Linux preempt-rt

Check our new training course

Real-Time Linux with PREEMPT_RT

Check our new training course
with Creative Commons CC-BY-SA
lecture and lab materials

Bootlin logo

Elixir Cross Referencer

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
// SPDX-License-Identifier: GPL-2.0
/*
 * USB Role Switch Support
 *
 * Copyright (C) 2018 Intel Corporation
 * Author: Heikki Krogerus <heikki.krogerus@linux.intel.com>
 *         Hans de Goede <hdegoede@redhat.com>
 */

#include <linux/usb/role.h>
#include <linux/property.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>

static struct class *role_class;

struct usb_role_switch {
	struct device dev;
	struct mutex lock; /* device lock*/
	enum usb_role role;

	/* From descriptor */
	struct device *usb2_port;
	struct device *usb3_port;
	struct device *udc;
	usb_role_switch_set_t set;
	usb_role_switch_get_t get;
	bool allow_userspace_control;
};

#define to_role_switch(d)	container_of(d, struct usb_role_switch, dev)

/**
 * usb_role_switch_set_role - Set USB role for a switch
 * @sw: USB role switch
 * @role: USB role to be switched to
 *
 * Set USB role @role for @sw.
 */
int usb_role_switch_set_role(struct usb_role_switch *sw, enum usb_role role)
{
	int ret;

	if (IS_ERR_OR_NULL(sw))
		return 0;

	mutex_lock(&sw->lock);

	ret = sw->set(sw, role);
	if (!ret) {
		sw->role = role;
		kobject_uevent(&sw->dev.kobj, KOBJ_CHANGE);
	}

	mutex_unlock(&sw->lock);

	return ret;
}
EXPORT_SYMBOL_GPL(usb_role_switch_set_role);

/**
 * usb_role_switch_get_role - Get the USB role for a switch
 * @sw: USB role switch
 *
 * Depending on the role-switch-driver this function returns either a cached
 * value of the last set role, or reads back the actual value from the hardware.
 */
enum usb_role usb_role_switch_get_role(struct usb_role_switch *sw)
{
	enum usb_role role;

	if (IS_ERR_OR_NULL(sw))
		return USB_ROLE_NONE;

	mutex_lock(&sw->lock);

	if (sw->get)
		role = sw->get(sw);
	else
		role = sw->role;

	mutex_unlock(&sw->lock);

	return role;
}
EXPORT_SYMBOL_GPL(usb_role_switch_get_role);

static void *usb_role_switch_match(struct fwnode_handle *fwnode, const char *id,
				   void *data)
{
	struct device *dev;

	if (id && !fwnode_property_present(fwnode, id))
		return NULL;

	dev = class_find_device_by_fwnode(role_class, fwnode);

	return dev ? to_role_switch(dev) : ERR_PTR(-EPROBE_DEFER);
}

static struct usb_role_switch *
usb_role_switch_is_parent(struct fwnode_handle *fwnode)
{
	struct fwnode_handle *parent = fwnode_get_parent(fwnode);
	struct device *dev;

	if (!parent || !fwnode_property_present(parent, "usb-role-switch"))
		return NULL;

	dev = class_find_device_by_fwnode(role_class, parent);
	return dev ? to_role_switch(dev) : ERR_PTR(-EPROBE_DEFER);
}

/**
 * usb_role_switch_get - Find USB role switch linked with the caller
 * @dev: The caller device
 *
 * Finds and returns role switch linked with @dev. The reference count for the
 * found switch is incremented.
 */
struct usb_role_switch *usb_role_switch_get(struct device *dev)
{
	struct usb_role_switch *sw;

	sw = usb_role_switch_is_parent(dev_fwnode(dev));
	if (!sw)
		sw = device_connection_find_match(dev, "usb-role-switch", NULL,
						  usb_role_switch_match);

	if (!IS_ERR_OR_NULL(sw))
		WARN_ON(!try_module_get(sw->dev.parent->driver->owner));

	return sw;
}
EXPORT_SYMBOL_GPL(usb_role_switch_get);

