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SubjectRe: [PATCH 1/3] iio: adc: add support for mcp3911
Hello,

> MCP3911 is a dual channel Analog Front End (AFE) containing two
> synchronous sampling delta-sigma Analog-to-Digital Converters (ADC).

some comments below...

> Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
> Signed-off-by: Kent Gustavsson <kent@minoris.se>
> ---
> drivers/iio/adc/Kconfig | 10 ++
> drivers/iio/adc/Makefile | 1 +
> drivers/iio/adc/mcp3911.c | 444 ++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 455 insertions(+)
> create mode 100644 drivers/iio/adc/mcp3911.c
>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 15606f237480..f9a41fa96fcc 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -501,6 +501,16 @@ config MCP3422
> This driver can also be built as a module. If so, the module will be
> called mcp3422.
>
> +config MCP3911
> + tristate "Microchip Technology MCP3911 driver"
> + depends on SPI
> + help
> + Say yes here to build support for Microchip Technology's MCP3911
> + analog to digital converter.
> +
> + This driver can also be built as a module. If so, the module will be
> + called mcp3911.
> +
> config MEDIATEK_MT6577_AUXADC
> tristate "MediaTek AUXADC driver"
> depends on ARCH_MEDIATEK || COMPILE_TEST
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 28a9423997f3..3cfebfff7d26 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -47,6 +47,7 @@ obj-$(CONFIG_MAX1363) += max1363.o
> obj-$(CONFIG_MAX9611) += max9611.o
> obj-$(CONFIG_MCP320X) += mcp320x.o
> obj-$(CONFIG_MCP3422) += mcp3422.o
> +obj-$(CONFIG_MCP3911) += mcp3911.o
> obj-$(CONFIG_MEDIATEK_MT6577_AUXADC) += mt6577_auxadc.o
> obj-$(CONFIG_MEN_Z188_ADC) += men_z188_adc.o
> obj-$(CONFIG_MESON_SARADC) += meson_saradc.o
> diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
> new file mode 100644
> index 000000000000..be74cb15827b
> --- /dev/null
> +++ b/drivers/iio/adc/mcp3911.c
> @@ -0,0 +1,444 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Driver for Microchip MCP3911, Two-channel Analog Front End
> + *
> + * Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@gmail.com>
> + * Copyright (C) 2018 Kent Gustavsson <kent@minoris.se>
> + *
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/iio/iio.h>
> +#include <linux/module.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/spi/spi.h>
> +
> +#define MCP3911_REG_CHANNEL0 0x00
> +#define MCP3911_REG_CHANNEL1 0x03
> +#define MCP3911_REG_MOD 0x06
> +#define MCP3911_REG_PHASE 0x07
> +
> +#define MCP3911_REG_GAIN 0x09
> +#define MCP3911_GAIN_MASK(ch) (0x7 << 3*ch)

space around * operator, maybe parenthesis around variable, i.e
(0x07 << (3 * (ch)))

> +#define MCP3911_GAIN_VAL(ch, val) ((val << 3*ch) & MCP3911_GAIN_MASK(ch))
> +
> +#define MCP3911_REG_STATUSCOM 0x0a
> +#define MCP3911_STATUSCOM_CH1_24WIDTH BIT(4)
> +#define MCP3911_STATUSCOM_CH0_24WIDTH BIT(3)
> +#define MCP3911_STATUSCOM_EN_OFFCAL BIT(2)
> +#define MCP3911_STATUSCOM_EN_GAINCAL BIT(1)
> +
> +#define MCP3911_REG_CONFIG 0x0c
> +#define MCP3911_CONFIG_CLKEXT BIT(1)
> +#define MCP3911_CONFIG_VREFEXT BIT(2)
> +
> +#define MCP3911_REG_OFFCAL_CH0 0x0e
> +#define MCP3911_REG_GAINCAL_CH0 0x11
> +#define MCP3911_REG_OFFCAL_CH1 0x14
> +#define MCP3911_REG_GAINCAL_CH1 0x17
> +#define MCP3911_REG_VREFCAL 0x1a
> +
> +#define MCP3911_CHANNEL(x) (MCP3911_REG_CHANNEL0 + x * 3)
> +#define MCP3911_OFFCAL(x) (MCP3911_REG_OFFCAL_CH0 + x * 6)
> +#define MCP3911_GAINCAL(x) (MCP3911_REG_GAINCAL_CH0 + x * 6)
> +

delete newline

> +
> +/* Internal voltage reference in uV */
> +#define MCP3911_INT_VREF_UV 1200000
> +
> +#define REG_READ(reg, id) (((reg << 1) | (id << 5) | (1 << 0)) & 0xff)
> +#define REG_WRITE(reg, id) (((reg << 1) | (id << 5) | (0 << 0)) & 0xff)

