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/init.h> 26 #include <linux/slab.h> 27 #include <linux/i2c.h> 28 #include <linux/err.h> 29 #include <linux/delay.h> 30 #include <linux/sysfs.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 if (strict_strtoul(buf, 10, &val)) 50 return -EINVAL; 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 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"); 156