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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
14static 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
41static 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 */
57void pci_pwrctrl_init(struct pci_pwrctrl *pwrctrl, struct device *dev)
58{
59 pwrctrl->dev = dev;
60 INIT_WORK(&pwrctrl->work, rescan_work_func);
61}
62EXPORT_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 */
78int 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(bus: &pci_bus_type, nb: &pwrctrl->nb);
87 if (ret)
88 return ret;
89
90 schedule_work(work: &pwrctrl->work);
91
92 return 0;
93}
94EXPORT_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 */
102void pci_pwrctrl_device_unset_ready(struct pci_pwrctrl *pwrctrl)
103{
104 cancel_work_sync(work: &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(bus: &pci_bus_type, nb: &pwrctrl->nb);
113}
114EXPORT_SYMBOL_GPL(pci_pwrctrl_device_unset_ready);
115
116static 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 */
133int 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}
146EXPORT_SYMBOL_GPL(devm_pci_pwrctrl_device_set_ready);
147
148MODULE_AUTHOR("Bartosz Golaszewski <bartosz.golaszewski@linaro.org>");
149MODULE_DESCRIPTION("PCI Device Power Control core driver");
150MODULE_LICENSE("GPL");
151

source code of linux/drivers/pci/pwrctrl/core.c