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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * USB Role Switch Support
4 *
5 * Copyright (C) 2018 Intel Corporation
6 * Author: Heikki Krogerus <[email protected]>
7 * Hans de Goede <[email protected]>
8 */
9
10#include <linux/component.h>
11#include <linux/usb/role.h>
12#include <linux/property.h>
13#include <linux/device.h>
14#include <linux/lockdep.h>
15#include <linux/module.h>
16#include <linux/mutex.h>
17#include <linux/slab.h>
18
19static const struct class role_class = {
20 .name = "usb_role",
21};
22
23struct usb_role_switch {
24 struct device dev;
25 struct lock_class_key key;
26 struct mutex lock; /* device lock*/
27 struct module *module; /* the module this device depends on */
28 enum usb_role role;
29 bool registered;
30
31 /* From descriptor */
32 struct device *usb2_port;
33 struct device *usb3_port;
34 struct device *udc;
35 usb_role_switch_set_t set;
36 usb_role_switch_get_t get;
37 bool allow_userspace_control;
38};
39
40#define to_role_switch(d) container_of(d, struct usb_role_switch, dev)
41
42static int connector_bind(struct device *dev, struct device *connector, void *data)
43{
44 int ret;
45
46 ret = sysfs_create_link(&dev->kobj, &connector->kobj, "connector");
47 if (ret)
48 return ret;
49
50 ret = sysfs_create_link(&connector->kobj, &dev->kobj, "usb-role-switch");
51 if (ret)
52 sysfs_remove_link(&dev->kobj, "connector");
53
54 return ret;
55}
56
57static void connector_unbind(struct device *dev, struct device *connector, void *data)
58{
59 sysfs_remove_link(&connector->kobj, "usb-role-switch");
60 sysfs_remove_link(&dev->kobj, "connector");
61}
62
63static const struct component_ops connector_ops = {
64 .bind = connector_bind,
65 .unbind = connector_unbind,
66};
67
68/**
69 * usb_role_switch_set_role - Set USB role for a switch
70 * @sw: USB role switch
71 * @role: USB role to be switched to
72 *
73 * Set USB role @role for @sw.
74 */
75int usb_role_switch_set_role(struct usb_role_switch *sw, enum usb_role role)
76{
77 int ret;
78
79 if (IS_ERR_OR_NULL(sw))
80 return 0;
81
82 if (!sw->registered)
83 return -EOPNOTSUPP;
84
85 mutex_lock(&sw->lock);
86
87 ret = sw->set(sw, role);
88 if (!ret) {
89 sw->role = role;
90 kobject_uevent(&sw->dev.kobj, KOBJ_CHANGE);
91 }
92
93 mutex_unlock(&sw->lock);
94
95 return ret;
96}
97EXPORT_SYMBOL_GPL(usb_role_switch_set_role);
98
99/**
100 * usb_role_switch_get_role - Get the USB role for a switch
101 * @sw: USB role switch
102 *
103 * Depending on the role-switch-driver this function returns either a cached
104 * value of the last set role, or reads back the actual value from the hardware.
105 */
106enum usb_role usb_role_switch_get_role(struct usb_role_switch *sw)
107{
108 enum usb_role role;
109
110 if (IS_ERR_OR_NULL(sw) || !sw->registered)
111 return USB_ROLE_NONE;
112
113 mutex_lock(&sw->lock);
114
115 if (sw->get)
116 role = sw->get(sw);
117 else
118 role = sw->role;
119
120 mutex_unlock(&sw->lock);
121
122 return role;
123}
124EXPORT_SYMBOL_GPL(usb_role_switch_get_role);
125
126static void *usb_role_switch_match(const struct fwnode_handle *fwnode, const char *id,
127 void *data)
128{
129 struct device *dev;
130
131 if (id && !fwnode_property_present(fwnode, id))
132 return NULL;
133
134 dev = class_find_device_by_fwnode(&role_class, fwnode);
135
136 return dev ? to_role_switch(dev) : ERR_PTR(-EPROBE_DEFER);
137}
138
139static struct usb_role_switch *
140usb_role_switch_is_parent(struct fwnode_handle *fwnode)
141{
142 struct fwnode_handle *parent;
143 struct device *dev;
144
145 if (!fwnode_device_is_compatible(fwnode, "usb-b-connector"))
146 return NULL;
147
148 parent = fwnode_get_parent(fwnode);
149
150 if (!fwnode_property_present(parent, "usb-role-switch")) {
151 fwnode_handle_put(parent);
152 return NULL;
153 }
154
155 dev = class_find_device_by_fwnode(&role_class, parent);
156 fwnode_handle_put(parent);
157 return dev ? to_role_switch(dev) : ERR_PTR(-EPROBE_DEFER);
158}
159
160/**
161 * usb_role_switch_get - Find USB role switch linked with the caller
162 * @dev: The caller device
163 *
164 * Finds and returns role switch linked with @dev. The reference count for the
165 * found switch is incremented.
