This chip is similar to the LTC2497 ADC, it just uses SPI instead of I2C and so has a slightly different protocol. The channel definitions are shared between the two drivers. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> --- drivers/iio/adc/Kconfig | 10 ++ drivers/iio/adc/Makefile | 1 + drivers/iio/adc/ltc2496.c | 208 ++++++++++++++++++++++++++++++++++++++ 3 files changed, 219 insertions(+) create mode 100644 drivers/iio/adc/ltc2496.c diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig index f0af3a42f53c..deb86f6039b3 100644 --- a/drivers/iio/adc/Kconfig +++ b/drivers/iio/adc/Kconfig @@ -492,6 +492,16 @@ config LTC2485 To compile this driver as a module, choose M here: the module will be called ltc2485. +config LTC2496 + tristate "Linear Technology LTC2496 ADC driver" + depends on SPI + help + Say yes here to build support for Linear Technology LTC2496 + 16-Bit 8-/16-Channel Delta Sigma ADC. + + To compile this driver as a module, choose M here: the module will be + called ltc2496. + config LTC2497 tristate "Linear Technology LTC2497 ADC driver" depends on I2C diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile index 660242c2cca7..afe2b6db4a5e 100644 --- a/drivers/iio/adc/Makefile +++ b/drivers/iio/adc/Makefile @@ -47,6 +47,7 @@ obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o obj-$(CONFIG_LPC32XX_ADC) += lpc32xx_adc.o obj-$(CONFIG_LTC2471) += ltc2471.o obj-$(CONFIG_LTC2485) += ltc2485.o +obj-$(CONFIG_LTC2496) += ltc2496.o ltc249x.o obj-$(CONFIG_LTC2497) += ltc2497.o ltc249x.o obj-$(CONFIG_MAX1027) += max1027.o obj-$(CONFIG_MAX11100) += max11100.o diff --git a/drivers/iio/adc/ltc2496.c b/drivers/iio/adc/ltc2496.c new file mode 100644 index 000000000000..0b0a7aa8987f --- /dev/null +++ b/drivers/iio/adc/ltc2496.c @@ -0,0 +1,208 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * ltc2496.c - Driver for Analog Devices/Linear Technology LTC2496 ADC + * + * Based on ltc2497.c which has + * Copyright (C) 2017 Analog Devices Inc. + * + * Licensed under the GPL-2. + * + * Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/2496fc.pdf + */ + +#include <linux/delay.h> +#include <linux/spi/spi.h> +#include <linux/iio/iio.h> +#include <linux/iio/driver.h> +#include <linux/iio/sysfs.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/regulator/consumer.h> + +#include "ltc249x.h" + +struct ltc2496_st { + struct spi_device *spi; + struct regulator *ref; + ktime_t time_prev; + u8 addr_prev; +}; + +static int ltc2496_wait_conv(struct ltc2496_st *st) +{ + s64 time_elapsed; + + time_elapsed = ktime_ms_delta(ktime_get(), st->time_prev); + + if (time_elapsed < LTC249X_CONVERSION_TIME_MS) { + /* delay if conversion time not passed + * since last read or write + */ + if (msleep_interruptible( + LTC249X_CONVERSION_TIME_MS - time_elapsed)) + return -ERESTARTSYS; + + return 0; + } + + if (time_elapsed - LTC249X_CONVERSION_TIME_MS <= 0) { + /* We're in automatic mode - + * so the last reading is still not outdated + */ + return 0; + } + + return 1; +} + +static int ltc2496_read(struct ltc2496_st *st, u8 address, int *val) +{ + struct spi_device *spi = st->spi; + int ret; + unsigned char txbuf[3] = { LTC249X_ENABLE | address, }; + unsigned char rxbuf[3]; + struct spi_transfer t = { + .tx_buf = txbuf, + .rx_buf = rxbuf, + .len = sizeof(txbuf), + }; + + ret = ltc2496_wait_conv(st); + if (ret < 0) + return ret; + + if (ret || st->addr_prev != address) { + ret = spi_sync_transfer(spi, &t, 1); + if (ret < 0) + return ret; + st->addr_prev = address; + if (msleep_interruptible(LTC249X_CONVERSION_TIME_MS)) + return -ERESTARTSYS; + } + + ret = spi_sync_transfer(spi, &t, 1); + if (ret < 0) { + dev_err(&spi->dev, "spi_sync_transfer failed\n"); + return ret; + } + st->time_prev = ktime_get(); + + /* convert and shift the result, + * and finally convert from offset binary to signed integer + */ + *val = ((rxbuf[0] & 0x3f) << 12 | rxbuf[1] << 4 | rxbuf[2] >> 4) + - (1 << 17); + + return ret; +} + +static int ltc2496_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + struct ltc2496_st *st = iio_priv(indio_dev); + int ret; + + switch (mask) { + case IIO_CHAN_INFO_RAW: + mutex_lock(&indio_dev->mlock); + ret = ltc2496_read(st, chan->address, val); + mutex_unlock(&indio_dev->mlock); + if (ret < 0) + return ret; + + return IIO_VAL_INT; + + case IIO_CHAN_INFO_SCALE: + ret = regulator_get_voltage(st->ref); + if (ret < 0) + return ret; + + *val = ret / 1000; + *val2 = 17; + + return IIO_VAL_FRACTIONAL_LOG2; + + default: + return -EINVAL; + } +} + +static const struct iio_info ltc2496_info = { + .read_raw = ltc2496_read_raw, +}; + +static int ltc2496_probe(struct spi_device *spi) +{ + struct iio_dev *indio_dev; + struct ltc2496_st *st; + int ret; + + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st)); + if (!indio_dev) + return -ENOMEM; + + st = iio_priv(indio_dev); + spi_set_drvdata(spi, indio_dev); + st->spi = spi; + + indio_dev->dev.parent = &spi->dev; + indio_dev->name = "ltc2496"; + indio_dev->info = <c2496_info; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = ltc249x_channel; + indio_dev->num_channels = ltc249x_num_channels; + + st->ref = devm_regulator_get(&spi->dev, "vref"); + if (IS_ERR(st->ref)) + return PTR_ERR(st->ref); + + ret = regulator_enable(st->ref); + if (ret < 0) + return ret; + + st->addr_prev = 0; + st->time_prev = ktime_get(); + + ret = iio_device_register(indio_dev); + if (ret < 0) + goto err_regulator_disable; + + return 0; + +err_regulator_disable: + regulator_disable(st->ref); + + return ret; +} + +static int ltc2496_remove(struct spi_device *spi) +{ + struct iio_dev *indio_dev = spi_get_drvdata(spi); + struct ltc2496_st *st = iio_priv(indio_dev); + + iio_device_unregister(indio_dev); + regulator_disable(st->ref); + + return 0; +} + +static const struct of_device_id ltc2496_of_match[] = { + { .compatible = "lltc,ltc2496", }, + {}, +}; +MODULE_DEVICE_TABLE(of, ltc2496_of_match); + +static struct spi_driver ltc2496_driver = { + .driver = { + .name = "ltc2496", + .of_match_table = of_match_ptr(ltc2496_of_match), + }, + .probe = ltc2496_probe, + .remove = ltc2496_remove, +}; +module_spi_driver(ltc2496_driver); + +MODULE_AUTHOR("Uwe Kleine-König <u.kleine-könig@xxxxxxxxxxxxxx>"); +MODULE_DESCRIPTION("Linear Technology LTC2496 ADC driver"); +MODULE_LICENSE("GPL v2"); -- 2.24.0.rc1
