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"); 158