/**
 * fwnode_usb_role_switch_get - Find USB role switch linked with the caller
 * @fwnode: The caller device node
 *
 * This is similar to the usb_role_switch_get() function above, but it searches
 * the switch using fwnode instead of device entry.
 */
struct usb_role_switch *fwnode_usb_role_switch_get(struct fwnode_handle *fwnode)
{
	struct usb_role_switch *sw;

	sw = usb_role_switch_is_parent(fwnode);
	if (!sw)
		sw = fwnode_connection_find_match(fwnode, "usb-role-switch",
						  NULL, usb_role_switch_match);
	if (!IS_ERR_OR_NULL(sw))
		WARN_ON(!try_module_get(sw->dev.parent->driver->owner));

	return sw;
}
EXPORT_SYMBOL_GPL(fwnode_usb_role_switch_get);

/**
 * usb_role_switch_put - Release handle to a switch
 * @sw: USB Role Switch
 *
 * Decrement reference count for @sw.
 */
void usb_role_switch_put(struct usb_role_switch *sw)
{
	if (!IS_ERR_OR_NULL(sw)) {
		module_put(sw->dev.parent->driver->owner);
		put_device(&sw->dev);
	}
}
EXPORT_SYMBOL_GPL(usb_role_switch_put);

/**
 * usb_role_switch_find_by_fwnode - Find USB role switch with its fwnode
 * @fwnode: fwnode of the USB Role Switch
 *
 * Finds and returns role switch with @fwnode. The reference count for the
 * found switch is incremented.
 */
struct usb_role_switch *
usb_role_switch_find_by_fwnode(const struct fwnode_handle *fwnode)
{
	struct device *dev;

	if (!fwnode)
		return NULL;

	dev = class_find_device_by_fwnode(role_class, fwnode);
	if (dev)
		WARN_ON(!try_module_get(dev->parent->driver->owner));

	return dev ? to_role_switch(dev) : NULL;
}
EXPORT_SYMBOL_GPL(usb_role_switch_find_by_fwnode);

static umode_t
usb_role_switch_is_visible(struct kobject *kobj, struct attribute *attr, int n)
{
	struct device *dev = kobj_to_dev(kobj);
	struct usb_role_switch *sw = to_role_switch(dev);

	if (sw->allow_userspace_control)
		return attr->mode;

	return 0;
}

static const char * const usb_roles[] = {
	[USB_ROLE_NONE]		= "none",
	[USB_ROLE_HOST]		= "host",
	[USB_ROLE_DEVICE]	= "device",
};

const char *usb_role_string(enum usb_role role)
{
	if (role < 0 || role >= ARRAY_SIZE(usb_roles))
		return "unknown";

	return usb_roles[role];
}
EXPORT_SYMBOL_GPL(usb_role_string);

static ssize_t
role_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct usb_role_switch *sw = to_role_switch(dev);
	enum usb_role role = usb_role_switch_get_role(sw);

	return sprintf(buf, "%s\n", usb_roles[role]);
}

static ssize_t role_store(struct device *dev, struct device_attribute *attr,
			  const char *buf, size_t size)
{
	struct usb_role_switch *sw = to_role_switch(dev);
	int ret;

	ret = sysfs_match_string(usb_roles, buf);
	if (ret < 0) {
		bool res;

		/* Extra check if the user wants to disable the switch */
		ret = kstrtobool(buf, &res);
		if (ret || res)
			return -EINVAL;
	}

	ret = usb_role_switch_set_role(sw, ret);
	if (ret)
		return ret;

	return size;
}
static DEVICE_ATTR_RW(role);

static struct attribute *usb_role_switch_attrs[] = {
	&dev_attr_role.attr,
	NULL,
};

static const struct attribute_group usb_role_switch_group = {
	.is_visible = usb_role_switch_is_visible,
	.attrs = usb_role_switch_attrs,
};

static const struct attribute_group *usb_role_switch_groups[] = {
	&usb_role_switch_group,
	NULL,
};

static int
usb_role_switch_uevent(struct device *dev, struct kobj_uevent_env *env)
{
	int ret;

	ret = add_uevent_var(env, "USB_ROLE_SWITCH=%s", dev_name(dev));
	if (ret)
		dev_err(dev, "failed to add uevent USB_ROLE_SWITCH\n");

	return ret;
}

static void usb_role_switch_release(struct device *dev)
{
	struct usb_role_switch *sw = to_role_switch(dev);

	kfree(sw);
}

static const struct device_type usb_role_dev_type = {
	.name = "usb_role_switch",
	.groups = usb_role_switch_groups,
	.uevent = usb_role_switch_uevent,
	.release = usb_role_switch_release,
};

