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
103 static const struct i2c_device_id mcp3021_id[];
104
mcp3021_probe(struct i2c_client * client)105 static 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
165 exit_remove:
166 sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
167 return err;
168 }
169
mcp3021_remove(struct i2c_client * client)170 static 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
180 static const struct i2c_device_id mcp3021_id[] = {
181 { "mcp3021", mcp3021 },
182 { "mcp3221", mcp3221 },
183 { }
184 };
185 MODULE_DEVICE_TABLE(i2c, mcp3021_id);
186
187 #ifdef CONFIG_OF
188 static const struct of_device_id of_mcp3021_match[] = {
189 { .compatible = "microchip,mcp3021", .data = (void *)mcp3021 },
190 { .compatible = "microchip,mcp3221", .data = (void *)mcp3221 },
191 { }
192 };
193 MODULE_DEVICE_TABLE(of, of_mcp3021_match);
194 #endif
195
196 static 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
206 module_i2c_driver(mcp3021_driver);
207
208 MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");
209 MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver");
210 MODULE_LICENSE("GPL");
211
