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 #include <linux/nospec.h>
  31
  32 static DEFINE_MUTEX(compass_mutex);
  33
  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
  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
  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
  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
  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
 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
 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");