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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (C) 2024 Linaro Ltd.4 */5 6#include <linux/device.h>7#include <linux/export.h>8#include <linux/kernel.h>9#include <linux/pci.h>10#include <linux/pci-pwrctl.h>11#include <linux/property.h>12#include <linux/slab.h>13 14static int pci_pwrctl_notify(struct notifier_block *nb, unsigned long action,15 void *data)16{17 struct pci_pwrctl *pwrctl = container_of(nb, struct pci_pwrctl, nb);18 struct device *dev = data;19 20 if (dev_fwnode(dev) != dev_fwnode(pwrctl->dev))21 return NOTIFY_DONE;22 23 switch (action) {24 case BUS_NOTIFY_ADD_DEVICE:25 /*26 * We will have two struct device objects bound to two different27 * drivers on different buses but consuming the same DT node. We28 * must not bind the pins twice in this case but only once for29 * the first device to be added.30 *31 * If we got here then the PCI device is the second after the32 * power control platform device. Mark its OF node as reused.33 */34 dev->of_node_reused = true;35 break;36 case BUS_NOTIFY_BOUND_DRIVER:37 pwrctl->link = device_link_add(dev, pwrctl->dev,38 DL_FLAG_AUTOREMOVE_CONSUMER);39 if (!pwrctl->link)40 dev_err(pwrctl->dev, "Failed to add device link\n");41 break;42 case BUS_NOTIFY_UNBOUND_DRIVER:43 if (pwrctl->link)44 device_link_remove(dev, pwrctl->dev);45 break;46 }47 48 return NOTIFY_DONE;49}50 51static void rescan_work_func(struct work_struct *work)52{53 struct pci_pwrctl *pwrctl = container_of(work, struct pci_pwrctl, work);54 55 pci_lock_rescan_remove();56 pci_rescan_bus(to_pci_dev(pwrctl->dev->parent)->bus);57 pci_unlock_rescan_remove();58}59 60/**61 * pci_pwrctl_init() - Initialize the PCI power control context struct62 *63 * @pwrctl: PCI power control data64 * @dev: Parent device65 */66void pci_pwrctl_init(struct pci_pwrctl *pwrctl, struct device *dev)67{68 pwrctl->dev = dev;69 INIT_WORK(&pwrctl->work, rescan_work_func);70}71EXPORT_SYMBOL_GPL(pci_pwrctl_init);72 73/**74 * pci_pwrctl_device_set_ready() - Notify the pwrctl subsystem that the PCI75 * device is powered-up and ready to be detected.76 *77 * @pwrctl: PCI power control data.78 *79 * Returns:80 * 0 on success, negative error number on error.81 *82 * Note:83 * This function returning 0 doesn't mean the device was detected. It means,84 * that the bus rescan was successfully started. The device will get bound to85 * its PCI driver asynchronously.86 */87int pci_pwrctl_device_set_ready(struct pci_pwrctl *pwrctl)88{89 int ret;90 91 if (!pwrctl->dev)92 return -ENODEV;93 94 pwrctl->nb.notifier_call = pci_pwrctl_notify;95 ret = bus_register_notifier(&pci_bus_type, &pwrctl->nb);96 if (ret)97 return ret;98 99 schedule_work(&pwrctl->work);100 101 return 0;102}103EXPORT_SYMBOL_GPL(pci_pwrctl_device_set_ready);104 105/**106 * pci_pwrctl_device_unset_ready() - Notify the pwrctl subsystem that the PCI107 * device is about to be powered-down.108 *109 * @pwrctl: PCI power control data.110 */111void pci_pwrctl_device_unset_ready(struct pci_pwrctl *pwrctl)112{113 /*114 * We don't have to delete the link here. Typically, this function115 * is only called when the power control device is being detached. If116 * it is being detached then the child PCI device must have already117 * been unbound too or the device core wouldn't let us unbind.118 */119 bus_unregister_notifier(&pci_bus_type, &pwrctl->nb);120}121EXPORT_SYMBOL_GPL(pci_pwrctl_device_unset_ready);122 123static void devm_pci_pwrctl_device_unset_ready(void *data)124{125 struct pci_pwrctl *pwrctl = data;126 127 pci_pwrctl_device_unset_ready(pwrctl);128}129 130/**131 * devm_pci_pwrctl_device_set_ready - Managed variant of132 * pci_pwrctl_device_set_ready().133 *134 * @dev: Device managing this pwrctl provider.135 * @pwrctl: PCI power control data.136 *137 * Returns:138 * 0 on success, negative error number on error.139 */140int devm_pci_pwrctl_device_set_ready(struct device *dev,141 struct pci_pwrctl *pwrctl)142{143 int ret;144 145 ret = pci_pwrctl_device_set_ready(pwrctl);146 if (ret)147 return ret;148 149 return devm_add_action_or_reset(dev,150 devm_pci_pwrctl_device_unset_ready,151 pwrctl);152}153EXPORT_SYMBOL_GPL(devm_pci_pwrctl_device_set_ready);154 155MODULE_AUTHOR("Bartosz Golaszewski <bartosz.golaszewski@linaro.org>");156MODULE_DESCRIPTION("PCI Device Power Control core driver");157MODULE_LICENSE("GPL");158