diff options
Diffstat (limited to 'drivers/hwmon/ads7871.c')
| -rw-r--r-- | drivers/hwmon/ads7871.c | 253 |
1 files changed, 253 insertions, 0 deletions
diff --git a/drivers/hwmon/ads7871.c b/drivers/hwmon/ads7871.c new file mode 100644 index 0000000..b300a20 --- /dev/null +++ b/drivers/hwmon/ads7871.c @@ -0,0 +1,253 @@ +/* + * 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 status, ret, err = 0; + uint8_t val; + struct ads7871_data *pdata; + + dev_dbg(&spi->dev, "probe\n"); + + pdata = kzalloc(sizeof(struct ads7871_data), GFP_KERNEL); + if (!pdata) { + err = -ENOMEM; + goto exit; + } + + status = sysfs_create_group(&spi->dev.kobj, &ads7871_group); + if (status < 0) + goto error_free; + + pdata->hwmon_dev = hwmon_device_register(&spi->dev); + if (IS_ERR(pdata->hwmon_dev)) { + err = PTR_ERR(pdata->hwmon_dev); + goto error_remove; + } + + spi_set_drvdata(spi, pdata); + + /* 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 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"); |
