Re: [PATCH 5/8] cxl/port: Limit the port driver to just the HDM Decoder Capability

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Tue, 15 Mar 2022 21:14:08 -0700
Dan Williams <dan.j.williams@intel.com> wrote:

> Update the port driver to use cxl_map_component_registers() so that the
> component register block can be shared between the cxl_pci driver and
> the cxl_port driver. I.e. stop the port driver from reserving the entire
> component register block for itself via request_region() when it only
> needs the HDM Decoder Capability subset.
> 
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

We go through a dance in the other callers to cxl_probe_component_regs
cxl_map_component_regs that means we don't have block mapped at tim
of calling cxl_map_component_regs().

I'd gotten it into my head that we had that separation for a reason,
and it doesn't exist here as both are called with the block mapped.
Looking again I think that was needed because of use of pci_iomap
for the bar so I guess the same constraint doesn't apply here?

Thanks,

Jonathan



> ---
>  drivers/cxl/core/hdm.c |   32 ++++++++++++++++++--------------
>  1 file changed, 18 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
> index 0e89a7a932d4..09221afca309 100644
> --- a/drivers/cxl/core/hdm.c
> +++ b/drivers/cxl/core/hdm.c
> @@ -77,18 +77,22 @@ static void parse_hdm_decoder_caps(struct cxl_hdm *cxlhdm)
>  		cxlhdm->interleave_mask |= GENMASK(14, 12);
>  }
>  
> -static void __iomem *map_hdm_decoder_regs(struct cxl_port *port,
> -					  void __iomem *crb)
> +static int map_hdm_decoder_regs(struct cxl_port *port, void __iomem *crb,
> +				struct cxl_component_regs *regs)
>  {
> -	struct cxl_component_reg_map map;
> +	struct cxl_register_map map = {
> +		.resource = port->component_reg_phys,
> +		.base = crb,
> +		.max_size = CXL_COMPONENT_REG_BLOCK_SIZE,
> +	};
>  
> -	cxl_probe_component_regs(&port->dev, crb, &map);
> -	if (!map.hdm_decoder.valid) {
> +	cxl_probe_component_regs(&port->dev, crb, &map.component_map);
> +	if (!map.component_map.hdm_decoder.valid) {
>  		dev_err(&port->dev, "HDM decoder registers invalid\n");
> -		return IOMEM_ERR_PTR(-ENXIO);
> +		return -ENXIO;
>  	}
>  
> -	return crb + map.hdm_decoder.offset;
> +	return cxl_map_component_regs(&port->dev, regs, &map);
>  }
>  
>  /**
> @@ -98,25 +102,25 @@ static void __iomem *map_hdm_decoder_regs(struct cxl_port *port,
>  struct cxl_hdm *devm_cxl_setup_hdm(struct cxl_port *port)
>  {
>  	struct device *dev = &port->dev;
> -	void __iomem *crb, *hdm;
>  	struct cxl_hdm *cxlhdm;
> +	void __iomem *crb;
> +	int rc;
>  
>  	cxlhdm = devm_kzalloc(dev, sizeof(*cxlhdm), GFP_KERNEL);
>  	if (!cxlhdm)
>  		return ERR_PTR(-ENOMEM);
>  
>  	cxlhdm->port = port;
> -	crb = devm_cxl_iomap_block(dev, port->component_reg_phys,
> -				   CXL_COMPONENT_REG_BLOCK_SIZE);
> +	crb = ioremap(port->component_reg_phys, CXL_COMPONENT_REG_BLOCK_SIZE);
>  	if (!crb) {
>  		dev_err(dev, "No component registers mapped\n");
>  		return ERR_PTR(-ENXIO);
>  	}
>  
> -	hdm = map_hdm_decoder_regs(port, crb);
> -	if (IS_ERR(hdm))
> -		return ERR_CAST(hdm);
> -	cxlhdm->regs.hdm_decoder = hdm;
> +	rc = map_hdm_decoder_regs(port, crb, &cxlhdm->regs);
> +	iounmap(crb);
> +	if (rc)
> +		return ERR_PTR(rc);
>  
>  	parse_hdm_decoder_caps(cxlhdm);
>  	if (cxlhdm->decoder_count == 0) {
>