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1 | /* | |
2 | * mcp3021.c - driver for Microchip MCP3021 and MCP3221 | |
3 | * | |
4 | * Copyright (C) 2008-2009, 2012 Freescale Semiconductor, Inc. | |
5 | * Author: Mingkai Hu <Mingkai.hu@freescale.com> | |
6 | * Reworked by Sven Schuchmann <schuchmann@schleissheimer.de> | |
7 | * DT support added by Clemens Gruber <clemens.gruber@pqgruber.com> | |
8 | * | |
9 | * This driver export the value of analog input voltage to sysfs, the | |
10 | * voltage unit is mV. Through the sysfs interface, lm-sensors tool | |
11 | * can also display the input voltage. | |
12 | * | |
13 | * This program is free software; you can redistribute it and/or modify | |
14 | * it under the terms of the GNU General Public License as published by | |
15 | * the Free Software Foundation; either version 2 of the License, or | |
16 | * (at your option) any later version. | |
17 | */ | |
18 | ||
19 | #include <linux/kernel.h> | |
20 | #include <linux/module.h> | |
21 | #include <linux/hwmon.h> | |
22 | #include <linux/slab.h> | |
23 | #include <linux/i2c.h> | |
24 | #include <linux/err.h> | |
25 | #include <linux/device.h> | |
26 | #include <linux/of.h> | |
27 | #include <linux/of_device.h> | |
28 | ||
29 | /* Vdd / reference voltage in millivolt */ | |
30 | #define MCP3021_VDD_REF_MAX 5500 | |
31 | #define MCP3021_VDD_REF_MIN 2700 | |
32 | #define MCP3021_VDD_REF_DEFAULT 3300 | |
33 | ||
34 | /* output format */ | |
35 | #define MCP3021_SAR_SHIFT 2 | |
36 | #define MCP3021_SAR_MASK 0x3ff | |
37 | #define MCP3021_OUTPUT_RES 10 /* 10-bit resolution */ | |
38 | ||
39 | #define MCP3221_SAR_SHIFT 0 | |
40 | #define MCP3221_SAR_MASK 0xfff | |
41 | #define MCP3221_OUTPUT_RES 12 /* 12-bit resolution */ | |
42 | ||
43 | enum chips { | |
44 | mcp3021, | |
45 | mcp3221 | |
46 | }; | |
47 | ||
48 | /* | |
49 | * Client data (each client gets its own) | |
50 | */ | |
51 | struct mcp3021_data { | |
52 | struct device *hwmon_dev; | |
53 | u32 vdd; /* supply and reference voltage in millivolt */ | |
54 | u16 sar_shift; | |
55 | u16 sar_mask; | |
56 | u8 output_res; | |
57 | }; | |
58 | ||
59 | static int mcp3021_read16(struct i2c_client *client) | |
60 | { | |
61 | struct mcp3021_data *data = i2c_get_clientdata(client); | |
62 | int ret; | |
63 | u16 reg; | |
64 | __be16 buf; | |
65 | ||
66 | ret = i2c_master_recv(client, (char *)&buf, 2); | |
67 | if (ret < 0) | |
68 | return ret; | |
69 | if (ret != 2) | |
70 | return -EIO; | |
71 | ||
72 | /* The output code of the MCP3021 is transmitted with MSB first. */ | |
73 | reg = be16_to_cpu(buf); | |
74 | ||
75 | /* | |
76 | * The ten-bit output code is composed of the lower 4-bit of the | |
77 | * first byte and the upper 6-bit of the second byte. | |
78 | */ | |
79 | reg = (reg >> data->sar_shift) & data->sar_mask; | |
80 | ||
81 | return reg; | |
82 | } | |
83 | ||
84 | static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val) | |
85 | { | |
86 | return DIV_ROUND_CLOSEST(data->vdd * val, 1 << data->output_res); | |
87 | } | |
88 | ||
89 | static ssize_t in0_input_show(struct device *dev, | |
90 | struct device_attribute *attr, char *buf) | |
91 | { | |
92 | struct i2c_client *client = to_i2c_client(dev); | |
93 | struct mcp3021_data *data = i2c_get_clientdata(client); | |
94 | int reg, in_input; | |
95 | ||
96 | reg = mcp3021_read16(client); | |
97 | if (reg < 0) | |
98 | return reg; | |
99 | ||
100 | in_input = volts_from_reg(data, reg); | |
101 | ||
102 | return sprintf(buf, "%d\n", in_input); | |
