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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 | ||
10775d18 GR |
37 | /* |
38 | * From figure 17 in the datasheet | |
39 | * These bits get ORed with the address to form | |
40 | * the instruction byte | |
41 | */ | |
e0c70b80 PT |
42 | /*Instruction Bit masks*/ |
43 | #define INST_MODE_bm (1<<7) | |
44 | #define INST_READ_bm (1<<6) | |
45 | #define INST_16BIT_bm (1<<5) | |
46 | ||
47 | /*From figure 18 in the datasheet*/ | |
48 | /*bit masks for Rev/Oscillator Control Register*/ | |
49 | #define MUX_CNV_bv 7 | |
50 | #define MUX_CNV_bm (1<<MUX_CNV_bv) | |
51 | #define MUX_M3_bm (1<<3) /*M3 selects single ended*/ | |
52 | #define MUX_G_bv 4 /*allows for reg = (gain << MUX_G_bv) | ...*/ | |
53 | ||
54 | /*From figure 18 in the datasheet*/ | |
55 | /*bit masks for Rev/Oscillator Control Register*/ | |
56 | #define OSC_OSCR_bm (1<<5) | |
57 | #define OSC_OSCE_bm (1<<4) | |
58 | #define OSC_REFE_bm (1<<3) | |
59 | #define OSC_BUFE_bm (1<<2) | |
60 | #define OSC_R2V_bm (1<<1) | |
61 | #define OSC_RBG_bm (1<<0) | |
62 | ||
63 | #include <linux/module.h> | |
64 | #include <linux/init.h> | |
65 | #include <linux/spi/spi.h> | |
66 | #include <linux/hwmon.h> | |
67 | #include <linux/hwmon-sysfs.h> | |
68 | #include <linux/err.h> | |
69 | #include <linux/mutex.h> | |
70 | #include <linux/delay.h> | |
71 | ||
72 | #define DEVICE_NAME "ads7871" | |
73 | ||
74 | struct ads7871_data { | |
75 | struct device *hwmon_dev; | |
76 | struct mutex update_lock; | |
77 | }; | |
78 | ||
79 | static int ads7871_read_reg8(struct spi_device *spi, int reg) | |
80 | { | |
81 | int ret; | |
82 | reg = reg | INST_READ_bm; | |
83 | ret = spi_w8r8(spi, reg); | |
84 | return ret; | |
85 | } | |
86 | ||
87 | static int ads7871_read_reg16(struct spi_device *spi, int reg) | |
88 | { | |
89 | int ret; | |
90 | reg = reg | INST_READ_bm | INST_16BIT_bm; | |
91 | ret = spi_w8r16(spi, reg); | |
92 | return ret; | |
93 | } | |
94 | ||
95 | static int ads7871_write_reg8(struct spi_device *spi, int reg, u8 val) | |
96 | { | |
97 | u8 tmp[2] = {reg, val}; | |
98 | return spi_write(spi, tmp, sizeof(tmp)); | |
99 | } | |
100 | ||
101 | static ssize_t show_voltage(struct device *dev, | |
102 | struct device_attribute *da, char *buf) | |
103 | { | |
104 | struct spi_device *spi = to_spi_device(dev); | |
105 | struct sensor_device_attribute *attr = to_sensor_dev_attr(da); | |
106 | int ret, val, i = 0; | |
107 | uint8_t channel, mux_cnv; | |
108 | ||
109 | channel = attr->index; | |
10775d18 GR |
110 | /* |
111 | * TODO: add support for conversions | |
112 | * other than single ended with a gain of 1 | |
113 | */ | |
e0c70b80 PT |
114 | /*MUX_M3_bm forces single ended*/ |
115 | /*This is also where the gain of the PGA would be set*/ | |
116 | ads7871_write_reg8(spi, REG_GAIN_MUX, | |
117 | (MUX_CNV_bm | MUX_M3_bm | channel)); | |
118 | ||
119 | ret = ads7871_read_reg8(spi, REG_GAIN_MUX); | |
120 | mux_cnv = ((ret & MUX_CNV_bm)>>MUX_CNV_bv); | |
10775d18 GR |
121 | /* |
122 | * on 400MHz arm9 platform the conversion | |
123 | * is already done when we do this test | |
124 | */ | |
e0c70b80 PT |
125 | while ((i < 2) && mux_cnv) { |
126 | i++; | |
127 | ret = ads7871_read_reg8(spi, REG_GAIN_MUX); | |
128 | mux_cnv = ((ret & MUX_CNV_bm)>>MUX_CNV_bv); | |
129 | msleep_interruptible(1); | |
130 | } | |
131 | ||
132 | if (mux_cnv == 0) { | |
133 | val = ads7871_read_reg16(spi, REG_LS_BYTE); | |
134 | /*result in volts*10000 = (val/8192)*2.5*10000*/ | |
135 | val = ((val>>2) * 25000) / 8192; | |
136 | return sprintf(buf, "%d\n", val); | |
137 | } else { | |
138 | return -1; | |
139 | } | |
140 | } | |
141 | ||
142 | static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, show_voltage, NULL, 0); | |
143 | static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, show_voltage, NULL, 1); | |
