diff options
Diffstat (limited to 'drivers/iio/adc/ti-ads8688.c')
| -rw-r--r-- | drivers/iio/adc/ti-ads8688.c | 486 |
1 files changed, 486 insertions, 0 deletions
diff --git a/drivers/iio/adc/ti-ads8688.c b/drivers/iio/adc/ti-ads8688.c new file mode 100644 index 000000000000..03e907028cb6 --- /dev/null +++ b/drivers/iio/adc/ti-ads8688.c @@ -0,0 +1,486 @@ +/* + * Copyright (C) 2015 Prevas A/S + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/device.h> +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/sysfs.h> +#include <linux/spi/spi.h> +#include <linux/regulator/consumer.h> +#include <linux/err.h> +#include <linux/module.h> +#include <linux/of.h> + +#include <linux/iio/iio.h> +#include <linux/iio/sysfs.h> + +#define ADS8688_CMD_REG(x) (x << 8) +#define ADS8688_CMD_REG_NOOP 0x00 +#define ADS8688_CMD_REG_RST 0x85 +#define ADS8688_CMD_REG_MAN_CH(chan) (0xC0 | (4 * chan)) +#define ADS8688_CMD_DONT_CARE_BITS 16 + +#define ADS8688_PROG_REG(x) (x << 9) +#define ADS8688_PROG_REG_RANGE_CH(chan) (0x05 + chan) +#define ADS8688_PROG_WR_BIT BIT(8) +#define ADS8688_PROG_DONT_CARE_BITS 8 + +#define ADS8688_REG_PLUSMINUS25VREF 0 +#define ADS8688_REG_PLUSMINUS125VREF 1 +#define ADS8688_REG_PLUSMINUS0625VREF 2 +#define ADS8688_REG_PLUS25VREF 5 +#define ADS8688_REG_PLUS125VREF 6 + +#define ADS8688_VREF_MV 4096 +#define ADS8688_REALBITS 16 + +/* + * enum ads8688_range - ADS8688 reference voltage range + * @ADS8688_PLUSMINUS25VREF: Device is configured for input range ±2.5 * VREF + * @ADS8688_PLUSMINUS125VREF: Device is configured for input range ±1.25 * VREF + * @ADS8688_PLUSMINUS0625VREF: Device is configured for input range ±0.625 * VREF + * @ADS8688_PLUS25VREF: Device is configured for input range 0 - 2.5 * VREF + * @ADS8688_PLUS125VREF: Device is configured for input range 0 - 1.25 * VREF + */ +enum ads8688_range { + ADS8688_PLUSMINUS25VREF, + ADS8688_PLUSMINUS125VREF, + ADS8688_PLUSMINUS0625VREF, + ADS8688_PLUS25VREF, + ADS8688_PLUS125VREF, +}; + +struct ads8688_chip_info { + const struct iio_chan_spec *channels; + unsigned int num_channels; +}; + +struct ads8688_state { + struct mutex lock; + const struct ads8688_chip_info *chip_info; + struct spi_device *spi; + struct regulator *reg; + unsigned int vref_mv; + enum ads8688_range range[8]; + union { + __be32 d32; + u8 d8[4]; + } data[2] ____cacheline_aligned; +}; + +enum ads8688_id { + ID_ADS8684, + ID_ADS8688, +}; + +struct ads8688_ranges { + enum ads8688_range range; + unsigned int scale; + int offset; + u8 reg; +}; + +static const struct ads8688_ranges ads8688_range_def[5] = { + { + .range = ADS8688_PLUSMINUS25VREF, + .scale = 76295, + .offset = -(1 << (ADS8688_REALBITS - 1)), + .reg = ADS8688_REG_PLUSMINUS25VREF, + }, { + .range = ADS8688_PLUSMINUS125VREF, + .scale = 38148, + .offset = -(1 << (ADS8688_REALBITS - 1)), + .reg = ADS8688_REG_PLUSMINUS125VREF, + }, { + .range = ADS8688_PLUSMINUS0625VREF, + .scale = 19074, + .offset = -(1 << (ADS8688_REALBITS - 1)), + .reg = ADS8688_REG_PLUSMINUS0625VREF, + }, { + .range = ADS8688_PLUS25VREF, + .scale = 38148, + .offset = 0, + .reg = ADS8688_REG_PLUS25VREF, + }, { + .range = ADS8688_PLUS125VREF, + .scale = 19074, + .offset = 0, + .reg = ADS8688_REG_PLUS125VREF, + } +}; + +static ssize_t ads8688_show_scales(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct ads8688_state *st = iio_priv(dev_to_iio_dev(dev)); + + return sprintf(buf, "0.