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e0c70b80 PT |
1 | /* |
2 | * ads7871 - driver for TI ADS7871 A/D converter | |
3 | * | |
4 | * Copyright (c) 2010 Paul Thomas <pthomas8589@gmail.com> | |
5 | * | |
6 | * This program is distributed in the hope that it will be useful, | |
7 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
8 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
9 | * GNU General Public License for more details. | |
10 | * | |
11 | * This program is free software; you can redistribute it and/or modify | |
12 | * it under the terms of the GNU General Public License version 2 or | |
13 | * later as publishhed by the Free Software Foundation. | |
14 | * | |
15 | * You need to have something like this in struct spi_board_info | |
16 | * { | |
17 | * .modalias = "ads7871", | |
18 | * .max_speed_hz = 2*1000*1000, | |
19 | * .chip_select = 0, | |
20 | * .bus_num = 1, | |
21 | * }, | |
22 | */ | |
23 | ||
24 | /*From figure 18 in the datasheet*/ | |
25 | /*Register addresses*/ | |
26 | #define REG_LS_BYTE 0 /*A/D Output Data, LS Byte*/ | |
27 | #define REG_MS_BYTE 1 /*A/D Output Data, MS Byte*/ | |
28 | #define REG_PGA_VALID 2 /*PGA Valid Register*/ | |
29 | #define REG_AD_CONTROL 3 /*A/D Control Register*/ | |
30 | #define REG_GAIN_MUX 4 /*Gain/Mux Register*/ | |
31 | #define REG_IO_STATE 5 /*Digital I/O State Register*/ | |
32 | #define REG_IO_CONTROL 6 /*Digital I/O Control Register*/ | |
33 | #define REG_OSC_CONTROL 7 /*Rev/Oscillator Control Register*/ | |
34 | #define REG_SER_CONTROL 24 /*Serial Interface Control Register*/ | |
35 | #define REG_ID 31 /*ID Register*/ | |
36 | ||
37 | /*From figure 17 in the datasheet | |
38 | * These bits get ORed with the address to form | |
39 | * the instruction byte */ | |
40 | /*Instruction Bit masks*/ | |
41 | #define INST_MODE_bm (1<<7) | |
42 | #define INST_READ_bm (1<<6) | |
43 | #define INST_16BIT_bm (1<<5) | |
44 | ||
45 | /*From figure 18 in the datasheet*/ | |
46 | /*bit masks for Rev/Oscillator Control Register*/ | |
47 | #define MUX_CNV_bv 7 | |
48 | #define MUX_CNV_bm (1<<MUX_CNV_bv) | |
49 | #define MUX_M3_bm (1<<3) /*M3 selects single ended*/ | |
50 | #define MUX_G_bv 4 /*allows for reg = (gain << MUX_G_bv) | ...*/ | |
51 | ||
52 | /*From figure 18 in the datasheet*/ | |
53 | /*bit masks for Rev/Oscillator Control Register*/ | |
54 | #define OSC_OSCR_bm (1<<5) | |
55 | #define OSC_OSCE_bm (1<<4) | |
56 | #define OSC_REFE_bm (1<<3) | |
57 | #define OSC_BUFE_bm (1<<2) | |
58 | #define OSC_R2V_bm (1<<1) | |
59 | #define OSC_RBG_bm (1<<0) | |
60 | ||
61 | #include <linux/module.h> | |
62 | #include <linux/init.h> | |
63 | #include <linux/spi/spi.h> | |
64 | #include <linux/hwmon.h> | |
65 | #include <linux/hwmon-sysfs.h> | |
66 | #include <linux/err.h> | |
67 | #include <linux/mutex.h> | |
68 | #include <linux/delay.h> | |
69 | ||
70 | #define DEVICE_NAME "ads7871" | |
71 | ||
72 | struct ads7871_data { | |
73 | struct device *hwmon_dev; | |
74 | struct mutex update_lock; | |
75 | }; | |
76 | ||
77 | static int ads7871_read_reg8(struct spi_device *spi, int reg) | |
78 | { | |
79 | int ret; | |