166 */
167struct usb_role_switch *usb_role_switch_get(struct device *dev)
168{
169 struct usb_role_switch *sw;
170
171 sw = usb_role_switch_is_parent(dev_fwnode(dev));
172 if (!sw)
173 sw = device_connection_find_match(dev, "usb-role-switch", NULL,
174 usb_role_switch_match);
175
176 if (!IS_ERR_OR_NULL(sw))
177 WARN_ON(!try_module_get(sw->module));
178
179 return sw;
180}
181EXPORT_SYMBOL_GPL(usb_role_switch_get);
182
183/**
184 * fwnode_usb_role_switch_get - Find USB role switch linked with the caller
185 * @fwnode: The caller device node
186 *
187 * This is similar to the usb_role_switch_get() function above, but it searches
188 * the switch using fwnode instead of device entry.
189 */
190struct usb_role_switch *fwnode_usb_role_switch_get(struct fwnode_handle *fwnode)
191{
192 struct usb_role_switch *sw;
193
194 sw = usb_role_switch_is_parent(fwnode);
195 if (!sw)
196 sw = fwnode_connection_find_match(fwnode, "usb-role-switch",
197 NULL, usb_role_switch_match);
198 if (!IS_ERR_OR_NULL(sw))
199 WARN_ON(!try_module_get(sw->module));
200
201 return sw;
202}
203EXPORT_SYMBOL_GPL(fwnode_usb_role_switch_get);
204
205/**
206 * usb_role_switch_put - Release handle to a switch
207 * @sw: USB Role Switch
208 *
209 * Decrement reference count for @sw.
210 */
211void usb_role_switch_put(struct usb_role_switch *sw)
212{
213 if (!IS_ERR_OR_NULL(sw)) {
214 module_put(sw->module);
215 put_device(&sw->dev);
216 }
217}
218EXPORT_SYMBOL_GPL(usb_role_switch_put);
219
220/**
221 * usb_role_switch_find_by_fwnode - Find USB role switch with its fwnode
222 * @fwnode: fwnode of the USB Role Switch
223 *
224 * Finds and returns role switch with @fwnode. The reference count for the
225 * found switch is incremented.
226 */
227struct usb_role_switch *
228usb_role_switch_find_by_fwnode(const struct fwnode_handle *fwnode)
229{
230 struct device *dev;
231 struct usb_role_switch *sw = NULL;
232
233 if (!fwnode)
234 return NULL;
235
236 dev = class_find_device_by_fwnode(&role_class, fwnode);
237 if (dev) {
238 sw = to_role_switch(dev);
239 WARN_ON(!try_module_get(sw->module));
240 }
241
242 return sw;
243}
244EXPORT_SYMBOL_GPL(usb_role_switch_find_by_fwnode);
245
246static umode_t
247usb_role_switch_is_visible(struct kobject *kobj, struct attribute *attr, int n)
248{
249 struct device *dev = kobj_to_dev(kobj);
250 struct usb_role_switch *sw = to_role_switch(dev);
251
252 if (sw->allow_userspace_control)
253 return attr->mode;
254
255 return 0;
256}
257
258static const char * const usb_roles[] = {
259 [USB_ROLE_NONE] = "none",
260 [USB_ROLE_HOST] = "host",
261 [USB_ROLE_DEVICE] = "device",
262};
263
264const char *usb_role_string(enum usb_role role)
265{
266 if (role < 0 || role >= ARRAY_SIZE(usb_roles))
267 return "unknown";
268
269 return usb_roles[role];
270}
271EXPORT_SYMBOL_GPL(usb_role_string);
272
273static ssize_t
274role_show(struct device *dev, struct device_attribute *attr, char *buf)
275{
276 struct usb_role_switch *sw = to_role_switch(dev);
277 enum usb_role role = usb_role_switch_get_role(sw);
278
279 return sprintf(buf, "%s\n", usb_roles[role]);
280}
281
282static ssize_t role_store(struct device *dev, struct device_attribute *attr,
283 const char *buf, size_t size)
284{
285 struct usb_role_switch *sw = to_role_switch(dev);
286 int ret;
287
288 ret = sysfs_match_string(usb_roles, buf);
289 if (ret < 0) {
290 bool res;
291
292 /* Extra check if the user wants to disable the switch */
293 ret = kstrtobool(buf, &res);
294 if (ret || res)
295 return -EINVAL;
296 }
297
298 ret = usb_role_switch_set_role(sw, ret);
299 if (ret)
300 return ret;
301
302 return size;
303}
304static DEVICE_ATTR_RW(role);
305
306static struct attribute *usb_role_switch_attrs[] = {
307 &dev_attr_role.attr,
308 NULL,
309};
310
311static const struct attribute_group usb_role_switch_group = {
312 .is_visible = usb_role_switch_is_visible,
313 .attrs = usb_role_switch_attrs,
314};
315
316static const struct attribute_group *usb_role_switch_groups[] = {
317 &usb_role_switch_group,
318 NULL,
319};
320
321static int usb_role_switch_uevent(const struct device *dev, struct kobj_uevent_env *env)
322{
323 int ret;
324
325 ret = add_uevent_var(env, "USB_ROLE_SWITCH=%s", dev_name(dev));
326 if (ret)
327 dev_err(dev, "failed to add uevent USB_ROLE_SWITCH\n");
328
329 return ret;
330}
331
332static void usb_role_switch_release(struct device *dev)
333{
334 struct usb_role_switch *sw = to_role_switch(dev);
335
336 mutex_destroy(&sw->lock);
337 lockdep_unregister_key(&sw->key);
338 kfree(sw);
339}
340
341static const struct device_type usb_role_dev_type = {
342 .name = "usb_role_switch",
343 .groups = usb_role_switch_groups,
344 .uevent = usb_role_switch_uevent,
345 .release = usb_role_switch_release,
346};
347
348/**
349 * usb_role_switch_register - Register USB Role Switch
350 * @parent: Parent device for the switch
351 * @desc: Description of the switch
352 *
353 * USB Role Switch is a device capable or choosing the role for USB connector.
