xref: /openbmc/linux/drivers/hwmon/mcp3021.c (revision 39f03438)
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 exports 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 
24 /* Vdd / reference voltage in millivolt */
25 #define MCP3021_VDD_REF_MAX	5500
26 #define MCP3021_VDD_REF_MIN	2700
27 #define MCP3021_VDD_REF_DEFAULT	3300
28 
29 /* output format */
30 #define MCP3021_SAR_SHIFT	2
31 #define MCP3021_SAR_MASK	0x3ff
32 #define MCP3021_OUTPUT_RES	10	/* 10-bit resolution */
33 
34 #define MCP3221_SAR_SHIFT	0
35 #define MCP3221_SAR_MASK	0xfff
36 #define MCP3221_OUTPUT_RES	12	/* 12-bit resolution */
37 
38 enum chips {
39 	mcp3021,
40 	mcp3221
41 };
42 
43 /*
44  * Client data (each client gets its own)
45  */
46 struct mcp3021_data {
47 	struct i2c_client *client;
48 	u32 vdd;        /* supply and reference voltage in millivolt */
49 	u16 sar_shift;
50 	u16 sar_mask;
51 	u8 output_res;
52 };
53 
volts_from_reg(struct mcp3021_data * data,u16 val)54 static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val)
55 {
56 	return DIV_ROUND_CLOSEST(data->vdd * val, 1 << data->output_res);
57 }
58 
mcp3021_read(struct device * dev,enum hwmon_sensor_types type,u32 attr,int channel,long * val)59 static int mcp3021_read(struct device *dev, enum hwmon_sensor_types type,
60 			u32 attr, int channel, long *val)
61 {
62 	struct mcp3021_data *data = dev_get_drvdata(dev);
63 	struct i2c_client *client = data->client;
64 	__be16 buf;
65 	u16 reg;
66 	int ret;
67 
68 	if (type != hwmon_in)
69 		return -EOPNOTSUPP;
70 
71 	ret = i2c_master_recv(client, (char *)&buf, 2);
72 	if (ret < 0)
73 		return ret;
74 	if (ret != 2)
75 		return -EIO;
76 
77 	/* The output code of the MCP3021 is transmitted with MSB first. */
78 	reg = be16_to_cpu(buf);
79 
80 	/*
81 	 * The ten-bit output code is composed of the lower 4-bit of the
82 	 * first byte and the upper 6-bit of the second byte.
83 	 */
84 	reg = (reg >> data->sar_shift) & data->sar_mask;
85 
86 	*val = volts_from_reg(data, reg);
87 
88 	return 0;
89 }
90 
mcp3021_is_visible(const void * _data,enum hwmon_sensor_types type,u32 attr,int channel)91 static umode_t mcp3021_is_visible(const void *_data,
92 				  enum hwmon_sensor_types type,
93 				  u32 attr, int channel)
94 {
95 	if (type != hwmon_in)
96 		return 0;
97 
98 	if (attr != hwmon_in_input)
99 		return 0;
100 
101 	return 0444;
102 }
103 
104 static const struct hwmon_channel_info * const mcp3021_info[] = {
105 	HWMON_CHANNEL_INFO(in, HWMON_I_INPUT),
106 	NULL
107 };
108 
109 static const struct hwmon_ops mcp3021_hwmon_ops = {
110 	.is_visible = mcp3021_is_visible,
111 	.read = mcp3021_read,
112 };
113 
114 static const struct hwmon_chip_info mcp3021_chip_info = {
115 	.ops = &mcp3021_hwmon_ops,
116 	.info = mcp3021_info,
117 };
118 
119 static const struct i2c_device_id mcp3021_id[];
120 
mcp3021_probe(struct i2c_client * client)121 static int mcp3021_probe(struct i2c_client *client)
122 {
123 	struct mcp3021_data *data = NULL;
124 	struct device_node *np = client->dev.of_node;
125 	struct device *hwmon_dev;
126 
127 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
128 		return -ENODEV;
129 
130 	data = devm_kzalloc(&client->dev, sizeof(struct mcp3021_data),
131 			    GFP_KERNEL);
132 	if (!data)
133 		return -ENOMEM;
134 
135 	i2c_set_clientdata(client, data);
136 
137 	if (np) {
138 		if (!of_property_read_u32(np, "reference-voltage-microvolt",
139 					  &data->vdd))
140 			data->vdd /= 1000;
141 		else
142 			data->vdd = MCP3021_VDD_REF_DEFAULT;
143 	} else {
144 		u32 *pdata = dev_get_platdata(&client->dev);
145 
146 		if (pdata)
147 			data->vdd = *pdata;
148 		else
149 			data->vdd = MCP3021_VDD_REF_DEFAULT;
150 	}
151 
152 	switch (i2c_match_id(mcp3021_id, client)->driver_data) {
153 	case mcp3021:
154 		data->sar_shift = MCP3021_SAR_SHIFT;
155 		data->sar_mask = MCP3021_SAR_MASK;
156 		data->output_res = MCP3021_OUTPUT_RES;
157 		break;
158 
159 	case mcp3221:
160 		data->sar_shift = MCP3221_SAR_SHIFT;
161 		data->sar_mask = MCP3221_SAR_MASK;
162 		data->output_res = MCP3221_OUTPUT_RES;
163 		break;
164 	}
165 
166 	data->client = client;
167 
168 	if (data->vdd > MCP3021_VDD_REF_MAX || data->vdd < MCP3021_VDD_REF_MIN)
169 		return -EINVAL;
170 
171 	hwmon_dev = devm_hwmon_device_register_with_info(&client->dev,
172 							 client->name,
173 							 data,
174 							 &mcp3021_chip_info,
175 							 NULL);
176 	return PTR_ERR_OR_ZERO(hwmon_dev);
177 }
178 
179 static const struct i2c_device_id mcp3021_id[] = {
180 	{ "mcp3021", mcp3021 },
181 	{ "mcp3221", mcp3221 },
182 	{ }
183 };
184 MODULE_DEVICE_TABLE(i2c, mcp3021_id);
185 
186 #ifdef CONFIG_OF
187 static const struct of_device_id of_mcp3021_match[] = {
188 	{ .compatible = "microchip,mcp3021", .data = (void *)mcp3021 },
189 	{ .compatible = "microchip,mcp3221", .data = (void *)mcp3221 },
190 	{ }
191 };
192 MODULE_DEVICE_TABLE(of, of_mcp3021_match);
193 #endif
194 
195 static struct i2c_driver mcp3021_driver = {
196 	.driver = {
197 		.name = "mcp3021",
198 		.of_match_table = of_match_ptr(of_mcp3021_match),
199 	},
200 	.probe = mcp3021_probe,
201 	.id_table = mcp3021_id,
202 };
203 
204 module_i2c_driver(mcp3021_driver);
205 
206 MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");
207 MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver");
208 MODULE_LICENSE("GPL");
209