linux-kernel - [RFC 0/9] power: sequencing: implement the subsystem and add first users

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Date: Thu,  1 Feb 2024 16:55:23 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konrad.dybcio@...aro.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Marcel Holtmann <marcel@...tmann.org>,
	Luiz Augusto von Dentz <luiz.dentz@...il.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Neil Armstrong <neil.armstrong@...aro.org>,
	Alex Elder <elder@...aro.org>,
	Srini Kandagatla <srinivas.kandagatla@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Arnd Bergmann <arnd@...db.de>,
	Abel Vesa <abel.vesa@...aro.org>,
	Manivannan Sadhasivam <mani@...nel.org>,
	Lukas Wunner <lukas@...ner.de>
Cc: linux-arm-msm@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-bluetooth@...r.kernel.org,
	linux-pci@...r.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [RFC 0/9] power: sequencing: implement the subsystem and add first users

From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

I'd like to preface the cover letter by saying right away that this
series is not complete. It's an RFC that presents my approach and is sent
to the list for discussion. There are no DT bindings nor docs in
Documentation/ yet. Please review it as an RFC and not an upstreambound
series. If the approach is accepted as correct, I'll add missing bits.

The RFC[1] presenting my proposed device-tree representation of the
QCA6391 package present on the RB5 board - while not really officially
accepted - was not outright rejected which is a good sign.

This series incorporates it and builds a proposed power sequencing
subsystem together with the first dedicated driver around it. Then it
adds first two users: the Bluetooth and WLAN modules of the QCA6391.

The Bluetooth part is pretty straightforward. The WLAN however is a PCIe
device and as such needs to be powered-up *before* it's detected on the
PCI bus. To that end, we modify the PCI core to instantiate platform
devices for existing DT child nodes of the PCIe ports. For those nodes
for which a power-sequencing driver exists, we bind it and let it probe.
The driver then triggers a rescan of the PCI bus with the aim of
detecting the now powered-on device. The device will consume the same DT
node as the platform, power-sequencing device. We use device links to
make the latter become the parent of the former.

The main advantage of the above approach (both for PCI as well as
generic power sequencers) is that we don't introduce significant changes
in DT bindings and don't introduce new properties. We merely define new
resources.

[1] https://lore.kernel.org/all/CAMRc=MckG32DQv7b1AQL-mbnYdx4fsdYWtLwCyXc5Ma7EeSAKw@mail.gmail.com/T/#md5dc62007d12f6833d4e51658b14e0493954ba68

Bartosz Golaszewski (9):
  of: provide a cleanup helper for OF nodes
  arm64: dts: qcom: qrb5165-rb5: model the PMU of the QCA6391
  power: sequencing: new subsystem
  power: pwrseq: add a driver for the QCA6390 PMU module
  Bluetooth: qca: use the power sequencer for QCA6390
  PCI: create platform devices for child OF nodes of the port node
  PCI: hold the rescan mutex when scanning for the first time
  PCI/pwrctl: add PCI power control core code
  PCI/pwrctl: add a PCI power control driver for power sequenced devices

 arch/arm64/boot/dts/qcom/qrb5165-rb5.dts  | 128 +++++-
 arch/arm64/boot/dts/qcom/sm8250.dtsi      |  10 +
 drivers/bluetooth/hci_qca.c               |  30 ++
 drivers/pci/Kconfig                       |   1 +
 drivers/pci/Makefile                      |   1 +
 drivers/pci/bus.c                         |   9 +-
 drivers/pci/probe.c                       |   2 +
 drivers/pci/pwrctl/Kconfig                |  17 +
 drivers/pci/pwrctl/Makefile               |   4 +
 drivers/pci/pwrctl/core.c                 |  82 ++++
 drivers/pci/pwrctl/pci-pwrctl-pwrseq.c    |  83 ++++
 drivers/pci/remove.c                      |   2 +
 drivers/power/Kconfig                     |   1 +
 drivers/power/Makefile                    |   1 +
 drivers/power/sequencing/Kconfig          |  28 ++
 drivers/power/sequencing/Makefile         |   6 +
 drivers/power/sequencing/core.c           | 482 ++++++++++++++++++++++
 drivers/power/sequencing/pwrseq-qca6390.c | 232 +++++++++++
 include/linux/of.h                        |   4 +
 include/linux/pci-pwrctl.h                |  24 ++
 include/linux/pwrseq/consumer.h           |  53 +++
 include/linux/pwrseq/provider.h           |  41 ++
 22 files changed, 1229 insertions(+), 12 deletions(-)
 create mode 100644 drivers/pci/pwrctl/Kconfig
 create mode 100644 drivers/pci/pwrctl/Makefile
 create mode 100644 drivers/pci/pwrctl/core.c
 create mode 100644 drivers/pci/pwrctl/pci-pwrctl-pwrseq.c
 create mode 100644 drivers/power/sequencing/Kconfig
 create mode 100644 drivers/power/sequencing/Makefile
 create mode 100644 drivers/power/sequencing/core.c
 create mode 100644 drivers/power/sequencing/pwrseq-qca6390.c
 create mode 100644 include/linux/pci-pwrctl.h
 create mode 100644 include/linux/pwrseq/consumer.h
 create mode 100644 include/linux/pwrseq/provider.h

-- 
2.40.1