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 
9 static LIST_HEAD(mii_timestamping_devices);
10 static DEFINE_MUTEX(tstamping_devices_lock);
11 
12 struct 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  */
26 int 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 }
45 EXPORT_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  */
52 void 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 }
68 EXPORT_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  */
78 struct 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 }
101 EXPORT_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  */
109 void unregister_mii_timestamper(struct mii_timestamper *mii_ts)
110 {
111 	struct mii_timestamping_desc *desc;
112 	struct list_head *this;
113 
114 	/* mii_timestamper statically registered by the PHY driver won't use the
115 	 * register_mii_timestamper() and thus don't have ->device set. Don't
116 	 * try to unregister these.
117 	 */
118 	if (!mii_ts->device)
119 		return;
120 
121 	mutex_lock(&tstamping_devices_lock);
122 	list_for_each(this, &mii_timestamping_devices) {
123 		desc = list_entry(this, struct mii_timestamping_desc, list);
124 		if (desc->device == mii_ts->device) {
125 			desc->ctrl->release_channel(desc->device, mii_ts);
126 			put_device(desc->device);
127 			break;
128 		}
129 	}
130 	mutex_unlock(&tstamping_devices_lock);
131 }
132 EXPORT_SYMBOL(unregister_mii_timestamper);
133