Re: [PATCH v20 03/15] EDAC: Add ECS control feature

[Fan Ni]

On Wed, Feb 12, 2025 at 02:36:41PM +0000, shiju.jose@xxxxxxxxxx wrote:
> From: Shiju Jose <shiju.jose@xxxxxxxxxx>
> 
> Add EDAC ECS (Error Check Scrub) control to manage a memory device's
> ECS 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 DDR5 device contains number of memory media FRUs per device. The
> DDR5 ECS feature and thus the ECS control driver supports configuring
> the ECS parameters per FRU.
> 
> Memory devices support the ECS feature register with the EDAC device
> driver, which retrieves the ECS descriptor from the EDAC ECS driver.
> This driver exposes sysfs ECS control attributes to userspace via
> /sys/bus/edac/devices/<dev-name>/ecs_fruX/.
> 
> The common sysfs ECS control interface abstracts the control of an
> arbitrary ECS functionality to a common set of functions.
> 
> Support for the ECS feature is added separately because the control
> attributes of the DDR5 ECS feature differ from those of the scrub
> feature.
> 
> The sysfs ECS attribute nodes are only present if the client driver
> has implemented the corresponding attribute callback function and
> passed the necessary operations to the EDAC RAS feature driver during
> registration.
> 
> Co-developed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> Signed-off-by: Shiju Jose <shiju.jose@xxxxxxxxxx>

Reviewed-by: Fan Ni <fan.ni@xxxxxxxxxxx>
Tested-by: Fan Ni <fan.ni@xxxxxxxxxxx>


> ---
>  Documentation/ABI/testing/sysfs-edac-ecs |  74 ++++++++
>  Documentation/edac/scrub.rst             |   2 +
>  drivers/edac/Kconfig                     |   9 +
>  drivers/edac/Makefile                    |   1 +
>  drivers/edac/ecs.c                       | 207 +++++++++++++++++++++++
>  drivers/edac/edac_device.c               |  17 ++
>  include/linux/edac.h                     |  48 +++++-
>  7 files changed, 356 insertions(+), 2 deletions(-)
>  create mode 100644 Documentation/ABI/testing/sysfs-edac-ecs
>  create mode 100755 drivers/edac/ecs.c
> 
> diff --git a/Documentation/ABI/testing/sysfs-edac-ecs b/Documentation/ABI/testing/sysfs-edac-ecs
> new file mode 100644
> index 000000000000..87c885c4eb1a
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-edac-ecs
> @@ -0,0 +1,74 @@
> +What:		/sys/bus/edac/devices/<dev-name>/ecs_fruX
> +Date:		March 2025
> +KernelVersion:	6.15
> +Contact:	linux-edac@xxxxxxxxxxxxxxx
> +Description:
> +		The sysfs EDAC bus devices /<dev-name>/ecs_fruX subdirectory
> +		pertains to the memory media ECS (Error Check Scrub) control
> +		feature, where <dev-name> directory corresponds to a device
> +		registered with the EDAC device driver for the ECS feature.
> +		/ecs_fruX belongs to the media FRUs (Field Replaceable Unit)
> +		under the memory device.
> +
> +		The sysfs ECS attr nodes are only present if the parent
> +		driver has implemented the corresponding attr callback
> +		function and provided the necessary operations to the EDAC
> +		device driver during registration.
> +
> +What:		/sys/bus/edac/devices/<dev-name>/ecs_fruX/log_entry_type
> +Date:		March 2025
> +KernelVersion:	6.15
> +Contact:	linux-edac@xxxxxxxxxxxxxxx
> +Description:
> +		(RW) The log entry type of how the DDR5 ECS log is reported.
> +
> +		- 0 - per DRAM.
> +
> +		- 1 - per memory media FRU.
> +
> +		- All other values are reserved.
> +
> +What:		/sys/bus/edac/devices/<dev-name>/ecs_fruX/mode
> +Date:		March 2025
> +KernelVersion:	6.15
> +Contact:	linux-edac@xxxxxxxxxxxxxxx
> +Description:
> +		(RW) The mode of how the DDR5 ECS counts the errors.
> +		Error count is tracked based on two different modes
> +		selected by DDR5 ECS Control Feature - Codeword mode and
> +		Row Count mode. If the ECS is under Codeword mode, then
> +		the error count increments each time a codeword with check
> +		bit errors is detected. If the ECS is under Row Count mode,
> +		then the error counter increments each time a row with
> +		check bit errors is detected.
