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Paul Thomase0c70b82010-05-24 14:33:38 -07001/*
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
Guenter Roeck10775d12012-01-19 11:02:15 -080037/*
38 * From figure 17 in the datasheet
39 * These bits get ORed with the address to form
40 * the instruction byte
41 */
Paul Thomase0c70b82010-05-24 14:33:38 -070042/*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
74struct ads7871_data {
75 struct device *hwmon_dev;
76 struct mutex update_lock;
77};
78
79static 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
87static 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
95static 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
101static 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;
Guenter Roeck10775d12012-01-19 11:02:15 -0800110 /*
111 * TODO: add support for conversions
112 * other than single ended with a gain of 1
113 */
Paul Thomase0c70b82010-05-24 14:33:38 -0700114 /*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);
Guenter Roeck10775d12012-01-19 11:02:15 -0800121 /*
122 * on 400MHz arm9 platform the conversion
123 * is already done when we do this test
124 */
Paul Thomase0c70b82010-05-24 14:33:38 -0700125 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
Guenter Roeck4e21f4e2012-09-11 13:39:08 -0700142static 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
Paul Thomase0c70b82010-05-24 14:33:38 -0700148static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, show_voltage, NULL, 0);
149static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, show_voltage, NULL, 1);
150static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, show_voltage, NULL, 2);
151static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, show_voltage, NULL, 3);
152static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, show_voltage, NULL, 4);
153static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, show_voltage, NULL, 5);
154static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, show_voltage, NULL, 6);
155static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, show_voltage, NULL, 7);
156
Guenter Roeck4e21f4e2012-09-11 13:39:08 -0700157static DEVICE_ATTR(name, S_IRUGO, ads7871_show_name, NULL);
158
Paul Thomase0c70b82010-05-24 14:33:38 -0700159static 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,
Guenter Roeck4e21f4e2012-09-11 13:39:08 -0700168 &dev_attr_name.attr,
Paul Thomase0c70b82010-05-24 14:33:38 -0700169 NULL
170};
171
172static const struct attribute_group ads7871_group = {
173 .attrs = ads7871_attributes,
174};
175
Bill Pemberton6c931ae2012-11-19 13:22:35 -0500176static int ads7871_probe(struct spi_device *spi)
Paul Thomase0c70b82010-05-24 14:33:38 -0700177{
Axel Linc12c5072010-08-25 15:42:10 +0200178 int ret, err;
Paul Thomase0c70b82010-05-24 14:33:38 -0700179 uint8_t val;
180 struct ads7871_data *pdata;
181
182 dev_dbg(&spi->dev, "probe\n");
183
Paul Thomase0c70b82010-05-24 14:33:38 -0700184 /* 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);
Guenter Roeck10775d12012-01-19 11:02:15 -0800197 /*
198 * because there is no other error checking on an SPI bus
199 * we need to make sure we really have a chip
200 */
Guenter Roeck33fd2b82012-06-02 09:58:00 -0700201 if (val != ret)
202 return -ENODEV;
Axel Linc12c5072010-08-25 15:42:10 +0200203
Guenter Roeck33fd2b82012-06-02 09:58:00 -0700204 pdata = devm_kzalloc(&spi->dev, sizeof(struct ads7871_data),
205 GFP_KERNEL);
206 if (!pdata)
207 return -ENOMEM;
Axel Linc12c5072010-08-25 15:42:10 +0200208
209 err = sysfs_create_group(&spi->dev.kobj, &ads7871_group);
210 if (err < 0)
Guenter Roeck33fd2b82012-06-02 09:58:00 -0700211 return err;
Axel Linc12c5072010-08-25 15:42:10 +0200212
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);
Paul Thomase0c70b82010-05-24 14:33:38 -0700218 goto error_remove;
219 }
220
221 return 0;
222
223error_remove:
224 sysfs_remove_group(&spi->dev.kobj, &ads7871_group);
Paul Thomase0c70b82010-05-24 14:33:38 -0700225 return err;
226}
227
Bill Pemberton281dfd02012-11-19 13:25:51 -0500228static int ads7871_remove(struct spi_device *spi)
Paul Thomase0c70b82010-05-24 14:33:38 -0700229{
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);
Paul Thomase0c70b82010-05-24 14:33:38 -0700234 return 0;
235}
236
237static struct spi_driver ads7871_driver = {
238 .driver = {
239 .name = DEVICE_NAME,
Paul Thomase0c70b82010-05-24 14:33:38 -0700240 .owner = THIS_MODULE,
241 },
242
243 .probe = ads7871_probe,
Bill Pemberton9e5e9b72012-11-19 13:21:20 -0500244 .remove = ads7871_remove,
Paul Thomase0c70b82010-05-24 14:33:38 -0700245};
246
Axel Lin91efffe2012-01-20 15:53:47 +0800247module_spi_driver(ads7871_driver);
Paul Thomase0c70b82010-05-24 14:33:38 -0700248
249MODULE_AUTHOR("Paul Thomas <pthomas8589@gmail.com>");
250MODULE_DESCRIPTION("TI ADS7871 A/D driver");
251MODULE_LICENSE("GPL");