144 | static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, show_voltage, NULL, 2); | |
145 | static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, show_voltage, NULL, 3); | |
146 | static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, show_voltage, NULL, 4); | |
147 | static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, show_voltage, NULL, 5); | |
148 | static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, show_voltage, NULL, 6); | |
149 | static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, show_voltage, NULL, 7); | |
150 | ||
151 | static struct attribute *ads7871_attributes[] = { | |
152 | &sensor_dev_attr_in0_input.dev_attr.attr, | |
153 | &sensor_dev_attr_in1_input.dev_attr.attr, | |
154 | &sensor_dev_attr_in2_input.dev_attr.attr, | |
155 | &sensor_dev_attr_in3_input.dev_attr.attr, | |
156 | &sensor_dev_attr_in4_input.dev_attr.attr, | |
157 | &sensor_dev_attr_in5_input.dev_attr.attr, | |
158 | &sensor_dev_attr_in6_input.dev_attr.attr, | |
159 | &sensor_dev_attr_in7_input.dev_attr.attr, | |
160 | NULL | |
161 | }; | |
162 | ||
163 | static const struct attribute_group ads7871_group = { | |
164 | .attrs = ads7871_attributes, | |
165 | }; | |
166 | ||
167 | static int __devinit ads7871_probe(struct spi_device *spi) | |
168 | { | |
c12c507d | 169 | int ret, err; |
e0c70b80 PT |
170 | uint8_t val; |
171 | struct ads7871_data *pdata; | |
172 | ||
173 | dev_dbg(&spi->dev, "probe\n"); | |
174 | ||
e0c70b80 PT |
175 | /* Configure the SPI bus */ |
176 | spi->mode = (SPI_MODE_0); | |
177 | spi->bits_per_word = 8; | |
178 | spi_setup(spi); | |
179 | ||
180 | ads7871_write_reg8(spi, REG_SER_CONTROL, 0); | |
181 | ads7871_write_reg8(spi, REG_AD_CONTROL, 0); | |
182 | ||
183 | val = (OSC_OSCR_bm | OSC_OSCE_bm | OSC_REFE_bm | OSC_BUFE_bm); | |
184 | ads7871_write_reg8(spi, REG_OSC_CONTROL, val); | |
185 | ret = ads7871_read_reg8(spi, REG_OSC_CONTROL); | |
186 | ||
187 | dev_dbg(&spi->dev, "REG_OSC_CONTROL write:%x, read:%x\n", val, ret); | |
10775d18 GR |
188 | /* |
189 | * because there is no other error checking on an SPI bus | |
190 | * we need to make sure we really have a chip | |
191 | */ | |
e0c70b80 PT |
192 | if (val != ret) { |
193 | err = -ENODEV; | |
c12c507d AL |
194 | goto exit; |
195 | } | |
196 | ||
197 | pdata = kzalloc(sizeof(struct ads7871_data), GFP_KERNEL); | |
198 | if (!pdata) { | |
199 | err = -ENOMEM; | |
200 | goto exit; | |
201 | } | |
202 | ||
203 | err = sysfs_create_group(&spi->dev.kobj, &ads7871_group); | |
204 | if (err < 0) | |
205 | goto error_free; | |
206 | ||
207 | spi_set_drvdata(spi, pdata); | |
208 | ||
209 | pdata->hwmon_dev = hwmon_device_register(&spi->dev); | |
210 | if (IS_ERR(pdata->hwmon_dev)) { | |
211 | err = PTR_ERR(pdata->hwmon_dev); | |
e0c70b80 PT |
212 | goto error_remove; |
213 | } | |
214 | ||
215 | return 0; | |
216 | ||
217 | error_remove: | |
218 | sysfs_remove_group(&spi->dev.kobj, &ads7871_group); | |
219 | error_free: | |
220 | kfree(pdata); | |
221 | exit: | |
222 | return err; | |
223 | } | |
224 | ||
225 | static int __devexit ads7871_remove(struct spi_device *spi) | |
226 | { | |
227 | struct ads7871_data *pdata = spi_get_drvdata(spi); | |
228 | ||
229 | hwmon_device_unregister(pdata->hwmon_dev); | |
230 | sysfs_remove_group(&spi->dev.kobj, &ads7871_group); | |
231 | kfree(pdata); | |
232 | return 0; | |
233 | } | |
234 | ||
235 | static struct spi_driver ads7871_driver = { | |
236 | .driver = { | |
237 | .name = DEVICE_NAME, | |
e0c70b80 PT |
238 | .owner = THIS_MODULE, |
239 | }, | |
240 | ||
241 | .probe = ads7871_probe, | |
242 | .remove = __devexit_p(ads7871_remove), | |
243 | }; | |
244 | ||
91efffe2 | 245 | module_spi_driver(ads7871_driver); |
e0c70b80 PT |
246 | |
247 | MODULE_AUTHOR("Paul Thomas <pthomas8589@gmail.com>"); | |
248 | MODULE_DESCRIPTION("TI ADS7871 A/D driver"); | |
249 | MODULE_LICENSE("GPL"); |