drivers/misc/hmc6352.c

   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
  31 static DEFINE_MUTEX(compass_mutex);
  32
  33 static 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
  41 static 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
  61 static 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
  67 static 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
  73 static 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
  98 static DEVICE_ATTR(heading0_input, S_IRUGO, compass_heading_data_show, NULL);
  99 static DEVICE_ATTR(calibration, S_IWUSR, NULL, compass_calibration_store);
 100 static DEVICE_ATTR(power_state, S_IWUSR, NULL, compass_power_mode_store);
 101
 102 static 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
 109 static const struct attribute_group m_compass_gr = {
 110         .name = "hmc6352",
 111         .attrs = mid_att_compass
 112 };
 113
 114 static 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
 129 static int hmc6352_remove(struct i2c_client *client)
 130 {
 131         sysfs_remove_group(&client->dev.kobj, &m_compass_gr);
 132         return 0;
 133 }
 134
 135 static const struct i2c_device_id hmc6352_id[] = {
 136         { "hmc6352", 0 },
 137         { }
 138 };
 139
 140 MODULE_DEVICE_TABLE(i2c, hmc6352_id);
 141
 142 static 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
 151 module_i2c_driver(hmc6352_driver);
 152
 153 MODULE_AUTHOR("Kalhan Trisal <kalhan.trisal@intel.com");
 154 MODULE_DESCRIPTION("hmc6352 Compass Driver");
 155 MODULE_LICENSE("GPL v2");