hmc6352.c
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/*
* hmc6352.c - Honeywell Compass Driver
*
* Copyright (C) 2009 Intel Corp
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/err.h>
#include <linux/delay.h>
#include <linux/sysfs.h>
static DEFINE_MUTEX(compass_mutex);
static int compass_command(struct i2c_client *c, u8 cmd)
{
int ret = i2c_master_send(c, &cmd, 1);
if (ret < 0)
dev_warn(&c->dev, "command '%c' failed.\n", cmd);
return ret;
}
static int compass_store(struct device *dev, const char *buf, size_t count,
const char *map)
{
struct i2c_client *c = to_i2c_client(dev);
int ret;
unsigned long val;
ret = kstrtoul(buf, 10, &val);
if (ret)
return ret;
if (val >= strlen(map))
return -EINVAL;
mutex_lock(&compass_mutex);
ret = compass_command(c, map[val]);
mutex_unlock(&compass_mutex);
if (ret < 0)
return ret;
return count;
}
static ssize_t compass_calibration_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
return compass_store(dev, buf, count, "EC");
}
static ssize_t compass_power_mode_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
return compass_store(dev, buf, count, "SW");
}
static ssize_t compass_heading_data_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct i2c_client *client = to_i2c_client(dev);
unsigned char i2c_data[2];
int ret;
mutex_lock(&compass_mutex);
ret = compass_command(client, 'A');
if (ret != 1) {
mutex_unlock(&compass_mutex);
return ret;
}
msleep(10); /* sending 'A' cmd we need to wait for 7-10 millisecs */
ret = i2c_master_recv(client, i2c_data, 2);
mutex_unlock(&compass_mutex);
if (ret < 0) {
dev_warn(dev, "i2c read data cmd failed\n");
return ret;
}
ret = (i2c_data[0] << 8) | i2c_data[1];
return sprintf(buf, "%d.%d\n", ret/10, ret%10);
}
static DEVICE_ATTR(heading0_input, S_IRUGO, compass_heading_data_show, NULL);
static DEVICE_ATTR(calibration, S_IWUSR, NULL, compass_calibration_store);
static DEVICE_ATTR(power_state, S_IWUSR, NULL, compass_power_mode_store);
static struct attribute *mid_att_compass[] = {
&dev_attr_heading0_input.attr,
&dev_attr_calibration.attr,
&dev_attr_power_state.attr,
NULL
};
static const struct attribute_group m_compass_gr = {
.name = "hmc6352",
.attrs = mid_att_compass
};
static int hmc6352_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
int res;
res = sysfs_create_group(&client->dev.kobj, &m_compass_gr);
if (res) {
dev_err(&client->dev, "device_create_file failed\n");
return res;
}
dev_info(&client->dev, "%s HMC6352 compass chip found\n",
client->name);
return 0;
}
static int hmc6352_remove(struct i2c_client *client)
{
sysfs_remove_group(&client->dev.kobj, &m_compass_gr);
return 0;
}
static struct i2c_device_id hmc6352_id[] = {
{ "hmc6352", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, hmc6352_id);
static struct i2c_driver hmc6352_driver = {
.driver = {
.name = "hmc6352",
},
.probe = hmc6352_probe,
.remove = hmc6352_remove,
.id_table = hmc6352_id,
};
module_i2c_driver(hmc6352_driver);
MODULE_AUTHOR("Kalhan Trisal <kalhan.trisal@intel.com");
MODULE_DESCRIPTION("hmc6352 Compass Driver");
MODULE_LICENSE("GPL v2");