drivers/hwmon/mcp3021.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * mcp3021.c - driver for Microchip MCP3021 and MCP3221
   4  *
   5  * Copyright (C) 2008-2009, 2012 Freescale Semiconductor, Inc.
   6  * Author: Mingkai Hu <Mingkai.hu@freescale.com>
   7  * Reworked by Sven Schuchmann <schuchmann@schleissheimer.de>
   8  * DT support added by Clemens Gruber <clemens.gruber@pqgruber.com>
   9  *
  10  * This driver exports the value of analog input voltage to sysfs, the
  11  * voltage unit is mV. Through the sysfs interface, lm-sensors tool
  12  * can also display the input voltage.
  13  */
  14
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/hwmon.h>
  18 #include <linux/slab.h>
  19 #include <linux/i2c.h>
  20 #include <linux/err.h>
  21 #include <linux/device.h>
  22 #include <linux/of.h>
  23
  24 /* Vdd / reference voltage in millivolt */
  25 #define MCP3021_VDD_REF_MAX     5500
  26 #define MCP3021_VDD_REF_MIN     2700
  27 #define MCP3021_VDD_REF_DEFAULT 3300
  28
  29 /* output format */
  30 #define MCP3021_SAR_SHIFT       2
  31 #define MCP3021_SAR_MASK        0x3ff
  32 #define MCP3021_OUTPUT_RES      10      /* 10-bit resolution */
  33
  34 #define MCP3221_SAR_SHIFT       0
  35 #define MCP3221_SAR_MASK        0xfff
  36 #define MCP3221_OUTPUT_RES      12      /* 12-bit resolution */
  37
  38 enum chips {
  39         mcp3021,
  40         mcp3221
  41 };
  42
  43 /*
  44  * Client data (each client gets its own)
  45  */
  46 struct mcp3021_data {
  47         struct i2c_client *client;
  48         u32 vdd;        /* supply and reference voltage in millivolt */
  49         u16 sar_shift;
  50         u16 sar_mask;
  51         u8 output_res;
  52 };
  53
  54 static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val)
  55 {
  56         return DIV_ROUND_CLOSEST(data->vdd * val, 1 << data->output_res);
  57 }
  58
  59 static int mcp3021_read(struct device *dev, enum hwmon_sensor_types type,
  60                         u32 attr, int channel, long *val)
  61 {
  62         struct mcp3021_data *data = dev_get_drvdata(dev);
  63         struct i2c_client *client = data->client;
  64         __be16 buf;
  65         u16 reg;
  66         int ret;
  67
  68         if (type != hwmon_in)
  69                 return -EOPNOTSUPP;
  70
  71         ret = i2c_master_recv(client, (char *)&buf, 2);
  72         if (ret < 0)
  73                 return ret;
  74         if (ret != 2)
  75                 return -EIO;
  76
  77         /* The output code of the MCP3021 is transmitted with MSB first. */
  78         reg = be16_to_cpu(buf);
  79
  80         /*
  81          * The ten-bit output code is composed of the lower 4-bit of the
  82          * first byte and the upper 6-bit of the second byte.
  83          */
  84         reg = (reg >> data->sar_shift) & data->sar_mask;
  85
  86         *val = volts_from_reg(data, reg);
  87
  88         return 0;
  89 }
  90
  91 static umode_t mcp3021_is_visible(const void *_data,
  92                                   enum hwmon_sensor_types type,
  93                                   u32 attr, int channel)
  94 {
  95         if (type != hwmon_in)
  96                 return 0;
  97
  98         if (attr != hwmon_in_input)
  99                 return 0;
 100
 101         return 0444;
 102 }
 103
 104 static const struct hwmon_channel_info * const mcp3021_info[] = {
 105         HWMON_CHANNEL_INFO(in, HWMON_I_INPUT),
 106         NULL
 107 };
 108
 109 static const struct hwmon_ops mcp3021_hwmon_ops = {
 110         .is_visible = mcp3021_is_visible,
 111         .read = mcp3021_read,
 112 };
 113
 114 static const struct hwmon_chip_info mcp3021_chip_info = {
 115         .ops = &mcp3021_hwmon_ops,
 116         .info = mcp3021_info,
 117 };
 118
 119 static int mcp3021_probe(struct i2c_client *client)
 120 {
 121         struct mcp3021_data *data = NULL;
 122         struct device_node *np = client->dev.of_node;
 123         struct device *hwmon_dev;
 124         enum chips type;
 125
 126         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 127                 return -ENODEV;
 128
 129         data = devm_kzalloc(&client->dev, sizeof(struct mcp3021_data),
 130                             GFP_KERNEL);
 131         if (!data)
 132                 return -ENOMEM;
 133
 134         i2c_set_clientdata(client, data);
 135
 136         if (np) {
 137                 if (!of_property_read_u32(np, "reference-voltage-microvolt",
 138                                           &data->vdd))
 139                         data->vdd /= 1000;
 140                 else
 141                         data->vdd = MCP3021_VDD_REF_DEFAULT;
 142         } else {
 143                 u32 *pdata = dev_get_platdata(&client->dev);
 144
 145                 if (pdata)
 146                         data->vdd = *pdata;
 147                 else
 148                         data->vdd = MCP3021_VDD_REF_DEFAULT;
 149         }
 150
 151         type = (uintptr_t)i2c_get_match_data(client);
 152         switch (type) {
 153         case mcp3021:
 154                 data->sar_shift = MCP3021_SAR_SHIFT;
 155                 data->sar_mask = MCP3021_SAR_MASK;
 156                 data->output_res = MCP3021_OUTPUT_RES;
 157                 break;
 158
 159         case mcp3221:
 160                 data->sar_shift = MCP3221_SAR_SHIFT;
 161                 data->sar_mask = MCP3221_SAR_MASK;
 162                 data->output_res = MCP3221_OUTPUT_RES;
 163                 break;
 164         }
 165
 166         data->client = client;
 167
 168         if (data->vdd > MCP3021_VDD_REF_MAX || data->vdd < MCP3021_VDD_REF_MIN)
 169                 return -EINVAL;
 170
 171         hwmon_dev = devm_hwmon_device_register_with_info(&client->dev,
 172                                                          client->name,
 173                                                          data,
 174                                                          &mcp3021_chip_info,
 175                                                          NULL);
 176         return PTR_ERR_OR_ZERO(hwmon_dev);
 177 }
 178
 179 static const struct i2c_device_id mcp3021_id[] = {
 180         { "mcp3021", mcp3021 },
 181         { "mcp3221", mcp3221 },
 182         { }
 183 };
 184 MODULE_DEVICE_TABLE(i2c, mcp3021_id);
 185
 186 #ifdef CONFIG_OF
 187 static const struct of_device_id of_mcp3021_match[] = {
 188         { .compatible = "microchip,mcp3021", .data = (void *)mcp3021 },
 189         { .compatible = "microchip,mcp3221", .data = (void *)mcp3221 },
 190         { }
 191 };
 192 MODULE_DEVICE_TABLE(of, of_mcp3021_match);
 193 #endif
 194
 195 static struct i2c_driver mcp3021_driver = {
 196         .driver = {
 197                 .name = "mcp3021",
 198                 .of_match_table = of_match_ptr(of_mcp3021_match),
 199         },
 200         .probe = mcp3021_probe,
 201         .id_table = mcp3021_id,
 202 };
 203
 204 module_i2c_driver(mcp3021_driver);
 205
 206 MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");
 207 MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver");
 208 MODULE_LICENSE("GPL");