Hi,

This series is the continuation of the series [1] that added the initial support
for the PCIe M.2 connectors. This series extends it by adding support for Key E
connectors. These connectors are used to connect the Wireless Connectivity
devices such as WiFi, BT, NFC and GNSS devices to the host machine over
interfaces such as PCIe/SDIO, USB/UART and NFC. This series adds support for
connectors that expose PCIe interface for WiFi and UART interface for BT. Other
interfaces are left for future improvements.

Serdev device support for BT
============================

Adding support for the PCIe interface was mostly straightforward and a lot
similar to the previous Key M connector. But adding UART interface has proved to
be tricky. This is mostly because of the fact UART is a non-discoverable bus,
unlike PCIe which is discoverable. So this series relied on the PCI notifier to
create the serdev device for UART/BT. This means the PCIe interface will be
brought up first and after the PCIe device enumeration, the serdev device will
be created by the pwrseq driver. This logic is necessary since the connector
driver and DT node don't describe the device, but just the connector. So to make
the connector interface Plug and Play, the connector driver uses the PCIe device
ID to identify the card and creates the serdev device. This logic could be
extended in the future to support more M.2 cards. Even if the M.2 card uses SDIO
interface for connecting WLAN, a SDIO notifier could be added to create the
serdev device.

Testing
=======

This series, together with the devicetree changes [2] was tested on the
Qualcomm X1e based Lenovo Thinkpad T14s Laptop which has the WCN7850 WLAN/BT
1620 LGA card connected over PCIe and UART.

Merge Strategy
==============

Due to the API dependency, both the serdev and pwrseq patches need to go through
a single tree, maybe through pwrseq tree. So the serdev patches need Ack from
Greg. But Bluetooth patch can be merged separately.

NOTE
====

This series is based on bluetooth-next/master to resolve the conflict with the
Bluetooth patch. Other pathces should apply cleanly on top of v7.0-rc1.

[1] https://lore.kernel.org/linux-pci/20260107-pci-m2-v5-0-8173d8a72641@oss.qualcomm.com
[2] https://github.com/Mani-Sadhasivam/linux/commit/b50f8386900990eed3dce8d91c3b643fb0e8739d

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
---
Changes in v7:
- Dropped the LGA binding change due to vendor prefix concern. This will be
  submitted later once I get clarity.
- Fixed several issues in the cleanup path of the pwrseq-pci-m2 driver which
  includes adding the .remove() callback.
- Rebased on top of bluetooth-next/master to resolve conflict with bluetooth
  patch.
- Link to v6: https://lore.kernel.org/r/20260317-pci-m2-e-v6-0-9c898f108d3d@oss.qualcomm.com

Changes in v6:
- Added a check to bail out if the serdev device was already added during notifier.
- Collected tags
- Link to v5: https://lore.kernel.org/r/20260224-pci-m2-e-v5-0-dd9b9501d33c@oss.qualcomm.com

Changes in v5:
- Incorporated comments in the binding patch by using single endpoint per port,
  reordering port nodes, adding missing properties and using a complete example.
- Incorporated comments in the pwrseq patch (nothing major)
- Fixed the build issue in patch 2
- Collected tags
- Rebased on top of 7.0-rc1
- Link to v4: https://lore.kernel.org/r/20260112-pci-m2-e-v4-0-eff84d2c6d26@oss.qualcomm.com

Changes in v4:
- Switched to dynamic OF node for serdev instead of swnode and dropped all
  swnode related patches
- Link to v3: https://lore.kernel.org/r/20260110-pci-m2-e-v3-0-4faee7d0d5ae@oss.qualcomm.com

Changes in v3:
- Switched to swnode for the serdev device and dropped the custom
  serdev_device_id related patches
- Added new swnode APIs to match the swnode with existing of_device_id
- Incorporated comments in the bindings patch
- Dropped the UIM interface from binding since it is not clear how it should get
  wired
- Incorporated comments in the pwrseq driver patch
- Splitted the pwrseq patch into two
- Added the 1620 LGA compatible with Key E fallback based on Stephan's finding
- Link to v2: https://lore.kernel.org/r/20251125-pci-m2-e-v2-0-32826de07cc5@oss.qualcomm.com

Changes in v2:
- Used '-' for GPIO names in the binding and removed led*-gpios properties
- Described the endpoint nodes for port@0 and port@1 nodes
- Added the OF graph port to the serial binding
- Fixed the hci_qca driver to return err if devm_pwrseq_get() fails
- Incorporated various review comments in pwrseq driver
- Collected Ack
- Link to v1: https://lore.kernel.org/r/20251112-pci-m2-e-v1-0-97413d6bf824@oss.qualcomm.com

---
Manivannan Sadhasivam (8):
      serdev: Convert to_serdev_*() helpers to macros and use container_of_const()
      serdev: Add an API to find the serdev controller associated with the devicetree node
      serdev: Do not return -ENODEV from of_serdev_register_devices() if external connector is used
      dt-bindings: serial: Document the graph port
      dt-bindings: connector: Add PCIe M.2 Mechanical Key E connector
      Bluetooth: hci_qca: Add M.2 Bluetooth device support using pwrseq
      power: sequencing: pcie-m2: Add support for PCIe M.2 Key E connectors
      power: sequencing: pcie-m2: Create serdev device for WCN7850 bluetooth

