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 * DT support added by Clemens Gruber <clemens.gruber@pqgruber.com>
8 *
9 * This driver export the value of analog input voltage to sysfs, the
10 * voltage unit is mV. Through the sysfs interface, lm-sensors tool
11 * can also display the input voltage.
12 *
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License as published by
15 * the Free Software Foundation; either version 2 of the License, or
16 * (at your option) any later version.
17 */
18
19#include <linux/kernel.h>
20#include <linux/module.h>
21#include <linux/hwmon.h>
22#include <linux/slab.h>
23#include <linux/i2c.h>
24#include <linux/err.h>
25#include <linux/device.h>
26#include <linux/of.h>
27#include <linux/of_device.h>
28
29/* Vdd / reference voltage in millivolt */
30#define MCP3021_VDD_REF_MAX 5500
31#define MCP3021_VDD_REF_MIN 2700
32#define MCP3021_VDD_REF_DEFAULT 3300
33
34/* output format */
35#define MCP3021_SAR_SHIFT 2
36#define MCP3021_SAR_MASK 0x3ff
37#define MCP3021_OUTPUT_RES 10 /* 10-bit resolution */
38
39#define MCP3221_SAR_SHIFT 0
40#define MCP3221_SAR_MASK 0xfff
41#define MCP3221_OUTPUT_RES 12 /* 12-bit resolution */
42
43enum chips {
44 mcp3021,
45 mcp3221
46};
47
48/*
49 * Client data (each client gets its own)
50 */
51struct mcp3021_data {
52 struct device *hwmon_dev;
53 u32 vdd; /* supply and reference voltage in millivolt */
54 u16 sar_shift;
55 u16 sar_mask;
56 u8 output_res;
57};
58
59static int mcp3021_read16(struct i2c_client *client)
60{
61 struct mcp3021_data *data = i2c_get_clientdata(client);
62 int ret;
63 u16 reg;
64 __be16 buf;
65
66 ret = i2c_master_recv(client, (char *)&buf, 2);
67 if (ret < 0)
68 return ret;
69 if (ret != 2)
70 return -EIO;
71
72 /* The output code of the MCP3021 is transmitted with MSB first. */
73 reg = be16_to_cpu(buf);
74
75 /*
76 * The ten-bit output code is composed of the lower 4-bit of the
77 * first byte and the upper 6-bit of the second byte.
78 */
79 reg = (reg >> data->sar_shift) & data->sar_mask;
80
81 return reg;
82}
83
84static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val)
85{
86 return DIV_ROUND_CLOSEST(data->vdd * val, 1 << data->output_res);
87}
88
89static ssize_t in0_input_show(struct device *dev,
90 struct device_attribute *attr, char *buf)
91{
92 struct i2c_client *client = to_i2c_client(dev);
93 struct mcp3021_data *data = i2c_get_clientdata(client);
94 int reg, in_input;
95
96 reg = mcp3021_read16(client);
97 if (reg < 0)
98 return reg;
99
100 in_input = volts_from_reg(data, reg);
101
102 return sprintf(buf, "%d\n", in_input);
103}
104
105static DEVICE_ATTR_RO(in0_input);
106
107static int mcp3021_probe(struct i2c_client *client,
108 const struct i2c_device_id *id)
109{
110 int err;
111 struct mcp3021_data *data = NULL;
112 struct device_node *np = client->dev.of_node;
113
114 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
115 return -ENODEV;
116
117 data = devm_kzalloc(&client->dev, sizeof(struct mcp3021_data),
118 GFP_KERNEL);
119 if (!data)
120 return -ENOMEM;
121
122 i2c_set_clientdata(client, data);
123
124 if (np) {
125 if (!of_property_read_u32(np, "reference-voltage-microvolt",
126 &data->vdd))
127 data->vdd /= 1000;
128 else
129 data->vdd = MCP3021_VDD_REF_DEFAULT;
130 } else {
131 u32 *pdata = dev_get_platdata(&client->dev);
132
133 if (pdata)
134 data->vdd = *pdata;
135 else
136 data->vdd = MCP3021_VDD_REF_DEFAULT;
137 }
138
139 switch (id->driver_data) {
140 case mcp3021:
141 data->sar_shift = MCP3021_SAR_SHIFT;
142 data->sar_mask = MCP3021_SAR_MASK;
143 data->output_res = MCP3021_OUTPUT_RES;
144 break;
145
146 case mcp3221:
147 data->sar_shift = MCP3221_SAR_SHIFT;
148 data->sar_mask = MCP3221_SAR_MASK;
149 data->output_res = MCP3221_OUTPUT_RES;
150 break;
151 }
152
153 if (data->vdd > MCP3021_VDD_REF_MAX || data->vdd < MCP3021_VDD_REF_MIN)
154 return -EINVAL;
155
156 err = sysfs_create_file(&client->dev.kobj, &dev_attr_in0_input.attr);
157 if (err)
158 return err;
159
160 data->hwmon_dev = hwmon_device_register(&client->dev);
161 if (IS_ERR(data->hwmon_dev)) {
162 err = PTR_ERR(data->hwmon_dev);
163 goto exit_remove;
164 }
165
166 return 0;
167
168exit_remove:
169 sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
170 return err;
171}
172
173static int mcp3021_remove(struct i2c_client *client)
174{
175 struct mcp3021_data *data = i2c_get_clientdata(client);
176
177 hwmon_device_unregister(data->hwmon_dev);
178 sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
179
180 return 0;
181}
182
183static const struct i2c_device_id mcp3021_id[] = {
184 { "mcp3021", mcp3021 },
185 { "mcp3221", mcp3221 },
186 { }
187};
188MODULE_DEVICE_TABLE(i2c, mcp3021_id);
189
190#ifdef CONFIG_OF
191static const struct of_device_id of_mcp3021_match[] = {
192 { .compatible = "microchip,mcp3021", .data = (void *)mcp3021 },
193 { .compatible = "microchip,mcp3221", .data = (void *)mcp3221 },
194 { }
195};
196MODULE_DEVICE_TABLE(of, of_mcp3021_match);
197#endif
198
199static struct i2c_driver mcp3021_driver = {
200 .driver = {
201 .name = "mcp3021",
202 .of_match_table = of_match_ptr(of_mcp3021_match),
203 },
204 .probe = mcp3021_probe,
205 .remove = mcp3021_remove,
206 .id_table = mcp3021_id,
207};
208
209module_i2c_driver(mcp3021_driver);
210
211MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");
212MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver");
213MODULE_LICENSE("GPL");
214