include/linux/pci-pwrctrl.h

root/include/linux/pci-pwrctrl.h
/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (C) 2024 Linaro Ltd.
 */

#ifndef __PCI_PWRCTRL_H__
#define __PCI_PWRCTRL_H__

#include <linux/notifier.h>
#include <linux/workqueue.h>

struct device;
struct device_link;

/*
 * This is a simple framework for solving the issue of PCI devices that require
 * certain resources (regulators, GPIOs, clocks) to be enabled before the
 * device can actually be detected on the PCI bus.
 *
 * The idea is to reuse the platform bus to populate OF nodes describing the
 * PCI device and its resources, let these platform devices probe and enable
 * relevant resources and then trigger a rescan of the PCI bus allowing for the
 * same device (with a second associated struct device) to be registered with
 * the PCI subsystem.
 *
 * To preserve a correct hierarchy for PCI power management and device reset,
 * we create a device link between the power control platform device (parent)
 * and the supplied PCI device (child).
 */

/**
 * struct pci_pwrctrl - PCI device power control context.
 * @dev: Address of the power controlling device.
 * @power_on: Callback to power on the power controlling device.
 * @power_off: Callback to power off the power controlling device.
 *
 * An object of this type must be allocated by the PCI power control device and
 * passed to the pwrctrl subsystem to trigger a bus rescan and setup a device
 * link with the device once it's up.
 */
struct pci_pwrctrl {
        struct device *dev;
        int (*power_on)(struct pci_pwrctrl *pwrctrl);
        int (*power_off)(struct pci_pwrctrl *pwrctrl);

        /* private: internal use only */
        struct notifier_block nb;
        struct device_link *link;
        struct work_struct work;
};

void pci_pwrctrl_init(struct pci_pwrctrl *pwrctrl, struct device *dev);
int pci_pwrctrl_device_set_ready(struct pci_pwrctrl *pwrctrl);
void pci_pwrctrl_device_unset_ready(struct pci_pwrctrl *pwrctrl);
int devm_pci_pwrctrl_device_set_ready(struct device *dev,
                                     struct pci_pwrctrl *pwrctrl);
#if IS_ENABLED(CONFIG_PCI_PWRCTRL)
int pci_pwrctrl_create_devices(struct device *parent);
void pci_pwrctrl_destroy_devices(struct device *parent);
int pci_pwrctrl_power_on_devices(struct device *parent);
void pci_pwrctrl_power_off_devices(struct device *parent);
#else
static inline int pci_pwrctrl_create_devices(struct device *parent) { return 0; }
static void pci_pwrctrl_destroy_devices(struct device *parent) { }
static inline int pci_pwrctrl_power_on_devices(struct device *parent) { return 0; }
static void pci_pwrctrl_power_off_devices(struct device *parent) { }
#endif
#endif /* __PCI_PWRCTRL_H__ */
Linux
