| Message ID | 20221110195015.207-1-jonathan.derrick@linux.dev (mailing list archive) |
|---|---|
| Headers | show |
| Series | PCIe Hotplug Slot Emulation driver | expand |
On Thursday 10 November 2022 12:50:08 Jonathan Derrick wrote: > The main intent of posting v2 is to help Vidya further along with his > GPIO-based hotplug driver. I have no direct need for a DLLSC-based emulated > mode, and I'm not certain the model is appropriate. The GPIO-based model could > modify some of the logic in patch 6 to check for GPIO instead of DLLSC. This approach for GPIO-based model introduce also a new hotplug driver HOTPLUG_PCI_PCIE_EMUL. But if you implement all callbacks of the pci-bridge-emul.c for standard PCIe hotplug capability then you do not need this new HOTPLUG_PCI_PCIE_EMUL at all. Existing HOTPLUG_PCI_PCIE driver would work without any issue. I have already implemented DLLSC basics for pci-mvebu.c and pci-aardvark.c controller drivers, patches are on the mailing list. I can help implementing it in other PCIe controller driver.
Please see note [1] about v2 This set adds an emulation driver for PCIe Hotplug. There may be platforms with specific configurations that can support hotplug but don't provide the logical slot hotplug hardware. For instance, the platform may use an electrically-tolerant interposer between the slot and the device. This driver utilizes the pci-bridge-emul architecture to manage register reads and writes. The underlying functionality of the hotplug emulation driver uses the Data Link Layer Link Active Reporting mechanism in a polling loop, but can tolerate other event sources such as AER or DPC. When enabled and a slot is managed by the driver, all port services are managed by the kernel. This is done to ensure that firmware hotplug and error architecture does not (correctly) halt/machine check the system when hotplug is performed on a non-hotplug slot. The driver offers two active mode: Auto and Force. auto: The driver will bind to non-hotplug slots force: The driver will bind to all slots and overrides the slot's services There are three kernel params: pciehp.pciehp_emul_mode={off, auto, force} pciehp.pciehp_emul_time=<msecs polling time> (def 1000, min 100, max 60000) pciehp.pciehp_emul_ports=<PCI [S]BDF/ID format string> The pciehp_emul_ports kernel parameter takes a semi-colon tokenized string representing PCI [S]BDFs and IDs. The pciehp_emul_mode will then be applied to only those slots, leaving other slots unmanaged by pciehp_emul. The string follows the pci_dev_str_match() format: [<domain>:]<bus>:<device>.<func>[/<device>.<func>]* pci:<vendor>:<device>[:<subvendor>:<subdevice>] When using the path format, the path for the device can be obtained using 'lspci -t' and further specified using the upstream bridge and the downstream port's device-function to be more robust against bus renumbering. When using the vendor-device format, a value of '0' in any field acts as a wildcard for that field, matching all values. The driver is enabled with CONFIG_HOTPLUG_PCI_PCIE_EMUL=y. The driver should be considered 'use at own risk' unless the platform/hardware vendor recommends this mode. [1] The main intent of posting v2 is to help Vidya further along with his GPIO-based hotplug driver. I have no direct need for a DLLSC-based emulated mode, and I'm not certain the model is appropriate. The GPIO-based model could modify some of the logic in patch 6 to check for GPIO instead of DLLSC. v1->v2: Indirects capacibility accessors instead of filtering pciehp slot operations Jonathan Derrick (7): PCI: Allow for indirecting capability registers PCI: Add pcie_port_slot_emulated stub PCI: pciehp: Expose the poll loop to other drivers PCI: Move pci_dev_str_match to search.c PCI: pci-bridge-emul: Provide a helper to set behavior PCI: pciehp: Add hotplug slot emulation driver PCI: pciehp: Wire up pcie_port_emulate_slot and drivers/pci/access.c | 29 +++ drivers/pci/hotplug/Makefile | 4 + drivers/pci/hotplug/pciehp.h | 20 ++ drivers/pci/hotplug/pciehp_emul.c | 380 ++++++++++++++++++++++++++++++ drivers/pci/hotplug/pciehp_hpc.c | 19 +- drivers/pci/pci-acpi.c | 3 + drivers/pci/pci-bridge-emul.c | 19 ++ drivers/pci/pci-bridge-emul.h | 10 + drivers/pci/pci.c | 163 ------------- drivers/pci/pcie/Kconfig | 13 + drivers/pci/pcie/portdrv_core.c | 12 +- drivers/pci/probe.c | 2 +- drivers/pci/search.c | 162 +++++++++++++ include/linux/pci.h | 22 ++ 14 files changed, 688 insertions(+), 170 deletions(-) create mode 100644 drivers/pci/hotplug/pciehp_emul.c