drivers/usb/core/ledtrig-usbport.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * USB port LED trigger
   4  *
   5  * Copyright (C) 2016 Rafał Miłecki <rafal@milecki.pl>
   6  */
   7
   8 #include <linux/device.h>
   9 #include <linux/leds.h>
  10 #include <linux/module.h>
  11 #include <linux/of.h>
  12 #include <linux/slab.h>
  13 #include <linux/usb.h>
  14 #include <linux/usb/of.h>
  15
  16 struct usbport_trig_data {
  17         struct led_classdev *led_cdev;
  18         struct list_head ports;
  19         struct notifier_block nb;
  20         int count; /* Amount of connected matching devices */
  21 };
  22
  23 struct usbport_trig_port {
  24         struct usbport_trig_data *data;
  25         struct usb_device *hub;
  26         int portnum;
  27         char *port_name;
  28         bool observed;
  29         struct device_attribute attr;
  30         struct list_head list;
  31 };
  32
  33 /***************************************
  34  * Helpers
  35  ***************************************/
  36
  37 /**
  38  * usbport_trig_usb_dev_observed - Check if dev is connected to observed port
  39  */
  40 static bool usbport_trig_usb_dev_observed(struct usbport_trig_data *usbport_data,
  41                                           struct usb_device *usb_dev)
  42 {
  43         struct usbport_trig_port *port;
  44
  45         if (!usb_dev->parent)
  46                 return false;
  47
  48         list_for_each_entry(port, &usbport_data->ports, list) {
  49                 if (usb_dev->parent == port->hub &&
  50                     usb_dev->portnum == port->portnum)
  51                         return port->observed;
  52         }
  53
  54         return false;
  55 }
  56
  57 static int usbport_trig_usb_dev_check(struct usb_device *usb_dev, void *data)
  58 {
  59         struct usbport_trig_data *usbport_data = data;
  60
  61         if (usbport_trig_usb_dev_observed(usbport_data, usb_dev))
  62                 usbport_data->count++;
  63
  64         return 0;
  65 }
  66
  67 /**
  68  * usbport_trig_update_count - Recalculate amount of connected matching devices
  69  */
  70 static void usbport_trig_update_count(struct usbport_trig_data *usbport_data)
  71 {
  72         struct led_classdev *led_cdev = usbport_data->led_cdev;
  73
  74         usbport_data->count = 0;
  75         usb_for_each_dev(usbport_data, usbport_trig_usb_dev_check);
  76         led_set_brightness(led_cdev, usbport_data->count ? LED_FULL : LED_OFF);
  77 }
  78
  79 /***************************************
  80  * Device attr
  81  ***************************************/
  82
  83 static ssize_t usbport_trig_port_show(struct device *dev,
  84                                       struct device_attribute *attr, char *buf)
  85 {
  86         struct usbport_trig_port *port = container_of(attr,
  87                                                       struct usbport_trig_port,
  88                                                       attr);
  89
  90         return sprintf(buf, "%d\n", port->observed) + 1;
  91 }
  92
  93 static ssize_t usbport_trig_port_store(struct device *dev,
  94                                        struct device_attribute *attr,
  95                                        const char *buf, size_t size)
  96 {
  97         struct usbport_trig_port *port = container_of(attr,
  98                                                       struct usbport_trig_port,
  99                                                       attr);
 100
 101         if (!strcmp(buf, "0") || !strcmp(buf, "0\n"))
 102                 port->observed = 0;
 103         else if (!strcmp(buf, "1") || !strcmp(buf, "1\n"))
 104                 port->observed = 1;
 105         else
 106                 return -EINVAL;
 107
 108         usbport_trig_update_count(port->data);
 109
 110         return size;
 111 }
 112
 113 static struct attribute *ports_attrs[] = {
 114         NULL,
 115 };
 116
 117 static const struct attribute_group ports_group = {
 118         .name = "ports",
 119         .attrs = ports_attrs,
 120 };
 121
 122 /***************************************
 123  * Adding & removing ports
 124  ***************************************/
 125
 126 /**
 127  * usbport_trig_port_observed - Check if port should be observed
 128  */
 129 static bool usbport_trig_port_observed(struct usbport_trig_data *usbport_data,
 130                                        struct usb_device *usb_dev, int port1)
 131 {
 132         struct device *dev = usbport_data->led_cdev->dev;
 133         struct device_node *led_np = dev->of_node;
 134         struct of_phandle_args args;
 135         struct device_node *port_np;
 136         int count, i;
 137
 138         if (!led_np)
 139                 return false;
 140
 141         /*
 142          * Get node of port being added
