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 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
 103 static struct usb_role_switch *
 104 usb_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  */
 123 struct 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 }
 137 EXPORT_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  */
 146 struct 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 }
 159 EXPORT_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  */
 167 void 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 }
 174 EXPORT_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  */
 183 struct usb_role_switch *
 184 usb_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
 193         return dev ? to_role_switch(dev) : NULL;
 194 }
 195 EXPORT_SYMBOL_GPL(usb_role_switch_find_by_fwnode);
 196
 197 static umode_t
 198 usb_role_switch_is_visible(struct kobject *kobj, struct attribute *attr, int n)
 199 {
 200         struct device *dev = kobj_to_dev(kobj);
 201         struct usb_role_switch *sw = to_role_switch(dev);
 202
 203         if (sw->allow_userspace_control)
 204                 return attr->mode;
 205
 206         return 0;
 207 }
 208
 209 static const char * const usb_roles[] = {
 210         [USB_ROLE_NONE]         = "none",
 211         [USB_ROLE_HOST]         = "host",
 212         [USB_ROLE_DEVICE]       = "device",
 213 };
 214
 215 static ssize_t
 216 role_show(struct device *dev, struct device_attribute *attr, char *buf)
 217 {
 218         struct usb_role_switch *sw = to_role_switch(dev);
 219         enum usb_role role = usb_role_switch_get_role(sw);
 220
 221         return sprintf(buf, "%s\n", usb_roles[role]);
 222 }
 223
 224 static ssize_t role_store(struct device *dev, struct device_attribute *attr,
 225                           const char *buf, size_t size)
 226 {
 227         struct usb_role_switch *sw = to_role_switch(dev);
 228         int ret;
 229
 230         ret = sysfs_match_string(usb_roles, buf);
 231         if (ret < 0) {
 232                 bool res;
 233
 234                 /* Extra check if the user wants to disable the switch */
 235                 ret = kstrtobool(buf, &res);
 236                 if (ret || res)
 237                         return -EINVAL;
 238         }
 239
 240         ret = usb_role_switch_set_role(sw, ret);
 241         if (ret)
 242                 return ret;
 243
 244         return size;
 245 }
 246 static DEVICE_ATTR_RW(role);
 247
 248 static struct attribute *usb_role_switch_attrs[] = {
 249         &dev_attr_role.attr,
 250         NULL,
 251 };
 252
 253 static const struct attribute_group usb_role_switch_group = {
 254         .is_visible = usb_role_switch_is_visible,
 255         .attrs = usb_role_switch_attrs,
 256 };
 257
 258 static const struct attribute_group *usb_role_switch_groups[] = {
 259         &usb_role_switch_group,
 260         NULL,
 261 };
 262
 263 static int
 264 usb_role_switch_uevent(struct device *dev, struct kobj_uevent_env *env)
 265 {
 266         int ret;
 267
 268         ret = add_uevent_var(env, "USB_ROLE_SWITCH=%s", dev_name(dev));
 269         if (ret)
 270                 dev_err(dev, "failed to add uevent USB_ROLE_SWITCH\n");
 271
 272         return ret;
 273 }
 274
 275 static void usb_role_switch_release(struct device *dev)
 276 {
 277         struct usb_role_switch *sw = to_role_switch(dev);
 278
 279         kfree(sw);
 280 }
 281
 282 static const struct device_type usb_role_dev_type = {
 283         .name = "usb_role_switch",
 284         .groups = usb_role_switch_groups,
 285         .uevent = usb_role_switch_uevent,
 286         .release = usb_role_switch_release,
 287 };
 288
 289 /**
 290  * usb_role_switch_register - Register USB Role Switch
 291  * @parent: Parent device for the switch
 292  * @desc: Description of the switch
 293  *
 294  * USB Role Switch is a device capable or choosing the role for USB connector.
