216 lines
6.1 KiB
C
216 lines
6.1 KiB
C
/*
|
|
* ads7871 - driver for TI ADS7871 A/D converter
|
|
*
|
|
* Copyright (c) 2010 Paul Thomas <pthomas8589@gmail.com>
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 or
|
|
* later as publishhed by the Free Software Foundation.
|
|
*
|
|
* 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 show_voltage(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(in0_input, S_IRUGO, show_voltage, NULL, 0);
|
|
static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, show_voltage, NULL, 1);
|
|
static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, show_voltage, NULL, 2);
|
|
static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, show_voltage, NULL, 3);
|
|
static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, show_voltage, NULL, 4);
|
|
static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, show_voltage, NULL, 5);
|
|
static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, show_voltage, NULL, 6);
|
|
static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, show_voltage, NULL, 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");
|