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
39 enum chips {
40 mcp3021,
41 mcp3221
42 };
43
44 /*
45 * Client data (each client gets its own)
46 */
47 struct 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
mcp3021_read16(struct i2c_client * client)55 static 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
volts_from_reg(struct mcp3021_data * data,u16 val)80 static 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
in0_input_show(struct device * dev,struct device_attribute * attr,char * buf)85 static 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
101 static DEVICE_ATTR_RO(in0_input);
102
mcp3021_probe(struct i2c_client * client,const struct i2c_device_id * id)103 static int mcp3021_probe(struct i2c_client *client,
104 const struct i2c_device_id *id)
105 {
106 int err;
107 struct mcp3021_data *data = NULL;
108 struct device_node *np = client->dev.of_node;
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 if (np) {
121 if (!of_property_read_u32(np, "reference-voltage-microvolt",
122 &data->vdd))
123 data->vdd /= 1000;
124 else
125 data->vdd = MCP3021_VDD_REF_DEFAULT;
126 } else {
127 u32 *pdata = dev_get_platdata(&client->dev);
128
129 if (pdata)
130 data->vdd = *pdata;
131 else
132 data->vdd = MCP3021_VDD_REF_DEFAULT;
133 }
134
135 switch (id->driver_data) {
136 case mcp3021:
137 data->sar_shift = MCP3021_SAR_SHIFT;
138 data->sar_mask = MCP3021_SAR_MASK;
139 data->output_res = MCP3021_OUTPUT_RES;
140 break;
141
142 case mcp3221:
143 data->sar_shift = MCP3221_SAR_SHIFT;
144 data->sar_mask = MCP3221_SAR_MASK;
145 data->output_res = MCP3221_OUTPUT_RES;
146 break;
147 }
148
149 if (data->vdd > MCP3021_VDD_REF_MAX || data->vdd < MCP3021_VDD_REF_MIN)
150 return -EINVAL;
151
152 err = sysfs_create_file(&client->dev.kobj, &dev_attr_in0_input.attr);
153 if (err)
154 return err;
155
156 data->hwmon_dev = hwmon_device_register(&client->dev);
157 if (IS_ERR(data->hwmon_dev)) {
158 err = PTR_ERR(data->hwmon_dev);
159 goto exit_remove;
160 }
161
162 return 0;
163
164 exit_remove:
165 sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
166 return err;
167 }
168
mcp3021_remove(struct i2c_client * client)169 static int mcp3021_remove(struct i2c_client *client)
170 {
171 struct mcp3021_data *data = i2c_get_clientdata(client);
172
173 hwmon_device_unregister(data->hwmon_dev);
174 sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
175
176 return 0;
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 .remove = mcp3021_remove,
202 .id_table = mcp3021_id,
203 };
204
205 module_i2c_driver(mcp3021_driver);
206
207 MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");
208 MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver");
209 MODULE_LICENSE("GPL");
210
