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  * DT support added by Clemens Gruber <clemens.gruber@pqgruber.com>
   8  *
   9  * This driver export the value of analog input voltage to sysfs, the
  10  * voltage unit is mV. Through the sysfs interface, lm-sensors tool
  11  * can also display the input voltage.
  12  *
  13  * This program is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU General Public License as published by
  15  * the Free Software Foundation; either version 2 of the License, or
  16  * (at your option) any later version.
  17  */
  18
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/hwmon.h>
  22 #include <linux/slab.h>
  23 #include <linux/i2c.h>
  24 #include <linux/err.h>
  25 #include <linux/device.h>
  26 #include <linux/of.h>
  27 #include <linux/of_device.h>
  28
  29 /* Vdd / reference voltage in millivolt */
  30 #define MCP3021_VDD_REF_MAX     5500
  31 #define MCP3021_VDD_REF_MIN     2700
  32 #define MCP3021_VDD_REF_DEFAULT 3300
  33
  34 /* output format */
  35 #define MCP3021_SAR_SHIFT       2
  36 #define MCP3021_SAR_MASK        0x3ff
  37 #define MCP3021_OUTPUT_RES      10      /* 10-bit resolution */
  38
  39 #define MCP3221_SAR_SHIFT       0
  40 #define MCP3221_SAR_MASK        0xfff
  41 #define MCP3221_OUTPUT_RES      12      /* 12-bit resolution */
  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;        /* supply and reference voltage in millivolt */
  54         u16 sar_shift;
  55         u16 sar_mask;
  56         u8 output_res;
  57 };
  58
  59 static int mcp3021_read16(struct i2c_client *client)
  60 {
  61         struct mcp3021_data *data = i2c_get_clientdata(client);
  62         int ret;
  63         u16 reg;
  64         __be16 buf;
  65
  66         ret = i2c_master_recv(client, (char *)&buf, 2);
  67         if (ret < 0)
  68                 return ret;
  69         if (ret != 2)
  70                 return -EIO;
  71
  72         /* The output code of the MCP3021 is transmitted with MSB first. */
  73         reg = be16_to_cpu(buf);
  74
  75         /*
  76          * The ten-bit output code is composed of the lower 4-bit of the
  77          * first byte and the upper 6-bit of the second byte.
  78          */
  79         reg = (reg >> data->sar_shift) & data->sar_mask;
  80
  81         return reg;
  82 }
  83
  84 static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val)
  85 {
  86         return DIV_ROUND_CLOSEST(data->vdd * val, 1 << data->output_res);
  87 }
  88
  89 static ssize_t show_in_input(struct device *dev, struct device_attribute *attr,
  90                 char *buf)
  91 {
  92         struct i2c_client *client = to_i2c_client(dev);
  93         struct mcp3021_data *data = i2c_get_clientdata(client);
  94         int reg, in_input;
  95
  96         reg = mcp3021_read16(client);
  97         if (reg < 0)
  98                 return reg;
  99
 100         in_input = volts_from_reg(data, reg);
 101
 102         return sprintf(buf, "%d\n", in_input);
 103 }
 104
 105 static DEVICE_ATTR(in0_input, 0444, show_in_input, NULL);
 106
 107 static int mcp3021_probe(struct i2c_client *client,
 108                                 const struct i2c_device_id *id)
 109 {
 110         int err;
 111         struct mcp3021_data *data = NULL;
 112         struct device_node *np = client->dev.of_node;
 113
 114         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 115                 return -ENODEV;
 116
 117         data = devm_kzalloc(&client->dev, sizeof(struct mcp3021_data),
 118                             GFP_KERNEL);
 119         if (!data)
 120                 return -ENOMEM;
 121
 122         i2c_set_clientdata(client, data);
 123
 124         if (np) {
 125                 if (!of_property_read_u32(np, "reference-voltage-microvolt",
 126                                           &data->vdd))
 127                         data->vdd /= 1000;
 128                 else
 129                         data->vdd = MCP3021_VDD_REF_DEFAULT;
 130         } else {
 131                 u32 *pdata = dev_get_platdata(&client->dev);
 132
 133                 if (pdata)
 134                         data->vdd = *pdata;
 135                 else
 136                         data->vdd = MCP3021_VDD_REF_DEFAULT;
 137         }
 138
 139         switch (id->driver_data) {
 140         case mcp3021:
 141                 data->sar_shift = MCP3021_SAR_SHIFT;
 142                 data->sar_mask = MCP3021_SAR_MASK;
 143                 data->output_res = MCP3021_OUTPUT_RES;
 144                 break;
 145
 146         case mcp3221:
 147                 data->sar_shift = MCP3221_SAR_SHIFT;
 148                 data->sar_mask = MCP3221_SAR_MASK;
 149                 data->output_res = MCP3221_OUTPUT_RES;
 150                 break;
 151         }
 152
 153         if (data->vdd > MCP3021_VDD_REF_MAX || data->vdd < MCP3021_VDD_REF_MIN)
 154                 return -EINVAL;
 155
 156         err = sysfs_create_file(&client->dev.kobj, &dev_attr_in0_input.attr);
 157         if (err)
 158                 return err;
 159
 160         data->hwmon_dev = hwmon_device_register(&client->dev);
 161         if (IS_ERR(data->hwmon_dev)) {
 162                 err = PTR_ERR(data->hwmon_dev);
 163                 goto exit_remove;
 164         }
 165
 166         return 0;
 167
 168 exit_remove:
 169         sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
 170         return err;
 171 }
 172
 173 static int mcp3021_remove(struct i2c_client *client)
 174 {
 175         struct mcp3021_data *data = i2c_get_clientdata(client);
 176
 177         hwmon_device_unregister(data->hwmon_dev);
 178         sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
 179
 180         return 0;
 181 }
 182
 183 static const struct i2c_device_id mcp3021_id[] = {
 184         { "mcp3021", mcp3021 },
 185         { "mcp3221", mcp3221 },
 186         { }
 187 };
 188 MODULE_DEVICE_TABLE(i2c, mcp3021_id);
 189
 190 #ifdef CONFIG_OF
 191 static const struct of_device_id of_mcp3021_match[] = {
 192         { .compatible = "microchip,mcp3021", .data = (void *)mcp3021 },
 193         { .compatible = "microchip,mcp3221", .data = (void *)mcp3221 },
 194         { }
 195 };
 196 MODULE_DEVICE_TABLE(of, of_mcp3021_match);
 197 #endif
 198
 199 static struct i2c_driver mcp3021_driver = {
 200         .driver = {
 201                 .name = "mcp3021",
 202                 .of_match_table = of_match_ptr(of_mcp3021_match),
 203         },
 204         .probe = mcp3021_probe,
 205         .remove = mcp3021_remove,
 206         .id_table = mcp3021_id,
 207 };
 208
 209 module_i2c_driver(mcp3021_driver);
 210
 211 MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");
 212 MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver");
 213 MODULE_LICENSE("GPL");