 143          *
 144          * FIXME: This is really the device node of the connected device
 145          */
 146         port_np = usb_of_get_device_node(usb_dev, port1);
 147         if (!port_np)
 148                 return false;
 149
 150         of_node_put(port_np);
 151
 152         /* Amount of trigger sources for this LED */
 153         count = of_count_phandle_with_args(led_np, "trigger-sources",
 154                                            "#trigger-source-cells");
 155         if (count < 0) {
 156                 dev_warn(dev, "Failed to get trigger sources for %pOF\n",
 157                          led_np);
 158                 return false;
 159         }
 160
 161         /* Check list of sources for this specific port */
 162         for (i = 0; i < count; i++) {
 163                 int err;
 164
 165                 err = of_parse_phandle_with_args(led_np, "trigger-sources",
 166                                                  "#trigger-source-cells", i,
 167                                                  &args);
 168                 if (err) {
 169                         dev_err(dev, "Failed to get trigger source phandle at index %d: %d\n",
 170                                 i, err);
 171                         continue;
 172                 }
 173
 174                 of_node_put(args.np);
 175
 176                 if (args.np == port_np)
 177                         return true;
 178         }
 179
 180         return false;
 181 }
 182
 183 static int usbport_trig_add_port(struct usbport_trig_data *usbport_data,
 184                                  struct usb_device *usb_dev,
 185                                  const char *hub_name, int portnum)
 186 {
 187         struct led_classdev *led_cdev = usbport_data->led_cdev;
 188         struct usbport_trig_port *port;
 189         size_t len;
 190         int err;
 191
 192         port = kzalloc(sizeof(*port), GFP_KERNEL);
 193         if (!port) {
 194                 err = -ENOMEM;
 195                 goto err_out;
 196         }
 197
 198         port->data = usbport_data;
 199         port->hub = usb_dev;
 200         port->portnum = portnum;
 201         port->observed = usbport_trig_port_observed(usbport_data, usb_dev,
 202                                                     portnum);
 203
 204         len = strlen(hub_name) + 8;
 205         port->port_name = kzalloc(len, GFP_KERNEL);
 206         if (!port->port_name) {
 207                 err = -ENOMEM;
 208                 goto err_free_port;
 209         }
 210         snprintf(port->port_name, len, "%s-port%d", hub_name, portnum);
 211
 212         sysfs_attr_init(&port->attr.attr);
 213         port->attr.attr.name = port->port_name;
 214         port->attr.attr.mode = S_IRUSR | S_IWUSR;
 215         port->attr.show = usbport_trig_port_show;
 216         port->attr.store = usbport_trig_port_store;
 217
 218         err = sysfs_add_file_to_group(&led_cdev->dev->kobj, &port->attr.attr,
 219                                       ports_group.name);
 220         if (err)
 221                 goto err_free_port_name;
 222
 223         list_add_tail(&port->list, &usbport_data->ports);
 224
 225         return 0;
 226
 227 err_free_port_name:
 228         kfree(port->port_name);
 229 err_free_port:
 230         kfree(port);
 231 err_out:
 232         return err;
 233 }
 234
 235 static int usbport_trig_add_usb_dev_ports(struct usb_device *usb_dev,
 236                                           void *data)
 237 {
 238         struct usbport_trig_data *usbport_data = data;
 239         int i;
 240
 241         for (i = 1; i <= usb_dev->maxchild; i++)
 242                 usbport_trig_add_port(usbport_data, usb_dev,
 243                                       dev_name(&usb_dev->dev), i);
 244
 245         return 0;
 246 }
 247
 248 static void usbport_trig_remove_port(struct usbport_trig_data *usbport_data,
 249                                      struct usbport_trig_port *port)
 250 {
 251         struct led_classdev *led_cdev = usbport_data->led_cdev;
 252
 253         list_del(&port->list);
 254         sysfs_remove_file_from_group(&led_cdev->dev->kobj, &port->attr.attr,
 255                                      ports_group.name);
 256         kfree(port->port_name);
 257         kfree(port);
 258 }
 259
 260 static void usbport_trig_remove_usb_dev_ports(struct usbport_trig_data *usbport_data,
 261                                               struct usb_device *usb_dev)
 262 {
 263         struct usbport_trig_port *port, *tmp;
 264
 265         list_for_each_entry_safe(port, tmp, &usbport_data->ports, list) {
 266                 if (port->hub == usb_dev)
 267                         usbport_trig_remove_port(usbport_data, port);
 268         }
 269 }
 270
 271 /***************************************
 272  * Init, exit, etc.
