1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright 2022 Google LLC
4 *
5 * USB Type-C Retimer support.
6 * Author: Prashant Malani <pmalani@chromium.org>
7 *
8 */
9
10#include <linux/device.h>
11#include <linux/list.h>
12#include <linux/module.h>
13#include <linux/mutex.h>
14#include <linux/property.h>
15#include <linux/slab.h>
16
17#include "class.h"
18#include "retimer.h"
19
20static int retimer_fwnode_match(struct device *dev, const void *fwnode)
21{
22	return is_typec_retimer(dev) && device_match_fwnode(dev, fwnode);
23}
24
25static void *typec_retimer_match(const struct fwnode_handle *fwnode, const char *id, void *data)
26{
27	struct device *dev;
28
29	if (id && !fwnode_property_present(fwnode, id))
30		return NULL;
31
32	dev = class_find_device(&retimer_class, NULL, fwnode,
33				retimer_fwnode_match);
34
35	return dev ? to_typec_retimer(dev) : ERR_PTR(-EPROBE_DEFER);
36}
37
38/**
39 * fwnode_typec_retimer_get - Find USB Type-C retimer.
40 * @fwnode: The caller device node.
41 *
42 * Finds a retimer linked to the caller. This function is primarily meant for the
43 * Type-C drivers. Returns a reference to the retimer on success, NULL if no
44 * matching connection was found, or ERR_PTR(-EPROBE_DEFER) when a connection
45 * was found but the retimer has not been enumerated yet.
46 */
47struct typec_retimer *fwnode_typec_retimer_get(struct fwnode_handle *fwnode)
48{
49	struct typec_retimer *retimer;
50
51	retimer = fwnode_connection_find_match(fwnode, "retimer-switch", NULL, typec_retimer_match);
52	if (!IS_ERR_OR_NULL(retimer))
53		WARN_ON(!try_module_get(retimer->dev.parent->driver->owner));
54
55	return retimer;
56}
57EXPORT_SYMBOL_GPL(fwnode_typec_retimer_get);
58
59/**
60 * typec_retimer_put - Release handle to a retimer.
61 * @retimer: USB Type-C Connector Retimer.
62 *
63 * Decrements reference count for @retimer.
64 */
65void typec_retimer_put(struct typec_retimer *retimer)
66{
67	if (!IS_ERR_OR_NULL(retimer)) {
68		module_put(retimer->dev.parent->driver->owner);
69		put_device(&retimer->dev);
70	}
71}
72EXPORT_SYMBOL_GPL(typec_retimer_put);
73
74int typec_retimer_set(struct typec_retimer *retimer, struct typec_retimer_state *state)
75{
76	if (IS_ERR_OR_NULL(retimer))
77		return 0;
78
79	return retimer->set(retimer, state);
80}
81EXPORT_SYMBOL_GPL(typec_retimer_set);
82
83static void typec_retimer_release(struct device *dev)
84{
85	kfree(to_typec_retimer(dev));
86}
87
88const struct device_type typec_retimer_dev_type = {
89	.name = "typec_retimer",
90	.release = typec_retimer_release,
91};
92
93/**
94 * typec_retimer_register - Register a retimer device.
95 * @parent: Parent device.
96 * @desc: Retimer description.
97 *
98 * Some USB Type-C connectors have their physical lines routed through retimers before they
99 * reach muxes or host controllers. In some cases (for example: using alternate modes)
100 * these retimers need to be reconfigured appropriately. This function registers retimer
101 * switches which route and potentially modify the signals on the Type C physical lines
102 * enroute to the host controllers.
103 */
104struct typec_retimer *
105typec_retimer_register(struct device *parent, const struct typec_retimer_desc *desc)
106{
107	struct typec_retimer *retimer;
108	int ret;
109
110	if (!desc || !desc->set)
111		return ERR_PTR(-EINVAL);
112
113	retimer = kzalloc(sizeof(*retimer), GFP_KERNEL);
114	if (!retimer)
115		return ERR_PTR(-ENOMEM);
116
117	retimer->set = desc->set;
118
119	device_initialize(&retimer->dev);
120	retimer->dev.parent = parent;
121	retimer->dev.fwnode = desc->fwnode;
122	retimer->dev.class = &retimer_class;
123	retimer->dev.type = &typec_retimer_dev_type;
124	retimer->dev.driver_data = desc->drvdata;
125	dev_set_name(&retimer->dev, "%s-retimer",
126		     desc->name ? desc->name : dev_name(parent));
127
128	ret = device_add(&retimer->dev);
129	if (ret) {
130		dev_err(parent, "failed to register retimer (%d)\n", ret);
131		put_device(&retimer->dev);
132		return ERR_PTR(ret);
133	}
134
135	return retimer;
136}
137EXPORT_SYMBOL_GPL(typec_retimer_register);
138
139/**
140 * typec_retimer_unregister - Unregister retimer device.
141 * @retimer: USB Type-C Connector retimer.
142 *
143 * Unregister retimer that was registered with typec_retimer_register().
144 */
145void typec_retimer_unregister(struct typec_retimer *retimer)
146{
147	if (!IS_ERR_OR_NULL(retimer))
148		device_unregister(&retimer->dev);
149}
150EXPORT_SYMBOL_GPL(typec_retimer_unregister);
151
152void *typec_retimer_get_drvdata(struct typec_retimer *retimer)
153{
154	return dev_get_drvdata(&retimer->dev);
155}
156EXPORT_SYMBOL_GPL(typec_retimer_get_drvdata);
157
158const struct class retimer_class = {
159	.name = "retimer",
160};
161