On Tue, 6 Dec 2016, Jacopo Mondi wrote:
> Add IIO driver for Maxim MAX11100 single-channel ADC.
> Support raw_read mode only.
comments below; very minimal driver, but several easy issues...
the read_raw() is supposed to return millivolts (after application of
offset and scale); maybe need _SCALE?
> Signed-off-by: Jacopo Mondi <jac...@jmondi.org>
> ---
> drivers/iio/adc/Kconfig | 9 +++
> drivers/iio/adc/Makefile | 1 +
> drivers/iio/adc/max11100.c | 165
> +++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 175 insertions(+)
> create mode 100644 drivers/iio/adc/max11100.c
>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 99c0514..e2f3340 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -285,6 +285,15 @@ config MAX1027
> To compile this driver as a module, choose M here: the module will be
> called max1027.
>
> +config MAX11100
> + tristate "Maxim max11100 ADC driver"
> + depends on SPI
> + help
> + Say yes here to build support for Maxim 11100 SPI ADC
Maxim max11100
> +
> + To compile this driver as a module, choose M here: the module will be
> + called max11100.
> +
> config MAX1363
> tristate "Maxim max1363 ADC driver"
> depends on I2C
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 7a40c04..1463044 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -29,6 +29,7 @@ obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
> obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o
> obj-$(CONFIG_LTC2485) += ltc2485.o
> obj-$(CONFIG_MAX1027) += max1027.o
> +obj-$(CONFIG_MAX11100) += max11100.o
> obj-$(CONFIG_MAX1363) += max1363.o
> obj-$(CONFIG_MCP320X) += mcp320x.o
> obj-$(CONFIG_MCP3422) += mcp3422.o
> diff --git a/drivers/iio/adc/max11100.c b/drivers/iio/adc/max11100.c
> new file mode 100644
> index 0000000..fbce287
> --- /dev/null
> +++ b/drivers/iio/adc/max11100.c
> @@ -0,0 +1,165 @@
> +/*
> + * iio/adc/max11100.c
> + * Maxim MAX11100 ADC Driver with IIO interface
MAX11100 or max11100
> + *
> + * Copyright (C) 2016 Renesas Electronics Corporation
> + * Copyright (C) 2016 Jacopo Mondi
> + *
> + * 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/kernel.h>
> +#include <linux/module.h>
> +#include <linux/spi/spi.h>
> +#include <linux/delay.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/buffer.h>
> +
> +struct max11100_state {
> + const struct max11100_chip_desc *desc;
> + struct spi_device *spi;
> + struct mutex lock;
> +};
> +
> +static struct iio_chan_spec max11100_channels[] = {
> + { /* [0] */
> + .type = IIO_VOLTAGE,
> + .channel = 0,
not indexed, so channel = 0 not needed
> + .address = 0,
address not needed (and no need to initialize to 0 anyway)
> + .scan_index = 0,
scan_index and scan_type not needed since no buffered support (yet); add
this when needed
> + .scan_type = {
> + .sign = 'u',
> + .realbits = 16,
> + .storagebits = 24,
> + .shift = 8,
> + .repeat = 1,
> + .endianness = IIO_BE,
> + },
> + .output = 1,
no, ADC is typically not an output channel
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> + },
> +};
> +
> +static const unsigned long max11100_scan_masks[] = {
scan_masks not needed since no buffered support
> + 0xffff,
> +};
> +
> +static struct max11100_chip_desc {
> + uint32_t num_chan;
why not just unsigned?
> + const unsigned long *scanmasks;
not needed (yet)
> + const struct iio_chan_spec *channels;
> +} max11100_desc = {
> + .num_chan = 1,
ARRAY_SIZE(max11100_channels)
> + .scanmasks = max11100_scan_masks,
> + .channels = max11100_channels,
> +};
> +
> +static int max11100_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + int ret;
> + struct max11100_state *state = iio_priv(indio_dev);
> + uint8_t buffer[3] = { 0, 0, 0 };
no need to initialize buffer; consider alignment requirements for SPI
> +
> + mutex_lock(&state->lock);
what is the mutex protecting?
must the spi_read() by protected? then the unlock can be placed right
after the call...
> +
> + ret = spi_read(state->spi, (void *) buffer, 3);
sizeof(buffer)
> + if (ret) {
> + dev_err(&indio_dev->dev, "SPI transfer failed\n");
mutex_unlock()!?
> + return ret;
> + }
> +
> + dev_dbg(&indio_dev->dev, "ADC output values: " \
> + "[0]: 0x%2x [1]: 0x%2x [2]: 0x%2x\n",
probably 0x%02x if really needed
> + buffer[0], buffer[1], buffer[2]);
> +
> + /* the first 8 bits sent out from ADC must be 0s */
> + if (buffer[0]) {
> + dev_err(&indio_dev->dev, "Invalid value: buffer[0] != 0\n");
mutex_unlock()!?
> + return -EINVAL;
> + }
> +
> + *val = (buffer[1] << 8) | buffer[2];
> + mutex_unlock(&state->lock);
> +
shouldn't this return IIO_VAL_INT?
> + return 0;
> +}
> +
> +static const struct iio_info max11100_info = {
> + .driver_module = THIS_MODULE,
> + .read_raw = max11100_read_raw,
> +};
> +
> +static int max11100_probe(struct spi_device *spi)
> +{
> + int ret;
> + struct iio_dev *indio_dev;
> + struct max11100_state *state;
> +
> + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
> + if (!indio_dev) {
> + pr_err("Can't allocate iio device\n");
error message really needed?
> + return -ENOMEM;
> + }
> + dev_dbg(&indio_dev->dev, "probe max11100 IIO SPI\n");
message really needed?
> +
> + spi_set_drvdata(spi, indio_dev);
> +
> + state = iio_priv(indio_dev);
> + state->spi = spi;
> + state->desc = &max11100_desc;
> +
> + mutex_init(&state->lock);
> +
> + indio_dev->dev.parent = &spi->dev;
> + indio_dev->dev.of_node = spi->dev.of_node;
> + indio_dev->info = &max11100_info;
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->channels = state->desc->channels;
> + indio_dev->num_channels = state->desc->num_chan;
> + indio_dev->available_scan_masks = state->desc->scanmasks;
> +
> + ret = iio_device_register(indio_dev);
could use devm_ variant...
> + if (ret) {
> + dev_err(&indio_dev->dev, "Failed to register iio device\n");
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static int max11100_remove(struct spi_device *spi)
function not needed if using devm_iio_device_register()
> +{
> + struct iio_dev *indio_dev = spi_get_drvdata(spi);
> +
> + dev_dbg(&indio_dev->dev, "remove max11100 IIO SPI\n");
> +
> + iio_device_unregister(indio_dev);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id max11100_ids[] = {
> + {.compatible = "maxim,max11100"},
> + { },
> +};
> +MODULE_DEVICE_TABLE(of, max11100_ids);
> +
> +static struct spi_driver max11100_driver = {
> + .driver = {
> + .name = "max11100",
> + .owner = THIS_MODULE,
> + .of_match_table = of_match_ptr(max11100_ids),
> + },
> + .probe = max11100_probe,
> + .remove = max11100_remove,
> +};
> +
> +module_spi_driver(max11100_driver);
> +
> +MODULE_AUTHOR("Jacopo Mondi <jac...@jmondi.org>");
> +MODULE_DESCRIPTION("Maxim MAX11100 ADC Driver");
> +MODULE_LICENSE("GPL v2");
>
--
Peter Meerwald-Stadler
+43-664-2444418 (mobile)
