[PATCH v4 0/2] PCI: cadence: Add LTSSM debugfs

[Hans Zhang]

Hi,

This series adds debugfs support to the Cadence PCIe controller driver,
allowing users to read the current LTSSM state of the link for debugging
purposes.

Patch 1 introduces a new flag 'is_hpa' in the cdns_pcie structure to
distinguish HPA (High Performance Architecture IP) platforms, which
have a different register layout for LTSSM status.

Patch 2 implements the debugfs file "ltssm_status" under a per-device
directory. It reads the LTSSM state from the appropriate hardware register
based on the 'is_hpa' flag and displays both a descriptive string and the
raw value.

=====================
Test:
root@orangepi6plus:~# ls -l /sys/kernel/debug/cdns_pcie_a0*
/sys/kernel/debug/cdns_pcie_a010000.pcie:
total 0
-r--r--r-- 1 root root 0 Jan  1  1970 ltssm_status

/sys/kernel/debug/cdns_pcie_a0c0000.pcie:
total 0
-r--r--r-- 1 root root 0 Jan  1  1970 ltssm_status

/sys/kernel/debug/cdns_pcie_a0e0000.pcie:
total 0
-r--r--r-- 1 root root 0 Jan  1  1970 ltssm_status
root@orangepi6plus:~# 
root@orangepi6plus:~# 
root@orangepi6plus:~# cat /sys/kernel/debug/cdns_pcie_a0*/ltss*
L0_STATE (0x29)
L0_STATE (0x29)
L0_STATE (0x29)
root@orangepi6plus:~# 
root@orangepi6plus:~# uname -a
Linux orangepi6plus 7.1.0-rc2-00377-gb898336dec53-dirty #43 SMP PREEMPT Fri May  8 11:15:00 CST 2026 aarch64 aarch64 aarch64 GNU/Linux
=====================

---
Changes for v4:
- Remove the copyright email address of the author of pcie-cadence-debugfs.c (Mani)
- Add cdns_pcie_hpa_host_disable() (Mani)
- Use DEFINE_SHOW_ATTRIBUTE() (Mani & Sashiko)

Changes for v3:
https://patchwork.kernel.org/project/linux-pci/patch/20260406103237.1203127-1-18255117159@xxxxxxx/

- Export cdns_pcie_debugfs_deinit (Mani)
- pcie-cadence-ep.c pcie-cadence-host.c pci-sky1.c call cdns_pcie_debugfs_deinit

Changes for v2:
https://patchwork.kernel.org/project/linux-pci/patch/20260321033035.3008585-3-18255117159@xxxxxxx/

- s/DW_PCIE_LTSSM_NAME/CDNS_PCIE_LTSSM_NAME/
- S/January 2026/March 2026/
- EXPORT_SYMBOL_GPL(cdns_pcie_debugfs_init); // Resolve the following error issues.
  >> ERROR: modpost: "cdns_pcie_debugfs_init" [drivers/pci/controller/cadence/pcie-cadence-host-mod.ko] undefined!
  >> ERROR: modpost: "cdns_pcie_debugfs_init" [drivers/pci/controller/cadence/pcie-cadence-ep-mod.ko] undefined!

v1:
https://patchwork.kernel.org/project/linux-pci/cover/20260315155514.127255-1-18255117159@xxxxxxx/

Hans Zhang (2):
  PCI: cadence: Add HPA architecture flag
  PCI: cadence: Add debugfs property to provide LTSSM status of the PCIe
    link

 Documentation/ABI/testing/debugfs-cdns-pcie   |   5 +
 drivers/pci/controller/cadence/Kconfig        |   9 +
 drivers/pci/controller/cadence/Makefile       |   1 +
 drivers/pci/controller/cadence/pci-sky1.c     |   4 +
 .../controller/cadence/pcie-cadence-debugfs.c | 208 ++++++++++++++++++
 .../pci/controller/cadence/pcie-cadence-ep.c  |   3 +
 .../cadence/pcie-cadence-host-hpa.c           |  20 +-
 .../controller/cadence/pcie-cadence-host.c    |   9 +-
 drivers/pci/controller/cadence/pcie-cadence.h | 152 +++++++++++++
 9 files changed, 409 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/ABI/testing/debugfs-cdns-pcie
 create mode 100644 drivers/pci/controller/cadence/pcie-cadence-debugfs.c


base-commit: 917719c412c48687d4a176965d1fa35320ec457c
-- 
2.34.1