[PATCH v13 03/15] cxl: Move HDM decoder programming helpers
From: Srirangan Madhavan
Date: Tue Sep 22 2026 - 04:44:55 EST
Move the HDM decoder programming helpers and cxl_rwsem from hdm.c to
resource.c for reuse by reset restoration. Keep their behavior unchanged
and expose only the cross-object helpers within cxl_core.
Signed-off-by: Srirangan Madhavan <smadhavan@xxxxxxxxxx>
---
drivers/cxl/core/Makefile | 1 +
drivers/cxl/core/core.h | 4 ++
drivers/cxl/core/hdm.c | 103 +--------------------------------
drivers/cxl/core/resource.c | 110 ++++++++++++++++++++++++++++++++++++
tools/testing/cxl/Kbuild | 1 +
5 files changed, 117 insertions(+), 102 deletions(-)
create mode 100644 drivers/cxl/core/resource.c
diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile
index ce7213818d3c..57995777af0d 100644
--- a/drivers/cxl/core/Makefile
+++ b/drivers/cxl/core/Makefile
@@ -6,6 +6,7 @@ ccflags-y += -I$(srctree)/drivers/cxl
CFLAGS_trace.o = -DTRACE_INCLUDE_PATH=. -I$(src)
cxl_core-y := port.o
+cxl_core-y += resource.o
cxl_core-y += pmem.o
cxl_core-y += regs.o
cxl_core-y += memdev.o
diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 983d7690c3a5..9c6d4b99f787 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -139,6 +139,10 @@ struct cxl_rwsem {
extern struct cxl_rwsem cxl_rwsem;
+int cxld_await_commit(void __iomem *hdm, int id);
+void cxlsd_set_targets(struct cxl_switch_decoder *cxlsd, u64 *tgt);
+void setup_hw_decoder(struct cxl_decoder *cxld, void __iomem *hdm);
+
int cxl_memdev_init(void);
void cxl_memdev_exit(void);
void cxl_mbox_init(void);
diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index 39fe283cbc74..008f04f0ca25 100644
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -16,11 +16,6 @@
* for enumerating these registers and capabilities.
*/
-struct cxl_rwsem cxl_rwsem = {
- .region = __RWSEM_INITIALIZER(cxl_rwsem.region),
- .dpa = __RWSEM_INITIALIZER(cxl_rwsem.dpa),
-};
-
static int add_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld)
{
int rc;
@@ -707,36 +702,7 @@ int cxl_dpa_alloc(struct cxl_endpoint_decoder *cxled, u64 size)
return devm_add_action_or_reset(&port->dev, cxl_dpa_release, cxled);
}
-static void cxld_set_interleave(struct cxl_decoder *cxld, u32 *ctrl)
-{
- u16 eig;
- u8 eiw;
-
- /*
- * Input validation ensures these warns never fire, but otherwise
- * suppress unititalized variable usage warnings.
- */
- if (WARN_ONCE(ways_to_eiw(cxld->interleave_ways, &eiw),
- "invalid interleave_ways: %d\n", cxld->interleave_ways))
- return;
- if (WARN_ONCE(granularity_to_eig(cxld->interleave_granularity, &eig),
- "invalid interleave_granularity: %d\n",
- cxld->interleave_granularity))
- return;
-
- u32p_replace_bits(ctrl, eig, CXL_HDM_DECODER0_CTRL_IG_MASK);
- u32p_replace_bits(ctrl, eiw, CXL_HDM_DECODER0_CTRL_IW_MASK);
- *ctrl |= CXL_HDM_DECODER0_CTRL_COMMIT;
-}
-
-static void cxld_set_type(struct cxl_decoder *cxld, u32 *ctrl)
-{
- u32p_replace_bits(ctrl,
- !!(cxld->target_type == CXL_DECODER_HOSTONLYMEM),
- CXL_HDM_DECODER0_CTRL_HOSTONLY);
-}
-
-static void cxlsd_set_targets(struct cxl_switch_decoder *cxlsd, u64 *tgt)
+void cxlsd_set_targets(struct cxl_switch_decoder *cxlsd, u64 *tgt)
{
struct cxl_dport **t = &cxlsd->target[0];
int ways = cxlsd->cxld.interleave_ways;
@@ -758,73 +724,6 @@ static void cxlsd_set_targets(struct cxl_switch_decoder *cxlsd, u64 *tgt)
*tgt |= FIELD_PREP(GENMASK_ULL(63, 56), t[7]->port_id);
}
-/*
