--- /dev/null
+.. SPDX-License-Identifier: GPL-2.0 OR GFDL-1.2-no-invariants-or-later
+
+=================
+EDAC/RAS features
+=================
+
+Copyright (c) 2024-2025 HiSilicon Limited.
+
+:Author: Shiju Jose <shiju.jose@huawei.com>
+:License: The GNU Free Documentation License, Version 1.2 without
+ Invariant Sections, Front-Cover Texts nor Back-Cover Texts.
+ (dual licensed under the GPL v2)
+
+- Written for: 6.15
+
+Introduction
+------------
+
+EDAC/RAS components plugging and high-level design:
+
+1. Scrub control
+
+2. Error Check Scrub (ECS) control
+
+3. ACPI RAS2 features
+
+4. Post Package Repair (PPR) control
+
+5. Memory Sparing Repair control
+
+High level design is illustrated in the following diagram::
+
+ +-----------------------------------------------+
+ | Userspace - Rasdaemon |
+ | +-------------+ |
+ | | RAS CXL mem | +---------------+ |
+ | |error handler|---->| | |
+ | +-------------+ | RAS dynamic | |
+ | +-------------+ | scrub, memory | |
+ | | RAS memory |---->| repair control| |
+ | |error handler| +----|----------+ |
+ | +-------------+ | |
+ +--------------------------|--------------------+
+ |
+ |
+ +-------------------------------|------------------------------+
+ | Kernel EDAC extension for | controlling RAS Features |
+ |+------------------------------|----------------------------+ |
+ || EDAC Core Sysfs EDAC| Bus | |
+ || +--------------------------|---------------------------+| |
+ || |/sys/bus/edac/devices/<dev>/scrubX/ | | EDAC device || |
+ || |/sys/bus/edac/devices/<dev>/ecsX/ |<->| EDAC MC || |
+ || |/sys/bus/edac/devices/<dev>/repairX | | EDAC sysfs || |
+ || +---------------------------|--------------------------+| |
+ || EDAC|Bus | |
+ || | | |
+ || +----------+ Get feature | Get feature | |
+ || | | desc +---------|------+ desc +----------+ | |
+ || |EDAC scrub|<-----| EDAC device | | | | |
+ || +----------+ | driver- RAS |----->| EDAC mem | | |
+ || +----------+ | feature control| | repair | | |
+ || | |<-----| | +----------+ | |
+ || |EDAC ECS | +---------|------+ | |
+ || +----------+ Register RAS|features | |
+ || ______________________|_____________ | |
+ |+---------|---------------|------------------|--------------+ |
+ | +-------|----+ +-------|-------+ +----|----------+ |
+ | | | | CXL mem driver| | Client driver | |
+ | | ACPI RAS2 | | scrub, ECS, | | memory repair | |
+ | | driver | | sparing, PPR | | features | |
+ | +-----|------+ +-------|-------+ +------|--------+ |
+ | | | | |
+ +--------|-----------------|--------------------|--------------+
+ | | |
+ +--------|-----------------|--------------------|--------------+
+ | +---|-----------------|--------------------|-------+ |
+ | | | |
+ | | Platform HW and Firmware | |
+ | +--------------------------------------------------+ |
+ +--------------------------------------------------------------+
+
+
+1. EDAC Features components - Create feature-specific descriptors. For
+ example: scrub, ECS, memory repair in the above diagram.
+
+2. EDAC device driver for controlling RAS Features - Get feature's attribute
+ descriptors from EDAC RAS feature component and registers device's RAS
+ features with EDAC bus and expose the features control attributes via
+ sysfs. For example, /sys/bus/edac/devices/<dev-name>/<feature>X/
+
+3. RAS dynamic feature controller - Userspace sample modules in rasdaemon for
+ dynamic scrub/repair control to issue scrubbing/repair when excess number
+ of corrected memory errors are reported in a short span of time.
block ? block->name : "N/A", count, msg);
}
EXPORT_SYMBOL_GPL(edac_device_handle_ue_count);
+
+static void edac_dev_release(struct device *dev)
+{
+ struct edac_dev_feat_ctx *ctx = container_of(dev, struct edac_dev_feat_ctx, dev);
+
+ kfree(ctx->dev.groups);
+ kfree(ctx);
+}
+
+static const struct device_type edac_dev_type = {
+ .name = "edac_dev",
+ .release = edac_dev_release,
+};
+
+static void edac_dev_unreg(void *data)
+{
+ device_unregister(data);
+}
+
+/**
+ * edac_dev_register - register device for RAS features with EDAC
+ * @parent: parent device.
+ * @name: name for the folder in the /sys/bus/edac/devices/,
+ * which is derived from the parent device.
+ * For e.g. /sys/bus/edac/devices/cxl_mem0/
+ * @private: parent driver's data to store in the context if any.
+ * @num_features: number of RAS features to register.
+ * @ras_features: list of RAS features to register.
+ *
+ * Return:
+ * * %0 - Success.
+ * * %-EINVAL - Invalid parameters passed.
+ * * %-ENOMEM - Dynamic memory allocation failed.
+ *
+ */
+int edac_dev_register(struct device *parent, char *name,
+ void *private, int num_features,
+ const struct edac_dev_feature *ras_features)
+{
+ const struct attribute_group **ras_attr_groups;
+ struct edac_dev_feat_ctx *ctx;
+ int attr_gcnt = 0;
+ int ret = -ENOMEM;
+ int feat;
+
+ if (!parent || !name || !num_features || !ras_features)
+ return -EINVAL;
+
+ /* Double parse to make space for attributes */
+ for (feat = 0; feat < num_features; feat++) {
+ switch (ras_features[feat].ft_type) {
+ /* Add feature specific code */
+ default:
+ return -EINVAL;
+ }
+ }
+
+ ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+ if (!ctx)
+ return -ENOMEM;
+
+ ras_attr_groups = kcalloc(attr_gcnt + 1, sizeof(*ras_attr_groups), GFP_KERNEL);
+ if (!ras_attr_groups)
+ goto ctx_free;
+
+ attr_gcnt = 0;
+ for (feat = 0; feat < num_features; feat++, ras_features++) {
+ switch (ras_features->ft_type) {
+ /* Add feature specific code */
+ default:
+ ret = -EINVAL;
+ goto groups_free;
+ }
+ }
+
+ ctx->dev.parent = parent;
+ ctx->dev.bus = edac_get_sysfs_subsys();
+ ctx->dev.type = &edac_dev_type;
+ ctx->dev.groups = ras_attr_groups;
+ ctx->private = private;
+ dev_set_drvdata(&ctx->dev, ctx);
+
+ ret = dev_set_name(&ctx->dev, name);
+ if (ret)
+ goto groups_free;
+
+ ret = device_register(&ctx->dev);
+ if (ret) {
+ put_device(&ctx->dev);
+ return ret;
+ }
+
+ return devm_add_action_or_reset(parent, edac_dev_unreg, &ctx->dev);
+
+groups_free:
+ kfree(ras_attr_groups);
+ctx_free:
+ kfree(ctx);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(edac_dev_register);
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