1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * ads7871 - driver for TI ADS7871 A/D converter |
4 | * |
5 | * Copyright (c) 2010 Paul Thomas <pthomas8589@gmail.com> |
6 | * |
7 | * You need to have something like this in struct spi_board_info |
8 | * { |
9 | * .modalias = "ads7871", |
10 | * .max_speed_hz = 2*1000*1000, |
11 | * .chip_select = 0, |
12 | * .bus_num = 1, |
13 | * }, |
14 | */ |
15 | |
16 | /*From figure 18 in the datasheet*/ |
17 | /*Register addresses*/ |
18 | #define REG_LS_BYTE 0 /*A/D Output Data, LS Byte*/ |
19 | #define REG_MS_BYTE 1 /*A/D Output Data, MS Byte*/ |
20 | #define REG_PGA_VALID 2 /*PGA Valid Register*/ |
21 | #define REG_AD_CONTROL 3 /*A/D Control Register*/ |
22 | #define REG_GAIN_MUX 4 /*Gain/Mux Register*/ |
23 | #define REG_IO_STATE 5 /*Digital I/O State Register*/ |
24 | #define REG_IO_CONTROL 6 /*Digital I/O Control Register*/ |
25 | #define REG_OSC_CONTROL 7 /*Rev/Oscillator Control Register*/ |
26 | #define REG_SER_CONTROL 24 /*Serial Interface Control Register*/ |
27 | #define REG_ID 31 /*ID Register*/ |
28 | |
29 | /* |
30 | * From figure 17 in the datasheet |
31 | * These bits get ORed with the address to form |
32 | * the instruction byte |
33 | */ |
34 | /*Instruction Bit masks*/ |
35 | #define INST_MODE_BM (1 << 7) |
36 | #define INST_READ_BM (1 << 6) |
37 | #define INST_16BIT_BM (1 << 5) |
38 | |
39 | /*From figure 18 in the datasheet*/ |
40 | /*bit masks for Rev/Oscillator Control Register*/ |
41 | #define MUX_CNV_BV 7 |
42 | #define MUX_CNV_BM (1 << MUX_CNV_BV) |
43 | #define MUX_M3_BM (1 << 3) /*M3 selects single ended*/ |
44 | #define MUX_G_BV 4 /*allows for reg = (gain << MUX_G_BV) | ...*/ |
45 | |
46 | /*From figure 18 in the datasheet*/ |
47 | /*bit masks for Rev/Oscillator Control Register*/ |
48 | #define OSC_OSCR_BM (1 << 5) |
49 | #define OSC_OSCE_BM (1 << 4) |
50 | #define OSC_REFE_BM (1 << 3) |
51 | #define OSC_BUFE_BM (1 << 2) |
52 | #define OSC_R2V_BM (1 << 1) |
53 | #define OSC_RBG_BM (1 << 0) |
54 | |
55 | #include <linux/module.h> |
56 | #include <linux/init.h> |
57 | #include <linux/spi/spi.h> |
58 | #include <linux/hwmon.h> |
59 | #include <linux/hwmon-sysfs.h> |
60 | #include <linux/err.h> |
61 | #include <linux/delay.h> |
62 | |
63 | #define DEVICE_NAME "ads7871" |
64 | |
65 | struct ads7871_data { |
66 | struct spi_device *spi; |
67 | }; |
68 | |
69 | static int ads7871_read_reg8(struct spi_device *spi, int reg) |
70 | { |
71 | int ret; |
72 | reg = reg | INST_READ_BM; |
73 | ret = spi_w8r8(spi, cmd: reg); |
74 | return ret; |
75 | } |
76 | |
77 | static int ads7871_read_reg16(struct spi_device *spi, int reg) |
78 | { |
79 | int ret; |
80 | reg = reg | INST_READ_BM | INST_16BIT_BM; |
81 | ret = spi_w8r16(spi, cmd: reg); |
82 | return ret; |
83 | } |
84 | |
85 | static int ads7871_write_reg8(struct spi_device *spi, int reg, u8 val) |
86 | { |
87 | u8 tmp[2] = {reg, val}; |
88 | return spi_write(spi, buf: tmp, len: sizeof(tmp)); |
89 | } |
90 | |
91 | static ssize_t voltage_show(struct device *dev, struct device_attribute *da, |
92 | char *buf) |
93 | { |
94 | struct ads7871_data *pdata = dev_get_drvdata(dev); |
95 | struct spi_device *spi = pdata->spi; |
96 | struct sensor_device_attribute *attr = to_sensor_dev_attr(da); |
97 | int ret, val, i = 0; |
98 | uint8_t channel, mux_cnv; |
99 | |
100 | channel = attr->index; |
101 | /* |
102 | * TODO: add support for conversions |
103 | * other than single ended with a gain of 1 |
104 | */ |
105 | /*MUX_M3_BM forces single ended*/ |
106 | /*This is also where the gain of the PGA would be set*/ |