- * Per CXL 2.0 8.2.5.12.20 Committing Decoder Programming, hardware must set
- * committed or error within 10ms, but just be generous with 20ms to account for
- * clock skew and other marginal behavior
- */
-#define COMMIT_TIMEOUT_MS 20
-static int cxld_await_commit(void __iomem *hdm, int id)
-{
- u32 ctrl;
- int i;
-
- for (i = 0; i < COMMIT_TIMEOUT_MS; i++) {
- ctrl = readl(hdm + CXL_HDM_DECODER0_CTRL_OFFSET(id));
- if (FIELD_GET(CXL_HDM_DECODER0_CTRL_COMMIT_ERROR, ctrl)) {
- ctrl &= ~CXL_HDM_DECODER0_CTRL_COMMIT;
- writel(ctrl, hdm + CXL_HDM_DECODER0_CTRL_OFFSET(id));
- return -EIO;
- }
- if (FIELD_GET(CXL_HDM_DECODER0_CTRL_COMMITTED, ctrl))
- return 0;
- fsleep(1000);
- }
-
- 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);
diff --git a/drivers/cxl/core/resource.c b/drivers/cxl/core/resource.c
new file mode 100644
index 000000000000..68d40f745acc
--- /dev/null
+++ b/drivers/cxl/core/resource.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2026 NVIDIA Corporation & Affiliates */
+#include <linux/delay.h>
+#include <linux/bug.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+
+#include "cxl.h"
+#include "core.h"
+
+struct cxl_rwsem cxl_rwsem = {
+ .region = __RWSEM_INITIALIZER(cxl_rwsem.region),
+ .dpa = __RWSEM_INITIALIZER(cxl_rwsem.dpa),
+};
+
+static void cxld_set_interleave(struct cxl_decoder *cxld, u32 *ctrl)
+{
+ u16 eig;
+ u8 eiw;
+
+ /*
+ * Input validation ensures these warns never fire, but otherwise
+ * suppress unititalized variable usage warnings.
+ */
+ if (WARN_ONCE(ways_to_eiw(cxld->interleave_ways, &eiw),
+ "invalid interleave_ways: %d\n", cxld->interleave_ways))
+ return;
+ if (WARN_ONCE(granularity_to_eig(cxld->interleave_granularity, &eig),
+ "invalid interleave_granularity: %d\n",
+ cxld->interleave_granularity))
+ return;
+
+ u32p_replace_bits(ctrl, eig, CXL_HDM_DECODER0_CTRL_IG_MASK);
+ u32p_replace_bits(ctrl, eiw, CXL_HDM_DECODER0_CTRL_IW_MASK);
+ *ctrl |= CXL_HDM_DECODER0_CTRL_COMMIT;
+}
+
+static void cxld_set_type(struct cxl_decoder *cxld, u32 *ctrl)
+{
+ u32p_replace_bits(ctrl,
+ !!(cxld->target_type == CXL_DECODER_HOSTONLYMEM),
+ CXL_HDM_DECODER0_CTRL_HOSTONLY);
+}
+
+/*
+ * Per CXL 2.0 8.2.5.12.20 Committing Decoder Programming, hardware must set
+ * committed or error within 10ms, but just be generous with 20ms to account for
+ * clock skew and other marginal behavior
+ */
+#define COMMIT_TIMEOUT_MS 20
+int cxld_await_commit(void __iomem *hdm, int id)
+{
+ u32 ctrl;
+ int i;
+
+ for (i = 0; i < COMMIT_TIMEOUT_MS; i++) {
+ ctrl = readl(hdm + CXL_HDM_DECODER0_CTRL_OFFSET(id));
+ if (FIELD_GET(CXL_HDM_DECODER0_CTRL_COMMIT_ERROR, ctrl)) {
+ ctrl &= ~CXL_HDM_DECODER0_CTRL_COMMIT;
+ writel(ctrl, hdm + CXL_HDM_DECODER0_CTRL_OFFSET(id));
+ return -EIO;
+ }
+ if (FIELD_GET(CXL_HDM_DECODER0_CTRL_COMMITTED, ctrl))
+ return 0;
+ fsleep(1000);
+ }
+
+ return -ETIMEDOUT;
+}
+
+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));
+}
diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild
index 2be1df80fcc9..6c09932587ce 100644
--- a/tools/testing/cxl/Kbuild
+++ b/tools/testing/cxl/Kbuild
@@ -60,6 +60,7 @@ cxl_core-y += $(CXL_CORE_SRC)/memdev.o
cxl_core-y += $(CXL_CORE_SRC)/mbox.o
cxl_core-y += $(CXL_CORE_SRC)/pci.o
cxl_core-y += $(CXL_CORE_SRC)/hdm.o
+cxl_core-y += $(CXL_CORE_SRC)/resource.o
cxl_core-y += $(CXL_CORE_SRC)/pmu.o
cxl_core-y += $(CXL_CORE_SRC)/cdat.o
cxl_core-$(CONFIG_TRACING) += $(CXL_CORE_SRC)/trace.o
--
2.43.0