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-pwrctrl.h> 11 #include <linux/property.h> 12 #include <linux/slab.h> 13 14 static int pci_pwrctrl_notify(struct notifier_block *nb, unsigned long action, 15 void *data) 16 { 17 struct pci_pwrctrl *pwrctrl = container_of(nb, struct pci_pwrctrl, nb); 18 struct device *dev = data; 19 20 if (dev_fwnode(dev) != dev_fwnode(pwrctrl->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 } 37 38 return NOTIFY_DONE; 39 } 40 41 static void rescan_work_func(struct work_struct *work) 42 { 43 struct pci_pwrctrl *pwrctrl = container_of(work, 44 struct pci_pwrctrl, work); 45 46 pci_lock_rescan_remove(); 47 pci_rescan_bus(to_pci_host_bridge(pwrctrl->dev->parent)->bus); 48 pci_unlock_rescan_remove(); 49 } 50 51 /** 52 * pci_pwrctrl_init() - Initialize the PCI power control context struct 53 * 54 * @pwrctrl: PCI power control data 55 * @dev: Parent device 56 */ 57 void pci_pwrctrl_init(struct pci_pwrctrl *pwrctrl, struct device *dev) 58 { 59 pwrctrl->dev = dev; 60 INIT_WORK(&pwrctrl->work, rescan_work_func); 61 } 62 EXPORT_SYMBOL_GPL(pci_pwrctrl_init); 63 64 /** 65 * pci_pwrctrl_device_set_ready() - Notify the pwrctrl subsystem that the PCI 66 * device is powered-up and ready to be detected. 67 * 68 * @pwrctrl: PCI power control data. 69 * 70 * Returns: 71 * 0 on success, negative error number on error. 72 * 73 * Note: 74 * This function returning 0 doesn't mean the device was detected. It means, 75 * that the bus rescan was successfully started. The device will get bound to 76 * its PCI driver asynchronously. 77 */ 78 int pci_pwrctrl_device_set_ready(struct pci_pwrctrl *pwrctrl) 79 { 80 int ret; 81 82 if (!pwrctrl->dev) 83 return -ENODEV; 84 85 pwrctrl->nb.notifier_call = pci_pwrctrl_notify; 86 ret = bus_register_notifier(&pci_bus_type, &pwrctrl->nb); 87 if (ret) 88 return ret; 89 90 schedule_work(&pwrctrl->work); 91 92 return 0; 93 } 94 EXPORT_SYMBOL_GPL(pci_pwrctrl_device_set_ready); 95 96 /** 97 * pci_pwrctrl_device_unset_ready() - Notify the pwrctrl subsystem that the PCI 98 * device is about to be powered-down. 99 * 100 * @pwrctrl: PCI power control data. 101 */ 102 void pci_pwrctrl_device_unset_ready(struct pci_pwrctrl *pwrctrl) 103 { 104 cancel_work_sync(&pwrctrl->work); 105 106 /* 107 * We don't have to delete the link here. Typically, this function 108 * is only called when the power control device is being detached. If 109 * it is being detached then the child PCI device must have already 110 * been unbound too or the device core wouldn't let us unbind. 111 */ 112 bus_unregister_notifier(&pci_bus_type, &pwrctrl->nb); 113 } 114 EXPORT_SYMBOL_GPL(pci_pwrctrl_device_unset_ready); 115 116 static void devm_pci_pwrctrl_device_unset_ready(void *data) 117 { 118 struct pci_pwrctrl *pwrctrl = data; 119 120 pci_pwrctrl_device_unset_ready(pwrctrl); 121 } 122 123 /** 124 * devm_pci_pwrctrl_device_set_ready - Managed variant of 125 * pci_pwrctrl_device_set_ready(). 126 * 127 * @dev: Device managing this pwrctrl provider. 128 * @pwrctrl: PCI power control data. 129 * 130 * Returns: 131 * 0 on success, negative error number on error. 132 */ 133 int devm_pci_pwrctrl_device_set_ready(struct device *dev, 134 struct pci_pwrctrl *pwrctrl) 135 { 136 int ret; 137 138 ret = pci_pwrctrl_device_set_ready(pwrctrl); 139 if (ret) 140 return ret; 141 142 return devm_add_action_or_reset(dev, 143 devm_pci_pwrctrl_device_unset_ready, 144 pwrctrl); 145 } 146 EXPORT_SYMBOL_GPL(devm_pci_pwrctrl_device_set_ready); 147 148 MODULE_AUTHOR("Bartosz Golaszewski <bartosz.golaszewski@linaro.org>"); 149 MODULE_DESCRIPTION("PCI Device Power Control core driver"); 150 MODULE_LICENSE("GPL"); 151