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