drivers/misc/hmc6352.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * hmc6352.c - Honeywell Compass Driver
   4  *
   5  * Copyright (C) 2009 Intel Corp
   6  *
   7  *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   8  *
   9  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/i2c.h>
  15 #include <linux/err.h>
  16 #include <linux/delay.h>
  17 #include <linux/sysfs.h>
  18 #include <linux/nospec.h>
  19
  20 static DEFINE_MUTEX(compass_mutex);
  21
  22 static int compass_command(struct i2c_client *c, u8 cmd)
  23 {
  24         int ret = i2c_master_send(c, &cmd, 1);
  25         if (ret < 0)
  26                 dev_warn(&c->dev, "command '%c' failed.\n", cmd);
  27         return ret;
  28 }
  29
  30 static int compass_store(struct device *dev, const char *buf, size_t count,
  31                         const char *map)
  32 {
  33         struct i2c_client *c = to_i2c_client(dev);
  34         int ret;
  35         unsigned long val;
  36
  37         ret = kstrtoul(buf, 10, &val);
  38         if (ret)
  39                 return ret;
  40         if (val >= strlen(map))
  41                 return -EINVAL;
  42         val = array_index_nospec(val, strlen(map));
  43         mutex_lock(&compass_mutex);
  44         ret = compass_command(c, map[val]);
  45         mutex_unlock(&compass_mutex);
  46         if (ret < 0)
  47                 return ret;
  48         return count;
  49 }
  50
  51 static ssize_t compass_calibration_store(struct device *dev,
  52                 struct device_attribute *attr, const char *buf, size_t count)
  53 {
  54         return compass_store(dev, buf, count, "EC");
  55 }
  56
  57 static ssize_t compass_power_mode_store(struct device *dev,
  58                 struct device_attribute *attr, const  char *buf, size_t count)
  59 {
  60         return compass_store(dev, buf, count, "SW");
  61 }
  62
  63 static ssize_t compass_heading_data_show(struct device *dev,
  64                         struct device_attribute *attr, char *buf)
  65 {
  66         struct i2c_client *client = to_i2c_client(dev);
  67         unsigned char i2c_data[2];
  68         int ret;
  69
  70         mutex_lock(&compass_mutex);
  71         ret = compass_command(client, 'A');
  72         if (ret != 1) {
  73                 mutex_unlock(&compass_mutex);
  74                 return ret;
  75         }
  76         msleep(10); /* sending 'A' cmd we need to wait for 7-10 millisecs */
  77         ret = i2c_master_recv(client, i2c_data, 2);
  78         mutex_unlock(&compass_mutex);
  79         if (ret < 0) {
  80                 dev_warn(dev, "i2c read data cmd failed\n");
  81                 return ret;
  82         }
  83         ret = (i2c_data[0] << 8) | i2c_data[1];
  84         return sprintf(buf, "%d.%d\n", ret/10, ret%10);
  85 }
  86
  87
  88 static DEVICE_ATTR(heading0_input, S_IRUGO, compass_heading_data_show, NULL);
  89 static DEVICE_ATTR(calibration, S_IWUSR, NULL, compass_calibration_store);
  90 static DEVICE_ATTR(power_state, S_IWUSR, NULL, compass_power_mode_store);
  91
  92 static struct attribute *mid_att_compass[] = {
  93         &dev_attr_heading0_input.attr,
  94         &dev_attr_calibration.attr,
  95         &dev_attr_power_state.attr,
  96         NULL
  97 };
  98
  99 static const struct attribute_group m_compass_gr = {
 100         .name = "hmc6352",
 101         .attrs = mid_att_compass
 102 };
 103
 104 static int hmc6352_probe(struct i2c_client *client,
 105                                         const struct i2c_device_id *id)
 106 {
 107         int res;
 108
 109         res = sysfs_create_group(&client->dev.kobj, &m_compass_gr);
 110         if (res) {
 111                 dev_err(&client->dev, "device_create_file failed\n");
 112                 return res;
 113         }
 114         dev_info(&client->dev, "%s HMC6352 compass chip found\n",
 115                                                         client->name);
 116         return 0;
 117 }
 118
 119 static int hmc6352_remove(struct i2c_client *client)
 120 {
 121         sysfs_remove_group(&client->dev.kobj, &m_compass_gr);
 122         return 0;
 123 }
 124
 125 static const struct i2c_device_id hmc6352_id[] = {
 126         { "hmc6352", 0 },
 127         { }
 128 };
 129
 130 MODULE_DEVICE_TABLE(i2c, hmc6352_id);
 131
 132 static struct i2c_driver hmc6352_driver = {
 133         .driver = {
 134                 .name = "hmc6352",
 135         },
 136         .probe = hmc6352_probe,
 137         .remove = hmc6352_remove,
 138         .id_table = hmc6352_id,
 139 };
 140
 141 module_i2c_driver(hmc6352_driver);
 142
 143 MODULE_AUTHOR("Kalhan Trisal <kalhan.trisal@intel.com");
 144 MODULE_DESCRIPTION("hmc6352 Compass Driver");
 145 MODULE_LICENSE("GPL v2");