drivers/usb/roles/class.c

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This source file includes following definitions.
usb_role_switch_set_role
usb_role_switch_get_role
usb_role_switch_match
usb_role_switch_is_parent
usb_role_switch_get
fwnode_usb_role_switch_get
usb_role_switch_put
usb_role_switch_is_visible
role_show
role_store
usb_role_switch_uevent
usb_role_switch_release
usb_role_switch_register
usb_role_switch_unregister
usb_roles_init
usb_roles_exit
   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 static umode_t
 179 usb_role_switch_is_visible(struct kobject *kobj, struct attribute *attr, int n)
 180 {
 181         struct device *dev = container_of(kobj, typeof(*dev), kobj);
 182         struct usb_role_switch *sw = to_role_switch(dev);
 183 
 184         if (sw->allow_userspace_control)
 185                 return attr->mode;
 186 
 187         return 0;
 188 }
 189 
 190 static const char * const usb_roles[] = {
 191         [USB_ROLE_NONE]         = "none",
 192         [USB_ROLE_HOST]         = "host",
 193         [USB_ROLE_DEVICE]       = "device",
 194 };
 195 
 196 static ssize_t
 197 role_show(struct device *dev, struct device_attribute *attr, char *buf)
 198 {
 199         struct usb_role_switch *sw = to_role_switch(dev);
 200         enum usb_role role = usb_role_switch_get_role(sw);
 201 
 202         return sprintf(buf, "%s\n", usb_roles[role]);
 203 }
 204 
 205 static ssize_t role_store(struct device *dev, struct device_attribute *attr,
 206                           const char *buf, size_t size)
 207 {
 208         struct usb_role_switch *sw = to_role_switch(dev);
 209         int ret;
 210 
 211         ret = sysfs_match_string(usb_roles, buf);
 212         if (ret < 0) {
 213                 bool res;
 214 
 215                 /* Extra check if the user wants to disable the switch */
 216                 ret = kstrtobool(buf, &res);
 217                 if (ret || res)
 218                         return -EINVAL;
 219         }
 220 
 221         ret = usb_role_switch_set_role(sw, ret);
 222         if (ret)
 223                 return ret;
 224 
 225         return size;
 226 }
 227 static DEVICE_ATTR_RW(role);
 228 
 229 static struct attribute *usb_role_switch_attrs[] = {
 230         &dev_attr_role.attr,
 231         NULL,
 232 };
 233 
 234 static const struct attribute_group usb_role_switch_group = {
 235         .is_visible = usb_role_switch_is_visible,
 236         .attrs = usb_role_switch_attrs,
 237 };
 238 
 239 static const struct attribute_group *usb_role_switch_groups[] = {
 240         &usb_role_switch_group,
 241         NULL,
 242 };
 243 
 244 static int
 245 usb_role_switch_uevent(struct device *dev, struct kobj_uevent_env *env)
 246 {
 247         int ret;
 248 
 249         ret = add_uevent_var(env, "USB_ROLE_SWITCH=%s", dev_name(dev));
 250         if (ret)
 251                 dev_err(dev, "failed to add uevent USB_ROLE_SWITCH\n");
 252 
 253         return ret;
 254 }
 255 
 256 static void usb_role_switch_release(struct device *dev)
 257 {
 258         struct usb_role_switch *sw = to_role_switch(dev);
 259 
 260         kfree(sw);
 261 }
 262 
 263 static const struct device_type usb_role_dev_type = {
 264         .name = "usb_role_switch",
 265         .groups = usb_role_switch_groups,
 266         .uevent = usb_role_switch_uevent,
 267         .release = usb_role_switch_release,
 268 };
 269 
 270 /**
 271  * usb_role_switch_register - Register USB Role Switch
 272  * @parent: Parent device for the switch
 273  * @desc: Description of the switch
 274  *
 275  * USB Role Switch is a device capable or choosing the role for USB connector.
 276  * On platforms where the USB controller is dual-role capable, the controller
 277  * driver will need to register the switch. On platforms where the USB host and
 278  * USB device controllers behind the connector are separate, there will be a
 279  * mux, and the driver for that mux will need to register the switch.
 280  *
 281  * Returns handle to a new role switch or ERR_PTR. The content of @desc is
 282  * copied.
 283  */
 284 struct usb_role_switch *
 285 usb_role_switch_register(struct device *parent,
 286                          const struct usb_role_switch_desc *desc)
 287 {
 288         struct usb_role_switch *sw;
 289         int ret;
 290 
 291         if (!desc || !desc->set)
 292                 return ERR_PTR(-EINVAL);
 293 
 294         sw = kzalloc(sizeof(*sw), GFP_KERNEL);
 295         if (!sw)
 296                 return ERR_PTR(-ENOMEM);
 297 
 298         mutex_init(&sw->lock);
 299 
 300         sw->allow_userspace_control = desc->allow_userspace_control;
 301         sw->usb2_port = desc->usb2_port;
 302         sw->usb3_port = desc->usb3_port;
 303         sw->udc = desc->udc;
 304         sw->set = desc->set;
 305         sw->get = desc->get;
 306 
 307         sw->dev.parent = parent;
 308         sw->dev.fwnode = desc->fwnode;
 309         sw->dev.class = role_class;
 310         sw->dev.type = &usb_role_dev_type;
 311         dev_set_name(&sw->dev, "%s-role-switch", dev_name(parent));
 312 
 313         ret = device_register(&sw->dev);
 314         if (ret) {
 315                 put_device(&sw->dev);
 316                 return ERR_PTR(ret);
 317         }
 318 
 319         /* TODO: Symlinks for the host port and the device controller. */
 320 
 321         return sw;
 322 }
 323 EXPORT_SYMBOL_GPL(usb_role_switch_register);
 324 
 325 /**
 326  * usb_role_switch_unregister - Unregsiter USB Role Switch
 327  * @sw: USB Role Switch
 328  *
 329  * Unregister switch that was registered with usb_role_switch_register().
 330  */
 331 void usb_role_switch_unregister(struct usb_role_switch *sw)
 332 {
 333         if (!IS_ERR_OR_NULL(sw))
 334                 device_unregister(&sw->dev);
 335 }
 336 EXPORT_SYMBOL_GPL(usb_role_switch_unregister);
 337 
 338 static int __init usb_roles_init(void)
 339 {
 340         role_class = class_create(THIS_MODULE, "usb_role");
 341         return PTR_ERR_OR_ZERO(role_class);
 342 }
 343 subsys_initcall(usb_roles_init);
 344 
 345 static void __exit usb_roles_exit(void)
 346 {
 347         class_destroy(role_class);
 348 }
 349 module_exit(usb_roles_exit);
 350 
 351 MODULE_AUTHOR("Heikki Krogerus <heikki.krogerus@linux.intel.com>");
 352 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
 353 MODULE_LICENSE("GPL v2");
 354 MODULE_DESCRIPTION("USB Role Class");
/* [<][>][^][v][top][bottom][index][help] */
root/drivers/usb/roles/class.c

DEFINITIONS