> +
> +		- 0 - ECS counts rows in the memory media that have ECC errors.
> +
> +		- 1 - ECS counts codewords with errors, specifically, it counts
> +		      the number of ECC-detected errors in the memory media.
> +
> +		- All other values are reserved.
> +
> +What:		/sys/bus/edac/devices/<dev-name>/ecs_fruX/reset
> +Date:		March 2025
> +KernelVersion:	6.15
> +Contact:	linux-edac@xxxxxxxxxxxxxxx
> +Description:
> +		(WO) ECS reset ECC counter.
> +
> +		- 1 - reset ECC counter to the default value.
> +
> +		- All other values are reserved.
> +
> +What:		/sys/bus/edac/devices/<dev-name>/ecs_fruX/threshold
> +Date:		March 2025
> +KernelVersion:	6.15
> +Contact:	linux-edac@xxxxxxxxxxxxxxx
> +Description:
> +		(RW) DDR5 ECS threshold count per gigabits of memory cells.
> +		The ECS error count is subject to the ECS Threshold count
> +		per Gbit, which masks error counts less than the Threshold.
> +
> +		Supported values are 256, 1024 and 4096.
> +
> +		All other values are reserved.
> diff --git a/Documentation/edac/scrub.rst b/Documentation/edac/scrub.rst
> index 50bb44b126fa..5f1ff2bf54b0 100644
> --- a/Documentation/edac/scrub.rst
> +++ b/Documentation/edac/scrub.rst
> @@ -257,3 +257,5 @@ sysfs
>  
>  Sysfs files are documented in
>  `Documentation/ABI/testing/sysfs-edac-scrub`
> +
> +`Documentation/ABI/testing/sysfs-edac-ecs`
> diff --git a/drivers/edac/Kconfig b/drivers/edac/Kconfig
> index 175d706168ab..9dfc2ea02df1 100644
> --- a/drivers/edac/Kconfig
> +++ b/drivers/edac/Kconfig
> @@ -84,6 +84,15 @@ config EDAC_SCRUB
>  	  into a unified set of functions.
>  	  Say 'y/n' to enable/disable EDAC scrub feature.
>  
> +config EDAC_ECS
> +	bool "EDAC ECS (Error Check Scrub) feature"
> +	help
> +	  The EDAC ECS feature is optional and is designed to control on-die
> +	  error check scrub (e.g., DDR5 ECS) in the system. The common sysfs
> +	  ECS interface abstracts the control of various ECS functionalities
> +	  into a unified set of functions.
> +	  Say 'y/n' to enable/disable EDAC ECS feature.
> +
>  config EDAC_AMD64
>  	tristate "AMD64 (Opteron, Athlon64)"
>  	depends on AMD_NB && EDAC_DECODE_MCE
> diff --git a/drivers/edac/Makefile b/drivers/edac/Makefile
> index f2a86ed997b7..21334b909ec4 100644
> --- a/drivers/edac/Makefile
> +++ b/drivers/edac/Makefile
> @@ -14,6 +14,7 @@ edac_core-y	+= edac_module.o edac_device_sysfs.o wq.o
>  edac_core-$(CONFIG_EDAC_DEBUG)		+= debugfs.o
>  
>  edac_core-$(CONFIG_EDAC_SCRUB)		+= scrub.o
> +edac_core-$(CONFIG_EDAC_ECS)		+= ecs.o
>  
>  ifdef CONFIG_PCI
>  edac_core-y	+= edac_pci.o edac_pci_sysfs.o
> diff --git a/drivers/edac/ecs.c b/drivers/edac/ecs.c
> new file mode 100755
> index 000000000000..7fd97984e039
> --- /dev/null
> +++ b/drivers/edac/ecs.c
> @@ -0,0 +1,207 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * The generic ECS driver is designed to support control of on-die error
> + * check scrub (e.g., DDR5 ECS). The common sysfs ECS interface abstracts
> + * the control of various ECS functionalities into a unified set of functions.
> + *
> + * Copyright (c) 2024-2025 HiSilicon Limited.
