1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * mcp3021.c - driver for Microchip MCP3021 and MCP3221
4 *
5 * Copyright (C) 2008-2009, 2012 Freescale Semiconductor, Inc.
6 * Author: Mingkai Hu <Mingkai.hu@freescale.com>
7 * Reworked by Sven Schuchmann <schuchmann@schleissheimer.de>
8 * DT support added by Clemens Gruber <clemens.gruber@pqgruber.com>
9 *
10 * This driver export the value of analog input voltage to sysfs, the
11 * voltage unit is mV. Through the sysfs interface, lm-sensors tool
12 * can also display the input voltage.
13 */
14
15#include <linux/kernel.h>
16#include <linux/module.h>
17#include <linux/hwmon.h>
18#include <linux/slab.h>
19#include <linux/i2c.h>
20#include <linux/err.h>
21#include <linux/device.h>
22#include <linux/of.h>
23#include <linux/of_device.h>
24
25/* Vdd / reference voltage in millivolt */
26#define MCP3021_VDD_REF_MAX	5500
27#define MCP3021_VDD_REF_MIN	2700
28#define MCP3021_VDD_REF_DEFAULT	3300
29
30/* output format */
31#define MCP3021_SAR_SHIFT	2
32#define MCP3021_SAR_MASK	0x3ff
33#define MCP3021_OUTPUT_RES	10	/* 10-bit resolution */
34
35#define MCP3221_SAR_SHIFT	0
36#define MCP3221_SAR_MASK	0xfff
37#define MCP3221_OUTPUT_RES	12	/* 12-bit resolution */
38
39enum chips {
40	mcp3021,
41	mcp3221
42};
43
44/*
45 * Client data (each client gets its own)
46 */
47struct mcp3021_data {
48	struct device *hwmon_dev;
49	u32 vdd;        /* supply and reference voltage in millivolt */
50	u16 sar_shift;
51	u16 sar_mask;
52	u8 output_res;
53};
54
55static int mcp3021_read16(struct i2c_client *client)
56{
57	struct mcp3021_data *data = i2c_get_clientdata(client);
58	int ret;
59	u16 reg;
60	__be16 buf;
61
62	ret = i2c_master_recv(client, (char *)&buf, 2);
63	if (ret < 0)
64		return ret;
65	if (ret != 2)
66		return -EIO;
67
68	/* The output code of the MCP3021 is transmitted with MSB first. */
69	reg = be16_to_cpu(buf);
70
71	/*
72	 * The ten-bit output code is composed of the lower 4-bit of the
73	 * first byte and the upper 6-bit of the second byte.
74	 */
75	reg = (reg >> data->sar_shift) & data->sar_mask;
76
77	return reg;
78}
79
80static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val)
81{
82	return DIV_ROUND_CLOSEST(data->vdd * val, 1 << data->output_res);
83}
84
85static ssize_t in0_input_show(struct device *dev,
86			      struct device_attribute *attr, char *buf)
87{
88	struct i2c_client *client = to_i2c_client(dev);
89	struct mcp3021_data *data = i2c_get_clientdata(client);
90	int reg, in_input;
91
92	reg = mcp3021_read16(client);
93	if (reg < 0)
94		return reg;
95
96	in_input = volts_from_reg(data, reg);
97
98	return sprintf(buf, "%d\n", in_input);
99}
100
101static DEVICE_ATTR_RO(in0_input);
102
103static const struct i2c_device_id mcp3021_id[];
104
105static int mcp3021_probe(struct i2c_client *client)
106{
107	int err;
108	struct mcp3021_data *data = NULL;
109	struct device_node *np = client->dev.of_node;
110
111	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
112		return -ENODEV;
113
114	data = devm_kzalloc(&client->dev, sizeof(struct mcp3021_data),
115			    GFP_KERNEL);
116	if (!data)
117		return -ENOMEM;
118
119	i2c_set_clientdata(client, data);
120
121	if (np) {
122		if (!of_property_read_u32(np, "reference-voltage-microvolt",
123					  &data->vdd))
124			data->vdd /= 1000;
125		else
126			data->vdd = MCP3021_VDD_REF_DEFAULT;
127	} else {
128		u32 *pdata = dev_get_platdata(&client->dev);
129
130		if (pdata)
131			data->vdd = *pdata;
132		else
133			data->vdd = MCP3021_VDD_REF_DEFAULT;
134	}
135
136	switch (i2c_match_id(mcp3021_id, client)->driver_data) {
137	case mcp3021:
138		data->sar_shift = MCP3021_SAR_SHIFT;
139		data->sar_mask = MCP3021_SAR_MASK;
140		data->output_res = MCP3021_OUTPUT_RES;
141		break;
142
143	case mcp3221:
144		data->sar_shift = MCP3221_SAR_SHIFT;
145		data->sar_mask = MCP3221_SAR_MASK;
146		data->output_res = MCP3221_OUTPUT_RES;
147		break;
148	}
149
150	if (data->vdd > MCP3021_VDD_REF_MAX || data->vdd < MCP3021_VDD_REF_MIN)
151		return -EINVAL;
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
165exit_remove:
166	sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
167	return err;
168}
169
170static 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
180static const struct i2c_device_id mcp3021_id[] = {
181	{ "mcp3021", mcp3021 },
182	{ "mcp3221", mcp3221 },
183	{ }
184};
185MODULE_DEVICE_TABLE(i2c, mcp3021_id);
186
187#ifdef CONFIG_OF
188static const struct of_device_id of_mcp3021_match[] = {
189	{ .compatible = "microchip,mcp3021", .data = (void *)mcp3021 },
190	{ .compatible = "microchip,mcp3221", .data = (void *)mcp3221 },
191	{ }
192};
193MODULE_DEVICE_TABLE(of, of_mcp3021_match);
194#endif
195
196static struct i2c_driver mcp3021_driver = {
197	.driver = {
198		.name = "mcp3021",
199		.of_match_table = of_match_ptr(of_mcp3021_match),
200	},
201	.probe_new = mcp3021_probe,
202	.remove = mcp3021_remove,
203	.id_table = mcp3021_id,
204};
205
206module_i2c_driver(mcp3021_driver);
207
208MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");
209MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver");
210MODULE_LICENSE("GPL");
211