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