[PATCH v19 09/15] cxl/memfeature: Add CXL memory device ECS control feature

shiju.jose
2025-02-07T14:45:51Z

CXL spec 3.1 section 8.2.9.9.11.2 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/

Signed-off-by: Shiju Jose <shiju.jose@huawei.com>
---
drivers/cxl/Kconfig | 1 +
drivers/cxl/core/memfeature.c | 355 +++++++++++++++++++++++++++++++++-
2 files changed, 355 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
index ac5ad2dc5996..892c9a3c5679 100644
--- a/drivers/cxl/Kconfig
+++ b/drivers/cxl/Kconfig
@@ -165,6 +165,7 @@ config CXL_RAS_FEATURES
tristate "CXL: Memory RAS features"
depends on CXL_MEM
depends on EDAC_SCRUB
+ depends on EDAC_ECS
help
The CXL memory RAS feature control is optional and allows host to
control the RAS features configurations of CXL Type 3 devices.
diff --git a/drivers/cxl/core/memfeature.c b/drivers/cxl/core/memfeature.c
index c13b25a18e1a..c8540df567f1 100644
--- a/drivers/cxl/core/memfeature.c
+++ b/drivers/cxl/core/memfeature.c
@@ -19,7 +19,7 @@
#include <cxlmem.h>
#include "core.h"

-#define CXL_DEV_NUM_RAS_FEATURES 1
+#define CXL_DEV_NUM_RAS_FEATURES 2
#define CXL_DEV_HOUR_IN_SECS 3600

#define CXL_DEV_NAME_LEN 128
@@ -426,6 +426,352 @@ static int cxl_region_scrub_init(struct cxl_region *cxlr,
return 0;
}

