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b35cf3b6aa
To fix bridge resource allocation issues when powering PCI bridges with the
pwrctrl driver, introduce APIs to explicitly power on and off all related
devices simultaneously.
Previously, the individual pwrctrl drivers powered on/off the PCI devices
autonomously, without any control from the controller drivers. But to
enforce ordering with respect to powering on the devices, these APIs will
power on/off all the devices at the same time.
The pci_pwrctrl_power_on_devices() API recursively scans the PCI child
nodes, makes sure that pwrctrl drivers are bound to devices, and calls
their power_on() callbacks. If any pwrctrl driver is not bound, it will
return -EPROBE_DEFER.
Similarly, pci_pwrctrl_power_off_devices() API powers off devices
recursively via their power_off() callbacks.
These APIs are expected to be called during the controller probe and
suspend/resume time to power on/off the devices. But before calling these
APIs, the pwrctrl devices should be created using the
pci_pwrctrl_{create/destroy}_devices() APIs.
Co-developed-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Link: https://patch.msgid.link/20260115-pci-pwrctrl-rework-v5-11-9d26da3ce903@oss.qualcomm.com
69 lines
2.5 KiB
C
69 lines
2.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2024 Linaro Ltd.
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*/
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#ifndef __PCI_PWRCTRL_H__
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#define __PCI_PWRCTRL_H__
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#include <linux/notifier.h>
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#include <linux/workqueue.h>
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struct device;
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struct device_link;
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/*
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* This is a simple framework for solving the issue of PCI devices that require
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* certain resources (regulators, GPIOs, clocks) to be enabled before the
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* device can actually be detected on the PCI bus.
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*
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* The idea is to reuse the platform bus to populate OF nodes describing the
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* PCI device and its resources, let these platform devices probe and enable
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* relevant resources and then trigger a rescan of the PCI bus allowing for the
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* same device (with a second associated struct device) to be registered with
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* the PCI subsystem.
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*
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* To preserve a correct hierarchy for PCI power management and device reset,
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* we create a device link between the power control platform device (parent)
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* and the supplied PCI device (child).
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*/
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/**
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* struct pci_pwrctrl - PCI device power control context.
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* @dev: Address of the power controlling device.
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* @power_on: Callback to power on the power controlling device.
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* @power_off: Callback to power off the power controlling device.
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*
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* An object of this type must be allocated by the PCI power control device and
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* passed to the pwrctrl subsystem to trigger a bus rescan and setup a device
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* link with the device once it's up.
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*/
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struct pci_pwrctrl {
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struct device *dev;
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int (*power_on)(struct pci_pwrctrl *pwrctrl);
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int (*power_off)(struct pci_pwrctrl *pwrctrl);
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/* private: internal use only */
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struct notifier_block nb;
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struct device_link *link;
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struct work_struct work;
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};
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void pci_pwrctrl_init(struct pci_pwrctrl *pwrctrl, struct device *dev);
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int pci_pwrctrl_device_set_ready(struct pci_pwrctrl *pwrctrl);
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void pci_pwrctrl_device_unset_ready(struct pci_pwrctrl *pwrctrl);
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int devm_pci_pwrctrl_device_set_ready(struct device *dev,
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struct pci_pwrctrl *pwrctrl);
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#if IS_ENABLED(CONFIG_PCI_PWRCTRL)
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int pci_pwrctrl_create_devices(struct device *parent);
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void pci_pwrctrl_destroy_devices(struct device *parent);
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int pci_pwrctrl_power_on_devices(struct device *parent);
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void pci_pwrctrl_power_off_devices(struct device *parent);
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#else
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static inline int pci_pwrctrl_create_devices(struct device *parent) { return 0; }
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static void pci_pwrctrl_destroy_devices(struct device *parent) { }
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static inline int pci_pwrctrl_power_on_devices(struct device *parent) { return 0; }
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static void pci_pwrctrl_power_off_devices(struct device *parent) { }
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#endif
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#endif /* __PCI_PWRCTRL_H__ */
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