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
40enum chips {
41	mcp3021,
42	mcp3221
43};
44
45/*
46 * Client data (each client gets its own)
47 */
48struct 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
56static 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
81static 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
86static 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
102static DEVICE_ATTR(in0_input, S_IRUGO, show_in_input, NULL);
103
104static 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
154exit_remove:
155	sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
156	return err;
157}
158
159static 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
169static const struct i2c_device_id mcp3021_id[] = {
170	{ "mcp3021", mcp3021 },
171	{ "mcp3221", mcp3221 },
172	{ }
173};
174MODULE_DEVICE_TABLE(i2c, mcp3021_id);
175
176static 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
185module_i2c_driver(mcp3021_driver);
186
187MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");
188MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver");
189MODULE_LICENSE("GPL");
190