%09u 0.%09u 0.%09u\n", + ads8688_range_def[0].scale * st->vref_mv, + ads8688_range_def[1].scale * st->vref_mv, + ads8688_range_def[2].scale * st->vref_mv); +} + +static ssize_t ads8688_show_offsets(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return sprintf(buf, "%d %d\n", ads8688_range_def[0].offset, + ads8688_range_def[3].offset); +} + +static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO, + ads8688_show_scales, NULL, 0); +static IIO_DEVICE_ATTR(in_voltage_offset_available, S_IRUGO, + ads8688_show_offsets, NULL, 0); + +static struct attribute *ads8688_attributes[] = { + &iio_dev_attr_in_voltage_scale_available.dev_attr.attr, + &iio_dev_attr_in_voltage_offset_available.dev_attr.attr, + NULL, +}; + +static const struct attribute_group ads8688_attribute_group = { + .attrs = ads8688_attributes, +}; + +#define ADS8688_CHAN(index) \ +{ \ + .type = IIO_VOLTAGE, \ + .indexed = 1, \ + .channel = index, \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \ + | BIT(IIO_CHAN_INFO_SCALE) \ + | BIT(IIO_CHAN_INFO_OFFSET), \ +} + +static const struct iio_chan_spec ads8684_channels[] = { + ADS8688_CHAN(0), + ADS8688_CHAN(1), + ADS8688_CHAN(2), + ADS8688_CHAN(3), +}; + +static const struct iio_chan_spec ads8688_channels[] = { + ADS8688_CHAN(0), + ADS8688_CHAN(1), + ADS8688_CHAN(2), + ADS8688_CHAN(3), + ADS8688_CHAN(4), + ADS8688_CHAN(5), + ADS8688_CHAN(6), + ADS8688_CHAN(7), +}; + +static int ads8688_prog_write(struct iio_dev *indio_dev, unsigned int addr, + unsigned int val) +{ + struct ads8688_state *st = iio_priv(indio_dev); + u32 tmp; + + tmp = ADS8688_PROG_REG(addr) | ADS8688_PROG_WR_BIT | val; + tmp <<= ADS8688_PROG_DONT_CARE_BITS; + st->data[0].d32 = cpu_to_be32(tmp); + + return spi_write(st->spi, &st->data[0].d8[1], 3); +} + +static int ads8688_reset(struct iio_dev *indio_dev) +{ + struct ads8688_state *st = iio_priv(indio_dev); + u32 tmp; + + tmp = ADS8688_CMD_REG(ADS8688_CMD_REG_RST); + tmp <<= ADS8688_CMD_DONT_CARE_BITS; + st->data[0].d32 = cpu_to_be32(tmp); + + return spi_write(st->spi, &st->data[0].d8[0], 4); +} + +static int ads8688_read(struct iio_dev *indio_dev, unsigned int chan) +{ + struct ads8688_state *st = iio_priv(indio_dev); + int ret; + u32 tmp; + struct spi_transfer t[] = { + { + .tx_buf = &st->data[0].d8[0], + .len = 4, + .cs_change = 1, + }, { + .tx_buf = &st->data[1].d8[0], + .rx_buf = &st->data[1].d8[0], + .len = 4, + }, + }; + + tmp = ADS8688_CMD_REG(ADS8688_CMD_REG_MAN_CH(chan)); + tmp <<= ADS8688_CMD_DONT_CARE_BITS; + st->data[0].d32 = cpu_to_be32(tmp); + + tmp = ADS8688_CMD_REG(ADS8688_CMD_REG_NOOP); + tmp <<= ADS8688_CMD_DONT_CARE_BITS; + st->data[1].d32 = cpu_to_be32(tmp); + + ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t)); + if (ret < 0) + return ret; + + return be32_to_cpu(st->data[1].d32) & 0xffff; +} + +static int ads8688_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long m) +{ + int ret, offset; + unsigned long scale_mv; + + struct ads8688_state *st = iio_priv(indio_dev); + + mutex_lock(&st->lock); + switch (m) { + case IIO_CHAN_INFO_RAW: + ret = ads8688_read(indio_dev, chan->channel); + mutex_unlock(&st->lock); + if (ret < 0) + return ret; + *val = ret; + return IIO_VAL_INT; + case IIO_CHAN_INFO_SCALE: + scale_mv = st->vref_mv; + scale_mv *= ads8688_range_def[st->range[chan->channel]].scale; + *val = 0; + *val2 = scale_mv; + mutex_unlock(&st->lock); + return IIO_VAL_INT_PLUS_NANO; + case IIO_CHAN_INFO_OFFSET: + offset = ads8688_range_def[st->range[chan->channel]].offset; + *val = offset; + mutex_unlock(&st->lock); + return IIO_VAL_INT; + } + mutex_unlock(&st->lock); + + return -EINVAL; +} + +static int ads8688_write_reg_range(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + enum ads8688_range range) +{ + unsigned int tmp; + int ret; + + tmp = ADS8688_PROG_REG_RANGE_CH(chan->channel); + ret = ads8688_prog_write(indio_dev, tmp, range); + + return ret; +} + +static int ads8688_write_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int val, int val2, long mask) +{ + struct ads8688_state *st = iio_priv(indio_dev); + unsigned int scale = 0; + int ret = -EINVAL, i, offset = 0; + + mutex_lock(&st->lock); + switch (mask) { + case IIO_CHAN_INFO_SCALE: + /* If the offset is 0 the ±2.5 * VREF mode is not available */ + offset = ads8688_range_def[st->range[chan->channel]].offset; + if (offset == 0 && val2 == ads8688_range_def[0].scale * st->vref_mv) { + mutex_unlock(&st->lock); + return -EINVAL; + } + + /* Lookup new mode */ + for (i = 0; i < ARRAY_SIZE(ads8688_range_def); i++) + if (val2 == ads8688_range_def[i].scale * st->vref_mv && + offset == ads8688_range_def[i].offset) { + ret = ads8688_write_reg_range(indio_dev, chan, + ads8688_range_def[i].reg); + break; + } + break; + case IIO_CHAN_INFO_OFFSET: + /* + * There are only two available offsets: + * 0 and -(1 << (ADS8688_REALBITS - 1)) + */ + if (!(ads8688_range_def[0].offset == val || + ads8688_range_def[3].offset == val)) { + mutex_unlock(&st->lock); + return -EINVAL; + } + + /* + * If the device are in ±2.5 * VREF mode, it's not allowed to + * switch to a mode where the offset is 0 + */ + if (val == 0 && + st->range[chan->channel] == ADS8688_PLUSMINUS25VREF) { + mutex_unlock(&st->lock); + return -EINVAL; + } + + scale = ads8688_range_def[st->range[chan->channel]].scale; + + /* Lookup new mode */ + for (i = 0; i < ARRAY_SIZE(ads8688_range_def); i++) + if (val == ads8688_range_def[i].offset && + scale == ads8688_range_def[i].scale) { + ret = ads8688_write_reg_range(indio_dev, chan, + ads8688_range_def[i].reg); + break; + } + break; + } + + if (!ret) + st->range[chan->channel] = ads8688_range_def[i].range; + + mutex_unlock(&st->lock); + + return ret; +} + +static