 .../bindings/connector/pcie-m2-e-connector.yaml    | 184 +++++++++++
 .../devicetree/bindings/serial/serial.yaml         |   3 +
 MAINTAINERS                                        |   1 +
 drivers/bluetooth/hci_qca.c                        |   9 +
 drivers/power/sequencing/Kconfig                   |   3 +-
 drivers/power/sequencing/pwrseq-pcie-m2.c          | 346 ++++++++++++++++++++-
 drivers/tty/serdev/core.c                          |  28 +-
 include/linux/serdev.h                             |  24 +-
 8 files changed, 570 insertions(+), 28 deletions(-)
---
base-commit: 559f264e403e4d58d56a17595c60a1de011c5e20
change-id: 20251112-pci-m2-e-94695ac9d657

Best regards,
--  
Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>

On Thu, 26 Mar 2026 09:06:28 +0100, Manivannan Sadhasivam via B4 Relay
<devnull+manivannan.sadhasivam.oss.qualcomm.com@kernel.org> said:
> Hi,
>
> This series is the continuation of the series [1] that added the initial support
> for the PCIe M.2 connectors. This series extends it by adding support for Key E
> connectors. These connectors are used to connect the Wireless Connectivity
> devices such as WiFi, BT, NFC and GNSS devices to the host machine over
> interfaces such as PCIe/SDIO, USB/UART and NFC. This series adds support for
> connectors that expose PCIe interface for WiFi and UART interface for BT. Other
> interfaces are left for future improvements.
>
> Serdev device support for BT
> ============================
>
> Adding support for the PCIe interface was mostly straightforward and a lot
> similar to the previous Key M connector. But adding UART interface has proved to
> be tricky. This is mostly because of the fact UART is a non-discoverable bus,
> unlike PCIe which is discoverable. So this series relied on the PCI notifier to
> create the serdev device for UART/BT. This means the PCIe interface will be
> brought up first and after the PCIe device enumeration, the serdev device will
> be created by the pwrseq driver. This logic is necessary since the connector
> driver and DT node don't describe the device, but just the connector. So to make
> the connector interface Plug and Play, the connector driver uses the PCIe device
> ID to identify the card and creates the serdev device. This logic could be
> extended in the future to support more M.2 cards. Even if the M.2 card uses SDIO
> interface for connecting WLAN, a SDIO notifier could be added to create the
> serdev device.
>
> Testing
> =======
>
> This series, together with the devicetree changes [2] was tested on the
> Qualcomm X1e based Lenovo Thinkpad T14s Laptop which has the WCN7850 WLAN/BT
> 1620 LGA card connected over PCIe and UART.
>
> Merge Strategy
> ==============
>
> Due to the API dependency, both the serdev and pwrseq patches need to go through
> a single tree, maybe through pwrseq tree. So the serdev patches need Ack from
> Greg. But Bluetooth patch can be merged separately.

I think Rob Herring is the man in charge here. The power sequencing parts look
good to me now so with an Ack on the serdev changes I can queue them for v7.1.
I can also put it on an immutable branch if needed.

Bart

On Thu, 26 Mar 2026 13:36:28 +0530, Manivannan Sadhasivam wrote:
> This series is the continuation of the series [1] that added the initial support
> for the PCIe M.2 connectors. This series extends it by adding support for Key E
> connectors. These connectors are used to connect the Wireless Connectivity
> devices such as WiFi, BT, NFC and GNSS devices to the host machine over
> interfaces such as PCIe/SDIO, USB/UART and NFC. This series adds support for
> connectors that expose PCIe interface for WiFi and UART interface for BT. Other
> interfaces are left for future improvements.
> 
> [...]

Applied, thanks!

[1/8] serdev: Convert to_serdev_*() helpers to macros and use container_of_const()
      https://git.kernel.org/brgl/c/e7fef85039ccdba67d97b2a09f313aceeb6691c8
[2/8] serdev: Add an API to find the serdev controller associated with the devicetree node
      https://git.kernel.org/brgl/c/a2b4814190af5944b276c5fd708d95ea146106b3
[3/8] serdev: Do not return -ENODEV from of_serdev_register_devices() if external connector is used
      https://git.kernel.org/brgl/c/92fa16ecad07dddc5703f7e2ff342441b04c45af
[4/8] dt-bindings: serial: Document the graph port
      https://git.kernel.org/brgl/c/1785c7bc1495e4e22377edffaf0ff8c3c697647d
[5/8] dt-bindings: connector: Add PCIe M.2 Mechanical Key E connector
      https://git.kernel.org/brgl/c/5970c1dafb8adbeab5f6d9a22a4ad5b1c0067888
[7/8] power: sequencing: pcie-m2: Add support for PCIe M.2 Key E connectors
      https://git.kernel.org/brgl/c/0d38285a12a283e12cd589ad5bb46c6f4a8cc647
[8/8] power: sequencing: pcie-m2: Create serdev device for WCN7850 bluetooth
      https://git.kernel.org/brgl/c/3f736aecbdc8e4faf2ed82c981812a6bfc76ea98

Best regards,
-- 
Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>