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