[v3,4/8] cxl/edac: Add CXL memory device ECS control feature

Commit Message

Shiju Jose April 7, 2025, 5:49 p.m. UTC

From: Shiju Jose <[e-mail]>

CXL spec 3.2 section 8.2.10.9.11.2 describes the DDR5 ECS (Error Check
Scrub) control feature.
The Error Check Scrub (ECS) is a feature defined in JEDEC DDR5 SDRAM
Specification (JESD79-5) and allows the DRAM to internally read, correct
single-bit errors, and write back corrected data bits to the DRAM array
while providing transparency to error counts.

The ECS control allows the requester to change the log entry type, the ECS
threshold count (provided the request falls within the limits specified in
DDR5 mode registers), switch between codeword mode and row count mode, and
reset the ECS counter.

Register with EDAC device driver, which retrieves the ECS attribute
descriptors from the EDAC ECS and exposes the ECS control attributes to
userspace via sysfs. For example, the ECS control for the memory media FRU0
in CXL mem0 device is located at /sys/bus/edac/devices/cxl_mem0/ecs_fru0/

Reviewed-by: Jonathan Cameron <[e-mail]>
Reviewed-by: Fan Ni <[e-mail]>
Signed-off-by: Shiju Jose <[e-mail]>
---
 drivers/cxl/Kconfig     |  17 ++
 drivers/cxl/core/edac.c | 363 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 378 insertions(+), 2 deletions(-)

Patch

diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
index af72416edcd4..51987f2a2548 100644
--- a/drivers/cxl/Kconfig
+++ b/drivers/cxl/Kconfig
@@ -147,6 +147,23 @@  config CXL_EDAC_SCRUB
 	  (e.g. scrub rates for the patrol scrub feature).
 	  Otherwise say 'n'.
 
+config CXL_EDAC_ECS
+	bool "Enable CXL Error Check Scrub (Repair)"
+	depends on CXL_EDAC_MEM_FEATURES
+	depends on EDAC_ECS
+	help
+	  The CXL EDAC ECS control is optional and allows host to
+	  control the ECS feature configurations of CXL memory expander
+	  devices.
+
+	  When enabled 'cxl_mem' EDAC devices are published with memory
+	  ECS control attributes as described by
+	  Documentation/ABI/testing/sysfs-edac-ecs.
+
+	  Say 'y' if you have an expert need to change default settings
+	  of a memory ECS feature established by the platform/device.
+	  Otherwise say 'n'.
+
 config CXL_PORT
 	default CXL_BUS
 	tristate
diff --git a/drivers/cxl/core/edac.c b/drivers/cxl/core/edac.c
index 3a4f9ed726d3..a624fc90caf9 100644
--- a/drivers/cxl/core/edac.c
+++ b/drivers/cxl/core/edac.c
@@ -19,7 +19,7 @@ 
 #include <cxlmem.h>
 #include "core.h"
 
-#define CXL_NR_EDAC_DEV_FEATURES 1
+#define CXL_NR_EDAC_DEV_FEATURES 2
 
 #ifdef CONFIG_CXL_EDAC_SCRUB
 struct cxl_patrol_scrub_context {
@@ -441,11 +441,361 @@  static int cxl_region_scrub_init(struct cxl_region *cxlr,
 }
 #endif /* CONFIG_CXL_EDAC_SCRUB */
 
