drivers/misc/hmc6352.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * hmc6352.c - Honeywell Compass Driver
0004  *
0005  * Copyright (C) 2009 Intel Corp
0006  *
0007  *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0008  *
0009  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0010  */
0011
0012 #include <linux/module.h>
0013 #include <linux/slab.h>
0014 #include <linux/i2c.h>
0015 #include <linux/err.h>
0016 #include <linux/delay.h>
0017 #include <linux/sysfs.h>
0018 #include <linux/nospec.h>
0019
0020 static DEFINE_MUTEX(compass_mutex);
0021
0022 static int compass_command(struct i2c_client *c, u8 cmd)
0023 {
0024     int ret = i2c_master_send(c, &cmd, 1);
0025     if (ret < 0)
0026         dev_warn(&c->dev, "command '%c' failed.\n", cmd);
0027     return ret;
0028 }
0029
0030 static int compass_store(struct device *dev, const char *buf, size_t count,
0031             const char *map)
0032 {
0033     struct i2c_client *c = to_i2c_client(dev);
0034     int ret;
0035     unsigned long val;
0036
0037     ret = kstrtoul(buf, 10, &val);
0038     if (ret)
0039         return ret;
0040     if (val >= strlen(map))
0041         return -EINVAL;
0042     val = array_index_nospec(val, strlen(map));
0043     mutex_lock(&compass_mutex);
0044     ret = compass_command(c, map[val]);
0045     mutex_unlock(&compass_mutex);
0046     if (ret < 0)
0047         return ret;
0048     return count;
0049 }
0050
0051 static ssize_t compass_calibration_store(struct device *dev,
0052         struct device_attribute *attr, const char *buf, size_t count)
0053 {
0054     return compass_store(dev, buf, count, "EC");
0055 }
0056
0057 static ssize_t compass_power_mode_store(struct device *dev,
0058         struct device_attribute *attr, const  char *buf, size_t count)
0059 {
0060     return compass_store(dev, buf, count, "SW");
0061 }
0062
0063 static ssize_t compass_heading_data_show(struct device *dev,
0064             struct device_attribute *attr, char *buf)
0065 {
0066     struct i2c_client *client = to_i2c_client(dev);
0067     unsigned char i2c_data[2];
0068     int ret;
0069
0070     mutex_lock(&compass_mutex);
0071     ret = compass_command(client, 'A');
0072     if (ret != 1) {
0073         mutex_unlock(&compass_mutex);
0074         return ret;
0075     }
0076     msleep(10); /* sending 'A' cmd we need to wait for 7-10 millisecs */
0077     ret = i2c_master_recv(client, i2c_data, 2);
0078     mutex_unlock(&compass_mutex);
0079     if (ret < 0) {
0080         dev_warn(dev, "i2c read data cmd failed\n");
0081         return ret;
0082     }
0083     ret = (i2c_data[0] << 8) | i2c_data[1];
0084     return sprintf(buf, "%d.%d\n", ret/10, ret%10);
0085 }
0086
0087
0088 static DEVICE_ATTR(heading0_input, S_IRUGO, compass_heading_data_show, NULL);
0089 static DEVICE_ATTR(calibration, S_IWUSR, NULL, compass_calibration_store);
0090 static DEVICE_ATTR(power_state, S_IWUSR, NULL, compass_power_mode_store);
0091
0092 static struct attribute *mid_att_compass[] = {
0093     &dev_attr_heading0_input.attr,
0094     &dev_attr_calibration.attr,
0095     &dev_attr_power_state.attr,
0096     NULL
0097 };
0098
0099 static const struct attribute_group m_compass_gr = {
0100     .name = "hmc6352",
0101     .attrs = mid_att_compass
0102 };
0103
0104 static int hmc6352_probe(struct i2c_client *client,
0105                     const struct i2c_device_id *id)
0106 {
0107     int res;
0108
0109     res = sysfs_create_group(&client->dev.kobj, &m_compass_gr);
0110     if (res) {
0111         dev_err(&client->dev, "device_create_file failed\n");
0112         return res;
0113     }
0114     dev_info(&client->dev, "%s HMC6352 compass chip found\n",
0115                             client->name);
0116     return 0;
0117 }
0118
0119 static int hmc6352_remove(struct i2c_client *client)
0120 {
0121     sysfs_remove_group(&client->dev.kobj, &m_compass_gr);
0122     return 0;
0123 }
0124
0125 static const struct i2c_device_id hmc6352_id[] = {
0126     { "hmc6352", 0 },
0127     { }
0128 };
0129
0130 MODULE_DEVICE_TABLE(i2c, hmc6352_id);
0131
0132 static struct i2c_driver hmc6352_driver = {
0133     .driver = {
0134         .name = "hmc6352",
0135     },
0136     .probe = hmc6352_probe,
0137     .remove = hmc6352_remove,
0138     .id_table = hmc6352_id,
0139 };
0140
0141 module_i2c_driver(hmc6352_driver);
0142
0143 MODULE_AUTHOR("Kalhan Trisal <kalhan.trisal@intel.com");
0144 MODULE_DESCRIPTION("hmc6352 Compass Driver");
0145 MODULE_LICENSE("GPL v2");