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
mcp3021_probe(struct i2c_client * client)119 static int mcp3021_probe(struct i2c_client *client)
120 {
121 struct mcp3021_data *data = NULL;
122 struct device_node *np = client->dev.of_node;
123 struct device *hwmon_dev;
124 enum chips type;
125
126 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
127 return -ENODEV;
128
129 data = devm_kzalloc(&client->dev, sizeof(struct mcp3021_data),
130 GFP_KERNEL);
131 if (!data)
132 return -ENOMEM;
133
134 i2c_set_clientdata(client, data);
135
136 if (np) {
137 if (!of_property_read_u32(np, "reference-voltage-microvolt",
138 &data->vdd))
139 data->vdd /= 1000;
140 else
141 data->vdd = MCP3021_VDD_REF_DEFAULT;
142 } else {
143 u32 *pdata = dev_get_platdata(&client->dev);
144
145 if (pdata)
146 data->vdd = *pdata;
147 else
148 data->vdd = MCP3021_VDD_REF_DEFAULT;
149 }
150
151 type = (uintptr_t)i2c_get_match_data(client);
152 switch (type) {
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