107 | ads7871_write_reg8(spi, REG_GAIN_MUX, |
108 | val: (MUX_CNV_BM | MUX_M3_BM | channel)); |
109 | |
110 | ret = ads7871_read_reg8(spi, REG_GAIN_MUX); |
111 | mux_cnv = ((ret & MUX_CNV_BM) >> MUX_CNV_BV); |
112 | /* |
113 | * on 400MHz arm9 platform the conversion |
114 | * is already done when we do this test |
115 | */ |
116 | while ((i < 2) && mux_cnv) { |
117 | i++; |
118 | ret = ads7871_read_reg8(spi, REG_GAIN_MUX); |
119 | mux_cnv = ((ret & MUX_CNV_BM) >> MUX_CNV_BV); |
120 | msleep_interruptible(msecs: 1); |
121 | } |
122 | |
123 | if (mux_cnv == 0) { |
124 | val = ads7871_read_reg16(spi, REG_LS_BYTE); |
125 | /*result in volts*10000 = (val/8192)*2.5*10000*/ |
126 | val = ((val >> 2) * 25000) / 8192; |
127 | return sprintf(buf, fmt: "%d\n" , val); |
128 | } else { |
129 | return -1; |
130 | } |
131 | } |
132 | |
133 | static SENSOR_DEVICE_ATTR_RO(in0_input, voltage, 0); |
134 | static SENSOR_DEVICE_ATTR_RO(in1_input, voltage, 1); |
135 | static SENSOR_DEVICE_ATTR_RO(in2_input, voltage, 2); |
136 | static SENSOR_DEVICE_ATTR_RO(in3_input, voltage, 3); |
137 | static SENSOR_DEVICE_ATTR_RO(in4_input, voltage, 4); |
138 | static SENSOR_DEVICE_ATTR_RO(in5_input, voltage, 5); |
139 | static SENSOR_DEVICE_ATTR_RO(in6_input, voltage, 6); |
140 | static SENSOR_DEVICE_ATTR_RO(in7_input, voltage, 7); |
141 | |
142 | static struct attribute *ads7871_attrs[] = { |
143 | &sensor_dev_attr_in0_input.dev_attr.attr, |
144 | &sensor_dev_attr_in1_input.dev_attr.attr, |
145 | &sensor_dev_attr_in2_input.dev_attr.attr, |
146 | &sensor_dev_attr_in3_input.dev_attr.attr, |
147 | &sensor_dev_attr_in4_input.dev_attr.attr, |
148 | &sensor_dev_attr_in5_input.dev_attr.attr, |
149 | &sensor_dev_attr_in6_input.dev_attr.attr, |
150 | &sensor_dev_attr_in7_input.dev_attr.attr, |
151 | NULL |
152 | }; |
153 | |
154 | ATTRIBUTE_GROUPS(ads7871); |
155 | |
156 | static int ads7871_probe(struct spi_device *spi) |
157 | { |
158 | struct device *dev = &spi->dev; |
159 | int ret; |
160 | uint8_t val; |
161 | struct ads7871_data *pdata; |
162 | struct device *hwmon_dev; |
163 | |
164 | /* Configure the SPI bus */ |
165 | spi->mode = (SPI_MODE_0); |
166 | spi->bits_per_word = 8; |
167 | spi_setup(spi); |
168 | |
169 | ads7871_write_reg8(spi, REG_SER_CONTROL, val: 0); |
170 | ads7871_write_reg8(spi, REG_AD_CONTROL, val: 0); |
171 | |
172 | val = (OSC_OSCR_BM | OSC_OSCE_BM | OSC_REFE_BM | OSC_BUFE_BM); |
173 | ads7871_write_reg8(spi, REG_OSC_CONTROL, val); |
174 | ret = ads7871_read_reg8(spi, REG_OSC_CONTROL); |
175 | |
176 | dev_dbg(dev, "REG_OSC_CONTROL write:%x, read:%x\n" , val, ret); |
177 | /* |
178 | * because there is no other error checking on an SPI bus |
179 | * we need to make sure we really have a chip |
180 | */ |
181 | if (val != ret) |
182 | return -ENODEV; |
183 | |
184 | pdata = devm_kzalloc(dev, size: sizeof(struct ads7871_data), GFP_KERNEL); |
185 | if (!pdata) |
186 | return -ENOMEM; |
187 | |
188 | pdata->spi = spi; |
189 | |
190 | hwmon_dev = devm_hwmon_device_register_with_groups(dev, name: spi->modalias, |
191 | drvdata: pdata, |
192 | groups: ads7871_groups); |
193 | return PTR_ERR_OR_ZERO(ptr: hwmon_dev); |
194 | } |
195 | |
196 | static struct spi_driver ads7871_driver = { |
197 | .driver = { |
198 | .name = DEVICE_NAME, |
199 | }, |
200 | .probe = ads7871_probe, |
201 | }; |
202 | |
203 | module_spi_driver(ads7871_driver); |
204 | |
205 | MODULE_AUTHOR("Paul Thomas <pthomas8589@gmail.com>" ); |
206 | MODULE_DESCRIPTION("TI ADS7871 A/D driver" ); |
207 | MODULE_LICENSE("GPL" ); |
208 | |