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
 17struct 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
 24struct 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 */
 41static 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
 58static 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 */
 71static 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
 84static 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
 94static 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
114static struct attribute *ports_attrs[] = {
115	NULL,
116};
117static const struct attribute_group ports_group = {
118	.name = "ports",
119	.attrs = ports_attrs,
120};
121
122/***************************************
123 * Adding & removing ports
124 ***************************************/
125
126static 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
167err_free_port_name:
168	kfree(port->port_name);
169err_free_port:
170	kfree(port);
171err_out:
172	return err;
173}
174
175static 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
188static 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
200static 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
215static 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
242static 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
267err_free:
268	kfree(usbport_data);
269}
270
271static 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
292static struct led_trigger usbport_led_trigger = {
293	.name     = "usbport",
294	.activate = usbport_trig_activate,
295	.deactivate = usbport_trig_deactivate,
296};
297
298static int __init usbport_trig_init(void)
299{
300	return led_trigger_register(&usbport_led_trigger);
301}
302
303static void __exit usbport_trig_exit(void)
304{
305	led_trigger_unregister(&usbport_led_trigger);
306}
307
308module_init(usbport_trig_init);
309module_exit(usbport_trig_exit);
310
311MODULE_AUTHOR("Rafał Miłecki <rafal@milecki.pl>");
312MODULE_DESCRIPTION("USB port trigger");
313MODULE_LICENSE("GPL v2");