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