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 export 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 #include <linux/of_device.h>
  24
  25 /* Vdd / reference voltage in millivolt */
  26 #define MCP3021_VDD_REF_MAX     5500
  27 #define MCP3021_VDD_REF_MIN     2700
  28 #define MCP3021_VDD_REF_DEFAULT 3300
  29
  30 /* output format */
  31 #define MCP3021_SAR_SHIFT       2
  32 #define MCP3021_SAR_MASK        0x3ff
  33 #define MCP3021_OUTPUT_RES      10      /* 10-bit resolution */
  34
  35 #define MCP3221_SAR_SHIFT       0
  36 #define MCP3221_SAR_MASK        0xfff
  37 #define MCP3221_OUTPUT_RES      12      /* 12-bit resolution */
  38
  39 enum chips {
  40         mcp3021,
  41         mcp3221
  42 };
  43
  44 /*
  45  * Client data (each client gets its own)
  46  */
  47 struct mcp3021_data {
  48         struct device *hwmon_dev;
  49         u32 vdd;        /* supply and reference voltage in millivolt */
  50         u16 sar_shift;
  51         u16 sar_mask;
  52         u8 output_res;
  53 };
  54
  55 static int mcp3021_read16(struct i2c_client *client)
  56 {
  57         struct mcp3021_data *data = i2c_get_clientdata(client);
  58         int ret;
  59         u16 reg;
  60         __be16 buf;
  61
  62         ret = i2c_master_recv(client, (char *)&buf, 2);
  63         if (ret < 0)
  64                 return ret;
  65         if (ret != 2)
  66                 return -EIO;
  67
  68         /* The output code of the MCP3021 is transmitted with MSB first. */
  69         reg = be16_to_cpu(buf);
  70
  71         /*
  72          * The ten-bit output code is composed of the lower 4-bit of the
  73          * first byte and the upper 6-bit of the second byte.
  74          */
  75         reg = (reg >> data->sar_shift) & data->sar_mask;
  76
  77         return reg;
  78 }
  79
  80 static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val)
  81 {
  82         return DIV_ROUND_CLOSEST(data->vdd * val, 1 << data->output_res);
  83 }
  84
  85 static ssize_t in0_input_show(struct device *dev,
  86                               struct device_attribute *attr, char *buf)
  87 {
  88         struct i2c_client *client = to_i2c_client(dev);
  89         struct mcp3021_data *data = i2c_get_clientdata(client);
  90         int reg, in_input;
  91
  92         reg = mcp3021_read16(client);
  93         if (reg < 0)
  94                 return reg;
  95
  96         in_input = volts_from_reg(data, reg);
  97
  98         return sprintf(buf, "%d\n", in_input);
  99 }
 100
 101 static DEVICE_ATTR_RO(in0_input);
 102
 103 static int mcp3021_probe(struct i2c_client *client,
 104                                 const struct i2c_device_id *id)
 105 {
 106         int err;
 107         struct mcp3021_data *data = NULL;
 108         struct device_node *np = client->dev.of_node;
 109
 110         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 111                 return -ENODEV;
 112
 113         data = devm_kzalloc(&client->dev, sizeof(struct mcp3021_data),
 114                             GFP_KERNEL);
 115         if (!data)
 116                 return -ENOMEM;
 117
 118         i2c_set_clientdata(client, data);
 119
 120         if (np) {
 121                 if (!of_property_read_u32(np, "reference-voltage-microvolt",
 122                                           &data->vdd))
 123                         data->vdd /= 1000;
 124                 else
 125                         data->vdd = MCP3021_VDD_REF_DEFAULT;
 126         } else {
 127                 u32 *pdata = dev_get_platdata(&client->dev);
 128
 129                 if (pdata)
 130                         data->vdd = *pdata;
 131                 else
 132                         data->vdd = MCP3021_VDD_REF_DEFAULT;
 133         }
 134
 135         switch (id->driver_data) {
 136         case mcp3021:
 137                 data->sar_shift = MCP3021_SAR_SHIFT;
 138                 data->sar_mask = MCP3021_SAR_MASK;
 139                 data->output_res = MCP3021_OUTPUT_RES;
 140                 break;
 141
 142         case mcp3221:
 143                 data->sar_shift = MCP3221_SAR_SHIFT;
 144                 data->sar_mask = MCP3221_SAR_MASK;
 145                 data->output_res = MCP3221_OUTPUT_RES;
 146                 break;
 147         }
 148
 149         if (data->vdd > MCP3021_VDD_REF_MAX || data->vdd < MCP3021_VDD_REF_MIN)
 150                 return -EINVAL;
 151
 152         err = sysfs_create_file(&client->dev.kobj, &dev_attr_in0_input.attr);
 153         if (err)
 154                 return err;
 155
 156         data->hwmon_dev = hwmon_device_register(&client->dev);
 157         if (IS_ERR(data->hwmon_dev)) {
 158                 err = PTR_ERR(data->hwmon_dev);
 159                 goto exit_remove;
 160         }
 161
 162         return 0;
 163
 164 exit_remove:
 165         sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
 166         return err;
 167 }
 168
 169 static int mcp3021_remove(struct i2c_client *client)
 170 {
 171         struct mcp3021_data *data = i2c_get_clientdata(client);
 172
 173         hwmon_device_unregister(data->hwmon_dev);
 174         sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
 175
 176         return 0;
 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         .remove = mcp3021_remove,
 202         .id_table = mcp3021_id,
 203 };
 204
 205 module_i2c_driver(mcp3021_driver);
 206
 207 MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");
 208 MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver");
 209 MODULE_LICENSE("GPL");