From: Srirangan Madhavan <smadhavan@nvidia.com>
To: Alison Schofield <alison.schofield@intel.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Dave Jiang <dave.jiang@intel.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Ira Weiny <ira.weiny@intel.com>,
Jonathan Cameron <jic23@kernel.org>,
Vishal Verma <vishal.l.verma@intel.com>,
linux-cxl@vger.kernel.org, linux-pci@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: Alex Williamson <alex.williamson@redhat.com>,
vsethi@nvidia.com, alwilliamson@nvidia.com,
Sai Yashwanth Reddy Kancherla <skancherla@nvidia.com>,
Vishal Aslot <vaslot@nvidia.com>,
Manish Honap <mhonap@nvidia.com>, Jiandi An <jan@nvidia.com>,
Richard Cheng <icheng@nvidia.com>,
linux-tegra@vger.kernel.org,
Srirangan Madhavan <smadhavan@nvidia.com>
Subject: [PATCH v15 06/16] cxl: Move HDM decoder helpers to built-in code
Date: Sun, 11 Oct 2026 02:14:12 +0000 [thread overview]
Message-ID: <20261011021422.3428136-7-smadhavan@nvidia.com> (raw)
In-Reply-To: <20261011021422.3428136-1-smadhavan@nvidia.com>
The PCI core will restore HDM decoders after a reset, possibly while no
CXL driver is loaded, so it cannot call into cxl_core.
Move the HDM register programming helpers from hdm.c to hdm_regs.c and
build that file into the kernel whenever CXL_BUS is enabled, including
when CXL_BUS is modular. Export only the symbols that cxl_core uses.
Keep the DPA lock assertion in the normal decoder programming caller so
the register helpers do not depend on cxl_rwsem. Leave cxl_rwsem in
cxl_core until built-in cache management needs it.
Link: https://git.kernel.org/pub/scm/linux/kernel/git/djiang/linux.git/commit/?id=e0b476ea99567fb5aa416eac0cf61bca20724880
Suggested-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Srirangan Madhavan <smadhavan@nvidia.com>
---
drivers/cxl/core/Makefile | 1 +
drivers/cxl/core/hdm.c | 102 +------------------------------
drivers/cxl/core/hdm_regs.c | 118 ++++++++++++++++++++++++++++++++++++
3 files changed, 121 insertions(+), 100 deletions(-)
create mode 100644 drivers/cxl/core/hdm_regs.c
diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile
index ce7213818d3c..6703c1729396 100644
--- a/drivers/cxl/core/Makefile
+++ b/drivers/cxl/core/Makefile
@@ -1,5 +1,6 @@
# SPDX-License-Identifier: GPL-2.0
obj-$(CONFIG_CXL_BUS) += cxl_core.o
+obj-$(subst m,y,$(CONFIG_CXL_BUS)) += hdm_regs.o
obj-$(CONFIG_CXL_SUSPEND) += suspend.o
ccflags-y += -I$(srctree)/drivers/cxl
diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index 7d3254a712e4..47cf49bcd2e5 100644
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -708,35 +708,6 @@ 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(const struct cxl_decoder_config *config, 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(config->interleave_ways, &eiw),
- "invalid interleave_ways: %d\n", config->interleave_ways))
