drivers/usb/roles/class.c

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