On 13/01/17 09:50, Jacopo Mondi wrote:
> From: Jacopo Mondi <jacopo@xxxxxxxxxx>
>
> Add iio driver for Maxim MAX11100 single-channel ADC.
>
> Signed-off-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> Tested-by: Marek Vasut <marek.vasut@xxxxxxxxx>
>
Small issue with DMA using SPI controllers and the location of buffer
in your read.
Otherwise looks good to me.
Jonathan
> ---
> drivers/iio/adc/Kconfig | 9 +++
> drivers/iio/adc/Makefile | 1 +
> drivers/iio/adc/max11100.c | 187 +++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 197 insertions(+)
> create mode 100644 drivers/iio/adc/max11100.c
>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 38bc319..c32bc7a 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -307,6 +307,15 @@ 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_MASTER
> + help
> + Say yes here to build support for Maxim max11100 SPI ADC
> +
> + 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 d36c4be..5684369 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -31,6 +31,7 @@ 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..78e2a45
> --- /dev/null
> +++ b/drivers/iio/adc/max11100.c
> @@ -0,0 +1,187 @@
> +/*
> + * iio/adc/max11100.c
> + * Maxim max11100 ADC Driver with IIO interface
> + *
> + * 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/delay.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/spi/spi.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/driver.h>
> +
> +/*
> + * LSB is the ADC single digital step
> + * 1 LSB = (vref_mv / 2 ^ 16)
> + *
> + * LSB is used to calculate analog voltage value
> + * from the number of ADC steps count
> + *
> + * Ain = (count * LSB)
> + */
> +#define MAX11100_LSB_DIV (1 << 16)
> +
> +struct max11100_state {
> + const struct max11100_chip_desc *desc;
> + struct regulator *vref_reg;
> + struct spi_device *spi;
> +};
> +
> +static struct iio_chan_spec max11100_channels[] = {
> + { /* [0] */
> + .type = IIO_VOLTAGE,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> + BIT(IIO_CHAN_INFO_SCALE),
> + },
> +};
> +
> +static struct max11100_chip_desc {
> + unsigned int num_chan;
> + const struct iio_chan_spec *channels;
> +} max11100_desc = {
> + .num_chan = ARRAY_SIZE(max11100_channels),
> + .channels = max11100_channels,
> +};
> +
> +static int max11100_read_single(struct iio_dev *indio_dev, int *val)
> +{
> + int ret;
> + struct max11100_state *state = iio_priv(indio_dev);
> + uint8_t buffer[3];
> +
> + ret = spi_read(state->spi, buffer, sizeof(buffer));
Buffer needs to be __cacheline_aligned to safely use spi_read on spi
controllers that use DMA.
Two easy ways of doing this, either allocate buffer using kmalloc or
take advantage of the fact that spi_priv() is cache line aligned and
stick you buffer at the end of your private structure and mark it
__cacheline_aligned to ensure it also appropriately aligned in it's own
cacheline.
> + if (ret) {
> + dev_err(&indio_dev->dev, "SPI transfer failed\n");
> + return ret;
> + }
> +
> + /* 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");
> + return -EINVAL;
> + }
> +
> + *val = (buffer[1] << 8) | buffer[2];
> +
> + return 0;
> +}
> +
> +static int max11100_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long info)
> +{
> + int ret, vref_uv;
> + struct max11100_state *state = iio_priv(indio_dev);
> +
> + switch (info) {
> + case IIO_CHAN_INFO_RAW:
> + ret = max11100_read_single(indio_dev, val);
> + if (ret)
> + return ret;
> +
> + return IIO_VAL_INT;
> +
> + case IIO_CHAN_INFO_SCALE:
> + vref_uv = regulator_get_voltage(state->vref_reg);
> + if (vref_uv < 0)
> + /* dummy regulator "get_voltage" returns -EINVAL */
> + return -EINVAL;
> +
> + *val = vref_uv / 1000;
> + *val2 = MAX11100_LSB_DIV;
> + return IIO_VAL_FRACTIONAL;
> + }
> +
> + return -EINVAL;
> +}
> +
> +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)
> + return -ENOMEM;
> +
> + spi_set_drvdata(spi, indio_dev);
> +
> + state = iio_priv(indio_dev);
> + state->spi = spi;
> + state->desc = &max11100_desc;
> +
> + 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;
> +
> + state->vref_reg = devm_regulator_get(&spi->dev, "vref");
> + if (IS_ERR(state->vref_reg))
> + return PTR_ERR(state->vref_reg);
> +
> + ret = regulator_enable(state->vref_reg);
> + if (ret)
> + return ret;
> +
> + ret = iio_device_register(indio_dev);
> + if (ret)
> + goto disable_regulator;
> +
> + return 0;
> +
> +disable_regulator:
> + regulator_disable(state->vref_reg);
> +
> + return ret;
> +}
> +
> +static int max11100_remove(struct spi_device *spi)
> +{
> + struct iio_dev *indio_dev = spi_get_drvdata(spi);
> + struct max11100_state *state = iio_priv(indio_dev);
> +
> + regulator_disable(state->vref_reg);
> +
> + 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 <jacopo@xxxxxxxxxx>");
> +MODULE_DESCRIPTION("Maxim max11100 ADC Driver");
> +MODULE_LICENSE("GPL v2");
>