103 | } | |
104 | ||
105 | static DEVICE_ATTR_RO(in0_input); | |
106 | ||
107 | static int mcp3021_probe(struct i2c_client *client, | |
108 | const struct i2c_device_id *id) | |
109 | { | |
110 | int err; | |
111 | struct mcp3021_data *data = NULL; | |
112 | struct device_node *np = client->dev.of_node; | |
113 | ||
114 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) | |
115 | return -ENODEV; | |
116 | ||
117 | data = devm_kzalloc(&client->dev, sizeof(struct mcp3021_data), | |
118 | GFP_KERNEL); | |
119 | if (!data) | |
120 | return -ENOMEM; | |
121 | ||
122 | i2c_set_clientdata(client, data); | |
123 | ||
124 | if (np) { | |
125 | if (!of_property_read_u32(np, "reference-voltage-microvolt", | |
126 | &data->vdd)) | |
127 | data->vdd /= 1000; | |
128 | else | |
129 | data->vdd = MCP3021_VDD_REF_DEFAULT; | |
130 | } else { | |
131 | u32 *pdata = dev_get_platdata(&client->dev); | |
132 | ||
133 | if (pdata) | |
134 | data->vdd = *pdata; | |
135 | else | |
136 | data->vdd = MCP3021_VDD_REF_DEFAULT; | |
137 | } | |
138 | ||
139 | switch (id->driver_data) { | |
140 | case mcp3021: | |
141 | data->sar_shift = MCP3021_SAR_SHIFT; | |
142 | data->sar_mask = MCP3021_SAR_MASK; | |
143 | data->output_res = MCP3021_OUTPUT_RES; | |
144 | break; | |
145 | ||
146 | case mcp3221: | |
147 | data->sar_shift = MCP3221_SAR_SHIFT; | |
148 | data->sar_mask = MCP3221_SAR_MASK; | |
149 | data->output_res = MCP3221_OUTPUT_RES; | |
150 | break; | |
151 | } | |
152 | ||
153 | if (data->vdd > MCP3021_VDD_REF_MAX || data->vdd < MCP3021_VDD_REF_MIN) | |
154 | return -EINVAL; | |
155 | ||
156 | err = sysfs_create_file(&client->dev.kobj, &dev_attr_in0_input.attr); | |
157 | if (err) | |
158 | return err; | |
159 | ||
160 | data->hwmon_dev = hwmon_device_register(&client->dev); | |
161 | if (IS_ERR(data->hwmon_dev)) { | |
162 | err = PTR_ERR(data->hwmon_dev); | |
163 | goto exit_remove; | |
164 | } | |
165 | ||
166 | return 0; | |
167 | ||
168 | exit_remove: | |
169 | sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr); | |
170 | return err; | |
171 | } | |
172 | ||
173 | static int mcp3021_remove(struct i2c_client *client) | |
174 | { | |
175 | struct mcp3021_data *data = i2c_get_clientdata(client); | |
176 | ||
177 | hwmon_device_unregister(data->hwmon_dev); | |
178 | sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr); | |
179 | ||
180 | return 0; | |
181 | } | |
182 | ||
183 | static const struct i2c_device_id mcp3021_id[] = { | |
184 | { "mcp3021", mcp3021 }, | |
185 | { "mcp3221", mcp3221 }, | |
186 | { } | |
187 | }; | |
188 | MODULE_DEVICE_TABLE(i2c, mcp3021_id); | |
189 | ||
190 | #ifdef CONFIG_OF | |
191 | static const struct of_device_id of_mcp3021_match[] = { | |
192 | { .compatible = "microchip,mcp3021", .data = (void *)mcp3021 }, | |
193 | { .compatible = "microchip,mcp3221", .data = (void *)mcp3221 }, | |
194 | { } | |
195 | }; | |
196 | MODULE_DEVICE_TABLE(of, of_mcp3021_match); | |
197 | #endif | |
198 | ||
199 | static struct i2c_driver mcp3021_driver = { | |
200 | .driver = { | |
201 | .name = "mcp3021", | |
202 | .of_match_table = of_match_ptr(of_mcp3021_match), | |
203 | }, | |
204 | .probe = mcp3021_probe, | |
205 | .remove = mcp3021_remove, | |
206 | .id_table = mcp3021_id, | |
207 | }; | |
208 | ||
209 | module_i2c_driver(mcp3021_driver); | |
210 | ||
211 | MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>"); | |
212 | MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver"); | |
213 | MODULE_LICENSE("GPL"); |