1// SPDX-License-Identifier: GPL-2.0
2//
3// Support for generic time stamping devices on MII buses.
4// Copyright (C) 2018 Richard Cochran <richardcochran@gmail.com>
5//
6
7#include <linux/mii_timestamper.h>
8
9static LIST_HEAD(mii_timestamping_devices);
10static DEFINE_MUTEX(tstamping_devices_lock);
11
12struct mii_timestamping_desc {
13	struct list_head list;
14	struct mii_timestamping_ctrl *ctrl;
15	struct device *device;
16};
17
18/**
19 * register_mii_tstamp_controller() - registers an MII time stamping device.
20 *
21 * @device:	The device to be registered.
22 * @ctrl:	Pointer to device's control interface.
23 *
24 * Returns zero on success or non-zero on failure.
25 */
26int register_mii_tstamp_controller(struct device *device,
27				   struct mii_timestamping_ctrl *ctrl)
28{
29	struct mii_timestamping_desc *desc;
30
31	desc = kzalloc(sizeof(*desc), GFP_KERNEL);
32	if (!desc)
33		return -ENOMEM;
34
35	INIT_LIST_HEAD(&desc->list);
36	desc->ctrl = ctrl;
37	desc->device = device;
38
39	mutex_lock(&tstamping_devices_lock);
40	list_add_tail(&mii_timestamping_devices, &desc->list);
41	mutex_unlock(&tstamping_devices_lock);
42
43	return 0;
44}
45EXPORT_SYMBOL(register_mii_tstamp_controller);
46
47/**
48 * unregister_mii_tstamp_controller() - unregisters an MII time stamping device.
49 *
50 * @device:	A device previously passed to register_mii_tstamp_controller().
51 */
52void unregister_mii_tstamp_controller(struct device *device)
53{
54	struct mii_timestamping_desc *desc;
55	struct list_head *this, *next;
56
57	mutex_lock(&tstamping_devices_lock);
58	list_for_each_safe(this, next, &mii_timestamping_devices) {
59		desc = list_entry(this, struct mii_timestamping_desc, list);
60		if (desc->device == device) {
61			list_del_init(&desc->list);
62			kfree(desc);
63			break;
64		}
65	}
66	mutex_unlock(&tstamping_devices_lock);
67}
68EXPORT_SYMBOL(unregister_mii_tstamp_controller);
69
70/**
71 * register_mii_timestamper - Enables a given port of an MII time stamper.
72 *
73 * @node:	The device tree node of the MII time stamp controller.
74 * @port:	The index of the port to be enabled.
75 *
76 * Returns a valid interface on success or ERR_PTR otherwise.
77 */
78struct mii_timestamper *register_mii_timestamper(struct device_node *node,
79						 unsigned int port)
80{
81	struct mii_timestamper *mii_ts = NULL;
82	struct mii_timestamping_desc *desc;
83	struct list_head *this;
84
85	mutex_lock(&tstamping_devices_lock);
86	list_for_each(this, &mii_timestamping_devices) {
87		desc = list_entry(this, struct mii_timestamping_desc, list);
88		if (desc->device->of_node == node) {
89			mii_ts = desc->ctrl->probe_channel(desc->device, port);
90			if (!IS_ERR(mii_ts)) {
91				mii_ts->device = desc->device;
92				get_device(desc->device);
93			}
94			break;
95		}
96	}
97	mutex_unlock(&tstamping_devices_lock);
98
99	return mii_ts ? mii_ts : ERR_PTR(-EPROBE_DEFER);
100}
101EXPORT_SYMBOL(register_mii_timestamper);
102
103/**
104 * unregister_mii_timestamper - Disables a given MII time stamper.
105 *
106 * @mii_ts:	An interface obtained via register_mii_timestamper().
107 *
108 */
109void unregister_mii_timestamper(struct mii_timestamper *mii_ts)
110{
111	struct mii_timestamping_desc *desc;
112	struct list_head *this;
113
114	if (!mii_ts)
115		return;
116
117	/* mii_timestamper statically registered by the PHY driver won't use the
118	 * register_mii_timestamper() and thus don't have ->device set. Don't
119	 * try to unregister these.
120	 */
121	if (!mii_ts->device)
122		return;
123
124	mutex_lock(&tstamping_devices_lock);
125	list_for_each(this, &mii_timestamping_devices) {
126		desc = list_entry(this, struct mii_timestamping_desc, list);
127		if (desc->device == mii_ts->device) {
128			desc->ctrl->release_channel(desc->device, mii_ts);
129			put_device(desc->device);
130			break;
131		}
132	}
133	mutex_unlock(&tstamping_devices_lock);
134}
135EXPORT_SYMBOL(unregister_mii_timestamper);
136