 295  * On platforms where the USB controller is dual-role capable, the controller
 296  * driver will need to register the switch. On platforms where the USB host and
 297  * USB device controllers behind the connector are separate, there will be a
 298  * mux, and the driver for that mux will need to register the switch.
 299  *
 300  * Returns handle to a new role switch or ERR_PTR. The content of @desc is
 301  * copied.
 302  */
 303 struct usb_role_switch *
 304 usb_role_switch_register(struct device *parent,
 305                          const struct usb_role_switch_desc *desc)
 306 {
 307         struct usb_role_switch *sw;
 308         int ret;
 309
 310         if (!desc || !desc->set)
 311                 return ERR_PTR(-EINVAL);
 312
 313         sw = kzalloc(sizeof(*sw), GFP_KERNEL);
 314         if (!sw)
 315                 return ERR_PTR(-ENOMEM);
 316
 317         mutex_init(&sw->lock);
 318
 319         sw->allow_userspace_control = desc->allow_userspace_control;
 320         sw->usb2_port = desc->usb2_port;
 321         sw->usb3_port = desc->usb3_port;
 322         sw->udc = desc->udc;
 323         sw->set = desc->set;
 324         sw->get = desc->get;
 325
 326         sw->dev.parent = parent;
 327         sw->dev.fwnode = desc->fwnode;
 328         sw->dev.class = role_class;
 329         sw->dev.type = &usb_role_dev_type;
 330         dev_set_drvdata(&sw->dev, desc->driver_data);
 331         dev_set_name(&sw->dev, "%s-role-switch",
 332                      desc->name ? desc->name : dev_name(parent));
 333
 334         ret = device_register(&sw->dev);
 335         if (ret) {
 336                 put_device(&sw->dev);
 337                 return ERR_PTR(ret);
 338         }
 339
 340         /* TODO: Symlinks for the host port and the device controller. */
 341
 342         return sw;
 343 }
 344 EXPORT_SYMBOL_GPL(usb_role_switch_register);
 345
 346 /**
 347  * usb_role_switch_unregister - Unregsiter USB Role Switch
 348  * @sw: USB Role Switch
 349  *
 350  * Unregister switch that was registered with usb_role_switch_register().
 351  */
 352 void usb_role_switch_unregister(struct usb_role_switch *sw)
 353 {
 354         if (!IS_ERR_OR_NULL(sw))
 355                 device_unregister(&sw->dev);
 356 }
 357 EXPORT_SYMBOL_GPL(usb_role_switch_unregister);
 358
 359 /**
 360  * usb_role_switch_set_drvdata - Assign private data pointer to a switch
 361  * @sw: USB Role Switch
 362  * @data: Private data pointer
 363  */
 364 void usb_role_switch_set_drvdata(struct usb_role_switch *sw, void *data)
 365 {
 366         dev_set_drvdata(&sw->dev, data);
 367 }
 368 EXPORT_SYMBOL_GPL(usb_role_switch_set_drvdata);
 369
 370 /**
 371  * usb_role_switch_get_drvdata - Get the private data pointer of a switch
 372  * @sw: USB Role Switch
 373  */
 374 void *usb_role_switch_get_drvdata(struct usb_role_switch *sw)
 375 {
 376         return dev_get_drvdata(&sw->dev);
 377 }
 378 EXPORT_SYMBOL_GPL(usb_role_switch_get_drvdata);
 379
 380 static int __init usb_roles_init(void)
 381 {
 382         role_class = class_create(THIS_MODULE, "usb_role");
 383         return PTR_ERR_OR_ZERO(role_class);
 384 }
 385 subsys_initcall(usb_roles_init);
 386
 387 static void __exit usb_roles_exit(void)
 388 {
 389         class_destroy(role_class);
 390 }
 391 module_exit(usb_roles_exit);
 392
 393 MODULE_AUTHOR("Heikki Krogerus <heikki.krogerus@linux.intel.com>");
 394 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
 395 MODULE_LICENSE("GPL v2");
 396 MODULE_DESCRIPTION("USB Role Class");