+/*
+ * CXL DDR5 ECS control definitions.
+ */
+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;
+};
+
+enum {
+ CXL_ECS_PARAM_LOG_ENTRY_TYPE,
+ CXL_ECS_PARAM_THRESHOLD,
+ CXL_ECS_PARAM_MODE,
+ CXL_ECS_PARAM_RESET_COUNTER,
+};
+
+#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,
+};
+
+/**
+ * struct cxl_ecs_params - CXL memory DDR5 ECS parameter data structure.
+ * @threshold: ECS threshold count per GB of memory cells.
+ * @log_entry_type: ECS log entry type, per DRAM or per memory media FRU.
+ * @reset_counter: [IN] reset ECC counter to default value.
+ * @count_mode: codeword/row count mode
+ * 0 : ECS counts rows with errors
+ * 1 : ECS counts codeword with errors
+ */
+struct cxl_ecs_params {
+ u16 threshold;
+ u8 log_entry_type;
+ u8 reset_counter;
+ enum cxl_ecs_count_mode count_mode;
+};
+
+/*
+ * See CXL spec rev 3.1 @8.2.9.9.11.2 Table 8-210 DDR5 ECS Control Feature
+ * Readable Attributes.
+ */
+struct cxl_ecs_fru_rd_attrs {
+ u8 ecs_cap;
+ __le16 ecs_config;
+ u8 ecs_flags;
+} __packed;
+
+struct cxl_ecs_rd_attrs {
+ u8 ecs_log_cap;
+ struct cxl_ecs_fru_rd_attrs fru_attrs[];
+} __packed;
+
+/*
+ * See CXL spec rev 3.1 @8.2.9.9.11.2 Table 8-211 DDR5 ECS Control Feature
+ * Writable Attributes.
+ */
+struct cxl_ecs_fru_wr_attrs {
+ __le16 ecs_config;
+} __packed;
+
+struct cxl_ecs_wr_attrs {
+ u8 ecs_log_cap;
+ struct cxl_ecs_fru_wr_attrs fru_attrs[];
+} __packed;
+
+/*
+ * CXL DDR5 ECS control functions.
+ */
+static int cxl_mem_ecs_get_attrs(struct device *dev,
+ struct cxl_ecs_context *cxl_ecs_ctx,
+ int fru_id, struct cxl_ecs_params *params)
+{
+ struct cxl_memdev *cxlmd = cxl_ecs_ctx->cxlmd;
+ struct cxl_mailbox *cxl_mbox = &cxlmd->cxlds->cxl_mbox;
+ struct cxl_ecs_fru_rd_attrs *fru_rd_attrs;
+ size_t rd_data_size;
+ u8 threshold_index;
+ size_t data_size;
+ u16 ecs_config;
+
+ rd_data_size = cxl_ecs_ctx->get_feat_size;
+
+ struct cxl_ecs_rd_attrs *rd_attrs __free(kvfree) =
+ kvzalloc(rd_data_size, GFP_KERNEL);
+ if (!rd_attrs)
+ return -ENOMEM;
+
+ params->log_entry_type = 0;
+ params->threshold = 0;
+ params->count_mode = 0;
+ data_size = cxl_get_feature(cxl_mbox, &CXL_FEAT_ECS_UUID,
+ CXL_GET_FEAT_SEL_CURRENT_VALUE,
+ rd_attrs, rd_data_size, 0, NULL);
+ if (!data_size)
+ return -EIO;
+
+ fru_rd_attrs = rd_attrs->fru_attrs;
+ params->log_entry_type = FIELD_GET(CXL_ECS_LOG_ENTRY_TYPE_MASK,
+ rd_attrs->ecs_log_cap);
+ ecs_config = le16_to_cpu(fru_rd_attrs[fru_id].ecs_config);
+ threshold_index = FIELD_GET(CXL_ECS_THRESHOLD_COUNT_MASK,
+ ecs_config);
+ params->threshold = ecs_supp_threshold[threshold_index];
+ params->count_mode = FIELD_GET(CXL_ECS_COUNT_MODE_MASK,
+ ecs_config);
+ return 0;
+}
+
+static int cxl_mem_ecs_set_attrs(struct device *dev,
+ struct cxl_ecs_context *cxl_ecs_ctx,
+ int fru_id, struct cxl_ecs_params *params,
+ u8 param_type)
+{
+ struct cxl_memdev *cxlmd = cxl_ecs_ctx->cxlmd;
+ struct cxl_mailbox *cxl_mbox = &cxlmd->cxlds->cxl_mbox;
+ struct cxl_ecs_fru_rd_attrs *fru_rd_attrs;
+ struct cxl_ecs_fru_wr_attrs *fru_wr_attrs;
+ size_t rd_data_size, wr_data_size;
+ u16 num_media_frus, count;
+ size_t data_size;
+ u16 ecs_config;
+
+ 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_attrs *rd_attrs __free(kvfree) =
+ kvzalloc(rd_data_size, GFP_KERNEL);
+ if (!rd_attrs)
+ return -ENOMEM;
+
+ data_size = cxl_get_feature(cxl_mbox, &CXL_FEAT_ECS_UUID,
+ CXL_GET_FEAT_SEL_CURRENT_VALUE,
+ rd_attrs, rd_data_size, 0, NULL);
+ if (!data_size)
+ return -EIO;
+
+ struct cxl_ecs_wr_attrs *wr_attrs __free(kvfree) =
+ kvzalloc(wr_data_size, GFP_KERNEL);
+ if (!wr_attrs)
+ return -ENOMEM;
+
+ /*
+ * Fill writable attributes from the current attributes read
+ * for all the media FRUs.
+ */
+ fru_rd_attrs = rd_attrs->fru_attrs;
+ fru_wr_attrs = wr_attrs->fru_attrs;
+ wr_attrs->ecs_log_cap = rd_attrs->ecs_log_cap;
+ for (count = 0; count < num_media_frus; count++)
+ fru_wr_attrs[count].ecs_config = fru_rd_attrs[count].ecs_config;
+
+ /*
