Add driver for the Maxim MAX1241 12-bit, single-channel ADC. The driver includes support for this device's low-power operation mode. Signed-off-by: Alexandru Lazar <alazar@xxxxxxxxxxxxx> --- drivers/iio/adc/Kconfig | 12 +++ drivers/iio/adc/Makefile | 1 + drivers/iio/adc/max1241.c | 215 ++++++++++++++++++++++++++++++++++++++ 3 files changed, 228 insertions(+) create mode 100644 drivers/iio/adc/max1241.c diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig index 5d8540b7b427..3a55beec69c9 100644 --- a/drivers/iio/adc/Kconfig +++ b/drivers/iio/adc/Kconfig @@ -566,6 +566,18 @@ config MAX1118 To compile this driver as a module, choose M here: the module will be called max1118. +config MAX1241 + tristate "Maxim max1241 ADC driver" + depends on SPI + select IIO_BUFFER + select IIO_TRIGGERED_BUFFER + help + Say yes here to build support for Maxim max1241 12-bit, single-channel + ADC. + + To compile this driver as a module, choose M here: the module will be + called max1118. + config MAX1363 tristate "Maxim max1363 ADC driver" depends on I2C diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile index a1f1fbec0f87..37d6f17559dc 100644 --- a/drivers/iio/adc/Makefile +++ b/drivers/iio/adc/Makefile @@ -54,6 +54,7 @@ obj-$(CONFIG_LTC2497) += ltc2497.o obj-$(CONFIG_MAX1027) += max1027.o obj-$(CONFIG_MAX11100) += max11100.o obj-$(CONFIG_MAX1118) += max1118.o +obj-$(CONFIG_MAX1241) += max1241.o obj-$(CONFIG_MAX1363) += max1363.o obj-$(CONFIG_MAX9611) += max9611.o obj-$(CONFIG_MCP320X) += mcp320x.o diff --git a/drivers/iio/adc/max1241.c b/drivers/iio/adc/max1241.c new file mode 100644 index 000000000000..2bd31f22fb2c --- /dev/null +++ b/drivers/iio/adc/max1241.c @@ -0,0 +1,215 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * MAX1241 low-power, 12-bit serial ADC + * + * Copyright (c) 2020 Ioan-Alexandru Lazar <alazar@xxxxxxxxxxxxx> + * + * This file is subject to the terms and conditions of version 2 of + * the GNU General Public License. See the file COPYING in the main + * directory of this archive for more details. + * + * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1240-MAX1241.pdf + */ + +#include <linux/regulator/consumer.h> +#include <linux/delay.h> +#include <linux/gpio/consumer.h> +#include <linux/gpio/driver.h> +#include <linux/gpio.h> +#include <linux/iio/iio.h> +#include <linux/module.h> +#include <linux/spi/spi.h> + +#define MAX1241_VAL_MASK 0xFFF +#define MAX1241_SHDN_DELAY_USEC 4 + +enum max1241_id { + max1241, +}; + +struct max1241 { + struct spi_device *spi; + struct mutex lock; + struct regulator *reg; + struct gpio_desc *shdn; + + __be16 data ____cacheline_aligned; +}; + +static const struct iio_chan_spec max1241_channels[] = { + { + .type = IIO_VOLTAGE, + .indexed = 1, + .channel = 0, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | + BIT(IIO_CHAN_INFO_SCALE), + .scan_index = 0, + .scan_type = { + .sign = 'u', + .realbits = 12, + .storagebits = 16, + }, + }, +}; + +static int max1241_read(struct max1241 *adc) +{ + int ret; + struct spi_device *spi = adc->spi; + struct spi_transfer xfers[] = { + /* + * Begin conversion by bringing /CS low for at least + * tconv us. + */ + { + .len = 0, + .delay_usecs = 8, + }, + /* + * Then read two bytes of data in our RX buffer. + */ + { + .rx_buf = &adc->data, + .len = 2, + }, + }; + + ret = spi_sync_transfer(spi, xfers, 2); + + return ret; +} + +static int max1241_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + int ret, vref_uV; + struct max1241 *adc = iio_priv(indio_dev); + + switch (mask) { + case IIO_CHAN_INFO_RAW: + mutex_lock(&adc->lock); + + if (adc->shdn) { + gpiod_set_value(adc->shdn, 0); + udelay(MAX1241_SHDN_DELAY_USEC); + } + + ret = max1241_read(adc); + + if (adc->shdn) + gpiod_set_value(adc->shdn, 1); + + if (ret) { + mutex_unlock(&adc->lock); + return ret; + } + + *val = (be16_to_cpu(adc->data) >> 3) & MAX1241_VAL_MASK; + + mutex_unlock(&adc->lock); + return IIO_VAL_INT; + case IIO_CHAN_INFO_SCALE: + vref_uV = regulator_get_voltage(adc->reg); + + if (vref_uV < 0) + return vref_uV; + + *val = vref_uV / 1000; + *val2 = 12; + + return IIO_VAL_FRACTIONAL_LOG2; + default: + return -EINVAL; + } +} + +static const struct iio_info max1241_info = { + .read_raw = max1241_read_raw, +}; + +static int max1241_probe(struct spi_device *spi) +{ + struct iio_dev *indio_dev; + struct max1241 *adc; + int ret = 0; + + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc)); + if (!indio_dev) + return -ENOMEM; + + adc = iio_priv(indio_dev); + adc->spi = spi; + mutex_init(&adc->lock); + + spi_set_drvdata(spi, indio_dev); + + adc->reg = devm_regulator_get(&spi->dev, "vref"); + if (IS_ERR(adc->reg)) { + dev_err(&spi->dev, "failed to get vref regulator\n"); + return PTR_ERR(adc->reg); + } + + ret = regulator_enable(adc->reg); + if (ret) + return ret; + + adc->shdn = devm_gpiod_get_optional(&spi->dev, "shdn", GPIOD_OUT_HIGH); + if (!adc->shdn) + dev_info(&spi->dev, "no shdn pin passed, low-power mode disabled"); + else + dev_info(&spi->dev, "shdn pin passed, low-power mode enabled"); + + indio_dev->name = spi_get_device_id(spi)->name; + indio_dev->dev.parent = &spi->dev; + indio_dev->info = &max1241_info; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = max1241_channels; + indio_dev->num_channels = ARRAY_SIZE(max1241_channels); + + ret = iio_device_register(indio_dev); + + return ret; +} + +static int max1241_remove(struct spi_device *spi) +{ + struct iio_dev *indio_dev = spi_get_drvdata(spi); + struct max1241 *adc = iio_priv(indio_dev); + int ret = 0; + + iio_device_unregister(indio_dev); + ret = regulator_disable(adc->reg); + + return ret; +} + +static const struct spi_device_id max1241_id[] = { + { "max1241", max1241 }, + {}, +}; + +#ifdef CONFIG_OF + +static const struct of_device_id max1241_dt_ids[] = { + { .compatible = "maxim,max1241" }, + {}, +}; +MODULE_DEVICE_TABLE(of, max1241_dt_ids); + +#endif + +static struct spi_driver max1241_spi_driver = { + .driver = { + .name = "max1241", + .of_match_table = of_match_ptr(max1241_dt_ids), + }, + .probe = max1241_probe, + .remove = max1241_remove, + .id_table = max1241_id, +}; +module_spi_driver(max1241_spi_driver); + +MODULE_AUTHOR("Alexandru Lazar <alazar@xxxxxxxxxxxxx>"); +MODULE_DESCRIPTION("MAX1241 ADC driver"); +MODULE_LICENSE("GPL v2"); -- 2.25.1
