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 #define MCP3021_OUTPUT_RES 10 /* 10-bit resolution */ 35 36 #define MCP3221_SAR_SHIFT 0 37 #define MCP3221_SAR_MASK 0xfff 38 #define MCP3221_OUTPUT_RES 12 /* 12-bit resolution */ 39 40 enum chips { 41 mcp3021, 42 mcp3221 43 }; 44 45 /* 46 * Client data (each client gets its own) 47 */ 48 struct mcp3021_data { 49 struct device *hwmon_dev; 50 u32 vdd; /* device power supply */ 51 u16 sar_shift; 52 u16 sar_mask; 53 u8 output_res; 54 }; 55 56 static int mcp3021_read16(struct i2c_client *client) 57 { 58 struct mcp3021_data *data = i2c_get_clientdata(client); 59 int ret; 60 u16 reg; 61 __be16 buf; 62 63 ret = i2c_master_recv(client, (char *)&buf, 2); 64 if (ret < 0) 65 return ret; 66 if (ret != 2) 67 return -EIO; 68 69 /* The output code of the MCP3021 is transmitted with MSB first. */ 70 reg = be16_to_cpu(buf); 71 72 /* 73 * The ten-bit output code is composed of the lower 4-bit of the 74 * first byte and the upper 6-bit of the second byte. 75 */ 76 reg = (reg >> data->sar_shift) & data->sar_mask; 77 78 return reg; 79 } 80 81 static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val) 82 { 83 return DIV_ROUND_CLOSEST(data->vdd * val, 1 << data->output_res); 84 } 85 86 static ssize_t show_in_input(struct device *dev, struct device_attribute *attr, 87 char *buf) 88 { 89 struct i2c_client *client = to_i2c_client(dev); 90 struct mcp3021_data *data = i2c_get_clientdata(client); 91 int reg, in_input; 92 93 reg = mcp3021_read16(client); 94 if (reg < 0) 95 return reg; 96 97 in_input = volts_from_reg(data, reg); 98 99 return sprintf(buf, "%d\n", in_input); 100 } 101 102 static DEVICE_ATTR(in0_input, S_IRUGO, show_in_input, NULL); 103 104 static int mcp3021_probe(struct i2c_client *client, 105 const struct i2c_device_id *id) 106 { 107 int err; 108 struct mcp3021_data *data = NULL; 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 switch (id->driver_data) { 121 case mcp3021: 122 data->sar_shift = MCP3021_SAR_SHIFT; 123 data->sar_mask = MCP3021_SAR_MASK; 124 data->output_res = MCP3021_OUTPUT_RES; 125 break; 126 127 case mcp3221: 128 data->sar_shift = MCP3221_SAR_SHIFT; 129 data->sar_mask = MCP3221_SAR_MASK; 130 data->output_res = MCP3221_OUTPUT_RES; 131 break; 132 } 133 134 if (dev_get_platdata(&client->dev)) { 135 data->vdd = *(u32 *)dev_get_platdata(&client->dev); 136 if (data->vdd > MCP3021_VDD_MAX || data->vdd < MCP3021_VDD_MIN) 137 return -EINVAL; 138 } else { 139 data->vdd = MCP3021_VDD_REF; 140 } 141 142 err = sysfs_create_file(&client->dev.kobj, &dev_attr_in0_input.attr); 143 if (err) 144 return err; 145 146 data->hwmon_dev = hwmon_device_register(&client->dev); 147 if (IS_ERR(data->hwmon_dev)) { 148 err = PTR_ERR(data->hwmon_dev); 149 goto exit_remove; 150 } 151 152 return 0; 153 154 exit_remove: 155 sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr); 156 return err; 157 } 158 159 static int mcp3021_remove(struct i2c_client *client) 160 { 161 struct mcp3021_data *data = i2c_get_clientdata(client); 162 163 hwmon_device_unregister(data->hwmon_dev); 164 sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr); 165 166 return 0; 167 } 168 169 static const struct i2c_device_id mcp3021_id[] = { 170 { "mcp3021", mcp3021 }, 171 { "mcp3221", mcp3221 }, 172 { } 173 }; 174 MODULE_DEVICE_TABLE(i2c, mcp3021_id); 175 176 static struct i2c_driver mcp3021_driver = { 177 .driver = { 178 .name = "mcp3021", 179 }, 180 .probe = mcp3021_probe, 181 .remove = mcp3021_remove, 182 .id_table = mcp3021_id, 183 }; 184 185 module_i2c_driver(mcp3021_driver); 186 187 MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>"); 188 MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver"); 189 MODULE_LICENSE("GPL"); 190