion]
> [djbw: reorder before cxl_pci_setup_regs() refactor to improver readability]
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> ---
> Changes since v3:
> - Fix a 0day report about printing a resource_size_t
> 
>  drivers/cxl/pci.c |   55 ++++++++++++++++++++++-------------------------------
>  1 file changed, 23 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index 21dd10a77eb3..f1de236ccd13 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -306,12 +306,13 @@ static int cxl_pci_setup_mailbox(struct cxl_mem *cxlm)
>  	return 0;
>  }
>  
> -static void __iomem *cxl_pci_map_regblock(struct cxl_mem *cxlm,
> -					  u8 bar, u64 offset)
> +static void __iomem *cxl_pci_map_regblock(struct pci_dev *pdev,
> +					  struct cxl_register_map *map)
>  {
>  	void __iomem *addr;
> -	struct device *dev = cxlm->dev;
> -	struct pci_dev *pdev = to_pci_dev(dev);
> +	int bar = map->barno;
> +	struct device *dev = &pdev->dev;
> +	resource_size_t offset = map->block_offset;
>  
>  	/* Basic sanity check that BAR is big enough */
>  	if (pci_resource_len(pdev, bar) < offset) {
> @@ -326,15 +327,15 @@ static void __iomem *cxl_pci_map_regblock(struct cxl_mem *cxlm,
>  		return addr;
>  	}
>  
> -	dev_dbg(dev, "Mapped CXL Memory Device resource bar %u @ %#llx\n",
> -		bar, offset);
> +	dev_dbg(dev, "Mapped CXL Memory Device resource bar %u @ %pa\n",
> +		bar, &offset);
>  
>  	return addr;
>  }
>  
> -static void cxl_pci_unmap_regblock(struct cxl_mem *cxlm, void __iomem *base)
> +static void cxl_pci_unmap_regblock(struct pci_dev *pdev, void __iomem *base)
>  {
> -	pci_iounmap(to_pci_dev(cxlm->dev), base);
> +	pci_iounmap(pdev, base);
>  }
>  
>  static int cxl_pci_dvsec(struct pci_dev *pdev, int dvsec)
> @@ -360,12 +361,12 @@ static int cxl_pci_dvsec(struct pci_dev *pdev, int dvsec)
>  	return 0;
>  }
>  
> -static int cxl_probe_regs(struct cxl_mem *cxlm, void __iomem *base,
> +static int cxl_probe_regs(struct pci_dev *pdev, void __iomem *base,
>  			  struct cxl_register_map *map)
>  {
>  	struct cxl_component_reg_map *comp_map;
>  	struct cxl_device_reg_map *dev_map;
> -	struct device *dev = cxlm->dev;
> +	struct device *dev = &pdev->dev;
>  
>  	switch (map->reg_type) {
>  	case CXL_REGLOC_RBI_COMPONENT:
> @@ -420,12 +421,13 @@ static int cxl_map_regs(struct cxl_mem *cxlm, struct cxl_register_map *map)
>  	return 0;
>  }
>  
> -static void cxl_decode_register_block(u32 reg_lo, u32 reg_hi,
> -				      u8 *bar, u64 *offset, u8 *reg_type)
> +static void cxl_decode_regblock(u32 reg_lo, u32 reg_hi,
> +				struct cxl_register_map *map)
>  {
> -	*offset = ((u64)reg_hi << 32) | (reg_lo & CXL_REGLOC_ADDR_MASK);
> -	*bar = FIELD_GET(CXL_REGLOC_BIR_MASK, reg_lo);
> -	*reg_type = FIELD_GET(CXL_REGLOC_RBI_MASK, reg_lo);
> +	map->block_offset =
> +		((u64)reg_hi << 32) | (reg_lo & CXL_REGLOC_ADDR_MASK);
> +	map->barno = FIELD_GET(CXL_REGLOC_BIR_MASK, reg_lo);
> +	map->reg_type = FIELD_GET(CXL_REGLOC_RBI_MASK, reg_lo);
>  }
>  
>  /**
> @@ -462,34 +464,23 @@ static int cxl_pci_setup_regs(struct cxl_mem *cxlm)
>  
>  	for (i = 0, n_maps = 0; i < regblocks; i++, regloc += 8) {
>  		u32 reg_lo, reg_hi;
> -		u8 reg_type;
> -		u64 offset;
> -		u8 bar;
>  
>  		pci_read_config_dword(pdev, regloc, &reg_lo);
>  		pci_read_config_dword(pdev, regloc + 4, &reg_hi);
>  
> -		cxl_decode_register_block(reg_lo, reg_hi, &bar, &offset,
> -					  &reg_type);
> +		map = &maps[n_maps];
> +		cxl_decode_regblock(reg_lo, reg_hi, map);
>  
>  		/* Ignore unknown register block types */
> -		if (reg_type > CXL_REGLOC_RBI_MEMDEV)
> +		if (map->reg_type > CXL_REGLOC_RBI_MEMDEV)
>  			continue;
>  
> -		base = cxl_pci_map_regblock(cxlm, bar, offset);
> +		base = cxl_pci_map_regblock(pdev, map);
>  		if (!base)
>  			return -ENOMEM;
>  
> -		map = &maps[n_maps];
> -		map->barno = bar;
> -		map->block_offset = offset;
> -		map->reg_type = reg_type;
> -
> -		ret = cxl_probe_regs(cxlm, base + offset, map);
> -
> -		/* Always unmap the regblock regardless of probe success */
> -		cxl_pci_unmap_regblock(cxlm, base);
> -
> +		ret = cxl_probe_regs(pdev, base + map->block_offset, map);
> +		cxl_pci_unmap_regblock(pdev, base);
>  		if (ret)
>  			return ret;
>  
>