drivers/hwmon/mcp3021.c

   1 /*
   2  * mcp3021.c - driver for Microchip MCP3021 and MCP3221
   3  *
   4  * Copyright (C) 2008-2009, 2012 Freescale Semiconductor, Inc.
   5  * Author: Mingkai Hu <Mingkai.hu@freescale.com>
   6  * Reworked by Sven Schuchmann <schuchmann@schleissheimer.de>
   7  *
   8  * This driver export the value of analog input voltage to sysfs, the
   9  * voltage unit is mV. Through the sysfs interface, lm-sensors tool
  10  * can also display the input voltage.
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  */
  17
  18 #include <linux/kernel.h>
  19 #include <linux/module.h>
  20 #include <linux/hwmon.h>
  21 #include <linux/slab.h>
  22 #include <linux/i2c.h>
  23 #include <linux/err.h>
  24 #include <linux/device.h>
  25
  26 /* Vdd info */
  27 #define MCP3021_VDD_MAX         5500
  28 #define MCP3021_VDD_MIN         2700
  29 #define MCP3021_VDD_REF         3300
  30
  31 /* output format */
  32 #define MCP3021_SAR_SHIFT       2
  33 #define MCP3021_SAR_MASK        0x3ff
  34
  35 #define MCP3021_OUTPUT_RES      10      /* 10-bit resolution */
  36 #define MCP3021_OUTPUT_SCALE    4
  37
  38 #define MCP3221_SAR_SHIFT       0
  39 #define MCP3221_SAR_MASK        0xfff
  40 #define MCP3221_OUTPUT_RES      12      /* 12-bit resolution */
  41 #define MCP3221_OUTPUT_SCALE    1
  42
  43 enum chips {
  44         mcp3021,
  45         mcp3221
  46 };
  47
  48 /*
  49  * Client data (each client gets its own)
  50  */
  51 struct mcp3021_data {
  52         struct device *hwmon_dev;
  53         u32 vdd;        /* device power supply */
  54         u16 sar_shift;
  55         u16 sar_mask;
  56         u8 output_res;
  57         u8 output_scale;
  58 };
  59
  60 static int mcp3021_read16(struct i2c_client *client)
  61 {
  62         struct mcp3021_data *data = i2c_get_clientdata(client);
  63         int ret;
  64         u16 reg;
  65         __be16 buf;
  66
  67         ret = i2c_master_recv(client, (char *)&buf, 2);
  68         if (ret < 0)
  69                 return ret;
  70         if (ret != 2)
  71                 return -EIO;
  72
  73         /* The output code of the MCP3021 is transmitted with MSB first. */
  74         reg = be16_to_cpu(buf);
  75
  76         /*
  77          * The ten-bit output code is composed of the lower 4-bit of the
  78          * first byte and the upper 6-bit of the second byte.
  79          */
  80         reg = (reg >> data->sar_shift) & data->sar_mask;
  81
  82         return reg;
  83 }
  84
  85 static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val)
  86 {
  87         if (val == 0)
  88                 return 0;
  89
  90         val = val * data->output_scale - data->output_scale / 2;
  91
  92         return val * DIV_ROUND_CLOSEST(data->vdd,
  93                         (1 << data->output_res) * data->output_scale);
  94 }
  95
  96 static ssize_t show_in_input(struct device *dev, struct device_attribute *attr,
  97                 char *buf)
  98 {
  99         struct i2c_client *client = to_i2c_client(dev);
 100         struct mcp3021_data *data = i2c_get_clientdata(client);
 101         int reg, in_input;
 102
 103         reg = mcp3021_read16(client);
 104         if (reg < 0)
 105                 return reg;
 106
 107         in_input = volts_from_reg(data, reg);
 108
 109         return sprintf(buf, "%d\n", in_input);
 110 }
 111
 112 static DEVICE_ATTR(in0_input, S_IRUGO, show_in_input, NULL);
 113
 114 static int mcp3021_probe(struct i2c_client *client,
 115                                 const struct i2c_device_id *id)
 116 {
 117         int err;
 118         struct mcp3021_data *data = NULL;
 119
 120         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 121                 return -ENODEV;
 122
 123         data = devm_kzalloc(&client->dev, sizeof(struct mcp3021_data),
 124                             GFP_KERNEL);
 125         if (!data)
 126                 return -ENOMEM;
 127
 128         i2c_set_clientdata(client, data);
 129
 130         switch (id->driver_data) {
 131         case mcp3021:
 132                 data->sar_shift = MCP3021_SAR_SHIFT;
 133                 data->sar_mask = MCP3021_SAR_MASK;
 134                 data->output_res = MCP3021_OUTPUT_RES;
 135                 data->output_scale = MCP3021_OUTPUT_SCALE;
 136                 break;
 137
 138         case mcp3221:
 139                 data->sar_shift = MCP3221_SAR_SHIFT;
 140                 data->sar_mask = MCP3221_SAR_MASK;
 141                 data->output_res = MCP3221_OUTPUT_RES;
 142                 data->output_scale = MCP3221_OUTPUT_SCALE;
 143                 break;
 144         }
 145
 146         if (dev_get_platdata(&client->dev)) {
 147                 data->vdd = *(u32 *)dev_get_platdata(&client->dev);
 148                 if (data->vdd > MCP3021_VDD_MAX || data->vdd < MCP3021_VDD_MIN)
 149                         return -EINVAL;
 150         } else {
 151                 data->vdd = MCP3021_VDD_REF;
 152         }
 153
 154         err = sysfs_create_file(&client->dev.kobj, &dev_attr_in0_input.attr);
 155         if (err)
 156                 return err;
 157
 158         data->hwmon_dev = hwmon_device_register(&client->dev);
 159         if (IS_ERR(data->hwmon_dev)) {
 160                 err = PTR_ERR(data->hwmon_dev);
 161                 goto exit_remove;
 162         }
 163
 164         return 0;
 165
 166 exit_remove:
 167         sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
 168         return err;
 169 }
 170
 171 static int mcp3021_remove(struct i2c_client *client)
 172 {
 173         struct mcp3021_data *data = i2c_get_clientdata(client);
 174
 175         hwmon_device_unregister(data->hwmon_dev);
 176         sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
 177
 178         return 0;
 179 }
 180
 181 static const struct i2c_device_id mcp3021_id[] = {
 182         { "mcp3021", mcp3021 },
 183         { "mcp3221", mcp3221 },
 184         { }
 185 };
 186 MODULE_DEVICE_TABLE(i2c, mcp3021_id);
 187
 188 static struct i2c_driver mcp3021_driver = {
 189         .driver = {
 190                 .name = "mcp3021",
 191         },
 192         .probe = mcp3021_probe,
 193         .remove = mcp3021_remove,
 194         .id_table = mcp3021_id,
 195 };
 196
 197 module_i2c_driver(mcp3021_driver);
 198
 199 MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");
 200 MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver");
 201 MODULE_LICENSE("GPL");