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
31static DEFINE_MUTEX(compass_mutex);
32
33static int compass_command(struct i2c_client *c, u8 cmd)
34{
35	int ret = i2c_master_send(c, &cmd, 1);
36	if (ret < 0)
37		dev_warn(&c->dev, "command '%c' failed.\n", cmd);
38	return ret;
39}
40
41static int compass_store(struct device *dev, const char *buf, size_t count,
42			const char *map)
43{
44	struct i2c_client *c = to_i2c_client(dev);
45	int ret;
46	unsigned long val;
47
48	ret = kstrtoul(buf, 10, &val);
49	if (ret)
50		return ret;
51	if (val >= strlen(map))
52		return -EINVAL;
53	mutex_lock(&compass_mutex);
54	ret = compass_command(c, map[val]);
55	mutex_unlock(&compass_mutex);
56	if (ret < 0)
57		return ret;
58	return count;
59}
60
61static ssize_t compass_calibration_store(struct device *dev,
62		struct device_attribute *attr, const char *buf, size_t count)
63{
64	return compass_store(dev, buf, count, "EC");
65}
66
67static ssize_t compass_power_mode_store(struct device *dev,
68		struct device_attribute *attr, const  char *buf, size_t count)
69{
70	return compass_store(dev, buf, count, "SW");
71}
72
73static ssize_t compass_heading_data_show(struct device *dev,
74			struct device_attribute *attr, char *buf)
75{
76	struct i2c_client *client = to_i2c_client(dev);
77	unsigned char i2c_data[2];
78	int ret;
79
80	mutex_lock(&compass_mutex);
81	ret = compass_command(client, 'A');
82	if (ret != 1) {
83		mutex_unlock(&compass_mutex);
84		return ret;
85	}
86	msleep(10); /* sending 'A' cmd we need to wait for 7-10 millisecs */
87	ret = i2c_master_recv(client, i2c_data, 2);
88	mutex_unlock(&compass_mutex);
89	if (ret < 0) {
90		dev_warn(dev, "i2c read data cmd failed\n");
91		return ret;
92	}
93	ret = (i2c_data[0] << 8) | i2c_data[1];
94	return sprintf(buf, "%d.%d\n", ret/10, ret%10);
95}
96
97
98static DEVICE_ATTR(heading0_input, S_IRUGO, compass_heading_data_show, NULL);
99static DEVICE_ATTR(calibration, S_IWUSR, NULL, compass_calibration_store);
100static DEVICE_ATTR(power_state, S_IWUSR, NULL, compass_power_mode_store);
101
102static struct attribute *mid_att_compass[] = {
103	&dev_attr_heading0_input.attr,
104	&dev_attr_calibration.attr,
105	&dev_attr_power_state.attr,
106	NULL
107};
108
109static const struct attribute_group m_compass_gr = {
110	.name = "hmc6352",
111	.attrs = mid_att_compass
112};
113
114static int hmc6352_probe(struct i2c_client *client,
115					const struct i2c_device_id *id)
116{
117	int res;
118
119	res = sysfs_create_group(&client->dev.kobj, &m_compass_gr);
120	if (res) {
121		dev_err(&client->dev, "device_create_file failed\n");
122		return res;
123	}
124	dev_info(&client->dev, "%s HMC6352 compass chip found\n",
125							client->name);
126	return 0;
127}
128
129static int hmc6352_remove(struct i2c_client *client)
130{
131	sysfs_remove_group(&client->dev.kobj, &m_compass_gr);
132	return 0;
133}
134
135static struct i2c_device_id hmc6352_id[] = {
136	{ "hmc6352", 0 },
137	{ }
138};
139
140MODULE_DEVICE_TABLE(i2c, hmc6352_id);
141
142static struct i2c_driver hmc6352_driver = {
143	.driver = {
144		.name = "hmc6352",
145	},
146	.probe = hmc6352_probe,
147	.remove = hmc6352_remove,
148	.id_table = hmc6352_id,
149};
150
151module_i2c_driver(hmc6352_driver);
152
153MODULE_AUTHOR("Kalhan Trisal <kalhan.trisal@intel.com");
154MODULE_DESCRIPTION("hmc6352 Compass Driver");
155MODULE_LICENSE("GPL v2");
156