+#ifdef CONFIG_CXL_EDAC_ECS
+struct cxl_ecs_context {
+	u16 num_media_frus;
+	u16 get_feat_size;
+	u16 set_feat_size;
+	u8 get_version;
+	u8 set_version;
+	u16 effects;
+	struct cxl_memdev *cxlmd;
+};
+
+/*
+ * See CXL spec rev 3.2 @8.2.10.9.11.2 Table 8-225 DDR5 ECS Control Feature
+ * Readable Attributes.
+ */
+struct cxl_ecs_fru_rd_attrbs {
+	u8 ecs_cap;
+	__le16 ecs_config;
+	u8 ecs_flags;
+} __packed;
+
+struct cxl_ecs_rd_attrbs {
+	u8 ecs_log_cap;
+	struct cxl_ecs_fru_rd_attrbs fru_attrbs[];
+} __packed;
+
+/*
+ * See CXL spec rev 3.2 @8.2.10.9.11.2 Table 8-226 DDR5 ECS Control Feature
+ * Writable Attributes.
+ */
+struct cxl_ecs_fru_wr_attrbs {
+	__le16 ecs_config;
+} __packed;
+
+struct cxl_ecs_wr_attrbs {
+	u8 ecs_log_cap;
+	struct cxl_ecs_fru_wr_attrbs fru_attrbs[];
+} __packed;
+
+#define CXL_ECS_LOG_ENTRY_TYPE_MASK GENMASK(1, 0)
+#define CXL_ECS_REALTIME_REPORT_CAP_MASK BIT(0)
+#define CXL_ECS_THRESHOLD_COUNT_MASK GENMASK(2, 0)
+#define CXL_ECS_COUNT_MODE_MASK BIT(3)
+#define CXL_ECS_RESET_COUNTER_MASK BIT(4)
+#define CXL_ECS_RESET_COUNTER 1
+
+enum {
+	ECS_THRESHOLD_256 = 256,
+	ECS_THRESHOLD_1024 = 1024,
+	ECS_THRESHOLD_4096 = 4096,
+};
+
+enum {
+	ECS_THRESHOLD_IDX_256 = 3,
+	ECS_THRESHOLD_IDX_1024 = 4,
+	ECS_THRESHOLD_IDX_4096 = 5,
+};
+
+static const u16 ecs_supp_threshold[] = {
+	[ECS_THRESHOLD_IDX_256] = 256,
+	[ECS_THRESHOLD_IDX_1024] = 1024,
+	[ECS_THRESHOLD_IDX_4096] = 4096,
+};
+
+enum {
+	ECS_LOG_ENTRY_TYPE_DRAM = 0x0,
+	ECS_LOG_ENTRY_TYPE_MEM_MEDIA_FRU = 0x1,
+};
+
+enum cxl_ecs_count_mode {
+	ECS_MODE_COUNTS_ROWS = 0,
+	ECS_MODE_COUNTS_CODEWORDS = 1,
+};
+
+static int cxl_mem_ecs_get_attrbs(struct device *dev,
+				  struct cxl_ecs_context *cxl_ecs_ctx,
+				  int fru_id, u8 *log_cap, u16 *config)
+{
+	struct cxl_memdev *cxlmd = cxl_ecs_ctx->cxlmd;
+	struct cxl_mailbox *cxl_mbox = &cxlmd->cxlds->cxl_mbox;
+	struct cxl_ecs_fru_rd_attrbs *fru_rd_attrbs;
+	size_t rd_data_size;
+	size_t data_size;
+
+	rd_data_size = cxl_ecs_ctx->get_feat_size;
+
+	struct cxl_ecs_rd_attrbs *rd_attrbs __free(kvfree) =
+		kvzalloc(rd_data_size, GFP_KERNEL);
+	if (!rd_attrbs)
+		return -ENOMEM;
+
+	data_size = cxl_get_feature(cxl_mbox, &CXL_FEAT_ECS_UUID,
+				    CXL_GET_FEAT_SEL_CURRENT_VALUE, rd_attrbs,
+				    rd_data_size, 0, NULL);
+	if (!data_size)
+		return -EIO;
+
+	fru_rd_attrbs = rd_attrbs->fru_attrbs;
+	*log_cap = rd_attrbs->ecs_log_cap;
+	*config = le16_to_cpu(fru_rd_attrbs[fru_id].ecs_config);
+
+	return 0;
+}
+
+static int cxl_mem_ecs_set_attrbs(struct device *dev,
+				  struct cxl_ecs_context *cxl_ecs_ctx,
+				  int fru_id, u8 log_cap, u16 config)