/**
 * usb_role_switch_register - Register USB Role Switch
 * @parent: Parent device for the switch
 * @desc: Description of the switch
 *
 * USB Role Switch is a device capable or choosing the role for USB connector.
 * On platforms where the USB controller is dual-role capable, the controller
 * driver will need to register the switch. On platforms where the USB host and
 * USB device controllers behind the connector are separate, there will be a
 * mux, and the driver for that mux will need to register the switch.
 *
 * Returns handle to a new role switch or ERR_PTR. The content of @desc is
 * copied.
 */
struct usb_role_switch *
usb_role_switch_register(struct device *parent,
			 const struct usb_role_switch_desc *desc)
{
	struct usb_role_switch *sw;
	int ret;

	if (!desc || !desc->set)
		return ERR_PTR(-EINVAL);

	sw = kzalloc(sizeof(*sw), GFP_KERNEL);
	if (!sw)
		return ERR_PTR(-ENOMEM);

	mutex_init(&sw->lock);

	sw->allow_userspace_control = desc->allow_userspace_control;
	sw->usb2_port = desc->usb2_port;
	sw->usb3_port = desc->usb3_port;
	sw->udc = desc->udc;
	sw->set = desc->set;
	sw->get = desc->get;

	sw->dev.parent = parent;
	sw->dev.fwnode = desc->fwnode;
	sw->dev.class = role_class;
	sw->dev.type = &usb_role_dev_type;
	dev_set_drvdata(&sw->dev, desc->driver_data);
	dev_set_name(&sw->dev, "%s-role-switch",
		     desc->name ? desc->name : dev_name(parent));

	ret = device_register(&sw->dev);
	if (ret) {
		put_device(&sw->dev);
		return ERR_PTR(ret);
	}

	/* TODO: Symlinks for the host port and the device controller. */

	return sw;
}
EXPORT_SYMBOL_GPL(usb_role_switch_register);

/**
 * usb_role_switch_unregister - Unregsiter USB Role Switch
 * @sw: USB Role Switch
 *
 * Unregister switch that was registered with usb_role_switch_register().
 */
void usb_role_switch_unregister(struct usb_role_switch *sw)
{
	if (!IS_ERR_OR_NULL(sw))
		device_unregister(&sw->dev);
}
EXPORT_SYMBOL_GPL(usb_role_switch_unregister);

/**
 * usb_role_switch_set_drvdata - Assign private data pointer to a switch
 * @sw: USB Role Switch
 * @data: Private data pointer
 */
void usb_role_switch_set_drvdata(struct usb_role_switch *sw, void *data)
{
	dev_set_drvdata(&sw->dev, data);
}
EXPORT_SYMBOL_GPL(usb_role_switch_set_drvdata);

/**
 * usb_role_switch_get_drvdata - Get the private data pointer of a switch
 * @sw: USB Role Switch
 */
void *usb_role_switch_get_drvdata(struct usb_role_switch *sw)
{
	return dev_get_drvdata(&sw->dev);
}
EXPORT_SYMBOL_GPL(usb_role_switch_get_drvdata);

static int __init usb_roles_init(void)
{
	role_class = class_create(THIS_MODULE, "usb_role");
	return PTR_ERR_OR_ZERO(role_class);
}
subsys_initcall(usb_roles_init);

static void __exit usb_roles_exit(void)
{
	class_destroy(role_class);
}
module_exit(usb_roles_exit);

MODULE_AUTHOR("Heikki Krogerus <heikki.krogerus@linux.intel.com>");
MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("USB Role Class");