> + */
> +
> +#include <linux/edac.h>
> +
> +#define EDAC_ECS_FRU_NAME "ecs_fru"
> +
> +enum edac_ecs_attributes {
> +	ECS_LOG_ENTRY_TYPE,
> +	ECS_MODE,
> +	ECS_RESET,
> +	ECS_THRESHOLD,
> +	ECS_MAX_ATTRS
> +};
> +
> +struct edac_ecs_dev_attr {
> +	struct device_attribute dev_attr;
> +	int fru_id;
> +};
> +
> +struct edac_ecs_fru_context {
> +	char name[EDAC_FEAT_NAME_LEN];
> +	struct edac_ecs_dev_attr dev_attr[ECS_MAX_ATTRS];
> +	struct attribute *ecs_attrs[ECS_MAX_ATTRS + 1];
> +	struct attribute_group group;
> +};
> +
> +struct edac_ecs_context {
> +	u16 num_media_frus;
> +	struct edac_ecs_fru_context *fru_ctxs;
> +};
> +
> +#define TO_ECS_DEV_ATTR(_dev_attr)	\
> +	container_of(_dev_attr, struct edac_ecs_dev_attr, dev_attr)
> +
> +#define EDAC_ECS_ATTR_SHOW(attrib, cb, type, format)				\
> +static ssize_t attrib##_show(struct device *ras_feat_dev,			\
> +			     struct device_attribute *attr, char *buf)		\
> +{										\
> +	struct edac_ecs_dev_attr *dev_attr = TO_ECS_DEV_ATTR(attr);		\
> +	struct edac_dev_feat_ctx *ctx = dev_get_drvdata(ras_feat_dev);		\
> +	const struct edac_ecs_ops *ops = ctx->ecs.ecs_ops;			\
> +	type data;								\
> +	int ret;								\
> +										\
> +	ret = ops->cb(ras_feat_dev->parent, ctx->ecs.private,			\
> +		      dev_attr->fru_id, &data);					\
> +	if (ret)								\
> +		return ret;							\
> +										\
> +	return sysfs_emit(buf, format, data);					\
> +}
> +
> +EDAC_ECS_ATTR_SHOW(log_entry_type, get_log_entry_type, u32, "%u\n")
> +EDAC_ECS_ATTR_SHOW(mode, get_mode, u32, "%u\n")
> +EDAC_ECS_ATTR_SHOW(threshold, get_threshold, u32, "%u\n")
> +
> +#define EDAC_ECS_ATTR_STORE(attrib, cb, type, conv_func)			\
> +static ssize_t attrib##_store(struct device *ras_feat_dev,			\
> +			      struct device_attribute *attr,			\
> +			      const char *buf, size_t len)			\
> +{										\
> +	struct edac_ecs_dev_attr *dev_attr = TO_ECS_DEV_ATTR(attr);		\
> +	struct edac_dev_feat_ctx *ctx = dev_get_drvdata(ras_feat_dev);		\
> +	const struct edac_ecs_ops *ops = ctx->ecs.ecs_ops;			\
> +	type data;								\
> +	int ret;								\
> +										\
> +	ret = conv_func(buf, 0, &data);						\
> +	if (ret < 0)								\
> +		return ret;							\
> +										\
> +	ret = ops->cb(ras_feat_dev->parent, ctx->ecs.private,			\
> +		      dev_attr->fru_id, data);					\
> +	if (ret)								\
> +		return ret;							\
> +										\
> +	return len;								\
> +}
> +
> +EDAC_ECS_ATTR_STORE(log_entry_type, set_log_entry_type, unsigned long, kstrtoul)
> +EDAC_ECS_ATTR_STORE(mode, set_mode, unsigned long, kstrtoul)
> +EDAC_ECS_ATTR_STORE(reset, reset, unsigned long, kstrtoul)
> +EDAC_ECS_ATTR_STORE(threshold, set_threshold, unsigned long, kstrtoul)
> +
> +static umode_t ecs_attr_visible(struct kobject *kobj, struct attribute *a, int attr_id)
> +{
> +	struct device *ras_feat_dev = kobj_to_dev(kobj);
> +	struct edac_dev_feat_ctx *ctx = dev_get_drvdata(ras_feat_dev);