+{
+	struct cxl_memdev *cxlmd = cxl_ecs_ctx->cxlmd;
+	struct cxl_mailbox *cxl_mbox = &cxlmd->cxlds->cxl_mbox;
+	struct cxl_ecs_fru_rd_attrbs *fru_rd_attrbs;
+	struct cxl_ecs_fru_wr_attrbs *fru_wr_attrbs;
+	size_t rd_data_size, wr_data_size;
+	u16 num_media_frus, count;
+	size_t data_size;
+
+	num_media_frus = cxl_ecs_ctx->num_media_frus;
+	rd_data_size = cxl_ecs_ctx->get_feat_size;
+	wr_data_size = cxl_ecs_ctx->set_feat_size;
+	struct cxl_ecs_rd_attrbs *rd_attrbs __free(kvfree) =
+		kvzalloc(rd_data_size, GFP_KERNEL);
+	if (!rd_attrbs)
+		return -ENOMEM;
+
+	data_size = cxl_get_feature(cxl_mbox, &CXL_FEAT_ECS_UUID,
+				    CXL_GET_FEAT_SEL_CURRENT_VALUE, rd_attrbs,
+				    rd_data_size, 0, NULL);
+	if (!data_size)
+		return -EIO;
+
+	struct cxl_ecs_wr_attrbs *wr_attrbs __free(kvfree) =
+		kvzalloc(wr_data_size, GFP_KERNEL);
+	if (!wr_attrbs)
+		return -ENOMEM;
+
+	/*
+	 * Fill writable attributes from the current attributes read
+	 * for all the media FRUs.
+	 */
+	fru_rd_attrbs = rd_attrbs->fru_attrbs;
+	fru_wr_attrbs = wr_attrbs->fru_attrbs;
+	wr_attrbs->ecs_log_cap = log_cap;
+	for (count = 0; count < num_media_frus; count++)
+		fru_wr_attrbs[count].ecs_config =
+			fru_rd_attrbs[count].ecs_config;
+
+	fru_wr_attrbs[fru_id].ecs_config = cpu_to_le16(config);
+
+	return cxl_set_feature(cxl_mbox, &CXL_FEAT_ECS_UUID,
+			       cxl_ecs_ctx->set_version, wr_attrbs,
+			       wr_data_size,
+			       CXL_SET_FEAT_FLAG_DATA_SAVED_ACROSS_RESET,
+			       0, NULL);
+}
+
+static u8 cxl_get_ecs_log_entry_type(u8 log_cap, u16 config)
+{
+	return FIELD_GET(CXL_ECS_LOG_ENTRY_TYPE_MASK, log_cap);
+}
+
+static u16 cxl_get_ecs_threshold(u8 log_cap, u16 config)
+{
+	u8 index = FIELD_GET(CXL_ECS_THRESHOLD_COUNT_MASK, config);
+
+	return ecs_supp_threshold[index];
+}
+
+static u8 cxl_get_ecs_count_mode(u8 log_cap, u16 config)
+{
+	return FIELD_GET(CXL_ECS_COUNT_MODE_MASK, config);
+}
+
+#define CXL_ECS_GET_ATTR(attrb)						    \
+	static int cxl_ecs_get_##attrb(struct device *dev, void *drv_data,  \
+				       int fru_id, u32 *val)		    \
+	{								    \
+		struct cxl_ecs_context *ctx = drv_data;			    \
+		u8 log_cap;						    \
+		u16 config;						    \
+		int ret;						    \
+									    \
+		ret = cxl_mem_ecs_get_attrbs(dev, ctx, fru_id, &log_cap,    \
+					     &config);			    \
+		if (ret)						    \
+			return ret;					    \
+									    \
+		*val = cxl_get_ecs_##attrb(log_cap, config);		    \
+									    \
+		return 0;						    \
+	}
+
+CXL_ECS_GET_ATTR(log_entry_type)
+CXL_ECS_GET_ATTR(count_mode)
+CXL_ECS_GET_ATTR(threshold)