80 | reg = reg | INST_READ_bm; | |
81 | ret = spi_w8r8(spi, reg); | |
82 | return ret; | |
83 | } | |
84 | ||
85 | static int ads7871_read_reg16(struct spi_device *spi, int reg) | |
86 | { | |
87 | int ret; | |
88 | reg = reg | INST_READ_bm | INST_16BIT_bm; | |
89 | ret = spi_w8r16(spi, reg); | |
90 | return ret; | |
91 | } | |
92 | ||
93 | static int ads7871_write_reg8(struct spi_device *spi, int reg, u8 val) | |
94 | { | |
95 | u8 tmp[2] = {reg, val}; | |
96 | return spi_write(spi, tmp, sizeof(tmp)); | |
97 | } | |
98 | ||
99 | static ssize_t show_voltage(struct device *dev, | |
100 | struct device_attribute *da, char *buf) | |
101 | { | |
102 | struct spi_device *spi = to_spi_device(dev); | |
103 | struct sensor_device_attribute *attr = to_sensor_dev_attr(da); | |
104 | int ret, val, i = 0; | |
105 | uint8_t channel, mux_cnv; | |
106 | ||
107 | channel = attr->index; | |
108 | /*TODO: add support for conversions | |
109 | *other than single ended with a gain of 1*/ | |
110 | /*MUX_M3_bm forces single ended*/ | |
111 | /*This is also where the gain of the PGA would be set*/ | |
112 | ads7871_write_reg8(spi, REG_GAIN_MUX, | |
113 | (MUX_CNV_bm | MUX_M3_bm | channel)); | |
114 | ||
115 | ret = ads7871_read_reg8(spi, REG_GAIN_MUX); | |
116 | mux_cnv = ((ret & MUX_CNV_bm)>>MUX_CNV_bv); | |
117 | /*on 400MHz arm9 platform the conversion | |
118 | *is already done when we do this test*/ | |
119 | while ((i < 2) && mux_cnv) { | |
120 | i++; | |
121 | ret = ads7871_read_reg8(spi, REG_GAIN_MUX); | |
122 | mux_cnv = ((ret & MUX_CNV_bm)>>MUX_CNV_bv); | |
123 | msleep_interruptible(1); | |
124 | } | |
125 | ||
126 | if (mux_cnv == 0) { | |
127 | val = ads7871_read_reg16(spi, REG_LS_BYTE); | |
128 | /*result in volts*10000 = (val/8192)*2.5*10000*/ | |
129 | val = ((val>>2) * 25000) / 8192; | |
130 | return sprintf(buf, "%d\n", val); | |
131 | } else { | |
132 | return -1; | |
133 | } | |
134 | } | |
135 | ||
136 | static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, show_voltage, NULL, 0); | |
137 | static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, show_voltage, NULL, 1); | |
138 | static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, show_voltage, NULL, 2); | |
139 | static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, show_voltage, NULL, 3); | |
140 | static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, show_voltage, NULL, 4); | |
141 | static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, show_voltage, NULL, 5); | |
142 | static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, show_voltage, NULL, 6); | |
143 | static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, show_voltage, NULL, 7); | |
144 | ||
145 | static struct attribute *ads7871_attributes[] = { | |
146 | &sensor_dev_attr_in0_input.dev_attr.attr, | |
147 | &sensor_dev_attr_in1_input.dev_attr.attr, | |
148 | &sensor_dev_attr_in2_input.dev_attr.attr, | |
149 | &sensor_dev_attr_in3_input.dev_attr.attr, | |
150 | &sensor_dev_attr_in4_input.dev_attr.attr, | |
151 | &sensor_dev_attr_in5_input.dev_attr.attr, | |
152 | &sensor_dev_attr_in6_input.dev_attr.attr, | |
