[v2,00/10] cxl: Add support for CXL feature commands, CXL device patrol scrub control and DDR5 ECS control features

From: Shiju Jose <shiju.jose@huawei.com>

1. Add support for CXL feature mailbox commands.
2. Add CXL device scrub driver supporting patrol scrub control and DDR5 ECS
control features.
3. Add scrub driver supports configuring memory scrubs in the system.
4. Add scrub attributes for DDR5 ECS control to the memory scrub driver.
5. Register CXL device patrol scrub and ECS with scrub control driver.
6. Add documentation for CXL memory device scrub control attributes.

The QEMU series to support these features is available here,
https://lore.kernel.org/qemu-devel/20231114124711.1128-1-shiju.jose@huawei.com/T/#t

Changes
v1 -> v2:
1. Changes for comments from Dave Jiang, Thanks.
 - Split patches.
 - reversed xmas tree declarations.   
 - declared flags as enums.
 - removed few unnecessary variable initializations.
 - replaced PTR_ERR_OR_ZERO() with IS_ERR() and PTR_ERR().
 - add auto clean declarations.
 - replaced while loop with for loop. 
 - Removed allocation from cxl_get_supported_features() and 
   cxl_get_feature() and make change to take allocated memory
   pointer from the caller.
 - replaced if/else with switch case.
 - replaced sprintf() with sysfs_emit() in 2 places.
 - replaced goto label with return in few functions. 
2. removed unused code for supported attributes from ecs.
3. Included following common dependency patch for scrub configure
   driver to this series.
   "memory: scrub: Add scrub driver supports configuring memory scrubbers
    in the system"

Shiju Jose (10):
  cxl/mbox: Add GET_SUPPORTED_FEATURES mailbox command
  cxl/mbox: Add GET_FEATURE mailbox command
  cxl/mbox: Add SET_FEATURE mailbox command
  cxl/memscrub: Add CXL device patrol scrub control feature
  cxl/memscrub: Add CXL device DDR5 ECS control feature
  memory: scrub: Add scrub driver supports configuring memory scrubbers
    in the system
  cxl/memscrub: Register CXL device patrol scrub with scrub configure
    driver
  memory: scrub: Add scrub control attributes for the DDR5 ECS
  cxl/memscrub: Register CXL device DDR5 ECS with scrub configure driver
  cxl: scrub: sysfs: Add Documentation for CXL memory device scrub
    control attributes

 .../testing/sysfs-class-cxl-scrub-configure   | 135 +++
 drivers/cxl/Kconfig                           |  23 +
 drivers/cxl/core/Makefile                     |   1 +
 drivers/cxl/core/mbox.c                       |  62 ++
 drivers/cxl/core/memscrub.c                   | 993 ++++++++++++++++++
 drivers/cxl/cxlmem.h                          | 120 +++
 drivers/cxl/pci.c                             |   8 +
 drivers/memory/Kconfig                        |   1 +
 drivers/memory/Makefile                       |   1 +
 drivers/memory/scrub/Kconfig                  |  11 +
 drivers/memory/scrub/Makefile                 |   6 +
 drivers/memory/scrub/memory-scrub.c           | 484 +++++++++
 include/memory/memory-scrub.h                 |  90 ++
 include/uapi/linux/cxl_mem.h                  |   3 +
 14 files changed, 1938 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-class-cxl-scrub-configure
 create mode 100644 drivers/cxl/core/memscrub.c
 create mode 100644 drivers/memory/scrub/Kconfig
 create mode 100644 drivers/memory/scrub/Makefile
 create mode 100755 drivers/memory/scrub/memory-scrub.c
 create mode 100755 include/memory/memory-scrub.h