drivers/usb/core/ledtrig-usbport.c

   1 /*
   2  * USB port LED trigger
   3  *
   4  * Copyright (C) 2016 Rafał Miłecki <rafal@milecki.pl>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/device.h>
  12 #include <linux/leds.h>
  13 #include <linux/module.h>
  14 #include <linux/slab.h>
  15 #include <linux/usb.h>
  16
  17 struct usbport_trig_data {
  18         struct led_classdev *led_cdev;
  19         struct list_head ports;
  20         struct notifier_block nb;
  21         int count; /* Amount of connected matching devices */
  22 };
  23
  24 struct usbport_trig_port {
  25         struct usbport_trig_data *data;
  26         struct usb_device *hub;
  27         int portnum;
  28         char *port_name;
  29         bool observed;
  30         struct device_attribute attr;
  31         struct list_head list;
  32 };
  33
  34 /***************************************
  35  * Helpers
  36  ***************************************/
  37
  38 /**
  39  * usbport_trig_usb_dev_observed - Check if dev is connected to observed port
  40  */
  41 static bool usbport_trig_usb_dev_observed(struct usbport_trig_data *usbport_data,
  42                                           struct usb_device *usb_dev)
  43 {
  44         struct usbport_trig_port *port;
  45
  46         if (!usb_dev->parent)
  47                 return false;
  48
  49         list_for_each_entry(port, &usbport_data->ports, list) {
  50                 if (usb_dev->parent == port->hub &&
  51                     usb_dev->portnum == port->portnum)
  52                         return port->observed;
  53         }
  54
  55         return false;
  56 }
  57
  58 static int usbport_trig_usb_dev_check(struct usb_device *usb_dev, void *data)
  59 {
  60         struct usbport_trig_data *usbport_data = data;
  61
  62         if (usbport_trig_usb_dev_observed(usbport_data, usb_dev))
  63                 usbport_data->count++;
  64
  65         return 0;
  66 }
  67
  68 /**
  69  * usbport_trig_update_count - Recalculate amount of connected matching devices
  70  */
  71 static void usbport_trig_update_count(struct usbport_trig_data *usbport_data)
  72 {
  73         struct led_classdev *led_cdev = usbport_data->led_cdev;
  74
  75         usbport_data->count = 0;
  76         usb_for_each_dev(usbport_data, usbport_trig_usb_dev_check);
  77         led_set_brightness(led_cdev, usbport_data->count ? LED_FULL : LED_OFF);
  78 }
  79
  80 /***************************************
  81  * Device attr
  82  ***************************************/
  83
  84 static ssize_t usbport_trig_port_show(struct device *dev,
  85                                       struct device_attribute *attr, char *buf)
  86 {
  87         struct usbport_trig_port *port = container_of(attr,
  88                                                       struct usbport_trig_port,
  89                                                       attr);
  90
  91         return sprintf(buf, "%d\n", port->observed) + 1;
  92 }
  93
  94 static ssize_t usbport_trig_port_store(struct device *dev,
  95                                        struct device_attribute *attr,
  96                                        const char *buf, size_t size)
  97 {
  98         struct usbport_trig_port *port = container_of(attr,
  99                                                       struct usbport_trig_port,
 100                                                       attr);
 101
 102         if (!strcmp(buf, "0") || !strcmp(buf, "0\n"))
 103                 port->observed = 0;
 104         else if (!strcmp(buf, "1") || !strcmp(buf, "1\n"))
 105                 port->observed = 1;
 106         else
 107                 return -EINVAL;
 108
 109         usbport_trig_update_count(port->data);
 110
 111         return size;
 112 }
 113
 114 static struct attribute *ports_attrs[] = {
 115         NULL,
 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 static int usbport_trig_add_port(struct usbport_trig_data *usbport_data,
 127                                  struct usb_device *usb_dev,
 128                                  const char *hub_name, int portnum)
 129 {
 130         struct led_classdev *led_cdev = usbport_data->led_cdev;
 131         struct usbport_trig_port *port;
 132         size_t len;
 133         int err;
 134
 135         port = kzalloc(sizeof(*port), GFP_KERNEL);
 136         if (!port) {
 137                 err = -ENOMEM;
 138                 goto err_out;
 139         }
 140
 141         port->data = usbport_data;
 142         port->hub = usb_dev;
 143         port->portnum = portnum;
 144
 145         len = strlen(hub_name) + 8;
 146         port->port_name = kzalloc(len, GFP_KERNEL);
 147         if (!port->port_name) {
 148                 err = -ENOMEM;
 149                 goto err_free_port;
 150         }
 151         snprintf(port->port_name, len, "%s-port%d", hub_name, portnum);
 152
 153         port->attr.attr.name = port->port_name;
 154         port->attr.attr.mode = S_IRUSR | S_IWUSR;
 155         port->attr.show = usbport_trig_port_show;
 156         port->attr.store = usbport_trig_port_store;
 157
 158         err = sysfs_add_file_to_group(&led_cdev->dev->kobj, &port->attr.attr,
 159                                       ports_group.name);
 160         if (err)
 161                 goto err_free_port_name;
 162
 163         list_add_tail(&port->list, &usbport_data->ports);
 164
 165         return 0;
 166
 167 err_free_port_name:
 168         kfree(port->port_name);
 169 err_free_port:
 170         kfree(port);
 171 err_out:
 172         return err;
 173 }
 174
 175 static int usbport_trig_add_usb_dev_ports(struct usb_device *usb_dev,
 176                                           void *data)
 177 {
 178         struct usbport_trig_data *usbport_data = data;
 179         int i;
 180
 181         for (i = 1; i <= usb_dev->maxchild; i++)
 182                 usbport_trig_add_port(usbport_data, usb_dev,
 183                                       dev_name(&usb_dev->dev), i);
 184
 185         return 0;
 186 }
 187
 188 static void usbport_trig_remove_port(struct usbport_trig_data *usbport_data,
 189                                      struct usbport_trig_port *port)
 190 {
 191         struct led_classdev *led_cdev = usbport_data->led_cdev;
 192
 193         list_del(&port->list);
 194         sysfs_remove_file_from_group(&led_cdev->dev->kobj, &port->attr.attr,
 195                                      ports_group.name);
 196         kfree(port->port_name);
 197         kfree(port);
 198 }
 199
 200 static void usbport_trig_remove_usb_dev_ports(struct usbport_trig_data *usbport_data,
 201                                               struct usb_device *usb_dev)
 202 {
 203         struct usbport_trig_port *port, *tmp;
 204
 205         list_for_each_entry_safe(port, tmp, &usbport_data->ports, list) {
 206                 if (port->hub == usb_dev)
 207                         usbport_trig_remove_port(usbport_data, port);
 208         }
 209 }
 210
 211 /***************************************
 212  * Init, exit, etc.