> +	const struct edac_ecs_ops *ops = ctx->ecs.ecs_ops;
> +
> +	switch (attr_id) {
> +	case ECS_LOG_ENTRY_TYPE:
> +		if (ops->get_log_entry_type)  {
> +			if (ops->set_log_entry_type)
> +				return a->mode;
> +			else
> +				return 0444;
> +		}
> +		break;
> +	case ECS_MODE:
> +		if (ops->get_mode) {
> +			if (ops->set_mode)
> +				return a->mode;
> +			else
> +				return 0444;
> +		}
> +		break;
> +	case ECS_RESET:
> +		if (ops->reset)
> +			return a->mode;
> +		break;
> +	case ECS_THRESHOLD:
> +		if (ops->get_threshold) {
> +			if (ops->set_threshold)
> +				return a->mode;
> +			else
> +				return 0444;
> +		}
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	return 0;
> +}
> +
> +#define EDAC_ECS_ATTR_RO(_name, _fru_id)       \
> +	((struct edac_ecs_dev_attr) { .dev_attr = __ATTR_RO(_name), \
> +				     .fru_id = _fru_id })
> +
> +#define EDAC_ECS_ATTR_WO(_name, _fru_id)       \
> +	((struct edac_ecs_dev_attr) { .dev_attr = __ATTR_WO(_name), \
> +				     .fru_id = _fru_id })
> +
> +#define EDAC_ECS_ATTR_RW(_name, _fru_id)       \
> +	((struct edac_ecs_dev_attr) { .dev_attr = __ATTR_RW(_name), \
> +				     .fru_id = _fru_id })
> +
> +static int ecs_create_desc(struct device *ecs_dev,
> +			   const struct attribute_group **attr_groups, u16 num_media_frus)
> +{
> +	struct edac_ecs_context *ecs_ctx;
> +	u32 fru;
> +
> +	ecs_ctx = devm_kzalloc(ecs_dev, sizeof(*ecs_ctx), GFP_KERNEL);
> +	if (!ecs_ctx)
> +		return -ENOMEM;
> +
> +	ecs_ctx->num_media_frus = num_media_frus;
> +	ecs_ctx->fru_ctxs = devm_kcalloc(ecs_dev, num_media_frus,
> +					 sizeof(*ecs_ctx->fru_ctxs),
> +					 GFP_KERNEL);
> +	if (!ecs_ctx->fru_ctxs)
> +		return -ENOMEM;
> +
> +	for (fru = 0; fru < num_media_frus; fru++) {
> +		struct edac_ecs_fru_context *fru_ctx = &ecs_ctx->fru_ctxs[fru];
> +		struct attribute_group *group = &fru_ctx->group;
> +		int i;
> +
> +		fru_ctx->dev_attr[ECS_LOG_ENTRY_TYPE] =
> +					EDAC_ECS_ATTR_RW(log_entry_type, fru);
> +		fru_ctx->dev_attr[ECS_MODE] = EDAC_ECS_ATTR_RW(mode, fru);
> +		fru_ctx->dev_attr[ECS_RESET] = EDAC_ECS_ATTR_WO(reset, fru);
> +		fru_ctx->dev_attr[ECS_THRESHOLD] =
> +					EDAC_ECS_ATTR_RW(threshold, fru);
> +
> +		for (i = 0; i < ECS_MAX_ATTRS; i++)
> +			fru_ctx->ecs_attrs[i] = &fru_ctx->dev_attr[i].dev_attr.attr;
> +
> +		sprintf(fru_ctx->name, "%s%d", EDAC_ECS_FRU_NAME, fru);
> +		group->name = fru_ctx->name;
> +		group->attrs = fru_ctx->ecs_attrs;
> +		group->is_visible  = ecs_attr_visible;
> +
> +		attr_groups[fru] = group;
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * edac_ecs_get_desc - get EDAC ECS descriptors
> + * @ecs_dev: client device, supports ECS feature
> + * @attr_groups: pointer to attribute group container
> + * @num_media_frus: number of media FRUs in the device
> + *
> + * Return:
> + *  * %0	- Success.
> + *  * %-EINVAL	- Invalid parameters passed.
> + *  * %-ENOMEM	- Dynamic memory allocation failed.
