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207 lines
5.5 KiB
207 lines
5.5 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* ads7871 - driver for TI ADS7871 A/D converter |
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* |
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* Copyright (c) 2010 Paul Thomas <[email protected]> |
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* |
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* You need to have something like this in struct spi_board_info |
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* { |
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* .modalias = "ads7871", |
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* .max_speed_hz = 2*1000*1000, |
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* .chip_select = 0, |
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* .bus_num = 1, |
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* }, |
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*/ |
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/*From figure 18 in the datasheet*/ |
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/*Register addresses*/ |
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#define REG_LS_BYTE 0 /*A/D Output Data, LS Byte*/ |
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#define REG_MS_BYTE 1 /*A/D Output Data, MS Byte*/ |
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#define REG_PGA_VALID 2 /*PGA Valid Register*/ |
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#define REG_AD_CONTROL 3 /*A/D Control Register*/ |
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#define REG_GAIN_MUX 4 /*Gain/Mux Register*/ |
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#define REG_IO_STATE 5 /*Digital I/O State Register*/ |
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#define REG_IO_CONTROL 6 /*Digital I/O Control Register*/ |
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#define REG_OSC_CONTROL 7 /*Rev/Oscillator Control Register*/ |
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#define REG_SER_CONTROL 24 /*Serial Interface Control Register*/ |
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#define REG_ID 31 /*ID Register*/ |
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/* |
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* From figure 17 in the datasheet |
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* These bits get ORed with the address to form |
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* the instruction byte |
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*/ |
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/*Instruction Bit masks*/ |
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#define INST_MODE_BM (1 << 7) |
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#define INST_READ_BM (1 << 6) |
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#define INST_16BIT_BM (1 << 5) |
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/*From figure 18 in the datasheet*/ |
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/*bit masks for Rev/Oscillator Control Register*/ |
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#define MUX_CNV_BV 7 |
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#define MUX_CNV_BM (1 << MUX_CNV_BV) |
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#define MUX_M3_BM (1 << 3) /*M3 selects single ended*/ |
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#define MUX_G_BV 4 /*allows for reg = (gain << MUX_G_BV) | ...*/ |
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/*From figure 18 in the datasheet*/ |
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/*bit masks for Rev/Oscillator Control Register*/ |
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#define OSC_OSCR_BM (1 << 5) |
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#define OSC_OSCE_BM (1 << 4) |
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#define OSC_REFE_BM (1 << 3) |
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#define OSC_BUFE_BM (1 << 2) |
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#define OSC_R2V_BM (1 << 1) |
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#define OSC_RBG_BM (1 << 0) |
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#include <linux/module.h> |
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#include <linux/init.h> |
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#include <linux/spi/spi.h> |
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#include <linux/hwmon.h> |
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#include <linux/hwmon-sysfs.h> |
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#include <linux/err.h> |
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#include <linux/delay.h> |
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#define DEVICE_NAME "ads7871" |
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struct ads7871_data { |
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struct spi_device *spi; |
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}; |
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static int ads7871_read_reg8(struct spi_device *spi, int reg) |
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{ |
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int ret; |
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reg = reg | INST_READ_BM; |
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ret = spi_w8r8(spi, reg); |
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return ret; |
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} |
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static int ads7871_read_reg16(struct spi_device *spi, int reg) |
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{ |
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int ret; |
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reg = reg | INST_READ_BM | INST_16BIT_BM; |
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ret = spi_w8r16(spi, reg); |
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return ret; |
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} |
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static int ads7871_write_reg8(struct spi_device *spi, int reg, u8 val) |
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{ |
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u8 tmp[2] = {reg, val}; |
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return spi_write(spi, tmp, sizeof(tmp)); |
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} |
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static ssize_t voltage_show(struct device *dev, struct device_attribute *da, |
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char *buf) |
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{ |
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struct ads7871_data *pdata = dev_get_drvdata(dev); |
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struct spi_device *spi = pdata->spi; |
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struct sensor_device_attribute *attr = to_sensor_dev_attr(da); |
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int ret, val, i = 0; |
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uint8_t channel, mux_cnv; |
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channel = attr->index; |
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/* |
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* TODO: add support for conversions |
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* other than single ended with a gain of 1 |
