/* * 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 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_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, NULL }; static const struct attribute_group ads7871_group = { .attrs = ads7871_attributes, }; static int __devinit 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) { err = -ENODEV; goto exit; } pdata = kzalloc(sizeof(struct ads7871_data), GFP_KERNEL); if (!pdata) { err = -ENOMEM; goto exit; } err = sysfs_create_group(&spi->dev.kobj, &ads7871_group); if (err < 0) goto error_free; 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); error_free: kfree(pdata); exit: return err; } static int __devexit 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); kfree(pdata); return 0; } static struct spi_driver ads7871_driver = { .driver = { .name = DEVICE_NAME, .bus = &spi_bus_type, .owner = THIS_MODULE, }, .probe = ads7871_probe, .remove = __devexit_p(ads7871_remove), }; static int __init ads7871_init(void) { return spi_register_driver(&ads7871_driver); } static void __exit ads7871_exit(void) { spi_unregister_driver(&ads7871_driver); } module_init(ads7871_init); module_exit(ads7871_exit); MODULE_AUTHOR("Paul Thomas <pthomas8589@gmail.com>"); MODULE_DESCRIPTION("TI ADS7871 A/D driver"); MODULE_LICENSE("GPL");