> + */
> +int edac_ecs_get_desc(struct device *ecs_dev,
> +		      const struct attribute_group **attr_groups, u16 num_media_frus)
> +{
> +	if (!ecs_dev || !attr_groups || !num_media_frus)
> +		return -EINVAL;
> +
> +	return ecs_create_desc(ecs_dev, attr_groups, num_media_frus);
> +}
> diff --git a/drivers/edac/edac_device.c b/drivers/edac/edac_device.c
> index 40407f0ee600..a8421dc9ab3c 100644
> --- a/drivers/edac/edac_device.c
> +++ b/drivers/edac/edac_device.c
> @@ -627,6 +627,9 @@ int edac_dev_register(struct device *parent, char *name,
>  			attr_gcnt++;
>  			scrub_cnt++;
>  			break;
> +		case RAS_FEAT_ECS:
> +			attr_gcnt += ras_features[feat].ecs_info.num_media_frus;
> +			break;
>  		default:
>  			return -EINVAL;
>  		}
> @@ -671,6 +674,20 @@ int edac_dev_register(struct device *parent, char *name,
>  			scrub_cnt++;
>  			attr_gcnt++;
>  			break;
> +		case RAS_FEAT_ECS:
> +			if (!ras_features->ecs_ops)
> +				goto data_mem_free;
> +
> +			dev_data = &ctx->ecs;
> +			dev_data->ecs_ops = ras_features->ecs_ops;
> +			dev_data->private = ras_features->ctx;
> +			ret = edac_ecs_get_desc(parent, &ras_attr_groups[attr_gcnt],
> +						ras_features->ecs_info.num_media_frus);
> +			if (ret)
> +				goto data_mem_free;
> +
> +			attr_gcnt += ras_features->ecs_info.num_media_frus;
> +			break;
>  		default:
>  			ret = -EINVAL;
>  			goto data_mem_free;
> diff --git a/include/linux/edac.h b/include/linux/edac.h
> index 1cbab08720df..f8346014c14e 100644
> --- a/include/linux/edac.h
> +++ b/include/linux/edac.h
> @@ -667,6 +667,7 @@ static inline struct dimm_info *edac_get_dimm(struct mem_ctl_info *mci,
>  /* RAS feature type */
>  enum edac_dev_feat {
>  	RAS_FEAT_SCRUB,
> +	RAS_FEAT_ECS,
>  	RAS_FEAT_MAX
>  };
>  
> @@ -707,9 +708,47 @@ static inline int edac_scrub_get_desc(struct device *scrub_dev,
>  { return -EOPNOTSUPP; }
>  #endif /* CONFIG_EDAC_SCRUB */
>  
> +/**
> + * struct edac_ecs_ops - ECS device operations (all elements optional)
> + * @get_log_entry_type: read the log entry type value.
> + * @set_log_entry_type: set the log entry type value.
> + * @get_mode: read the mode value.
> + * @set_mode: set the mode value.
> + * @reset: reset the ECS counter.
> + * @get_threshold: read the threshold count per gigabits of memory cells.
> + * @set_threshold: set the threshold count per gigabits of memory cells.
> + */
> +struct edac_ecs_ops {
> +	int (*get_log_entry_type)(struct device *dev, void *drv_data, int fru_id, u32 *val);
> +	int (*set_log_entry_type)(struct device *dev, void *drv_data, int fru_id, u32 val);
> +	int (*get_mode)(struct device *dev, void *drv_data, int fru_id, u32 *val);
> +	int (*set_mode)(struct device *dev, void *drv_data, int fru_id, u32 val);
> +	int (*reset)(struct device *dev, void *drv_data, int fru_id, u32 val);
> +	int (*get_threshold)(struct device *dev, void *drv_data, int fru_id, u32 *threshold);
> +	int (*set_threshold)(struct device *dev, void *drv_data, int fru_id, u32 threshold);
> +};
> +
> +struct edac_ecs_ex_info {
> +	u16 num_media_frus;
> +};
> +
> +#if IS_ENABLED(CONFIG_EDAC_ECS)
> +int edac_ecs_get_desc(struct device *ecs_dev,
> +		      const struct attribute_group **attr_groups,
> +		      u16 num_media_frus);
> +#else
> +static inline int edac_ecs_get_desc(struct device *ecs_dev,
> +				    const struct attribute_group **attr_groups,
> +				    u16 num_media_frus)
> +{ return -EOPNOTSUPP; }
> +#endif /* CONFIG_EDAC_ECS */
> +
>  /* EDAC device feature information structure */
>  struct edac_dev_data {
> -	const struct edac_scrub_ops *scrub_ops;
> +	union {
> +		const struct edac_scrub_ops *scrub_ops;
> +		const struct edac_ecs_ops *ecs_ops;
> +	};
>  	u8 instance;
>  	void *private;
>  };
> @@ -718,13 +757,18 @@ struct edac_dev_feat_ctx {
>  	struct device dev;
>  	void *private;
>  	struct edac_dev_data *scrub;
> +	struct edac_dev_data ecs;
>  };
>  
>  struct edac_dev_feature {
>  	enum edac_dev_feat ft_type;
>  	u8 instance;
> -	const struct edac_scrub_ops *scrub_ops;
> +	union {
> +		const struct edac_scrub_ops *scrub_ops;
> +		const struct edac_ecs_ops *ecs_ops;
> +	};
>  	void *ctx;
> +	struct edac_ecs_ex_info ecs_info;
>  };
>  
>  int edac_dev_register(struct device *parent, char *dev_name,
> -- 
> 2.43.0
>