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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 | /* |
38 | * From figure 17 in the datasheet |
39 | * These bits get ORed with the address to form |
40 | * the instruction byte |
41 | */ |
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; |
110 | /* |
111 | * TODO: add support for conversions |
112 | * other than single ended with a gain of 1 |
113 | */ |
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); |
121 | /* |
122 | * on 400MHz arm9 platform the conversion |
123 | * is already done when we do this test |
124 | */ |
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 ssize_t ads7871_show_name(struct device *dev, |
143 | struct device_attribute *devattr, char *buf) |
144 | { |
145 | return sprintf(buf, "%s\n", to_spi_device(dev)->modalias); |
146 | } |
147 | |
148 | static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, show_voltage, NULL, 0); |
149 | static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, show_voltage, NULL, 1); |
150 | static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, show_voltage, NULL, 2); |
151 | static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, show_voltage, NULL, 3); |
152 | static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, show_voltage, NULL, 4); |
153 | static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, show_voltage, NULL, 5); |
154 | static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, show_voltage, NULL, 6); |
155 | static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, show_voltage, NULL, 7); |
156 | |
157 | static DEVICE_ATTR(name, S_IRUGO, ads7871_show_name, NULL); |
158 | |
159 | static struct attribute *ads7871_attributes[] = { |
160 | &sensor_dev_attr_in0_input.dev_attr.attr, |
161 | &sensor_dev_attr_in1_input.dev_attr.attr, |
162 | &sensor_dev_attr_in2_input.dev_attr.attr, |
163 | &sensor_dev_attr_in3_input.dev_attr.attr, |
164 | &sensor_dev_attr_in4_input.dev_attr.attr, |
165 | &sensor_dev_attr_in5_input.dev_attr.attr, |
166 | &sensor_dev_attr_in6_input.dev_attr.attr, |
167 | &sensor_dev_attr_in7_input.dev_attr.attr, |
168 | &dev_attr_name.attr, |
169 | NULL |
170 | }; |
171 | |
172 | static const struct attribute_group ads7871_group = { |
173 | .attrs = ads7871_attributes, |
174 | }; |
175 | |
176 | static int ads7871_probe(struct spi_device *spi) |
177 | { |
178 | int ret, err; |
179 | uint8_t val; |
180 | struct ads7871_data *pdata; |
181 | |
182 | dev_dbg(&spi->dev, "probe\n"); |
183 | |
184 | /* Configure the SPI bus */ |
185 | spi->mode = (SPI_MODE_0); |
186 | spi->bits_per_word = 8; |
187 | spi_setup(spi); |
188 | |
189 | ads7871_write_reg8(spi, REG_SER_CONTROL, 0); |
190 | ads7871_write_reg8(spi, REG_AD_CONTROL, 0); |
191 | |
192 | val = (OSC_OSCR_bm | OSC_OSCE_bm | OSC_REFE_bm | OSC_BUFE_bm); |
193 | ads7871_write_reg8(spi, REG_OSC_CONTROL, val); |
194 | ret = ads7871_read_reg8(spi, REG_OSC_CONTROL); |
195 | |
196 | dev_dbg(&spi->dev, "REG_OSC_CONTROL write:%x, read:%x\n", val, ret); |
197 | /* |
198 | * because there is no other error checking on an SPI bus |
199 | * we need to make sure we really have a chip |
200 | */ |
201 | if (val != ret) |
202 | return -ENODEV; |
203 | |
204 | pdata = devm_kzalloc(&spi->dev, sizeof(struct ads7871_data), |
205 | GFP_KERNEL); |
206 | if (!pdata) |
207 | return -ENOMEM; |
208 | |
209 | err = sysfs_create_group(&spi->dev.kobj, &ads7871_group); |
210 | if (err < 0) |
211 | return err; |
212 | |
213 | spi_set_drvdata(spi, pdata); |
214 | |
215 | pdata->hwmon_dev = hwmon_device_register(&spi->dev); |
216 | if (IS_ERR(pdata->hwmon_dev)) { |
217 | err = PTR_ERR(pdata->hwmon_dev); |
218 | goto error_remove; |
219 | } |
220 | |
221 | return 0; |
222 | |
223 | error_remove: |
224 | sysfs_remove_group(&spi->dev.kobj, &ads7871_group); |
225 | return err; |
226 | } |
227 | |
228 | static int ads7871_remove(struct spi_device *spi) |
229 | { |
230 | struct ads7871_data *pdata = spi_get_drvdata(spi); |
231 | |
232 | hwmon_device_unregister(pdata->hwmon_dev); |
233 | sysfs_remove_group(&spi->dev.kobj, &ads7871_group); |
234 | return 0; |
235 | } |
236 | |
237 | static struct spi_driver ads7871_driver = { |
238 | .driver = { |
239 | .name = DEVICE_NAME, |
240 | .owner = THIS_MODULE, |
241 | }, |
242 | |
243 | .probe = ads7871_probe, |
244 | .remove = ads7871_remove, |
245 | }; |
246 | |
247 | module_spi_driver(ads7871_driver); |
248 | |
249 | MODULE_AUTHOR("Paul Thomas <pthomas8589@gmail.com>"); |
250 | MODULE_DESCRIPTION("TI ADS7871 A/D driver"); |
251 | MODULE_LICENSE("GPL"); |
252 |
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