MCP3911_ prefix please
parenthesis around variables

> +
> +#define MCP3911_NUM_CHANNELS 2
> +
> +
> +struct mcp3911 {
> + struct spi_device *spi;
> + struct device_node *np;
> + struct mutex lock;
> +
> + u32 gain[MCP3911_NUM_CHANNELS];
> + u32 width[MCP3911_NUM_CHANNELS];
> +
> + u32 dev_addr;
> + bool vrefext;
> + struct regulator *vref;
> +};
> +
> +static int mcp3911_read(struct mcp3911 *adc, u8 reg, u32 *val, u8 len)
> +{
> + int ret;
> +
> + reg = REG_READ(reg, adc->dev_addr);
> + ret = spi_write_then_read(adc->spi, &reg, 1, val, len);
> + if (ret < 0)
> + return ret;
> +
> + *val <<= ((4-len)*8);

space around - and * operator, here and elsewhere

shouldn't the endiness conversion happen before the value is shifted?
(here and below)?

> + be32_to_cpus(val);
> + dev_dbg(&adc->spi->dev, "Reading 0x%x from register 0x%x\n", *val,
> + reg>>1);
> + return ret;
> +}
> +
> +static int mcp3911_write(struct mcp3911 *adc, u8 reg, u32 val, u8 len)
> +{
> + dev_dbg(&adc->spi->dev, "Writing 0x%x to register 0x%x\n", val, reg);
> +
> + cpu_to_be32s(&val);
> + val >>= (3-len)*8;
> + val |= REG_WRITE(reg, adc->dev_addr);
> +
> + return spi_write(adc->spi, &val, len+1);
> +}
> +
> +static int mcp3911_update(struct mcp3911 *adc, u8 reg, u32 mask,
> + u32 val, u8 len)
> +{
> + u32 tmp;
> + int ret;
> +
> + ret = mcp3911_read(adc, reg, &tmp, len);
> + if (ret)
> + return ret;
> +
> + val &= mask;
> + val |= tmp & ~mask;
> + return mcp3911_write(adc, reg, val, len);
> +}
> +
> +static int mcp3911_get_hwgain(struct mcp3911 *adc, u8 channel, u32 *val)
> +{
> + int ret = mcp3911_read(adc, MCP3911_REG_GAIN, val, 1);
> +
> + if (ret)
> + return ret;
> +
> + *val >>= channel*3;
> + *val &= 0x07;
> + *val = (1 << *val);
> +
> + return 0;
> +}
> +
> +static int mcp3911_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *channel, int *val,
> + int *val2, long mask)
> +{
> + struct mcp3911 *adc = iio_priv(indio_dev);
> + int ret = -EINVAL;
> +
> + mutex_lock(&adc->lock);
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + ret = mcp3911_read(adc,
> + MCP3911_CHANNEL(channel->channel), val, 3);
> + if (ret)
> + goto out;
> +
> + ret = IIO_VAL_INT;
> + break;
> +
> + case IIO_CHAN_INFO_OFFSET:
> + ret = mcp3911_read(adc,
> + MCP3911_OFFCAL(channel->channel), val, 3);
> + if (ret)
> + goto out;
> +
> + ret = IIO_VAL_INT;
> + break;
> +
> + case IIO_CHAN_INFO_HARDWAREGAIN:
> + ret = mcp3911_get_hwgain(adc, channel->channel, val);
> + if (ret)
> + goto out;
> +
> + ret = IIO_VAL_INT;
> + break;
> +
> + case IIO_CHAN_INFO_SCALE:
> + if (adc->vrefext) {
> + ret = regulator_get_voltage(adc->vref);
> + if (ret < 0) {
> + dev_err(indio_dev->dev.parent,
> + "failed to get vref voltage:%d\n", ret);

start message consistently with upper/lowercase
maybe space before :

> + goto out;
> + }
> +
> + *val = ret / 1000;
> + } else {
> + *val = MCP3911_INT_VREF_UV;
> + }
> +
> + /* apply with gain value */
> + *val /= adc->gain[channel->channel];
> + *val2 = adc->width[channel->channel];
> +
> + ret = IIO_VAL_FRACTIONAL_LOG2;
> + break;
> + }
> +
> +out:
> + mutex_unlock(&adc->lock);
> +
> + return ret;
> +}
> +
> +static int mcp3911_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *channel, int val,
> + int val2, long mask)
> +{
> + struct mcp3911 *adc = iio_priv(indio_dev);
> + int ret = -EINVAL;
> +
> + mutex_lock(&adc->lock);
> + switch (mask) {
> + case IIO_CHAN_INFO_OFFSET:
> +

val2 should probably be zero and checked?

