Changes since v1 [1]: - Make use pci_info() and FLAG(), as in pcie_init(). - Wrap new cxl_cap in pci_dev struct within #ifdef PCI_CXL. (Bjorn Helgaas) - Added functionality for some CXL.mem and CXL.cache helper functions. Snoop filter helper functions along with a performance hint as well as a toggle for viral self-isolation mode could be implemented. However, in the absence of CXL devices with their associated drivers, it perhaps makes best sense to be in a holding pattern on this until we have something to exercise it with. Thoughts? [1] https://lore.kernel.org/linux-pci/20200515175528.980103-1-sean.v.kelley@xxxxxxxxxxxxxxx/ This patch series implements basic Designated Vendor-Specific Extended Capabilities (DVSEC) decode for Compute eXpress Link devices, a new CPU interconnect building upon PCIe. As a basis for the CXL support it provides PCI init handling for detection, decode, and caching of CXL device capabilities. Moreover, it makes use of the DVSEC Vendor ID and DVSEC ID so as to identify a CXL capable device. (PCIe r5.0, sec 7.9.6.2) DocLink: https://www.computeexpresslink.org/ For your reference, a parallel series of patches have been submitted to enable lspci decode of CXL DVSEC and may be tracked. Link: https://lore.kernel.org/linux-pci/20200511174618.10589-1-sean.v.kelley@xxxxxxxxxxxxxxx/ This patch makes use of pending DVSEC related header additions and the first patch of that series is included here. It can be sorted out when the upstream merge is done. Link: https://lore.kernel.org/linux-pci/20200508021844.6911-2-david.e.box@xxxxxxxxxxxxxxx/ Sample dmesg output of a CXL Type 3 device (CXL.io, CXL.mem): [ 2.997177] pci 0000:6b:00.0: CXL: Cache- IO+ Mem+ Viral- HDMCount 1 [ 2.997188] pci 0000:6b:00.0: CXL: cap ctrl status ctrl2 status2 lock [ 2.997201] pci 0000:6b:00.0: CXL: 001e 0002 0000 0000 0000 0000 David E. Box (1): pci: Add Designated Vendor Specific Capability Sean V Kelley (2): PCI: Add basic Compute eXpress Link DVSEC decode PCI: Add helpers to enable/disable CXL.mem and CXL.cache drivers/pci/Kconfig | 9 ++ drivers/pci/Makefile | 1 + drivers/pci/cxl.c | 175 ++++++++++++++++++++++++++++++++++ drivers/pci/pci.h | 15 +++ drivers/pci/probe.c | 1 + include/linux/pci.h | 3 + include/uapi/linux/pci_regs.h | 5 + 7 files changed, 209 insertions(+) create mode 100644 drivers/pci/cxl.c -- 2.26.2