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*/ |
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/*MUX_M3_BM forces single ended*/ |
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/*This is also where the gain of the PGA would be set*/ |
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ads7871_write_reg8(spi, REG_GAIN_MUX, |
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(MUX_CNV_BM | MUX_M3_BM | channel)); |
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ret = ads7871_read_reg8(spi, REG_GAIN_MUX); |
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mux_cnv = ((ret & MUX_CNV_BM) >> MUX_CNV_BV); |
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/* |
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* on 400MHz arm9 platform the conversion |
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* is already done when we do this test |
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*/ |
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while ((i < 2) && mux_cnv) { |
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i++; |
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ret = ads7871_read_reg8(spi, REG_GAIN_MUX); |
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mux_cnv = ((ret & MUX_CNV_BM) >> MUX_CNV_BV); |
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msleep_interruptible(1); |
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} |
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if (mux_cnv == 0) { |
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val = ads7871_read_reg16(spi, REG_LS_BYTE); |
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/*result in volts*10000 = (val/8192)*2.5*10000*/ |
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val = ((val >> 2) * 25000) / 8192; |
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return sprintf(buf, "%d\n", val); |
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} else { |
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return -1; |
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} |
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} |
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static SENSOR_DEVICE_ATTR_RO(in0_input, voltage, 0); |
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static SENSOR_DEVICE_ATTR_RO(in1_input, voltage, 1); |
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static SENSOR_DEVICE_ATTR_RO(in2_input, voltage, 2); |
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static SENSOR_DEVICE_ATTR_RO(in3_input, voltage, 3); |
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static SENSOR_DEVICE_ATTR_RO(in4_input, voltage, 4); |
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static SENSOR_DEVICE_ATTR_RO(in5_input, voltage, 5); |
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static SENSOR_DEVICE_ATTR_RO(in6_input, voltage, 6); |
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static SENSOR_DEVICE_ATTR_RO(in7_input, voltage, 7); |
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static struct attribute *ads7871_attrs[] = { |
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&sensor_dev_attr_in0_input.dev_attr.attr, |
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&sensor_dev_attr_in1_input.dev_attr.attr, |
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&sensor_dev_attr_in2_input.dev_attr.attr, |
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&sensor_dev_attr_in3_input.dev_attr.attr, |
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&sensor_dev_attr_in4_input.dev_attr.attr, |
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&sensor_dev_attr_in5_input.dev_attr.attr, |
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&sensor_dev_attr_in6_input.dev_attr.attr, |
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&sensor_dev_attr_in7_input.dev_attr.attr, |
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NULL |
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}; |
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ATTRIBUTE_GROUPS(ads7871); |
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static int ads7871_probe(struct spi_device *spi) |
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{ |
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struct device *dev = &spi->dev; |
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int ret; |
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uint8_t val; |
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struct ads7871_data *pdata; |
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struct device *hwmon_dev; |
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/* Configure the SPI bus */ |
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spi->mode = (SPI_MODE_0); |
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spi->bits_per_word = 8; |
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spi_setup(spi); |
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ads7871_write_reg8(spi, REG_SER_CONTROL, 0); |
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ads7871_write_reg8(spi, REG_AD_CONTROL, 0); |
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val = (OSC_OSCR_BM | OSC_OSCE_BM | OSC_REFE_BM | OSC_BUFE_BM); |
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ads7871_write_reg8(spi, REG_OSC_CONTROL, val); |
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ret = ads7871_read_reg8(spi, REG_OSC_CONTROL); |
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dev_dbg(dev, "REG_OSC_CONTROL write:%x, read:%x\n", val, ret); |
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/* |
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* because there is no other error checking on an SPI bus |
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* we need to make sure we really have a chip |
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*/ |
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if (val != ret) |
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return -ENODEV; |
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pdata = devm_kzalloc(dev, sizeof(struct ads7871_data), GFP_KERNEL); |
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if (!pdata) |
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return -ENOMEM; |
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pdata->spi = spi; |
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hwmon_dev = devm_hwmon_device_register_with_groups(dev, spi->modalias, |
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pdata, |
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ads7871_groups); |
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return PTR_ERR_OR_ZERO(hwmon_dev); |
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} |
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static struct spi_driver ads7871_driver = { |
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.driver = { |
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.name = DEVICE_NAME, |
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}, |
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.probe = ads7871_probe, |
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}; |
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module_spi_driver(ads7871_driver); |
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MODULE_AUTHOR("Paul Thomas <[email protected]>"); |
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MODULE_DESCRIPTION("TI ADS7871 A/D driver"); |
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MODULE_LICENSE("GPL");
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