1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 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 14 static 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 different 27 * drivers on different buses but consuming the same DT node. We 28 * must not bind the pins twice in this case but only once for 29 * the first device to be added. 30 * 31 * If we got here then the PCI device is the second after the 32 * 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 51 /** 52 * pci_pwrctl_device_set_ready() - Notify the pwrctl subsystem that the PCI 53 * device is powered-up and ready to be detected. 54 * 55 * @pwrctl: PCI power control data. 56 * 57 * Returns: 58 * 0 on success, negative error number on error. 59 * 60 * Note: 61 * This function returning 0 doesn't mean the device was detected. It means, 62 * that the bus rescan was successfully started. The device will get bound to 63 * its PCI driver asynchronously. 64 */ 65 int pci_pwrctl_device_set_ready(struct pci_pwrctl *pwrctl) 66 { 67 int ret; 68 69 if (!pwrctl->dev) 70 return -ENODEV; 71 72 pwrctl->nb.notifier_call = pci_pwrctl_notify; 73 ret = bus_register_notifier(&pci_bus_type, &pwrctl->nb); 74 if (ret) 75 return ret; 76 77 pci_lock_rescan_remove(); 78 pci_rescan_bus(to_pci_dev(pwrctl->dev->parent)->bus); 79 pci_unlock_rescan_remove(); 80 81 return 0; 82 } 83 EXPORT_SYMBOL_GPL(pci_pwrctl_device_set_ready); 84 85 /** 86 * pci_pwrctl_device_unset_ready() - Notify the pwrctl subsystem that the PCI 87 * device is about to be powered-down. 88 * 89 * @pwrctl: PCI power control data. 90 */ 91 void pci_pwrctl_device_unset_ready(struct pci_pwrctl *pwrctl) 92 { 93 /* 94 * We don't have to delete the link here. Typically, this function 95 * is only called when the power control device is being detached. If 96 * it is being detached then the child PCI device must have already 97 * been unbound too or the device core wouldn't let us unbind. 98 */ 99 bus_unregister_notifier(&pci_bus_type, &pwrctl->nb); 100 } 101 EXPORT_SYMBOL_GPL(pci_pwrctl_device_unset_ready); 102 103 static void devm_pci_pwrctl_device_unset_ready(void *data) 104 { 105 struct pci_pwrctl *pwrctl = data; 106 107 pci_pwrctl_device_unset_ready(pwrctl); 108 } 109 110 /** 111 * devm_pci_pwrctl_device_set_ready - Managed variant of 112 * pci_pwrctl_device_set_ready(). 113 * 114 * @dev: Device managing this pwrctl provider. 115 * @pwrctl: PCI power control data. 116 * 117 * Returns: 118 * 0 on success, negative error number on error. 119 */ 120 int devm_pci_pwrctl_device_set_ready(struct device *dev, 121 struct pci_pwrctl *pwrctl) 122 { 123 int ret; 124 125 ret = pci_pwrctl_device_set_ready(pwrctl); 126 if (ret) 127 return ret; 128 129 return devm_add_action_or_reset(dev, 130 devm_pci_pwrctl_device_unset_ready, 131 pwrctl); 132 } 133 EXPORT_SYMBOL_GPL(devm_pci_pwrctl_device_set_ready); 134 135 MODULE_AUTHOR("Bartosz Golaszewski <bartosz.golaszewski@linaro.org>"); 136 MODULE_DESCRIPTION("PCI Device Power Control core driver"); 137 MODULE_LICENSE("GPL"); 138