linux-kernel - Re: [PATCH v2 3/8] cxl/decoder: Move decoder register programming to a helper

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Message-ID: <20250623115152.00005aba@huawei.com>
Date: Mon, 23 Jun 2025 11:51:52 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Dan Williams <dan.j.williams@...el.com>
CC: <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Davidlohr
 Bueso <dave@...olabs.net>, Dave Jiang <dave.jiang@...el.com>, Alison
 Schofield <alison.schofield@...el.com>, Vishal Verma
	<vishal.l.verma@...el.com>, "Ira Weiny" <ira.weiny@...el.com>
Subject: Re: [PATCH v2 3/8] cxl/decoder: Move decoder register programming
 to a helper

On Wed, 18 Jun 2025 22:04:11 -0700
Dan Williams <dan.j.williams@...el.com> wrote:

> In preparation for converting to rw_semaphore_acquire semantics move the
> contents of an open-coded {down,up}_read(&cxl_dpa_rwsem) section to a
> helper function.
> 
> Cc: Davidlohr Bueso <dave@...olabs.net>
> Cc: Jonathan Cameron <jonathan.cameron@...wei.com>
> Cc: Dave Jiang <dave.jiang@...el.com>
> Cc: Alison Schofield <alison.schofield@...el.com>
> Cc: Vishal Verma <vishal.l.verma@...el.com>
> Cc: Ira Weiny <ira.weiny@...el.com>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>

Seems reasonable.

Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>

> ---
>  drivers/cxl/core/hdm.c | 77 +++++++++++++++++++++++-------------------
>  1 file changed, 42 insertions(+), 35 deletions(-)
> 
> diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
> index ab1007495f6b..81556d12e9b8 100644
> --- a/drivers/cxl/core/hdm.c
> +++ b/drivers/cxl/core/hdm.c
> @@ -764,14 +764,53 @@ static int cxld_await_commit(void __iomem *hdm, int id)
>  	return -ETIMEDOUT;
>  }
>  
> +static void setup_hw_decoder(struct cxl_decoder *cxld, void __iomem *hdm)
> +{
> +	int id = cxld->id;
> +	u64 base, size;
> +	u32 ctrl;
> +
> +	/* common decoder settings */
> +	ctrl = readl(hdm + CXL_HDM_DECODER0_CTRL_OFFSET(cxld->id));
> +	cxld_set_interleave(cxld, &ctrl);
> +	cxld_set_type(cxld, &ctrl);
> +	base = cxld->hpa_range.start;
> +	size = range_len(&cxld->hpa_range);
> +
> +	writel(upper_32_bits(base), hdm + CXL_HDM_DECODER0_BASE_HIGH_OFFSET(id));
> +	writel(lower_32_bits(base), hdm + CXL_HDM_DECODER0_BASE_LOW_OFFSET(id));
> +	writel(upper_32_bits(size), hdm + CXL_HDM_DECODER0_SIZE_HIGH_OFFSET(id));
> +	writel(lower_32_bits(size), hdm + CXL_HDM_DECODER0_SIZE_LOW_OFFSET(id));
> +
> +	if (is_switch_decoder(&cxld->dev)) {
> +		struct cxl_switch_decoder *cxlsd =
> +			to_cxl_switch_decoder(&cxld->dev);
> +		void __iomem *tl_hi = hdm + CXL_HDM_DECODER0_TL_HIGH(id);
> +		void __iomem *tl_lo = hdm + CXL_HDM_DECODER0_TL_LOW(id);
> +		u64 targets;
> +
> +		cxlsd_set_targets(cxlsd, &targets);
> +		writel(upper_32_bits(targets), tl_hi);
> +		writel(lower_32_bits(targets), tl_lo);
> +	} else {
> +		struct cxl_endpoint_decoder *cxled =
> +			to_cxl_endpoint_decoder(&cxld->dev);
> +		void __iomem *sk_hi = hdm + CXL_HDM_DECODER0_SKIP_HIGH(id);
> +		void __iomem *sk_lo = hdm + CXL_HDM_DECODER0_SKIP_LOW(id);
> +
> +		writel(upper_32_bits(cxled->skip), sk_hi);
> +		writel(lower_32_bits(cxled->skip), sk_lo);
> +	}
> +
> +	writel(ctrl, hdm + CXL_HDM_DECODER0_CTRL_OFFSET(id));
> +}
> +
>  static int cxl_decoder_commit(struct cxl_decoder *cxld)
>  {
>  	struct cxl_port *port = to_cxl_port(cxld->dev.parent);
>  	struct cxl_hdm *cxlhdm = dev_get_drvdata(&port->dev);
>  	void __iomem *hdm = cxlhdm->regs.hdm_decoder;
>  	int id = cxld->id, rc;
> -	u64 base, size;
> -	u32 ctrl;
>  
>  	if (cxld->flags & CXL_DECODER_F_ENABLE)
>  		return 0;
> @@ -804,39 +843,7 @@ static int cxl_decoder_commit(struct cxl_decoder *cxld)
>  	}
>  
>  	down_read(&cxl_dpa_rwsem);
> -	/* common decoder settings */
> -	ctrl = readl(hdm + CXL_HDM_DECODER0_CTRL_OFFSET(cxld->id));
> -	cxld_set_interleave(cxld, &ctrl);
> -	cxld_set_type(cxld, &ctrl);
> -	base = cxld->hpa_range.start;
> -	size = range_len(&cxld->hpa_range);
> -
> -	writel(upper_32_bits(base), hdm + CXL_HDM_DECODER0_BASE_HIGH_OFFSET(id));
> -	writel(lower_32_bits(base), hdm + CXL_HDM_DECODER0_BASE_LOW_OFFSET(id));
> -	writel(upper_32_bits(size), hdm + CXL_HDM_DECODER0_SIZE_HIGH_OFFSET(id));
> -	writel(lower_32_bits(size), hdm + CXL_HDM_DECODER0_SIZE_LOW_OFFSET(id));
> -
> -	if (is_switch_decoder(&cxld->dev)) {
> -		struct cxl_switch_decoder *cxlsd =
> -			to_cxl_switch_decoder(&cxld->dev);
> -		void __iomem *tl_hi = hdm + CXL_HDM_DECODER0_TL_HIGH(id);
> -		void __iomem *tl_lo = hdm + CXL_HDM_DECODER0_TL_LOW(id);
> -		u64 targets;
> -
> -		cxlsd_set_targets(cxlsd, &targets);
> -		writel(upper_32_bits(targets), tl_hi);
> -		writel(lower_32_bits(targets), tl_lo);
> -	} else {
> -		struct cxl_endpoint_decoder *cxled =
> -			to_cxl_endpoint_decoder(&cxld->dev);
> -		void __iomem *sk_hi = hdm + CXL_HDM_DECODER0_SKIP_HIGH(id);
> -		void __iomem *sk_lo = hdm + CXL_HDM_DECODER0_SKIP_LOW(id);
> -
> -		writel(upper_32_bits(cxled->skip), sk_hi);
> -		writel(lower_32_bits(cxled->skip), sk_lo);
> -	}
> -
> -	writel(ctrl, hdm + CXL_HDM_DECODER0_CTRL_OFFSET(id));
> +	setup_hw_decoder(cxld, hdm);
>  	up_read(&cxl_dpa_rwsem);
>  
>  	port->commit_end++;