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Release 4.11 drivers/hwmon/ads7871.c

Directory: drivers/hwmon
/*
 *  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;
}


Contributors
PersonTokensPropCommitsCommitProp
Paul Thomas3497.14%150.00%


Guenter Roeck12.86%150.00%


Total35100.00%2100.00%






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;
}


Contributors
PersonTokensPropCommitsCommitProp
Paul Thomas3594.59%150.00%


Guenter Roeck25.41%150.00%


Total37100.00%2100.00%






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));
}


Contributors
PersonTokensPropCommitsCommitProp
Paul Thomas42100.00%1100.00%


Total42100.00%1100.00%






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;
	}
}


Contributors
PersonTokensPropCommitsCommitProp
Paul Thomas17889.45%125.00%


Axel Lin126.03%125.00%


Guenter Roeck94.52%250.00%


Total199100.00%4100.00%



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);
}


Contributors
PersonTokensPropCommitsCommitProp
Paul Thomas11665.17%116.67%


Axel Lin5028.09%233.33%


Guenter Roeck126.74%350.00%


Total178100.00%6100.00%




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");

Overall Contributors
PersonTokensPropCommitsCommitProp
Paul Thomas74385.90%114.29%


Axel Lin728.32%342.86%


Guenter Roeck505.78%342.86%


Total865100.00%7100.00%


Directory: drivers/hwmon



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