cxl/decoder: Move decoder register programming to a helper

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@stgolabs.net>
Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Alison Schofield <alison.schofield@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Link: https://patch.msgid.link/20250711234932.671292-4-dan.j.williams@intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Author: djbw

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++;