 213  ***************************************/
 214
 215 static int usbport_trig_notify(struct notifier_block *nb, unsigned long action,
 216                                void *data)
 217 {
 218         struct usbport_trig_data *usbport_data =
 219                 container_of(nb, struct usbport_trig_data, nb);
 220         struct led_classdev *led_cdev = usbport_data->led_cdev;
 221         struct usb_device *usb_dev = data;
 222         bool observed;
 223
 224         observed = usbport_trig_usb_dev_observed(usbport_data, usb_dev);
 225
 226         switch (action) {
 227         case USB_DEVICE_ADD:
 228                 usbport_trig_add_usb_dev_ports(usb_dev, usbport_data);
 229                 if (observed && usbport_data->count++ == 0)
 230                         led_set_brightness(led_cdev, LED_FULL);
 231                 return NOTIFY_OK;
 232         case USB_DEVICE_REMOVE:
 233                 usbport_trig_remove_usb_dev_ports(usbport_data, usb_dev);
 234                 if (observed && --usbport_data->count == 0)
 235                         led_set_brightness(led_cdev, LED_OFF);
 236                 return NOTIFY_OK;
 237         }
 238
 239         return NOTIFY_DONE;
 240 }
 241
 242 static void usbport_trig_activate(struct led_classdev *led_cdev)
 243 {
 244         struct usbport_trig_data *usbport_data;
 245         int err;
 246
 247         usbport_data = kzalloc(sizeof(*usbport_data), GFP_KERNEL);
 248         if (!usbport_data)
 249                 return;
 250         usbport_data->led_cdev = led_cdev;
 251
 252         /* List of ports */
 253         INIT_LIST_HEAD(&usbport_data->ports);
 254         err = sysfs_create_group(&led_cdev->dev->kobj, &ports_group);
 255         if (err)
 256                 goto err_free;
 257         usb_for_each_dev(usbport_data, usbport_trig_add_usb_dev_ports);
 258
 259         /* Notifications */
 260         usbport_data->nb.notifier_call = usbport_trig_notify,
 261         led_cdev->trigger_data = usbport_data;
 262         usb_register_notify(&usbport_data->nb);
 263
 264         led_cdev->activated = true;
 265         return;
 266
 267 err_free:
 268         kfree(usbport_data);
 269 }
 270
 271 static void usbport_trig_deactivate(struct led_classdev *led_cdev)
 272 {
 273         struct usbport_trig_data *usbport_data = led_cdev->trigger_data;
 274         struct usbport_trig_port *port, *tmp;
 275
 276         if (!led_cdev->activated)
 277                 return;
 278
 279         list_for_each_entry_safe(port, tmp, &usbport_data->ports, list) {
 280                 usbport_trig_remove_port(usbport_data, port);
 281         }
 282
 283         usb_unregister_notify(&usbport_data->nb);
 284
 285         sysfs_remove_group(&led_cdev->dev->kobj, &ports_group);
 286
 287         kfree(usbport_data);
 288
 289         led_cdev->activated = false;
 290 }
 291
 292 static struct led_trigger usbport_led_trigger = {
 293         .name     = "usbport",
 294         .activate = usbport_trig_activate,
 295         .deactivate = usbport_trig_deactivate,
 296 };
 297
 298 static int __init usbport_trig_init(void)
 299 {
 300         return led_trigger_register(&usbport_led_trigger);
 301 }
 302
 303 static void __exit usbport_trig_exit(void)
 304 {
 305         led_trigger_unregister(&usbport_led_trigger);
 306 }
 307
 308 module_init(usbport_trig_init);
 309 module_exit(usbport_trig_exit);
 310
 311 MODULE_AUTHOR("Rafał Miłecki <rafal@milecki.pl>");
 312 MODULE_DESCRIPTION("USB port trigger");
 313 MODULE_LICENSE("GPL v2");