[PATCH v14 05/16] cxl: Introduce reusable HDM decoder settings
From: Srirangan Madhavan
Date: Thu Oct 01 2026 - 05:34:52 EST
Represent HDM programming state with struct cxl_decoder_settings and pass
it to the commit helpers. Keep endpoint skip and switch targets with their
owning types and flatten them only into transient programming settings.
Place flags with the programming state and leave runtime region ownership
outside the snapshot.
Separate commit initiation from completion waiting so reset restoration
can reuse register programming without changing normal DPA-lock policy.
Signed-off-by: Srirangan Madhavan <smadhavan@xxxxxxxxxx>
---
drivers/cxl/core/core.h | 3 ++
drivers/cxl/core/hdm.c | 82 ++++++++++++++++++++++++++---------------
include/cxl/cxl.h | 10 +++++
3 files changed, 66 insertions(+), 29 deletions(-)
diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 983d7690c3a5..a3fddb2bed63 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -139,6 +139,9 @@ struct cxl_rwsem {
extern struct cxl_rwsem cxl_rwsem;
+void cxl_commit_start(void __iomem *hdm, struct cxl_decoder_settings *settings);
+int cxld_await_commit(void __iomem *hdm, int id);
+
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 9e05032a5426..d3f21dfda146 100644
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -707,7 +707,7 @@ 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)
+static void cxld_set_interleave(struct cxl_decoder_config *config, u32 *ctrl)
{
u16 eig;
u8 eiw;
@@ -716,12 +716,12 @@ static void cxld_set_interleave(struct cxl_decoder *cxld, u32 *ctrl)
* Input validation ensures these warns never fire, but otherwise
* suppress unititalized variable usage warnings.
*/
- if (WARN_ONCE(ways_to_eiw(cxld->config.interleave_ways, &eiw),
- "invalid interleave_ways: %d\n", cxld->config.interleave_ways))
+ 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(cxld->config.interleave_granularity, &eig),
+ if (WARN_ONCE(granularity_to_eig(config->interleave_granularity, &eig),
"invalid interleave_granularity: %d\n",
- cxld->config.interleave_granularity))
+ config->interleave_granularity))
return;
u32p_replace_bits(ctrl, eig, CXL_HDM_DECODER0_CTRL_IG_MASK);
@@ -729,10 +729,10 @@ static void cxld_set_interleave(struct cxl_decoder *cxld, u32 *ctrl)
*ctrl |= CXL_HDM_DECODER0_CTRL_COMMIT;
}
-static void cxld_set_type(struct cxl_decoder *cxld, u32 *ctrl)
+static void cxld_set_type(struct cxl_decoder_config *config, u32 *ctrl)
{
u32p_replace_bits(ctrl,
- !!(cxld->config.target_type == CXL_DECODER_HOSTONLYMEM),
+ !!(config->target_type == CXL_DECODER_HOSTONLYMEM),
CXL_HDM_DECODER0_CTRL_HOSTONLY);
}
@@ -764,7 +764,7 @@ static void cxlsd_set_targets(struct cxl_switch_decoder *cxlsd, u64 *tgt)
* clock skew and other marginal behavior
*/
#define COMMIT_TIMEOUT_MS 20
-static int cxld_await_commit(void __iomem *hdm, int id)
+int cxld_await_commit(void __iomem *hdm, int id)
{
u32 ctrl;
int i;
@@ -784,45 +784,66 @@ static int cxld_await_commit(void __iomem *hdm, int id)
return -ETIMEDOUT;
}
-static void setup_hw_decoder(struct cxl_decoder *cxld, void __iomem *hdm)
+static void setup_hw_decoder(void __iomem *hdm,
+ struct cxl_decoder_settings *settings)
{
- int id = cxld->config.id;
