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+/*
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+ * hmc6352.c - Honeywell Compass Driver
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+ *
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+ * Copyright (C) 2009 Intel Corp
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+ *
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+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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+ *
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+ * This program is free software; you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License as published by
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+ * the Free Software Foundation; version 2 of the License.
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+ *
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+ * This program is distributed in the hope that it will be useful, but
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+ * WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ * General Public License for more details.
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+ *
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+ * You should have received a copy of the GNU General Public License along
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+ * with this program; if not, write to the Free Software Foundation, Inc.,
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+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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+ *
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+ */
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+
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+#include <linux/module.h>
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+#include <linux/init.h>
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+#include <linux/slab.h>
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+#include <linux/i2c.h>
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+#include <linux/err.h>
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+#include <linux/delay.h>
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+#include <linux/sysfs.h>
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+
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+static DEFINE_MUTEX(compass_mutex);
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+
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+static int compass_command(struct i2c_client *c, u8 cmd)
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+{
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+ int ret = i2c_master_send(c, &cmd, 1);
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+ if (ret < 0)
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+ dev_warn(&c->dev, "command '%c' failed.\n", cmd);
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+ return ret;
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+}
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+
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+static int compass_store(struct device *dev, const char *buf, size_t count,
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+ const char *map)
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+{
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+ struct i2c_client *c = to_i2c_client(dev);
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+ int ret;
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+ unsigned long val;
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+
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+ if (strict_strtoul(buf, 10, &val))
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+ return -EINVAL;
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+ if (val >= strlen(map))
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+ return -EINVAL;
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+ mutex_lock(&compass_mutex);
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+ ret = compass_command(c, map[val]);
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+ mutex_unlock(&compass_mutex);
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+ if (ret < 0)
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+ return ret;
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+ return count;
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+}
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+
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+static ssize_t compass_calibration_store(struct device *dev,
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+ struct device_attribute *attr, const char *buf, size_t count)
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+{
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+ return compass_store(dev, buf, count, "EC");
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+}
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+
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+static ssize_t compass_power_mode_store(struct device *dev,
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+ struct device_attribute *attr, const char *buf, size_t count)
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+{
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+ return compass_store(dev, buf, count, "SW");
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+}
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+
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+static ssize_t compass_heading_data_show(struct device *dev,
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+ struct device_attribute *attr, char *buf)
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+{
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+ struct i2c_client *client = to_i2c_client(dev);
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+ unsigned char i2c_data[2];
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+ unsigned int ret;
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+
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+ mutex_lock(&compass_mutex);
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+ ret = compass_command(client, 'A');
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+ if (ret != 1) {
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+ mutex_unlock(&compass_mutex);
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+ return ret;
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+ }
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+ msleep(10); /* sending 'A' cmd we need to wait for 7-10 millisecs */
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+ ret = i2c_master_recv(client, i2c_data, 2);
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+ mutex_unlock(&compass_mutex);
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+ if (ret != 1) {
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+ dev_warn(dev, "i2c read data cmd failed\n");
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+ return ret;
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+ }
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+ ret = (i2c_data[0] << 8) | i2c_data[1];
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+ return sprintf(buf, "%d.%d\n", ret/10, ret%10);
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+}
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+
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+
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+static DEVICE_ATTR(heading0_input, S_IRUGO, compass_heading_data_show, NULL);
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+static DEVICE_ATTR(calibration, S_IWUSR, NULL, compass_calibration_store);
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+static DEVICE_ATTR(power_state, S_IWUSR, NULL, compass_power_mode_store);
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+
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+static struct attribute *mid_att_compass[] = {
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+ &dev_attr_heading0_input.attr,
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+ &dev_attr_calibration.attr,
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+ &dev_attr_power_state.attr,
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+ NULL
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+};
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+
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+static const struct attribute_group m_compass_gr = {
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+ .name = "hmc6352",
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+ .attrs = mid_att_compass
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+};
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+
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+static int hmc6352_probe(struct i2c_client *client,
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+ const struct i2c_device_id *id)
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+{
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+ int res;
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+
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+ res = sysfs_create_group(&client->dev.kobj, &m_compass_gr);
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+ if (res) {
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+ dev_err(&client->dev, "device_create_file failed\n");
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+ return res;
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+ }
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+ dev_info(&client->dev, "%s HMC6352 compass chip found\n",
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+ client->name);
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+ return 0;
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+}
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+
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+static int hmc6352_remove(struct i2c_client *client)
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+{
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+ sysfs_remove_group(&client->dev.kobj, &m_compass_gr);
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+ return 0;
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+}
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+
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+static struct i2c_device_id hmc6352_id[] = {
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+ { "hmc6352", 0 },
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+ { }
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+};
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+
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+MODULE_DEVICE_TABLE(i2c, hmc6352_id);
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+
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+static struct i2c_driver hmc6352_driver = {
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+ .driver = {
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+ .name = "hmc6352",
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+ },
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+ .probe = hmc6352_probe,
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+ .remove = hmc6352_remove,
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+ .id_table = hmc6352_id,
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+};
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+
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+static int __init sensor_hmc6352_init(void)
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+{
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+ return i2c_add_driver(&hmc6352_driver);
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+}
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+
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+static void __exit sensor_hmc6352_exit(void)
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+{
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+ i2c_del_driver(&hmc6352_driver);
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+}
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+
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+module_init(sensor_hmc6352_init);
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+module_exit(sensor_hmc6352_exit);
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+
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+MODULE_AUTHOR("Kalhan Trisal <kalhan.trisal@intel.com");
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+MODULE_DESCRIPTION("hmc6352 Compass Driver");
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+MODULE_LICENSE("GPL v2");
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Kalhan Trisal