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 (client->dev.platform_data) { 147 data->vdd = *(u32 *)client->dev.platform_data; 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 err = sysfs_create_file(&client->dev.kobj, &dev_attr_in0_input.attr); 154 if (err) 155 return err; 156 157 data->hwmon_dev = hwmon_device_register(&client->dev); 158 if (IS_ERR(data->hwmon_dev)) { 159 err = PTR_ERR(data->hwmon_dev); 160 goto exit_remove; 161 } 162 163 return 0; 164 165 exit_remove: 166 sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr); 167 return err; 168 } 169 170 static int mcp3021_remove(struct i2c_client *client) 171 { 172 struct mcp3021_data *data = i2c_get_clientdata(client); 173 174 hwmon_device_unregister(data->hwmon_dev); 175 sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr); 176 177 return 0; 178 } 179 180 static const struct i2c_device_id mcp3021_id[] = { 181 { "mcp3021", mcp3021 }, 182 { "mcp3221", mcp3221 }, 183 { } 184 }; 185 MODULE_DEVICE_TABLE(i2c, mcp3021_id); 186 187 static struct i2c_driver mcp3021_driver = { 188 .driver = { 189 .name = "mcp3021", 190 }, 191 .probe = mcp3021_probe, 192 .remove = mcp3021_remove, 193 .id_table = mcp3021_id, 194 }; 195 196 module_i2c_driver(mcp3021_driver); 197 198 MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>"); 199 MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver"); 200 MODULE_LICENSE("GPL"); 201