> + /* Write offset */
> + ret = mcp3911_write(adc, MCP3911_OFFCAL(channel->channel), val,
> + 3);
> + if (ret)
> + goto out;
> +
> + /* Enable offset*/
> + ret = mcp3911_update(adc, MCP3911_REG_STATUSCOM,
> + MCP3911_STATUSCOM_EN_OFFCAL,
> + MCP3911_STATUSCOM_EN_OFFCAL, 2);
> + if (ret)
> + goto out;
> +
> + break;
> +
> + case IIO_CHAN_INFO_HARDWAREGAIN:

val2?

> + if (!is_power_of_2(val) && val <= 32) {

the check looks suspicious, maybe || val > 32

> + ret = -EINVAL;
> + goto out;
> + }
> +
> + adc->gain[channel->channel] = val;
> +
> + val = ilog2(val);
> + ret = mcp3911_update(adc, MCP3911_REG_GAIN,
> + MCP3911_GAIN_MASK(channel->channel),
> + MCP3911_GAIN_VAL(channel->channel,
> + val), 1);
> + break;
> + }
> +
> +out:
> + mutex_unlock(&adc->lock);
> +
> + return ret;
> +}
> +
> +static const struct iio_chan_spec mcp3911_channels[] = {
> + {

maybe use a MACRO(), e.g. MCP3911_CHANNEL(idx) ...

> + .type = IIO_VOLTAGE,
> + .indexed = 1,
> + .channel = 0,
> + .address = MCP3911_REG_CHANNEL0,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> + BIT(IIO_CHAN_INFO_OFFSET) |
> + BIT(IIO_CHAN_INFO_SCALE) |
> + BIT(IIO_CHAN_INFO_HARDWAREGAIN),
> + },
> + {
> + .type = IIO_VOLTAGE,
> + .indexed = 1,
> + .channel = 1,
> + .address = MCP3911_REG_CHANNEL1,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> + BIT(IIO_CHAN_INFO_OFFSET) |
> + BIT(IIO_CHAN_INFO_SCALE) |
> + BIT(IIO_CHAN_INFO_HARDWAREGAIN),
> + },
> +};
> +
> +static const struct iio_info mcp3911_info = {
> + .read_raw = mcp3911_read_raw,
> + .write_raw = mcp3911_write_raw,
> +};
> +
> +static int mcp3911_config_of(struct mcp3911 *adc)
> +{
> + u32 configreg;
> + u32 statuscomreg;
> + int ret;
> +
> + of_property_read_u32(adc->np, "device-addr", &adc->dev_addr);
> + if (adc->dev_addr > 3) {
> + dev_err(&adc->spi->dev,
> + "invalid device address (%i). Must be in range 0-3.\n",
> + adc->dev_addr);
> + return -EINVAL;
> + }
> + dev_dbg(&adc->spi->dev, "use device address %i\n", adc->dev_addr);
> +
> + ret = mcp3911_read(adc, MCP3911_REG_CONFIG, &configreg, 2);
> + if (ret)
> + return ret;
> +
> + adc->vrefext = of_property_read_bool(adc->np, "external-vref");
> + if (adc->vrefext) {
> + dev_dbg(&adc->spi->dev, "use external voltage reference\n");
> + configreg |= MCP3911_CONFIG_VREFEXT;
> +
> + } else {
> + dev_dbg(&adc->spi->dev, "use internal voltage reference (1.2V)\n");
> + configreg &= ~MCP3911_CONFIG_VREFEXT;
> + }
> +
> + if (of_property_read_bool(adc->np, "external-clock")) {
> + dev_dbg(&adc->spi->dev, "use external clock as clocksource\n");
> + configreg |= MCP3911_CONFIG_CLKEXT;
> + } else {
> + dev_dbg(&adc->spi->dev, "use crystal oscillator as clocksource\n");
> + configreg &= ~MCP3911_CONFIG_CLKEXT;
> + }
> +
> + ret = mcp3911_write(adc, MCP3911_REG_CONFIG, configreg, 2);
> + if (ret)
> + return ret;
> +
> +
> + ret = mcp3911_read(adc, MCP3911_REG_STATUSCOM, &statuscomreg, 2);
> + if (ret)
> + return ret;
> +

no duplicate newlines (here and elsewhere)

