From b1956e2d0713e210a56ae65ad3488ae36f833e76 Mon Sep 17 00:00:00 2001 From: Dave Jiang Date: Thu, 2 May 2024 09:57:32 -0700 Subject: PCI/CXL: Fail bus reset if upstream CXL Port has SBR masked Per CXL spec r3.1, sec 8.1.5.2, the Secondary Bus Reset (SBR) bit in the Bridge Control register of a CXL port has no effect unless the "Unmask SBR" bit is set. Return -ENOTTY if we attempt a bus reset on a device below a CXL Port where "Unmask SBR" is 0. Otherwise, the bus reset would appear to have succeeded even though setting the bridge SBR bit had no effect. Link: https://lore.kernel.org/linux-cxl/20240220203956.GA1502351@bhelgaas/ Link: https://lore.kernel.org/r/20240502165851.1948523-4-dave.jiang@intel.com Signed-off-by: Dave Jiang [bhelgaas: simplify commit log and comments] Signed-off-by: Bjorn Helgaas Reviewed-by: Jonathan Cameron Reviewed-by: Kuppuswamy Sathyanarayanan Reviewed-by: Dan Williams --- include/uapi/linux/pci_regs.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h index a39193213ff2..6024eb2e9a2f 100644 --- a/include/uapi/linux/pci_regs.h +++ b/include/uapi/linux/pci_regs.h @@ -1148,4 +1148,9 @@ #define PCI_DOE_DATA_OBJECT_DISC_RSP_3_PROTOCOL 0x00ff0000 #define PCI_DOE_DATA_OBJECT_DISC_RSP_3_NEXT_INDEX 0xff000000 +/* Compute Express Link (CXL r3.1, sec 8.1.5) */ +#define PCI_DVSEC_CXL_PORT 3 +#define PCI_DVSEC_CXL_PORT_CTL 0x0c +#define PCI_DVSEC_CXL_PORT_CTL_UNMASK_SBR 0x00000001 + #endif /* LINUX_PCI_REGS_H */ -- cgit v1.2.3