Loadable Module support for PCIe Cadence and J721E

From:		Siddharth Vadapalli <s-vadapalli-AT-ti.com>
To:		<lpieralisi-AT-kernel.org>, <kw-AT-linux.com>, <manivannan.sadhasivam-AT-linaro.org>, <robh-AT-kernel.org>, <bhelgaas-AT-google.com>, <vigneshr-AT-ti.com>, <kishon-AT-kernel.org>, <18255117159-AT-163.com>, <cassel-AT-kernel.org>, <wojciech.jasko-EXT-AT-continental-corporation.com>, <thomas.richard-AT-bootlin.com>, <bwawrzyn-AT-cisco.com>
Subject:		[PATCH v2 0/4] Loadable Module support for PCIe Cadence and J721E
Date:		Sun, 30 Mar 2025 14:09:10 +0530
Message-ID:		<20250330083914.529222-1-s-vadapalli@ti.com>
Cc:		<linux-pci-AT-vger.kernel.org>, <linux-omap-AT-vger.kernel.org>, <linux-kernel-AT-vger.kernel.org>, <linux-arm-kernel-AT-lists.infradead.org>, <srk-AT-ti.com>, <s-vadapalli-AT-ti.com>
Archive-link:		Article

Hello,

This series enables support to build the PCIe Cadence Controller drivers
and the PCI J721E Application/Wrapper/Glue driver as Loadable Kernel
Modules. The motivation for this series is that PCIe is not a necessity
for booting the SoC, due to which it doesn't have to be a built-in
module. Additionally, the defconfig doesn't enable the PCIe Cadence
Controller drivers and the PCI J721E driver, due to which PCIe is not
supported by default. Enabling the configs as of now (i.e. without this
series) will result in built-in drivers i.e. a bloated Linux Image for
everyone who doesn't have the PCIe Controller. Therefore, with this
series, after enabling support for building the drivers as loadable
modules, the driver configs can be enabled in the defconfig to build
the drivers as loadable modules, thereby enabling PCIe.

Series is based on linux-next tagged next-20250328.

Series has been tested by loading and unloading the PCI J721E driver
when operating in the Root-Complex mode on J700-EVM with an NVMe SSD
connected to the PCIe Connector. "hdparm" based reads of the NVMe SSD
have been performed to validate functionality before and after a module
unload-load sequence using modprobe. Additionally, the module unload
was performed while running "hdparm" in the background. No crash was
seen and reloading the module enumerated the NVMe SSD and "hdparm" could
be re-run successfully.

v1 of this series is at:
https://lore.kernel.org/r/20250307103128.3287497-1-s-vada...
Changes since v1:
- Collected "Reviewed-by" tags from:
  Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
  for the first two patches in this series.
- Based on feedback from Mani on the third patch of the v1 series at:
  https://lore.kernel.org/r/20250318080304.jsmrxqil6pn74nzh...
  pci_epc_deinit_notify() has been included in cdns_pcie_ep_disable().
- Based on feedback from Thomas on the fourth patch of the v1 series at:
  https://lore.kernel.org/r/88b3ecbe-32b6-4310-afb9-da19a2d...
  the "check" for a non-NULL "pcie-refclk" in j721e_pcie_remove() has been
  dropped.

Regards,
Siddharth.

Kishon Vijay Abraham I (1):
  PCI: cadence: Add support to build pcie-cadence library as a kernel
    module

Siddharth Vadapalli (3):
  PCI: cadence-host: Introduce cdns_pcie_host_disable helper for cleanup
  PCI: cadence-ep: Introduce cdns_pcie_ep_disable helper for cleanup
  PCI: j721e: Add support to build as a loadable module

 drivers/pci/controller/cadence/Kconfig        |  12 +-
 drivers/pci/controller/cadence/pci-j721e.c    |  33 ++++-
 .../pci/controller/cadence/pcie-cadence-ep.c  |  17 +++
 .../controller/cadence/pcie-cadence-host.c    | 113 ++++++++++++++++++
 drivers/pci/controller/cadence/pcie-cadence.c |  12 ++
 drivers/pci/controller/cadence/pcie-cadence.h |  14 ++-
 6 files changed, 192 insertions(+), 9 deletions(-)

-- 
2.34.1