1 /*
2  * hmc6352.c - Honeywell Compass Driver
3  *
4  * Copyright (C) 2009 Intel Corp
5  *
6  *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License as published by
10  * the Free Software Foundation; version 2 of the License.
11  *
12  * This program is distributed in the hope that it will be useful, but
13  * WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License along
18  * with this program; if not, write to the Free Software Foundation, Inc.,
19  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
20  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
21  *
22  */
23 
24 #include <linux/module.h>
25 #include <linux/slab.h>
26 #include <linux/i2c.h>
27 #include <linux/err.h>
28 #include <linux/delay.h>
29 #include <linux/sysfs.h>
30 #include <linux/nospec.h>
31 
32 static DEFINE_MUTEX(compass_mutex);
33 
compass_command(struct i2c_client * c,u8 cmd)34 static int compass_command(struct i2c_client *c, u8 cmd)
35 {
36 	int ret = i2c_master_send(c, &cmd, 1);
37 	if (ret < 0)
38 		dev_warn(&c->dev, "command '%c' failed.\n", cmd);
39 	return ret;
40 }
41 
compass_store(struct device * dev,const char * buf,size_t count,const char * map)42 static int compass_store(struct device *dev, const char *buf, size_t count,
43 			const char *map)
44 {
45 	struct i2c_client *c = to_i2c_client(dev);
46 	int ret;
47 	unsigned long val;
48 
49 	ret = kstrtoul(buf, 10, &val);
50 	if (ret)
51 		return ret;
52 	if (val >= strlen(map))
53 		return -EINVAL;
54 	val = array_index_nospec(val, strlen(map));
55 	mutex_lock(&compass_mutex);
56 	ret = compass_command(c, map[val]);
57 	mutex_unlock(&compass_mutex);
58 	if (ret < 0)
59 		return ret;
60 	return count;
61 }
62 
compass_calibration_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)63 static ssize_t compass_calibration_store(struct device *dev,
64 		struct device_attribute *attr, const char *buf, size_t count)
65 {
66 	return compass_store(dev, buf, count, "EC");
67 }
68 
compass_power_mode_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)69 static ssize_t compass_power_mode_store(struct device *dev,
70 		struct device_attribute *attr, const  char *buf, size_t count)
71 {
72 	return compass_store(dev, buf, count, "SW");
73 }
74 
compass_heading_data_show(struct device * dev,struct device_attribute * attr,char * buf)75 static ssize_t compass_heading_data_show(struct device *dev,
76 			struct device_attribute *attr, char *buf)
77 {
78 	struct i2c_client *client = to_i2c_client(dev);
79 	unsigned char i2c_data[2];
80 	int ret;
81 
82 	mutex_lock(&compass_mutex);
83 	ret = compass_command(client, 'A');
84 	if (ret != 1) {
85 		mutex_unlock(&compass_mutex);
86 		return ret;
87 	}
88 	msleep(10); /* sending 'A' cmd we need to wait for 7-10 millisecs */
89 	ret = i2c_master_recv(client, i2c_data, 2);
90 	mutex_unlock(&compass_mutex);
91 	if (ret < 0) {
92 		dev_warn(dev, "i2c read data cmd failed\n");
93 		return ret;
94 	}
95 	ret = (i2c_data[0] << 8) | i2c_data[1];
96 	return sprintf(buf, "%d.%d\n", ret/10, ret%10);
97 }
98 
99 
100 static DEVICE_ATTR(heading0_input, S_IRUGO, compass_heading_data_show, NULL);
101 static DEVICE_ATTR(calibration, S_IWUSR, NULL, compass_calibration_store);
102 static DEVICE_ATTR(power_state, S_IWUSR, NULL, compass_power_mode_store);
103 
104 static struct attribute *mid_att_compass[] = {
105 	&dev_attr_heading0_input.attr,
106 	&dev_attr_calibration.attr,
107 	&dev_attr_power_state.attr,
108 	NULL
109 };
110 
111 static const struct attribute_group m_compass_gr = {
112 	.name = "hmc6352",
113 	.attrs = mid_att_compass
114 };
115 
hmc6352_probe(struct i2c_client * client,const struct i2c_device_id * id)116 static int hmc6352_probe(struct i2c_client *client,
117 					const struct i2c_device_id *id)
118 {
119 	int res;
120 
121 	res = sysfs_create_group(&client->dev.kobj, &m_compass_gr);
122 	if (res) {
123 		dev_err(&client->dev, "device_create_file failed\n");
124 		return res;
125 	}
126 	dev_info(&client->dev, "%s HMC6352 compass chip found\n",
127 							client->name);
128 	return 0;
129 }
130 
hmc6352_remove(struct i2c_client * client)131 static int hmc6352_remove(struct i2c_client *client)
132 {
133 	sysfs_remove_group(&client->dev.kobj, &m_compass_gr);
134 	return 0;
135 }
136 
137 static const struct i2c_device_id hmc6352_id[] = {
138 	{ "hmc6352", 0 },
139 	{ }
140 };
141 
142 MODULE_DEVICE_TABLE(i2c, hmc6352_id);
143 
144 static struct i2c_driver hmc6352_driver = {
145 	.driver = {
146 		.name = "hmc6352",
147 	},
148 	.probe = hmc6352_probe,
149 	.remove = hmc6352_remove,
150 	.id_table = hmc6352_id,
151 };
152 
153 module_i2c_driver(hmc6352_driver);
154 
155 MODULE_AUTHOR("Kalhan Trisal <kalhan.trisal@intel.com");
156 MODULE_DESCRIPTION("hmc6352 Compass Driver");
157 MODULE_LICENSE("GPL v2");
158