int ads8688_write_raw_get_fmt(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + long mask) +{ + switch (mask) { + case IIO_CHAN_INFO_SCALE: + return IIO_VAL_INT_PLUS_NANO; + case IIO_CHAN_INFO_OFFSET: + return IIO_VAL_INT; + } + + return -EINVAL; +} + +static const struct iio_info ads8688_info = { + .read_raw = &ads8688_read_raw, + .write_raw = &ads8688_write_raw, + .write_raw_get_fmt = &ads8688_write_raw_get_fmt, + .attrs = &ads8688_attribute_group, + .driver_module = THIS_MODULE, +}; + +static const struct ads8688_chip_info ads8688_chip_info_tbl[] = { + [ID_ADS8684] = { + .channels = ads8684_channels, + .num_channels = ARRAY_SIZE(ads8684_channels), + }, + [ID_ADS8688] = { + .channels = ads8688_channels, + .num_channels = ARRAY_SIZE(ads8688_channels), + }, +}; + +static int ads8688_probe(struct spi_device *spi) +{ + struct ads8688_state *st; + struct iio_dev *indio_dev; + int ret; + + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st)); + if (indio_dev == NULL) + return -ENOMEM; + + st = iio_priv(indio_dev); + + st->reg = devm_regulator_get_optional(&spi->dev, "vref"); + if (!IS_ERR(st->reg)) { + ret = regulator_enable(st->reg); + if (ret) + return ret; + + ret = regulator_get_voltage(st->reg); + if (ret < 0) + goto error_out; + + st->vref_mv = ret / 1000; + } else { + /* Use internal reference */ + st->vref_mv = ADS8688_VREF_MV; + } + + st->chip_info = &ads8688_chip_info_tbl[spi_get_device_id(spi)->driver_data]; + + spi->mode = SPI_MODE_1; + + spi_set_drvdata(spi, indio_dev); + + st->spi = spi; + + indio_dev->name = spi_get_device_id(spi)->name; + indio_dev->dev.parent = &spi->dev; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = st->chip_info->channels; + indio_dev->num_channels = st->chip_info->num_channels; + indio_dev->info = &ads8688_info; + + ads8688_reset(indio_dev); + + mutex_init(&st->lock); + + ret = iio_device_register(indio_dev); + if (ret) + goto error_out; + + return 0; + +error_out: + if (!IS_ERR_OR_NULL(st->reg)) + regulator_disable(st->reg); + + return ret; +} + +static int ads8688_remove(struct spi_device *spi) +{ + struct iio_dev *indio_dev = spi_get_drvdata(spi); + struct ads8688_state *st = iio_priv(indio_dev); + + iio_device_unregister(indio_dev); + + if (!IS_ERR_OR_NULL(st->reg)) + regulator_disable(st->reg); + + return 0; +} + +static const struct spi_device_id ads8688_id[] = { + {"ads8684", ID_ADS8684}, + {"ads8688", ID_ADS8688}, + {} +}; +MODULE_DEVICE_TABLE(spi, ads8688_id); + +static const struct of_device_id ads8688_of_match[] = { + { .compatible = "ti,ads8684" }, + { .compatible = "ti,ads8688" }, + { } +}; +MODULE_DEVICE_TABLE(of, ads8688_of_match); + +static struct spi_driver ads8688_driver = { + .driver = { + .name = "ads8688", + .owner = THIS_MODULE, + }, + .probe = ads8688_probe, + .remove = ads8688_remove, + .id_table = ads8688_id, +}; +module_spi_driver(ads8688_driver); + +MODULE_AUTHOR("Sean Nyekjaer <sean.nyekjaer@prevas.dk>"); +MODULE_DESCRIPTION("Texas Instruments ADS8688 driver"); +MODULE_LICENSE("GPL v2"); |