cxl/edac: Add CXL memory device ECS control feature

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 <[email protected]>
Reviewed-by: Fan Ni <[email protected]>
Reviewed-by: Dave Jiang <[email protected]>
Signed-off-by: Shiju Jose <[email protected]>
Reviewed-by: Alison Schofield <[email protected]>
Acked-by: Dan Williams <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Dave Jiang <[email protected]>

Author: shijujose4

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