- return;
- if (WARN_ONCE(granularity_to_eig(config->interleave_granularity, &eig),
- "invalid interleave_granularity: %d\n",
- config->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(const struct cxl_decoder_config *config, u32 *ctrl)
-{
- u32p_replace_bits(ctrl,
- !!(config->target_type == CXL_DECODER_HOSTONLYMEM),
- CXL_HDM_DECODER0_CTRL_HOSTONLY);
-}
-
static void cxlsd_set_targets(struct cxl_switch_decoder *cxlsd, u64 *tgt)
{
struct cxl_dport **t = &cxlsd->target[0];
@@ -759,77 +730,6 @@ 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
-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 u32 cxl_hdm_write_range(void __iomem *hdm,
- const struct cxl_decoder_config *config)
-{
- u64 size = range_len(&config->hpa_range);
- u64 base = config->hpa_range.start;
- int id = config->id;
- u32 ctrl;
-
- ctrl = readl(hdm + CXL_HDM_DECODER0_CTRL_OFFSET(id));
- cxld_set_interleave(config, &ctrl);
- cxld_set_type(config, &ctrl);
-
- 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));
- return ctrl;
-}
-
-void cxl_commit_start_endpoint(const struct cxl_endpoint_decoder_settings *settings,
- void __iomem *hdm)
-{
- int id = settings->config.id;
- u32 ctrl;
-
- lockdep_assert_held(&cxl_rwsem.dpa);
- ctrl = cxl_hdm_write_range(hdm, &settings->config);
- writel(upper_32_bits(settings->skip), hdm + CXL_HDM_DECODER0_SKIP_HIGH(id));
- writel(lower_32_bits(settings->skip), hdm + CXL_HDM_DECODER0_SKIP_LOW(id));
- writel(ctrl, hdm + CXL_HDM_DECODER0_CTRL_OFFSET(id));
-}
-
-void cxl_commit_start_switch(const struct cxl_decoder_config *config,
- u64 targets, void __iomem *hdm)
-{
- int id = config->id;
- u32 ctrl;
-
- lockdep_assert_held(&cxl_rwsem.dpa);
- ctrl = cxl_hdm_write_range(hdm, config);
- writel(upper_32_bits(targets), hdm + CXL_HDM_DECODER0_TL_HIGH(id));
- writel(lower_32_bits(targets), hdm + CXL_HDM_DECODER0_TL_LOW(id));
- writel(ctrl, hdm + CXL_HDM_DECODER0_CTRL_OFFSET(id));
-}
-
static void
cxl_endpoint_decoder_snapshot(struct cxl_endpoint_decoder *cxled,
struct cxl_endpoint_decoder_settings *settings)
@@ -846,6 +746,8 @@ static void setup_hw_decoder(struct cxl_decoder *cxld, void __iomem *hdm)
{
struct cxl_endpoint_decoder_settings settings;
+ lockdep_assert_held(&cxl_rwsem.dpa);
+
if (is_switch_decoder(&cxld->dev)) {
struct cxl_switch_decoder *cxlsd =
to_cxl_switch_decoder(&cxld->dev);
diff --git a/drivers/cxl/core/hdm_regs.c b/drivers/cxl/core/hdm_regs.c
new file mode 100644
index 000000000000..53d2f236e49c
--- /dev/null
+++ b/drivers/cxl/core/hdm_regs.c
@@ -0,0 +1,118 @@
+// 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/export.h>
+#include <linux/kernel.h>
+
+#include <cxl/hdm.h>
+
+#include "cxl.h"
+#include "core.h"
+
+/*
+ * HDM decoder register helpers are built in whenever CXL_BUS is enabled,
+ * including when cxl_core is modular. Callers provide any required locking.