+ struct cxl_decoder_config *config = &settings->config;
+ int id = config->id;
+ u64 target_or_skip_reg_val;
u64 base, size;
u32 ctrl;
- /* common decoder settings */
- ctrl = readl(hdm + CXL_HDM_DECODER0_CTRL_OFFSET(cxld->config.id));
- cxld_set_interleave(cxld, &ctrl);
- cxld_set_type(cxld, &ctrl);
- base = cxld->config.hpa_range.start;
- size = range_len(&cxld->config.hpa_range);
+ ctrl = readl(hdm + CXL_HDM_DECODER0_CTRL_OFFSET(id));
+ cxld_set_interleave(config, &ctrl);
+ cxld_set_type(config, &ctrl);
+ base = config->hpa_range.start;
+ size = range_len(&config->hpa_range);
+ target_or_skip_reg_val = settings->target_or_skip_reg_val;
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));
+ /* Target-list and endpoint-skip registers alias the same slot. */
+ writel(upper_32_bits(target_or_skip_reg_val), hdm + CXL_HDM_DECODER0_TL_HIGH(id));
+ writel(lower_32_bits(target_or_skip_reg_val), hdm + CXL_HDM_DECODER0_TL_LOW(id));
+
+ writel(ctrl, hdm + CXL_HDM_DECODER0_CTRL_OFFSET(id));
+}
+
+void cxl_commit_start(void __iomem *hdm, struct cxl_decoder_settings *settings)
+{
+ lockdep_assert_held(&cxl_rwsem.dpa);
+ setup_hw_decoder(hdm, settings);
+}
+
+/*
+ * Endpoint skip and switch targets have different owners. Keep that state with
+ * its owning type and flatten it only into a transient register-programming
+ * snapshot.
+ */
+static void cxl_decoder_snapshot(struct cxl_decoder *cxld,
+ struct cxl_decoder_settings *settings)
+{
+ lockdep_assert_held(&cxl_rwsem.dpa);
+
+ *settings = (struct cxl_decoder_settings) {
+ .config = cxld->config,
+ };
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);
+ settings->target_or_skip_reg_val = targets;
} 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);
+ settings->target_or_skip_reg_val = cxled->skip;
}
-
- writel(ctrl, hdm + CXL_HDM_DECODER0_CTRL_OFFSET(id));
}
static int cxl_decoder_commit(struct cxl_decoder *cxld)
@@ -830,6 +851,7 @@ 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;
+ struct cxl_decoder_settings settings;
int id = cxld->config.id, rc;
if (cxld->config.flags & CXL_DECODER_F_ENABLE)
@@ -862,10 +884,12 @@ static int cxl_decoder_commit(struct cxl_decoder *cxld)
}
}
- scoped_guard(rwsem_read, &cxl_rwsem.dpa)
- setup_hw_decoder(cxld, hdm);
+ scoped_guard(rwsem_read, &cxl_rwsem.dpa) {
+ cxl_decoder_snapshot(cxld, &settings);
+ cxl_commit_start(hdm, &settings);
+ }
- rc = cxld_await_commit(hdm, cxld->config.id);
+ rc = cxld_await_commit(hdm, settings.config.id);
if (rc) {
dev_dbg(&port->dev, "%s: error %d committing decoder\n",
dev_name(&cxld->dev), rc);
diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
index 237b31d54249..67c81be47fbb 100644
--- a/include/cxl/cxl.h
+++ b/include/cxl/cxl.h
@@ -72,6 +72,16 @@ struct cxl_decoder {
void (*reset)(struct cxl_decoder *cxld);
};
+/**
+ * struct cxl_decoder_settings - CXL HDM decoder programming snapshot
+ * @config: common decoder configuration
+ * @target_or_skip_reg_val: switch target list or endpoint skip register value
+ */
+struct cxl_decoder_settings {
+ struct cxl_decoder_config config;
+ u64 target_or_skip_reg_val;
+};
+
/*
* Using struct_group() allows for per register-block-type helper routines,
* without requiring block-type agnostic code to include the prefix.
--
2.43.0