From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx> Linus, I'm sending this early as this is the initial pull-request for a new driver subsystem living under drivers/power/sequencing/. I'll try to be brief here and allow myself to link the cover letter from the last time the series was sent in its entirety[1] (as opposed to smaller chunks targetting specific maintainers) for a very detailed description of the problem and the solution. I'll just stick to the key points below. This has been in development since last year's Linux Plumbers Conference and was inspired by the need to enable support upstream for Bluetooth/WLAN chips on Qualcomm platforms. The main problem we're fixing is powering up devices which are represented as separate objects in the kernel (binding to different drivers) but which share parts of the power-up sequence and thus need some kind of a mediator who knows the possible interactions and can assure they don't interfere with neither device's bring up. An example of such an inter-driver interaction is the WCN family of BT/WLAN chips from Qualcomm of which some models require the user to observe a certain delay between driving the bt-enable and wlan-enable GPIOs. This is not a new problem but up to this point all attempts at addressing it ended up hitting one wall or another and being dropped. The main obstacle was the fact that most these attempts tried to introduce the concept of a "power sequence" into the device-tree bindings which breaks the main DT rule: describe the hardware, not its behavior. The solution I proposed focuses on making the power sequencer drivers interpret the actual HW description flexibly. More details on that are in the linked cover letter. The second problem fixed here is powering up PCI devices before they are detected on the bus. This is achieved by creating special platform devices for device-tree nodes describing hard-wired PCI devices which bind to the so-called PCI power control drivers which enable required resources and trigger a bus rescan once the controlled device is up then setup the correct devlink hierarchy for power-management. By combining the two new frameworks we implemented the power sequencing PCI power control driver which is capable of powering up the WLAN modules of the QCom WCN family of chipsets. All this has spent a significant amount of time in linux-next and enabled WLAN/BT support on several Qualcomm platforms. To further prove that this is useful and needed: right after this was picked up into next, I was sent a series using the subsystem for a similar use-case on Amlogic platforms[2]. This PR contains the core power sequencing framework, the first driver, PCI changes using the pwrseq library (blessed by Bjorn Helgaas) and some fixes that came later. You'll also see the pwrseq core pulled into the Bluetooth tree to satisfy the build-time dependency on power sequencing in the hci_qca driver which uses the same power sequence provider as the PCI pwrctl driver added in this PR. More changes that don't have build-time dependencies on pwrseq are scattered across three other maintainer trees: there will be DT bindings in the regulator and wireless trees and DTS changes in the arm64 tree. Please consider pulling for v6.11. Best Regards, Bartosz Golaszewski [1] https://lore.kernel.org/all/20240528-pwrseq-v8-0-d354d52b763c@xxxxxxxxxx/ [2] https://lore.kernel.org/lkml/20240705-pwrseq-v1-0-31829b47fc72@xxxxxxxxxxx/ The following changes since commit 83a7eefedc9b56fe7bfeff13b6c7356688ffa670: Linux 6.10-rc3 (2024-06-09 14:19:43 -0700) are available in the Git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux.git tags/pwrseq-updates-for-v6.11-rc1 for you to fetch changes up to 50b040ef373293b4ae2ecdc5873daa4656724868: PCI/pwrctl: only call of_platform_populate() if CONFIG_OF is enabled (2024-07-08 21:15:26 +0200) ---------------------------------------------------------------- pwrseq updates for v6.11-rc1 - add the pwrseq core framework - add the first power sequencing driver: pwrseq-qcom-wcn - add power control (pwrctl) changes to PCI core - add the first PCI pwrctl power sequencing driver ---------------------------------------------------------------- Bartosz Golaszewski (7): power: sequencing: implement the pwrseq core power: pwrseq: add a driver for the PMU module on the QCom WCN chipsets PCI: Hold the rescan mutex when scanning for the first time PCI/pwrctl: Reuse the OF node for power controlled devices PCI/pwrctl: Create platform devices for child OF nodes of the port node PCI/pwrctl: Add PCI power control core code PCI/pwrctl: Add a PCI power control driver for power sequenced devices Bert Karwatzki (1): PCI/pwrctl: only call of_platform_populate() if CONFIG_OF is enabled Krzysztof Kozlowski (1): power: sequencing: simplify returning pointer without cleanup MAINTAINERS | 16 + drivers/pci/Kconfig | 1 + drivers/pci/Makefile | 1 + drivers/pci/bus.c | 9 + drivers/pci/of.c | 14 +- drivers/pci/probe.c | 2 + drivers/pci/pwrctl/Kconfig | 17 + drivers/pci/pwrctl/Makefile | 6 + drivers/pci/pwrctl/core.c | 137 ++++ drivers/pci/pwrctl/pci-pwrctl-pwrseq.c | 89 +++ drivers/pci/remove.c | 3 +- drivers/power/Kconfig | 1 + drivers/power/Makefile | 1 + drivers/power/sequencing/Kconfig | 29 + drivers/power/sequencing/Makefile | 6 + drivers/power/sequencing/core.c | 1105 ++++++++++++++++++++++++++++ drivers/power/sequencing/pwrseq-qcom-wcn.c | 336 +++++++++ include/linux/pci-pwrctl.h | 51 ++ include/linux/pwrseq/consumer.h | 56 ++ include/linux/pwrseq/provider.h | 75 ++ 20 files changed, 1950 insertions(+), 5 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-qcom-wcn.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
