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->dev.parent, role);
  52         if (!ret)
  53                 sw->role = role;
  54
  55         mutex_unlock(&sw->lock);
  56
  57         return ret;
  58 }
  59 EXPORT_SYMBOL_GPL(usb_role_switch_set_role);
  60
  61 /**
  62  * usb_role_switch_get_role - Get the USB role for a switch
  63  * @sw: USB role switch
  64  *
  65  * Depending on the role-switch-driver this function returns either a cached
  66  * value of the last set role, or reads back the actual value from the hardware.
  67  */
  68 enum usb_role usb_role_switch_get_role(struct usb_role_switch *sw)
  69 {
  70         enum usb_role role;
  71
  72         if (IS_ERR_OR_NULL(sw))
  73                 return USB_ROLE_NONE;
  74
  75         mutex_lock(&sw->lock);
  76
  77         if (sw->get)
  78                 role = sw->get(sw->dev.parent);
  79         else
  80                 role = sw->role;
  81
  82         mutex_unlock(&sw->lock);
  83
  84         return role;
  85 }
  86 EXPORT_SYMBOL_GPL(usb_role_switch_get_role);
  87
  88 static void *usb_role_switch_match(struct device_connection *con, int ep,
  89                                    void *data)
  90 {
  91         struct device *dev;
  92
  93         if (con->fwnode) {
  94                 if (con->id && !fwnode_property_present(con->fwnode, con->id))
  95                         return NULL;
  96
  97                 dev = class_find_device_by_fwnode(role_class, con->fwnode);
  98         } else {
  99                 dev = class_find_device_by_name(role_class, con->endpoint[ep]);
 100         }
 101
 102         return dev ? to_role_switch(dev) : ERR_PTR(-EPROBE_DEFER);
 103 }
 104
 105 static struct usb_role_switch *
 106 usb_role_switch_is_parent(struct fwnode_handle *fwnode)
 107 {
 108         struct fwnode_handle *parent = fwnode_get_parent(fwnode);
 109         struct device *dev;
 110
 111         if (!parent || !fwnode_property_present(parent, "usb-role-switch"))
 112                 return NULL;
 113
 114         dev = class_find_device_by_fwnode(role_class, parent);
 115         return dev ? to_role_switch(dev) : ERR_PTR(-EPROBE_DEFER);
 116 }
 117
 118 /**
 119  * usb_role_switch_get - Find USB role switch linked with the caller
 120  * @dev: The caller device
 121  *
 122  * Finds and returns role switch linked with @dev. The reference count for the
 123  * found switch is incremented.
 124  */
 125 struct usb_role_switch *usb_role_switch_get(struct device *dev)
 126 {
 127         struct usb_role_switch *sw;
 128
 129         sw = usb_role_switch_is_parent(dev_fwnode(dev));
 130         if (!sw)
 131                 sw = device_connection_find_match(dev, "usb-role-switch", NULL,
 132                                                   usb_role_switch_match);
 133
 134         if (!IS_ERR_OR_NULL(sw))
 135                 WARN_ON(!try_module_get(sw->dev.parent->driver->owner));
 136
 137         return sw;
 138 }
 139 EXPORT_SYMBOL_GPL(usb_role_switch_get);
 140
 141 /**
 142  * fwnode_usb_role_switch_get - Find USB role switch linked with the caller
 143  * @fwnode: The caller device node
 144  *
 145  * This is similar to the usb_role_switch_get() function above, but it searches
 146  * the switch using fwnode instead of device entry.
 147  */
 148 struct usb_role_switch *fwnode_usb_role_switch_get(struct fwnode_handle *fwnode)
 149 {
 150         struct usb_role_switch *sw;
 151
 152         sw = usb_role_switch_is_parent(fwnode);
 153         if (!sw)
 154                 sw = fwnode_connection_find_match(fwnode, "usb-role-switch",
 155                                                   NULL, usb_role_switch_match);
 156         if (!IS_ERR_OR_NULL(sw))
 157                 WARN_ON(!try_module_get(sw->dev.parent->driver->owner));
 158
 159         return sw;
 160 }
 161 EXPORT_SYMBOL_GPL(fwnode_usb_role_switch_get);
 162
 163 /**
 164  * usb_role_switch_put - Release handle to a switch
 165  * @sw: USB Role Switch
 166  *
 167  * Decrement reference count for @sw.
 168  */
 169 void usb_role_switch_put(struct usb_role_switch *sw)
 170 {
 171         if (!IS_ERR_OR_NULL(sw)) {
 172                 module_put(sw->dev.parent->driver->owner);
 173                 put_device(&sw->dev);
 174         }
 175 }
 176 EXPORT_SYMBOL_GPL(usb_role_switch_put);
 177
 178 /**
 179  * usb_role_switch_find_by_fwnode - Find USB role switch with its fwnode
 180  * @fwnode: fwnode of the USB Role Switch
 181  *
 182  * Finds and returns role switch with @fwnode. The reference count for the
 183  * found switch is incremented.
