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);