tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * mcp3021.c - driver for the Microchip MCP3021 chip
3 *
4 * Copyright (C) 2008-2009, 2012 Freescale Semiconductor, Inc.
5 * Author: Mingkai Hu <Mingkai.hu@freescale.com>
6 *
7 * This driver export the value of analog input voltage to sysfs, the
8 * voltage unit is mV. Through the sysfs interface, lm-sensors tool
9 * can also display the input voltage.
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
15 */
16
17#include <linux/kernel.h>
18#include <linux/module.h>
19#include <linux/hwmon.h>
20#include <linux/slab.h>
21#include <linux/i2c.h>
22#include <linux/err.h>
23#include <linux/device.h>
24
25/* Vdd info */
26#define MCP3021_VDD_MAX 5500
27#define MCP3021_VDD_MIN 2700
28#define MCP3021_VDD_REF 3300
29
30/* output format */
31#define MCP3021_SAR_SHIFT 2
32#define MCP3021_SAR_MASK 0x3ff
33
34#define MCP3021_OUTPUT_RES 10 /* 10-bit resolution */
35#define MCP3021_OUTPUT_SCALE 4
36
37/*
38 * Client data (each client gets its own)
39 */
40struct mcp3021_data {
41 struct device *hwmon_dev;
42 u32 vdd; /* device power supply */
43};
44
45static int mcp3021_read16(struct i2c_client *client)
46{
47 int ret;
48 u16 reg;
49 __be16 buf;
50
51 ret = i2c_master_recv(client, (char *)&buf, 2);
52 if (ret < 0)
53 return ret;
54 if (ret != 2)
55 return -EIO;
56
57 /* The output code of the MCP3021 is transmitted with MSB first. */
58 reg = be16_to_cpu(buf);
59
60 /*
61 * The ten-bit output code is composed of the lower 4-bit of the
62 * first byte and the upper 6-bit of the second byte.
63 */
64 reg = (reg >> MCP3021_SAR_SHIFT) & MCP3021_SAR_MASK;
65
66 return reg;
67}
68
69static inline u16 volts_from_reg(u16 vdd, u16 val)
70{
71 if (val == 0)
72 return 0;
73
74 val = val * MCP3021_OUTPUT_SCALE - MCP3021_OUTPUT_SCALE / 2;
75
76 return val * DIV_ROUND_CLOSEST(vdd,
77 (1 << MCP3021_OUTPUT_RES) * MCP3021_OUTPUT_SCALE);
78}
79
80static ssize_t show_in_input(struct device *dev, struct device_attribute *attr,
81 char *buf)
82{
83 struct i2c_client *client = to_i2c_client(dev);
84 struct mcp3021_data *data = i2c_get_clientdata(client);
85 int reg, in_input;
86
87 reg = mcp3021_read16(client);
88 if (reg < 0)
89 return reg;
90
91 in_input = volts_from_reg(data->vdd, reg);
92 return sprintf(buf, "%d\n", in_input);
93}
94
95static DEVICE_ATTR(in0_input, S_IRUGO, show_in_input, NULL);
96
97static int mcp3021_probe(struct i2c_client *client,
98 const struct i2c_device_id *id)
99{
100 int err;
101 struct mcp3021_data *data = NULL;
102
103 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
104 return -ENODEV;
105
106 data = kzalloc(sizeof(struct mcp3021_data), GFP_KERNEL);
107 if (!data)
108 return -ENOMEM;
109
110 i2c_set_clientdata(client, data);
111
112 if (client->dev.platform_data) {
113 data->vdd = *(u32 *)client->dev.platform_data;
114 if (data->vdd > MCP3021_VDD_MAX ||
115 data->vdd < MCP3021_VDD_MIN) {
116 err = -EINVAL;
117 goto exit_free;
118 }
119 } else
120 data->vdd = MCP3021_VDD_REF;
121
122 err = sysfs_create_file(&client->dev.kobj, &dev_attr_in0_input.attr);
123 if (err)
124 goto exit_free;
125
126 data->hwmon_dev = hwmon_device_register(&client->dev);
127 if (IS_ERR(data->hwmon_dev)) {
128 err = PTR_ERR(data->hwmon_dev);
129 goto exit_remove;
130 }
131
132 return 0;
133
134exit_remove:
135 sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
136exit_free:
137 kfree(data);
138 return err;
139}
140
141static int mcp3021_remove(struct i2c_client *client)
142{
143 struct mcp3021_data *data = i2c_get_clientdata(client);
144
145 hwmon_device_unregister(data->hwmon_dev);
146 sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
147 kfree(data);
148
149 return 0;
150}
151
152static const struct i2c_device_id mcp3021_id[] = {
153 { "mcp3021", 0 },
154 { }
155};
156MODULE_DEVICE_TABLE(i2c, mcp3021_id);
157
158static struct i2c_driver mcp3021_driver = {
159 .driver = {
160 .name = "mcp3021",
161 },
162 .probe = mcp3021_probe,
163 .remove = mcp3021_remove,
164 .id_table = mcp3021_id,
165};
166
167module_i2c_driver(mcp3021_driver);
168
169MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");
170MODULE_DESCRIPTION("Microchip MCP3021 driver");
171MODULE_LICENSE("GPL");