 273  ***************************************/
 274
 275 static int usbport_trig_notify(struct notifier_block *nb, unsigned long action,
 276                                void *data)
 277 {
 278         struct usbport_trig_data *usbport_data =
 279                 container_of(nb, struct usbport_trig_data, nb);
 280         struct led_classdev *led_cdev = usbport_data->led_cdev;
 281         struct usb_device *usb_dev = data;
 282         bool observed;
 283
 284         observed = usbport_trig_usb_dev_observed(usbport_data, usb_dev);
 285
 286         switch (action) {
 287         case USB_DEVICE_ADD:
 288                 usbport_trig_add_usb_dev_ports(usb_dev, usbport_data);
 289                 if (observed && usbport_data->count++ == 0)
 290                         led_set_brightness(led_cdev, LED_FULL);
 291                 return NOTIFY_OK;
 292         case USB_DEVICE_REMOVE:
 293                 usbport_trig_remove_usb_dev_ports(usbport_data, usb_dev);
 294                 if (observed && --usbport_data->count == 0)
 295                         led_set_brightness(led_cdev, LED_OFF);
 296                 return NOTIFY_OK;
 297         }
 298
 299         return NOTIFY_DONE;
 300 }
 301
 302 static int usbport_trig_activate(struct led_classdev *led_cdev)
 303 {
 304         struct usbport_trig_data *usbport_data;
 305         int err;
 306
 307         usbport_data = kzalloc(sizeof(*usbport_data), GFP_KERNEL);
 308         if (!usbport_data)
 309                 return -ENOMEM;
 310         usbport_data->led_cdev = led_cdev;
 311
 312         /* List of ports */
 313         INIT_LIST_HEAD(&usbport_data->ports);
 314         err = sysfs_create_group(&led_cdev->dev->kobj, &ports_group);
 315         if (err)
 316                 goto err_free;
 317         usb_for_each_dev(usbport_data, usbport_trig_add_usb_dev_ports);
 318         usbport_trig_update_count(usbport_data);
 319
 320         /* Notifications */
 321         usbport_data->nb.notifier_call = usbport_trig_notify;
 322         led_set_trigger_data(led_cdev, usbport_data);
 323         usb_register_notify(&usbport_data->nb);
 324         return 0;
 325
 326 err_free:
 327         kfree(usbport_data);
 328         return err;
 329 }
 330
 331 static void usbport_trig_deactivate(struct led_classdev *led_cdev)
 332 {
 333         struct usbport_trig_data *usbport_data = led_get_trigger_data(led_cdev);
 334         struct usbport_trig_port *port, *tmp;
 335
 336         list_for_each_entry_safe(port, tmp, &usbport_data->ports, list) {
 337                 usbport_trig_remove_port(usbport_data, port);
 338         }
 339
 340         sysfs_remove_group(&led_cdev->dev->kobj, &ports_group);
 341
 342         usb_unregister_notify(&usbport_data->nb);
 343
 344         kfree(usbport_data);
 345 }
 346
 347 static struct led_trigger usbport_led_trigger = {
 348         .name     = "usbport",
 349         .activate = usbport_trig_activate,
 350         .deactivate = usbport_trig_deactivate,
 351 };
 352
 353 static int __init usbport_trig_init(void)
 354 {
 355         return led_trigger_register(&usbport_led_trigger);
 356 }
 357
 358 static void __exit usbport_trig_exit(void)
 359 {
 360         led_trigger_unregister(&usbport_led_trigger);
 361 }
 362
 363 module_init(usbport_trig_init);
 364 module_exit(usbport_trig_exit);
 365
 366 MODULE_AUTHOR("Rafał Miłecki <rafal@milecki.pl>");
 367 MODULE_DESCRIPTION("USB port trigger");
 368 MODULE_LICENSE("GPL v2");