+
+static int cxl_set_ecs_log_entry_type(struct device *dev, u8 *log_cap,
+				      u16 *config, u32 val)
+{
+	if (val != ECS_LOG_ENTRY_TYPE_DRAM &&
+	    val != ECS_LOG_ENTRY_TYPE_MEM_MEDIA_FRU)
+		return -EINVAL;
+
+	*log_cap = FIELD_PREP(CXL_ECS_LOG_ENTRY_TYPE_MASK, val);
+
+	return 0;
+}
+
+static int cxl_set_ecs_threshold(struct device *dev, u8 *log_cap, u16 *config,
+				 u32 val)
+{
+	*config &= ~CXL_ECS_THRESHOLD_COUNT_MASK;
+
+	switch (val) {
+	case ECS_THRESHOLD_256:
+		*config |= FIELD_PREP(CXL_ECS_THRESHOLD_COUNT_MASK,
+				      ECS_THRESHOLD_IDX_256);
+		break;
+	case ECS_THRESHOLD_1024:
+		*config |= FIELD_PREP(CXL_ECS_THRESHOLD_COUNT_MASK,
+				      ECS_THRESHOLD_IDX_1024);
+		break;
+	case ECS_THRESHOLD_4096:
+		*config |= FIELD_PREP(CXL_ECS_THRESHOLD_COUNT_MASK,
+				      ECS_THRESHOLD_IDX_4096);
+		break;
+	default:
+		dev_dbg(dev, "Invalid CXL ECS threshold count(%d) to set\n",
+			val);
+		dev_dbg(dev, "Supported ECS threshold counts: %u, %u, %u\n",
+			ECS_THRESHOLD_256, ECS_THRESHOLD_1024,
+			ECS_THRESHOLD_4096);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int cxl_set_ecs_count_mode(struct device *dev, u8 *log_cap, u16 *config,
+				  u32 val)
+{
+	if (val != ECS_MODE_COUNTS_ROWS && val != ECS_MODE_COUNTS_CODEWORDS) {
+		dev_dbg(dev, "Invalid CXL ECS scrub mode(%d) to set\n", val);
+		dev_dbg(dev,
+			"Supported ECS Modes: 0: ECS counts rows with errors,"
+			" 1: ECS counts codewords with errors\n");
+		return -EINVAL;
+	}
+
+	*config &= ~CXL_ECS_COUNT_MODE_MASK;
+	*config |= FIELD_PREP(CXL_ECS_COUNT_MODE_MASK, val);
+
+	return 0;
+}
+
+static int cxl_set_ecs_reset_counter(struct device *dev, u8 *log_cap,
+				     u16 *config, u32 val)
+{
+	if (val != CXL_ECS_RESET_COUNTER)
+		return -EINVAL;
+
+	*config &= ~CXL_ECS_RESET_COUNTER_MASK;
+	*config |= FIELD_PREP(CXL_ECS_RESET_COUNTER_MASK, val);
+
+	return 0;
+}
+
+#define CXL_ECS_SET_ATTR(attrb)						    \
+	static int cxl_ecs_set_##attrb(struct device *dev, void *drv_data,  \
+					int fru_id, u32 val)		    \
+	{								    \
+		struct cxl_ecs_context *ctx = drv_data;			    \
+		u8 log_cap;						    \
+		u16 config;						    \
+		int ret;						    \
+									    \
+		if (!capable(CAP_SYS_RAWIO))				    \
+			return -EPERM;					    \
+									    \
+		ret = cxl_mem_ecs_get_attrbs(dev, ctx, fru_id, &log_cap,    \
+					     &config);			    \
+		if (ret)						    \
+			return ret;					    \
+									    \
+		ret = cxl_set_ecs_##attrb(dev, &log_cap, &config, val);     \
+		if (ret)						    \
+			return ret;					    \
+									    \
