LXR linux/drivers/hwmon/ads7871.c

   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
  65struct ads7871_data {
  66        struct spi_device *spi;
  67};
  68
  69static 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, reg);
  74        return ret;
  75}
  76
  77static 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, reg);
  82        return ret;
  83}
  84
  85static int ads7871_write_reg8(struct spi_device *spi, int reg, u8 val)
  86{
  87        u8 tmp[2] = {reg, val};
  88        return spi_write(spi, tmp, sizeof(tmp));
  89}
  90
  91static 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                (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(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, "%d\n", val);
 128        } else {
 129                return -1;
 130        }
 131}
 132
 133static SENSOR_DEVICE_ATTR_RO(in0_input, voltage, 0);
 134static SENSOR_DEVICE_ATTR_RO(in1_input, voltage, 1);
 135static SENSOR_DEVICE_ATTR_RO(in2_input, voltage, 2);
 136static SENSOR_DEVICE_ATTR_RO(in3_input, voltage, 3);
 137static SENSOR_DEVICE_ATTR_RO(in4_input, voltage, 4);
 138static SENSOR_DEVICE_ATTR_RO(in5_input, voltage, 5);
 139static SENSOR_DEVICE_ATTR_RO(in6_input, voltage, 6);
 140static SENSOR_DEVICE_ATTR_RO(in7_input, voltage, 7);
 141
 142static 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
 154ATTRIBUTE_GROUPS(ads7871);
 155
 156static 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, 0);
 170        ads7871_write_reg8(spi, REG_AD_CONTROL, 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, 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, spi->modalias,
 191                                                           pdata,
 192                                                           ads7871_groups);
 193        return PTR_ERR_OR_ZERO(hwmon_dev);
 194}
 195
 196static struct spi_driver ads7871_driver = {
 197        .driver = {
 198                .name = DEVICE_NAME,
 199        },
 200        .probe = ads7871_probe,
 201};
 202
 203module_spi_driver(ads7871_driver);
 204
 205MODULE_AUTHOR("Paul Thomas <pthomas8589@gmail.com>");
 206MODULE_DESCRIPTION("TI ADS7871 A/D driver");
 207MODULE_LICENSE("GPL");
 208