> +
> + of_property_read_u32(adc->np, "ch0-width", &adc->width[0]);
> + switch (adc->width[0]) {
> + case 24:
> + statuscomreg &= ~MCP3911_STATUSCOM_CH0_24WIDTH;
> + dev_dbg(&adc->spi->dev, "set channel 0 into 24bit mode\n");
> + break;
> + case 16:
> + statuscomreg |= MCP3911_STATUSCOM_CH0_24WIDTH;
> + dev_dbg(&adc->spi->dev, "set channel 0 into 16bit mode\n");
> + break;
> + default:
> + adc->width[0] = 24;
> + dev_info(&adc->spi->dev, "invalid width for channel 0. Use 24bit.\n");
> + break;
> + }
> +
> + of_property_read_u32(adc->np, "ch1-width", &adc->width[1]);
> + switch (adc->width[1]) {
> + case 24:
> + statuscomreg &= ~MCP3911_STATUSCOM_CH1_24WIDTH;
> + dev_dbg(&adc->spi->dev, "set channel 1 into 24bit mode\n");
> + break;
> + case 16:
> + statuscomreg |= MCP3911_STATUSCOM_CH1_24WIDTH;
> + dev_dbg(&adc->spi->dev, "set channel 1 into 16bit mode\n");
> + break;
> + default:
> + adc->width[1] = 24;
> + dev_info(&adc->spi->dev, "invalid width for channel 1. Use 24bit.\n");
> + break;
> + }
> +
> + return mcp3911_write(adc, MCP3911_REG_STATUSCOM, statuscomreg, 2);
> +}
> +
> +static int mcp3911_probe(struct spi_device *spi)
> +{
> + struct iio_dev *indio_dev;
> + struct mcp3911 *adc;
> + int ret;
> +
> + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + adc = iio_priv(indio_dev);
> + adc->spi = spi;
> + adc->np = spi->dev.of_node;
> +
> + ret = mcp3911_config_of(adc);
> + if (ret)
> + return ret;
> +
> + if (adc->vrefext) {
> + adc->vref = devm_regulator_get(&adc->spi->dev, "vref");
> + if (IS_ERR(adc->vref))
> + return PTR_ERR(adc->vref);
> +
> + ret = regulator_enable(adc->vref);
> + if (ret < 0)
> + return ret;
> + }
> +
> + /* Store gain values to better calculate scale values */
> + mcp3911_get_hwgain(adc, 0, &adc->gain[0]);
> + mcp3911_get_hwgain(adc, 1, &adc->gain[1]);
> +
> + indio_dev->dev.parent = &spi->dev;
> + indio_dev->dev.of_node = spi->dev.of_node;
> + indio_dev->name = spi_get_device_id(spi)->name;
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->info = &mcp3911_info;
> + spi_set_drvdata(spi, indio_dev);
> +
> + indio_dev->channels = mcp3911_channels;
> + indio_dev->num_channels = ARRAY_SIZE(mcp3911_channels);
> +
> + mutex_init(&adc->lock);
> +
> + ret = iio_device_register(indio_dev);
> + if (ret)
> + goto reg_disable;
> +
> + return ret;
> +
> +reg_disable:
> + if (adc->vref)
> + regulator_disable(adc->vref);
> +
> + return ret;
> +}
> +
> +static int mcp3911_remove(struct spi_device *spi)
> +{
> + struct iio_dev *indio_dev = spi_get_drvdata(spi);
> + struct mcp3911 *adc = iio_priv(indio_dev);
> +
> + iio_device_unregister(indio_dev);
> +
> + if (adc->vref)
> + regulator_disable(adc->vref);
> +
> + return 0;
> +}
> +
> +#if defined(CONFIG_OF)
> +static const struct of_device_id mcp3911_dt_ids[] = {
> + { .compatible = "microchip,mcp3911" },
> + { }
> +};
> +MODULE_DEVICE_TABLE(of, mcp3911_dt_ids);
> +#endif
> +
> +static const struct spi_device_id mcp3911_id[] = {
> + { "mcp3911", 0 },
> + { }
> +};
> +MODULE_DEVICE_TABLE(spi, mcp3911_id);
> +
> +static struct spi_driver mcp3911_driver = {
> + .driver = {
> + .name = "mcp3911",
> + .of_match_table = of_match_ptr(mcp3911_dt_ids),
> + },
> + .probe = mcp3911_probe,
> + .remove = mcp3911_remove,
> + .id_table = mcp3911_id,
> +};
> +module_spi_driver(mcp3911_driver);
> +
> +MODULE_AUTHOR("Marcus Folkesson <marcus.folkesson@gmail.com>");
> +MODULE_AUTHOR("Kent Gustavsson <kent@minoris.se>");
> +MODULE_DESCRIPTION("Microchip Technology MCP3911");
> +MODULE_LICENSE("GPL v2");
>

--

Peter Meerwald-Stadler
Mobile: +43 664 24 44 418

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