+		return cxl_mem_ecs_set_attrbs(dev, ctx, fru_id, log_cap,    \
+					      config);			    \
+	}
+CXL_ECS_SET_ATTR(log_entry_type)
+CXL_ECS_SET_ATTR(count_mode)
+CXL_ECS_SET_ATTR(reset_counter)
+CXL_ECS_SET_ATTR(threshold)
+
+static const struct edac_ecs_ops cxl_ecs_ops = {
+	.get_log_entry_type = cxl_ecs_get_log_entry_type,
+	.set_log_entry_type = cxl_ecs_set_log_entry_type,
+	.get_mode = cxl_ecs_get_count_mode,
+	.set_mode = cxl_ecs_set_count_mode,
+	.reset = cxl_ecs_set_reset_counter,
+	.get_threshold = cxl_ecs_get_threshold,
+	.set_threshold = cxl_ecs_set_threshold,
+};
+
+static int cxl_memdev_ecs_init(struct cxl_memdev *cxlmd,
+			       struct edac_dev_feature *ras_feature)
+{
+	struct cxl_ecs_context *cxl_ecs_ctx;
+	struct cxl_feat_entry *feat_entry;
+	int num_media_frus;
+
+	feat_entry =
+		cxl_feature_info(to_cxlfs(cxlmd->cxlds), &CXL_FEAT_ECS_UUID);
+	if (!feat_entry)
+		return -EOPNOTSUPP;
+
+	if (!(le32_to_cpu(feat_entry->flags) & CXL_FEATURE_F_CHANGEABLE))
+		return -EOPNOTSUPP;
+
+	num_media_frus = (le16_to_cpu(feat_entry->get_feat_size) -
+			  sizeof(struct cxl_ecs_rd_attrbs)) /
+			 sizeof(struct cxl_ecs_fru_rd_attrbs);
+	if (!num_media_frus)
+		return -EOPNOTSUPP;
+
+	cxl_ecs_ctx =
+		devm_kzalloc(&cxlmd->dev, sizeof(*cxl_ecs_ctx), GFP_KERNEL);
+	if (!cxl_ecs_ctx)
+		return -ENOMEM;
+
+	*cxl_ecs_ctx = (struct cxl_ecs_context){
+		.get_feat_size = le16_to_cpu(feat_entry->get_feat_size),
+		.set_feat_size = le16_to_cpu(feat_entry->set_feat_size),
+		.get_version = feat_entry->get_feat_ver,
+		.set_version = feat_entry->set_feat_ver,
+		.effects = le16_to_cpu(feat_entry->effects),
+		.num_media_frus = num_media_frus,
+		.cxlmd = cxlmd,
+	};
+
+	ras_feature->ft_type = RAS_FEAT_ECS;
+	ras_feature->ecs_ops = &cxl_ecs_ops;
+	ras_feature->ctx = cxl_ecs_ctx;
+	ras_feature->ecs_info.num_media_frus = num_media_frus;
+
+	return 0;
+}
+#endif /* CONFIG_CXL_EDAC_ECS */
+
 int devm_cxl_memdev_edac_register(struct cxl_memdev *cxlmd)
 {
 	struct edac_dev_feature ras_features[CXL_NR_EDAC_DEV_FEATURES];
 	int num_ras_features = 0;
-#if defined(CONFIG_CXL_EDAC_SCRUB)
+#if defined(CONFIG_CXL_EDAC_SCRUB) || defined(CONFIG_CXL_EDAC_ECS)
 	int rc;
 #endif
 
@@ -458,6 +808,15 @@  int devm_cxl_memdev_edac_register(struct cxl_memdev *cxlmd)
 		num_ras_features++;
 #endif
 
+#ifdef CONFIG_CXL_EDAC_ECS
+	rc = cxl_memdev_ecs_init(cxlmd, &ras_features[num_ras_features]);
+	if (rc < 0 && rc != -EOPNOTSUPP)
+		return rc;
+
+	if (rc != -EOPNOTSUPP)
+		num_ras_features++;
+#endif
+
 	char *cxl_dev_name __free(kfree) =
 		kasprintf(GFP_KERNEL, "cxl_%s", dev_name(&cxlmd->dev));
 	if (!cxl_dev_name)