On Fri, 20 Mar 2020 17:01:15 +0200 Alexandru Lazar <alazar@xxxxxxxxxxxxx> wrote: > Add driver for the Maxim MAX1241 12-bit, single-channel ADC. The driver > includes support for this device's low-power operation mode. > > Reviewed-by: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx> > Signed-off-by: Alexandru Lazar <alazar@xxxxxxxxxxxxx> Few minor things inline, but looks good in general. > --- > drivers/iio/adc/Kconfig | 10 ++ > drivers/iio/adc/Makefile | 1 + > drivers/iio/adc/max1241.c | 206 ++++++++++++++++++++++++++++++++++++++ > 3 files changed, 217 insertions(+) > create mode 100644 drivers/iio/adc/max1241.c > > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig > index 5d8540b7b427..55f6462cd93f 100644 > --- a/drivers/iio/adc/Kconfig > +++ b/drivers/iio/adc/Kconfig > @@ -566,6 +566,16 @@ 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_MASTER > + 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 max1241. > + > 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..0278510ec346 > --- /dev/null > +++ b/drivers/iio/adc/max1241.c > @@ -0,0 +1,206 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * MAX1241 low-power, 12-bit serial ADC > + * > + * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1240-MAX1241.pdf > + */ > + > +#include <linux/regulator/consumer.h> Nitpick; Tidy up ordering of headers. If no other reason to have a particular order go with alphabetical. > +#include <linux/delay.h> > +#include <linux/gpio/consumer.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, > + }, No need to specify scan_index or scan_type unless the driver supports buffered modes. Nothing will use them until then. > + }, > +}; > + > +static int max1241_read(struct max1241 *adc) > +{ > + struct spi_transfer xfers[] = { > + /* > + * Begin conversion by bringing /CS low for at least > + * tconv us. > + */ > + { > + .len = 0, > + .delay.value = 8, > + .delay.unit = SPI_DELAY_UNIT_USECS, > + }, > + /* > + * Then read two bytes of data in our RX buffer. > + */ > + { > + .rx_buf = &adc->data, > + .len = 2, > + }, > + }; > + > + return spi_sync_transfer(adc->spi, xfers, ARRAY_SIZE(xfers)); > +} > + > +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 void max1241_disable_reg_action(void *data) > +{ > + struct max1241 *adc = data; > + int err; > + > + err = regulator_disable(adc->reg); > + if (err) > + dev_err(&adc->spi->dev, "could not disable reference regulator.\n"); > +} > + > +static int max1241_probe(struct spi_device *spi) > +{ > + struct iio_dev *indio_dev; > + struct max1241 *adc; > + int ret = 0; Looks like ret is always set in all the paths that can use it. Hence no need to initialize here. > + > + 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; > + > + ret = devm_add_action_or_reset(&spi->dev, max1241_disable_reg_action, > + adc); > + if (ret) { > + dev_err(&spi->dev, "could not set up regulator cleanup action!\n"); > + return ret; > + } > + > + adc->shdn = devm_gpiod_get_optional(&spi->dev, "shdn", GPIOD_OUT_HIGH); > + > + if (IS_ERR(adc->shdn)) > + return PTR_ERR(adc->shdn); > + > + if (!adc->shdn) > + dev_dbg(&spi->dev, "no shdn pin passed, low-power mode disabled"); > + else > + dev_dbg(&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); > + > + return devm_iio_device_register(&spi->dev, indio_dev); > +} > + > +static const struct spi_device_id max1241_id[] = { > + { "max1241", max1241 }, > + {}, > +}; > + > +static const struct of_device_id max1241_dt_ids[] = { > + { .compatible = "maxim,max1241" }, > + {}, > +}; > +MODULE_DEVICE_TABLE(of, max1241_dt_ids); > + > +static struct spi_driver max1241_spi_driver = { > + .driver = { > + .name = "max1241", > + .of_match_table = max1241_dt_ids, > + }, > + .probe = max1241_probe, > + .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");