 184  */
 185 struct usb_role_switch *
 186 usb_role_switch_find_by_fwnode(const struct fwnode_handle *fwnode)
 187 {
 188         struct device *dev;
 189
 190         if (!fwnode)
 191                 return NULL;
 192
 193         dev = class_find_device_by_fwnode(role_class, fwnode);
 194
 195         return dev ? to_role_switch(dev) : NULL;
 196 }
 197 EXPORT_SYMBOL_GPL(usb_role_switch_find_by_fwnode);
 198
 199 static umode_t
 200 usb_role_switch_is_visible(struct kobject *kobj, struct attribute *attr, int n)
 201 {
 202         struct device *dev = container_of(kobj, typeof(*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
 211 static const char * const usb_roles[] = {
 212         [USB_ROLE_NONE]         = "none",
 213         [USB_ROLE_HOST]         = "host",
 214         [USB_ROLE_DEVICE]       = "device",
 215 };
 216
 217 static ssize_t
 218 role_show(struct device *dev, struct device_attribute *attr, char *buf)
 219 {
 220         struct usb_role_switch *sw = to_role_switch(dev);
 221         enum usb_role role = usb_role_switch_get_role(sw);
 222
 223         return sprintf(buf, "%s\n", usb_roles[role]);
 224 }
 225
 226 static ssize_t role_store(struct device *dev, struct device_attribute *attr,
 227                           const char *buf, size_t size)
 228 {
 229         struct usb_role_switch *sw = to_role_switch(dev);
 230         int ret;
 231
 232         ret = sysfs_match_string(usb_roles, buf);
 233         if (ret < 0) {
 234                 bool res;
 235
 236                 /* Extra check if the user wants to disable the switch */
 237                 ret = kstrtobool(buf, &res);
 238                 if (ret || res)
 239                         return -EINVAL;
 240         }
 241
 242         ret = usb_role_switch_set_role(sw, ret);
 243         if (ret)
 244                 return ret;
 245
 246         return size;
 247 }
 248 static DEVICE_ATTR_RW(role);
 249
 250 static struct attribute *usb_role_switch_attrs[] = {
 251         &dev_attr_role.attr,
 252         NULL,
 253 };
 254
 255 static const struct attribute_group usb_role_switch_group = {
 256         .is_visible = usb_role_switch_is_visible,
 257         .attrs = usb_role_switch_attrs,
 258 };
 259
 260 static const struct attribute_group *usb_role_switch_groups[] = {
 261         &usb_role_switch_group,
 262         NULL,
 263 };
 264
 265 static int
 266 usb_role_switch_uevent(struct device *dev, struct kobj_uevent_env *env)
 267 {
 268         int ret;
 269
 270         ret = add_uevent_var(env, "USB_ROLE_SWITCH=%s", dev_name(dev));
 271         if (ret)
 272                 dev_err(dev, "failed to add uevent USB_ROLE_SWITCH\n");
 273
 274         return ret;
 275 }
 276
 277 static void usb_role_switch_release(struct device *dev)
 278 {
 279         struct usb_role_switch *sw = to_role_switch(dev);
 280
 281         kfree(sw);
 282 }
 283
 284 static const struct device_type usb_role_dev_type = {
 285         .name = "usb_role_switch",
 286         .groups = usb_role_switch_groups,
 287         .uevent = usb_role_switch_uevent,
 288         .release = usb_role_switch_release,
 289 };
 290
 291 /**
 292  * usb_role_switch_register - Register USB Role Switch
 293  * @parent: Parent device for the switch
 294  * @desc: Description of the switch
 295  *
 296  * USB Role Switch is a device capable or choosing the role for USB connector.
 297  * On platforms where the USB controller is dual-role capable, the controller
 298  * driver will need to register the switch. On platforms where the USB host and
 299  * USB device controllers behind the connector are separate, there will be a
 300  * mux, and the driver for that mux will need to register the switch.
 301  *
 302  * Returns handle to a new role switch or ERR_PTR. The content of @desc is
 303  * copied.
 304  */
 305 struct usb_role_switch *
 306 usb_role_switch_register(struct device *parent,
 307                          const struct usb_role_switch_desc *desc)
 308 {
 309         struct usb_role_switch *sw;
 310         int ret;
 311
 312         if (!desc || !desc->set)
 313                 return ERR_PTR(-EINVAL);
 314
 315         sw = kzalloc(sizeof(*sw), GFP_KERNEL);
 316         if (!sw)
 317                 return ERR_PTR(-ENOMEM);
 318
 319         mutex_init(&sw->lock);
 320
 321         sw->allow_userspace_control = desc->allow_userspace_control;
 322         sw->usb2_port = desc->usb2_port;
 323         sw->usb3_port = desc->usb3_port;
 324         sw->udc = desc->udc;
 325         sw->set = desc->set;
 326         sw->get = desc->get;
 327
 328         sw->dev.parent = parent;
 329         sw->dev.fwnode = desc->fwnode;
 330         sw->dev.class = role_class;
 331         sw->dev.type = &usb_role_dev_type;
 332         dev_set_name(&sw->dev, "%s-role-switch", 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 static int __init usb_roles_init(void)
 360 {
 361         role_class = class_create(THIS_MODULE, "usb_role");
 362         return PTR_ERR_OR_ZERO(role_class);
 363 }
 364 subsys_initcall(usb_roles_init);
 365
 366 static void __exit usb_roles_exit(void)
 367 {
 368         class_destroy(role_class);
 369 }
 370 module_exit(usb_roles_exit);
 371
 372 MODULE_AUTHOR("Heikki Krogerus <heikki.krogerus@linux.intel.com>");
 373 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
 374 MODULE_LICENSE("GPL v2");
 375 MODULE_DESCRIPTION("USB Role Class");