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
mcp3021_read16(struct i2c_client * client)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
volts_from_reg(struct mcp3021_data * data,u16 val)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
show_in_input(struct device * dev,struct device_attribute * attr,char * buf)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
mcp3021_probe(struct i2c_client * client,const struct i2c_device_id * id)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
mcp3021_remove(struct i2c_client * client)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