354 * On platforms where the USB controller is dual-role capable, the controller
355 * driver will need to register the switch. On platforms where the USB host and
356 * USB device controllers behind the connector are separate, there will be a
357 * mux, and the driver for that mux will need to register the switch.
358 *
359 * Returns handle to a new role switch or ERR_PTR. The content of @desc is
360 * copied.
361 */
362struct usb_role_switch *
363usb_role_switch_register(struct device *parent,
364 const struct usb_role_switch_desc *desc)
365{
366 struct usb_role_switch *sw;
367 int ret;
368
369 if (!desc || !desc->set)
370 return ERR_PTR(-EINVAL);
371
372 sw = kzalloc_obj(*sw);
373 if (!sw)
374 return ERR_PTR(-ENOMEM);
375
376 lockdep_register_key(&sw->key);
377 mutex_init_with_key(&sw->lock, &sw->key);
378
379 sw->allow_userspace_control = desc->allow_userspace_control;
380 sw->usb2_port = desc->usb2_port;
381 sw->usb3_port = desc->usb3_port;
382 sw->udc = desc->udc;
383 sw->set = desc->set;
384 sw->get = desc->get;
385
386 sw->module = parent->driver->owner;
387 sw->dev.parent = parent;
388 sw->dev.fwnode = desc->fwnode;
389 sw->dev.class = &role_class;
390 sw->dev.type = &usb_role_dev_type;
391 dev_set_drvdata(&sw->dev, desc->driver_data);
392 dev_set_name(&sw->dev, "%s-role-switch",
393 desc->name ? desc->name : dev_name(parent));
394
395 sw->registered = true;
396
397 ret = device_register(&sw->dev);
398 if (ret) {
399 sw->registered = false;
400 put_device(&sw->dev);
401 return ERR_PTR(ret);
402 }
403
404 if (dev_fwnode(&sw->dev)) {
405 ret = component_add(&sw->dev, &connector_ops);
406 if (ret)
407 dev_warn(&sw->dev, "failed to add component\n");
408 }
409
410 /* TODO: Symlinks for the host port and the device controller. */
411
412 return sw;
413}
414EXPORT_SYMBOL_GPL(usb_role_switch_register);
415
416/**
417 * usb_role_switch_unregister - Unregsiter USB Role Switch
418 * @sw: USB Role Switch
419 *
420 * Unregister switch that was registered with usb_role_switch_register().
421 */
422void usb_role_switch_unregister(struct usb_role_switch *sw)
423{
424 if (IS_ERR_OR_NULL(sw))
425 return;
426 sw->registered = false;
427 if (dev_fwnode(&sw->dev))
428 component_del(&sw->dev, &connector_ops);
429 device_unregister(&sw->dev);
430}
431EXPORT_SYMBOL_GPL(usb_role_switch_unregister);
432
433/**
434 * usb_role_switch_set_drvdata - Assign private data pointer to a switch
435 * @sw: USB Role Switch
436 * @data: Private data pointer
437 */
438void usb_role_switch_set_drvdata(struct usb_role_switch *sw, void *data)
439{
440 dev_set_drvdata(&sw->dev, data);
441}
442EXPORT_SYMBOL_GPL(usb_role_switch_set_drvdata);
443
444/**
445 * usb_role_switch_get_drvdata - Get the private data pointer of a switch
446 * @sw: USB Role Switch
447 */
448void *usb_role_switch_get_drvdata(struct usb_role_switch *sw)
449{
450 return dev_get_drvdata(&sw->dev);
451}
452EXPORT_SYMBOL_GPL(usb_role_switch_get_drvdata);
453
454static int __init usb_roles_init(void)
455{
456 return class_register(&role_class);
457}
458subsys_initcall(usb_roles_init);
459
460static void __exit usb_roles_exit(void)
461{
462 class_unregister(&role_class);
463}
464module_exit(usb_roles_exit);
465
466MODULE_AUTHOR("Heikki Krogerus <[email protected]>");
467MODULE_AUTHOR("Hans de Goede <[email protected]>");
468MODULE_LICENSE("GPL v2");
469MODULE_DESCRIPTION("USB Role Class");