This patch series introduces support for the CXL Reset method
for CXL devices, implementing the reset procedure outlined in
CXL Spec [1] v3.2, Sections 9.6 and 9.7.
v2 changes:
- de-duplicate CXL DVSEC register defines under include/cxl/pci.h
- fix style related issues.
v1 changes:
- Added cover letter and dropped the RFC.
The RFC patche can be found here [2]
Motivation:
-----------
This change is broadly useful for reasons including but not limited to the
following:
- As support for Type 2 devices [3] is being introduced, more devices will
require finer-grained reset mechanisms beyond bus-wide reset methods.
- FLR does not affect CXL.cache or CXL.mem protocols, making CXL Reset
the preferred method in some cases.
- The CXL spec (Sections 7.2.3 Binding and Unbinding, 9.5 FLR) highlights use
cases like function rebinding and error recovery, where CXL Reset is
explicitly mentioned.
Change Description:
-------------------
The patch implements the required steps for CXL reset and introduces a new reset
method in the pci_reset_fn_methods. It also defines the necessary CXL DVSEC
register macros. The actual steps for rest are broadly: disable cache lines and
asserts WB+I, wait for cache and memory clear signals, initial reset, wait for
complete and return status.
Command line to test the CXL reset on a capable device:
echo cxl_reset > /sys/bus/pci/devices/<pci_device>/reset_method
echo 1 > /sys/bus/pci/devices/<pci_device>/reset
[1] https://computeexpresslink.org/cxl-specification/
[2] https://lore.kernel.org/all/20241213074143.374-1-smadhavan@xxxxxxxxxx/
[3] https://lore.kernel.org/linux-cxl/20241216161042.42108-1-alejandro.lucero-palau@xxxxxxx/
Srirangan Madhavan (2):
cxl: de-duplicate cxl DVSEC reg defines
cxl: add support for cxl reset
drivers/cxl/core/pci.c | 1 +
drivers/cxl/core/regs.c | 1 +
drivers/cxl/cxlpci.h | 53 -----------
drivers/cxl/pci.c | 1 +
drivers/pci/pci.c | 163 ++++++++++++++++++++++++++++++++--
include/cxl/pci.h | 76 ++++++++++++++++
include/linux/pci.h | 2 +-
include/uapi/linux/pci_regs.h | 5 --
8 files changed, 235 insertions(+), 67 deletions(-)
create mode 100644 include/cxl/pci.h
--
2.25.1