153 | &sensor_dev_attr_in7_input.dev_attr.attr, | |
154 | NULL | |
155 | }; | |
156 | ||
157 | static const struct attribute_group ads7871_group = { | |
158 | .attrs = ads7871_attributes, | |
159 | }; | |
160 | ||
161 | static int __devinit ads7871_probe(struct spi_device *spi) | |
162 | { | |
c12c507d | 163 | int ret, err; |
e0c70b80 PT |
164 | uint8_t val; |
165 | struct ads7871_data *pdata; | |
166 | ||
167 | dev_dbg(&spi->dev, "probe\n"); | |
168 | ||
e0c70b80 PT |
169 | /* Configure the SPI bus */ |
170 | spi->mode = (SPI_MODE_0); | |
171 | spi->bits_per_word = 8; | |
172 | spi_setup(spi); | |
173 | ||
174 | ads7871_write_reg8(spi, REG_SER_CONTROL, 0); | |
175 | ads7871_write_reg8(spi, REG_AD_CONTROL, 0); | |
176 | ||
177 | val = (OSC_OSCR_bm | OSC_OSCE_bm | OSC_REFE_bm | OSC_BUFE_bm); | |
178 | ads7871_write_reg8(spi, REG_OSC_CONTROL, val); | |
179 | ret = ads7871_read_reg8(spi, REG_OSC_CONTROL); | |
180 | ||
181 | dev_dbg(&spi->dev, "REG_OSC_CONTROL write:%x, read:%x\n", val, ret); | |
182 | /*because there is no other error checking on an SPI bus | |
183 | we need to make sure we really have a chip*/ | |
184 | if (val != ret) { | |
185 | err = -ENODEV; | |
c12c507d AL |
186 | goto exit; |
187 | } | |
188 | ||
189 | pdata = kzalloc(sizeof(struct ads7871_data), GFP_KERNEL); | |
190 | if (!pdata) { | |
191 | err = -ENOMEM; | |
192 | goto exit; | |
193 | } | |
194 | ||
195 | err = sysfs_create_group(&spi->dev.kobj, &ads7871_group); | |
196 | if (err < 0) | |
197 | goto error_free; | |
198 | ||
199 | spi_set_drvdata(spi, pdata); | |
200 | ||
201 | pdata->hwmon_dev = hwmon_device_register(&spi->dev); | |
202 | if (IS_ERR(pdata->hwmon_dev)) { | |
203 | err = PTR_ERR(pdata->hwmon_dev); | |
e0c70b80 PT |
204 | goto error_remove; |
205 | } | |
206 | ||
207 | return 0; | |
208 | ||
209 | error_remove: | |
210 | sysfs_remove_group(&spi->dev.kobj, &ads7871_group); | |
211 | error_free: | |
212 | kfree(pdata); | |
213 | exit: | |
214 | return err; | |
215 | } | |
216 | ||
217 | static int __devexit ads7871_remove(struct spi_device *spi) | |
218 | { | |
219 | struct ads7871_data *pdata = spi_get_drvdata(spi); | |
220 | ||
221 | hwmon_device_unregister(pdata->hwmon_dev); | |
222 | sysfs_remove_group(&spi->dev.kobj, &ads7871_group); | |
223 | kfree(pdata); | |
224 | return 0; | |
225 | } | |
226 | ||
227 | static struct spi_driver ads7871_driver = { | |
228 | .driver = { | |
229 | .name = DEVICE_NAME, | |
230 | .bus = &spi_bus_type, | |
231 | .owner = THIS_MODULE, | |
232 | }, | |
233 | ||
234 | .probe = ads7871_probe, | |
235 | .remove = __devexit_p(ads7871_remove), | |
236 | }; | |
237 | ||
238 | static int __init ads7871_init(void) | |
239 | { | |
240 | return spi_register_driver(&ads7871_driver); | |
241 | } | |
242 | ||
243 | static void __exit ads7871_exit(void) | |
244 | { | |
245 | spi_unregister_driver(&ads7871_driver); | |
246 | } | |
247 | ||
248 | module_init(ads7871_init); | |
249 | module_exit(ads7871_exit); | |
250 | ||
251 | MODULE_AUTHOR("Paul Thomas <pthomas8589@gmail.com>"); | |
252 | MODULE_DESCRIPTION("TI ADS7871 A/D driver"); | |
253 | MODULE_LICENSE("GPL"); |