+ */
+
+static void cxld_set_interleave(const struct cxl_decoder_config *config, 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(config->interleave_ways, &eiw),
+ "invalid interleave_ways: %d\n", config->interleave_ways))
+ return;
+ if (WARN_ONCE(granularity_to_eig(config->interleave_granularity, &eig),
+ "invalid interleave_granularity: %d\n",
+ config->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(const struct cxl_decoder_config *config, u32 *ctrl)
+{
+ u32p_replace_bits(ctrl,
+ !!(config->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;
+}
+EXPORT_SYMBOL_FOR_MODULES(cxld_await_commit, "cxl_core");
+
+static u32 cxl_hdm_write_range(void __iomem *hdm,
+ const struct cxl_decoder_config *config)
+{
+ u64 size = range_len(&config->hpa_range);
+ u64 base = config->hpa_range.start;
+ int id = config->id;
+ u32 ctrl;
+
+ ctrl = readl(hdm + CXL_HDM_DECODER0_CTRL_OFFSET(id));
+ cxld_set_interleave(config, &ctrl);
+ cxld_set_type(config, &ctrl);
+
+ 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));
+ return ctrl;
+}
+
+void cxl_commit_start_endpoint(const struct cxl_endpoint_decoder_settings *settings,
+ void __iomem *hdm)
+{
+ int id = settings->config.id;
+ u32 ctrl;
+
+ ctrl = cxl_hdm_write_range(hdm, &settings->config);
+ writel(upper_32_bits(settings->skip), hdm + CXL_HDM_DECODER0_SKIP_HIGH(id));
+ writel(lower_32_bits(settings->skip), hdm + CXL_HDM_DECODER0_SKIP_LOW(id));
+ writel(ctrl, hdm + CXL_HDM_DECODER0_CTRL_OFFSET(id));
+}
+EXPORT_SYMBOL_FOR_MODULES(cxl_commit_start_endpoint, "cxl_core");
+
+void cxl_commit_start_switch(const struct cxl_decoder_config *config,
+ u64 targets, void __iomem *hdm)
+{
+ int id = config->id;
+ u32 ctrl;
+
+ ctrl = cxl_hdm_write_range(hdm, config);
+ writel(upper_32_bits(targets), hdm + CXL_HDM_DECODER0_TL_HIGH(id));
+ writel(lower_32_bits(targets), hdm + CXL_HDM_DECODER0_TL_LOW(id));
+ writel(ctrl, hdm + CXL_HDM_DECODER0_CTRL_OFFSET(id));
+}
+EXPORT_SYMBOL_FOR_MODULES(cxl_commit_start_switch, "cxl_core");
--
2.43.0
next prev parent reply other threads:[~2026-10-11 2:14 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-11 2:14 [PATCH v15 00/16] PCI/CXL: Add CXL reset support for Type 2 devices Srirangan Madhavan
2026-10-11 2:14 ` [PATCH v15 01/16] cxl: Drop stale decoder interleave limit comment Srirangan Madhavan
2026-10-11 2:14 ` [PATCH v15 02/16] cxl: Share CXL port upstream PCI device lookup Srirangan Madhavan
2026-10-11 2:14 ` [PATCH v15 03/16] cxl: Move decoder declarations to shared header Srirangan Madhavan
2026-10-11 2:14 ` [PATCH v15 04/16] cxl: Embed decoder configuration in a standalone structure Srirangan Madhavan
2026-10-11 2:14 ` [PATCH v15 05/16] cxl: Introduce endpoint HDM decoder settings Srirangan Madhavan
2026-10-11 2:14 ` Srirangan Madhavan [this message]
2026-10-11 2:14 ` [PATCH v15 07/16] cxl: Share HDM decoder register unpacking Srirangan Madhavan
2026-10-11 2:14 ` [PATCH v15 08/16] cxl: Refresh cached PCI HDM decoder settings Srirangan Madhavan
2026-10-11 2:14 ` [PATCH v15 09/16] PCI/CXL: Cache endpoint HDM state during PCI enumeration Srirangan Madhavan
2026-10-11 2:14 ` [PATCH v15 10/16] PCI/CXL: Add CXL Device Reset sequencing Srirangan Madhavan
2026-10-11 2:14 ` [PATCH v15 11/16] cxl: Validate and synchronize HDM ranges around reset Srirangan Madhavan
2026-10-11 2:14 ` [PATCH v15 12/16] PCI/CXL: Reject reset with unsafe function scope Srirangan Madhavan
2026-10-11 2:14 ` [PATCH v15 13/16] PCI/CXL: Restore CXL state after PCI reset Srirangan Madhavan
2026-10-11 2:14 ` [PATCH v15 14/16] PCI/CXL: Expose CXL Reset as a PCI reset method Srirangan Madhavan
2026-10-11 2:14 ` [PATCH v15 15/16] PCI/CXL: Restore CXL state after CXL bus reset Srirangan Madhavan
2026-10-11 2:14 ` [PATCH v15 16/16] tools/testing/cxl: Add HDM decoder range checks Srirangan Madhavan
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