+ * Fill attribute to be set for the media FRU
+ */
+ ecs_config = le16_to_cpu(fru_rd_attrs[fru_id].ecs_config);
+ switch (param_type) {
+ case CXL_ECS_PARAM_LOG_ENTRY_TYPE:
+ if (params->log_entry_type != ECS_LOG_ENTRY_TYPE_DRAM &&
+ params->log_entry_type != ECS_LOG_ENTRY_TYPE_MEM_MEDIA_FRU)
+ return -EINVAL;
+
+ wr_attrs->ecs_log_cap = FIELD_PREP(CXL_ECS_LOG_ENTRY_TYPE_MASK,
+ params->log_entry_type);
+ break;
+ case CXL_ECS_PARAM_THRESHOLD:
+ ecs_config &= ~CXL_ECS_THRESHOLD_COUNT_MASK;
+ switch (params->threshold) {
+ case ECS_THRESHOLD_256:
+ ecs_config |= FIELD_PREP(CXL_ECS_THRESHOLD_COUNT_MASK,
+ ECS_THRESHOLD_IDX_256);
+ break;
+ case ECS_THRESHOLD_1024:
+ ecs_config |= FIELD_PREP(CXL_ECS_THRESHOLD_COUNT_MASK,
+ ECS_THRESHOLD_IDX_1024);
+ break;
+ case ECS_THRESHOLD_4096:
+ ecs_config |= FIELD_PREP(CXL_ECS_THRESHOLD_COUNT_MASK,
+ ECS_THRESHOLD_IDX_4096);
+ break;
+ default:
+ dev_dbg(dev,
+ "Invalid CXL ECS scrub threshold count(%d) to set\n",
+ params->threshold);
+ dev_dbg(dev,
+ "Supported scrub threshold counts: %u, %u, %u\n",
+ ECS_THRESHOLD_256, ECS_THRESHOLD_1024, ECS_THRESHOLD_4096);
+ return -EINVAL;
+ }
+ break;
+ case CXL_ECS_PARAM_MODE:
+ if (params->count_mode != ECS_MODE_COUNTS_ROWS &&
+ params->count_mode != ECS_MODE_COUNTS_CODEWORDS) {
+ dev_dbg(dev,
+ "Invalid CXL ECS scrub mode(%d) to set\n",
+ params->count_mode);
+ dev_dbg(dev,
+ "Supported ECS Modes: 0: ECS counts rows with errors,"
+ " 1: ECS counts codewords with errors\n");
+ return -EINVAL;
+ }
+ ecs_config &= ~CXL_ECS_COUNT_MODE_MASK;
+ ecs_config |= FIELD_PREP(CXL_ECS_COUNT_MODE_MASK, params->count_mode);
+ break;
+ case CXL_ECS_PARAM_RESET_COUNTER:
+ if (params->reset_counter != CXL_ECS_RESET_COUNTER)
+ return -EINVAL;
+
+ ecs_config &= ~CXL_ECS_RESET_COUNTER_MASK;
+ ecs_config |= FIELD_PREP(CXL_ECS_RESET_COUNTER_MASK, params->reset_counter);
+ break;
+ default:
+ return -EINVAL;
+ }
+ fru_wr_attrs[fru_id].ecs_config = cpu_to_le16(ecs_config);
+
+ return cxl_set_feature(cxl_mbox, &CXL_FEAT_ECS_UUID,
+ cxl_ecs_ctx->set_version,
+ wr_attrs, wr_data_size,
+ CXL_SET_FEAT_FLAG_DATA_SAVED_ACROSS_RESET,
+ 0, NULL);
+}
+
+#define CXL_ECS_GET_ATTR(attrib) \
+static int cxl_ecs_get_##attrib(struct device *dev, void *drv_data, \
+ int fru_id, u32 *val) \
+{ \
+ struct cxl_ecs_context *ctx = drv_data; \
+ struct cxl_ecs_params params; \
+ int ret; \
+ \
+ ret = cxl_mem_ecs_get_attrs(dev, ctx, fru_id, &params); \
+ if (ret) \
+ return ret; \
+ \
+ *val = params.attrib; \
+ \
+ return 0; \
+}
+
+CXL_ECS_GET_ATTR(log_entry_type)
+CXL_ECS_GET_ATTR(count_mode)
+CXL_ECS_GET_ATTR(threshold)
+
+#define CXL_ECS_SET_ATTR(attrib, param_type) \
+static int cxl_ecs_set_##attrib(struct device *dev, void *drv_data, \
+ int fru_id, u32 val) \
+{ \
+ struct cxl_ecs_context *ctx = drv_data; \
+ struct cxl_ecs_params params = { \
+ .attrib = val, \
+ }; \
+ \
+ return cxl_mem_ecs_set_attrs(dev, ctx, fru_id, &params, (param_type)); \
+}
+CXL_ECS_SET_ATTR(log_entry_type, CXL_ECS_PARAM_LOG_ENTRY_TYPE)
+CXL_ECS_SET_ATTR(count_mode, CXL_ECS_PARAM_MODE)
+CXL_ECS_SET_ATTR(reset_counter, CXL_ECS_PARAM_RESET_COUNTER)
+CXL_ECS_SET_ATTR(threshold, CXL_ECS_PARAM_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_get_feature_entry(cxlmd, &CXL_FEAT_ECS_UUID);
+ if (IS_ERR(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_attrs)) /
+ sizeof(struct cxl_ecs_fru_rd_attrs);
+ 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;
+}
+
int devm_cxl_memdev_edac_register(struct cxl_memdev *cxlmd)
{
struct edac_dev_feature ras_features[CXL_DEV_NUM_RAS_FEATURES];
@@ -442,6 +788,13 @@ int devm_cxl_memdev_edac_register(struct cxl_memdev *cxlmd)
if (rc != -EOPNOTSUPP)
num_ras_features++;

+ rc = cxl_memdev_ecs_init(cxlmd, &ras_features[num_ras_features]);
+ if (rc < 0 && rc != -EOPNOTSUPP)
+ return rc;
+
+ if (rc != -EOPNOTSUPP)
+ num_ras_features++;
+
snprintf(cxl_dev_name, sizeof(cxl_dev_name), "%s_%s",
"cxl", dev_name(&cxlmd->dev));

--
2.43.0