--- /dev/null
+/*
+ * 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/mutex.h>
+#include <linux/delay.h>
+
+#define DEVICE_NAME "ads7871"
+
+struct ads7871_data {
+ struct device *hwmon_dev;
+ struct mutex update_lock;
+};
+
+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 spi_device *spi = to_spi_device(dev);
+ 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 ssize_t ads7871_show_name(struct device *dev,
+ struct device_attribute *devattr, char *buf)
+{
+ return sprintf(buf, "%s\n", to_spi_device(dev)->modalias);
+}
+
+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 DEVICE_ATTR(name, S_IRUGO, ads7871_show_name, NULL);
+
+static struct attribute *ads7871_attributes[] = {
+ &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,
+ &dev_attr_name.attr,
+ NULL
+};
+
+static const struct attribute_group ads7871_group = {
+ .attrs = ads7871_attributes,
+};
+
+static int ads7871_probe(struct spi_device *spi)
+{
+ int ret, err;
+ uint8_t val;
+ struct ads7871_data *pdata;
+
+ dev_dbg(&spi->dev, "probe\n");
+
+ /* 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(&spi->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(&spi->dev, sizeof(struct ads7871_data),
+ GFP_KERNEL);
+ if (!pdata)
+ return -ENOMEM;
+
+ err = sysfs_create_group(&spi->dev.kobj, &ads7871_group);
+ if (err < 0)
+ return err;
+
+ spi_set_drvdata(spi, pdata);
+
+ pdata->hwmon_dev = hwmon_device_register(&spi->dev);
+ if (IS_ERR(pdata->hwmon_dev)) {
+ err = PTR_ERR(pdata->hwmon_dev);
+ goto error_remove;
+ }
+
+ return 0;
+
+error_remove:
+ sysfs_remove_group(&spi->dev.kobj, &ads7871_group);
+ return err;
+}
+
+static int ads7871_remove(struct spi_device *spi)
+{
+ struct ads7871_data *pdata = spi_get_drvdata(spi);
+
+ hwmon_device_unregister(pdata->hwmon_dev);
+ sysfs_remove_group(&spi->dev.kobj, &ads7871_group);
+ return 0;
+}
+
+static struct spi_driver ads7871_driver = {
+ .driver = {
+ .name = DEVICE_NAME,
+ .owner = THIS_MODULE,
+ },
+
+ .probe = ads7871_probe,
+ .remove = ads7871_remove,
+};
+
+module_spi_driver(ads7871_driver);
+
+MODULE_AUTHOR("Paul Thomas <pthomas8589@gmail.com>");
+MODULE_DESCRIPTION("TI ADS7871 A/D driver");
+MODULE_LICENSE("GPL");
Code Review / kvmfornfv.git / blobdiff