/drivers/switch/switch_class.c

  1/*
  2 *  drivers/switch/switch_class.c
  3 *
  4 * Copyright (C) 2008 Google, Inc.
  5 * Copyright (C) 2012 - NVIDIA, Inc.
  6 * Author: Mike Lockwood <lockwood@android.com>
  7 *
  8 * This software is licensed under the terms of the GNU General Public
  9 * License version 2, as published by the Free Software Foundation, and
 10 * may be copied, distributed, and modified under those terms.
 11 *
 12 * This program is distributed in the hope that it will be useful,
 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 15 * GNU General Public License for more details.
 16 *
 17*/
 18
 19#include <linux/module.h>
 20#include <linux/types.h>
 21#include <linux/init.h>
 22#include <linux/device.h>
 23#include <linux/fs.h>
 24#include <linux/err.h>
 25#include <linux/switch.h>
 26
 27struct class *switch_class;
 28static atomic_t device_count;
 29
 30static ssize_t state_show(struct device *dev, struct device_attribute *attr,
 31		char *buf)
 32{
 33	struct switch_dev *sdev = (struct switch_dev *)
 34		dev_get_drvdata(dev);
 35
 36	if (sdev->print_state) {
 37		int ret = sdev->print_state(sdev, buf);
 38		if (ret >= 0)
 39			return ret;
 40	}
 41	return sprintf(buf, "%d\n", sdev->state);
 42}
 43
 44static ssize_t name_show(struct device *dev, struct device_attribute *attr,
 45		char *buf)
 46{
 47	struct switch_dev *sdev = (struct switch_dev *)
 48		dev_get_drvdata(dev);
 49
 50	if (sdev->print_name) {
 51		int ret = sdev->print_name(sdev, buf);
 52		if (ret >= 0)
 53			return ret;
 54	}
 55	return sprintf(buf, "%s\n", sdev->name);
 56}
 57
 58static DEVICE_ATTR(state, S_IRUGO | S_IWUSR, state_show, NULL);
 59static DEVICE_ATTR(name, S_IRUGO | S_IWUSR, name_show, NULL);
 60
 61void switch_set_state(struct switch_dev *sdev, int state)
 62{
 63	char name_buf[120];
 64	char state_buf[120];
 65	char *prop_buf;
 66	char *envp[3];
 67	int env_offset = 0;
 68	int length;
 69
 70	if (sdev->state != state) {
 71		sdev->state = state;
 72
 73		prop_buf = (char *)get_zeroed_page(GFP_KERNEL);
 74		if (prop_buf) {
 75			length = name_show(sdev->dev, NULL, prop_buf);
 76			if (length > 0) {
 77				if (prop_buf[length - 1] == '\n')
 78					prop_buf[length - 1] = 0;
 79				snprintf(name_buf, sizeof(name_buf),
 80					"SWITCH_NAME=%s", prop_buf);
 81				envp[env_offset++] = name_buf;
 82			}
 83			length = state_show(sdev->dev, NULL, prop_buf);
 84			if (length > 0) {
 85				if (prop_buf[length - 1] == '\n')
 86					prop_buf[length - 1] = 0;
 87				snprintf(state_buf, sizeof(state_buf),
 88					"SWITCH_STATE=%s", prop_buf);
 89				envp[env_offset++] = state_buf;
 90			}
 91			envp[env_offset] = NULL;
 92			kobject_uevent_env(&sdev->dev->kobj, KOBJ_CHANGE, envp);
 93			free_page((unsigned long)prop_buf);
 94		} else {
 95			printk(KERN_ERR "out of memory in switch_set_state\n");
 96			kobject_uevent(&sdev->dev->kobj, KOBJ_CHANGE);
 97		}
 98	}
 99}
100EXPORT_SYMBOL_GPL(switch_set_state);
101
102static int create_switch_class(void)
103{
104	if (!switch_class) {
105		switch_class = class_create(THIS_MODULE, "switch");
106		if (IS_ERR(switch_class))
107			return PTR_ERR(switch_class);
108		atomic_set(&device_count, 0);
109	}
110
111	return 0;
112}
113
114int switch_dev_register(struct switch_dev *sdev)
115{
116	int ret;
117
118	if (!switch_class) {
119		ret = create_switch_class();
120		if (ret < 0)
121			return ret;
122	}
123
124	sdev->index = atomic_inc_return(&device_count);
125	sdev->dev = device_create(switch_class, NULL,
126		MKDEV(0, sdev->index), NULL, sdev->name);
127	if (IS_ERR(sdev->dev))
128		return PTR_ERR(sdev->dev);
129
130	ret = device_create_file(sdev->dev, &dev_attr_state);
131	if (ret < 0)
132		goto err_create_file_1;
133	ret = device_create_file(sdev->dev, &dev_attr_name);
134	if (ret < 0)
135		goto err_create_file_2;
136
137	dev_set_drvdata(sdev->dev, sdev);
138	sdev->state = 0;
139	return 0;
140
141err_create_file_2:
142	device_remove_file(sdev->dev, &dev_attr_state);
143err_create_file_1:
144	device_destroy(switch_class, MKDEV(0, sdev->index));
145	printk(KERN_ERR "switch: Failed to register driver %s\n", sdev->name);
146
147	return ret;
148}
149EXPORT_SYMBOL_GPL(switch_dev_register);
150
151void switch_dev_unregister(struct switch_dev *sdev)
152{
153	device_remove_file(sdev->dev, &dev_attr_name);
154	device_remove_file(sdev->dev, &dev_attr_state);
155	dev_set_drvdata(sdev->dev, NULL);
156	device_destroy(switch_class, MKDEV(0, sdev->index));
157}
158EXPORT_SYMBOL_GPL(switch_dev_unregister);
159
160static int __init switch_class_init(void)
161{
162	return create_switch_class();
163}
164
165static void __exit switch_class_exit(void)
166{
167	class_destroy(switch_class);
168}
169
170module_init(switch_class_init);
171module_exit(switch_class_exit);
172
173MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
174MODULE_DESCRIPTION("Switch class driver");
175MODULE_LICENSE("GPL");