Re: [PATCH v2 1/3] iio: adc: add support for mcp3911

From: Marcus Folkesson
Date: Thu Aug 02 2018 - 14:58:56 EST

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Hi Jonathan,

Sorry for the delay, I've been away from keyboard for a few days.

On Sun, Jul 29, 2018 at 12:44:22PM +0100, Jonathan Cameron wrote:
> On Tue, 24 Jul 2018 20:30:02 +0200
> Marcus Folkesson <marcus.folkesson@xxxxxxxxx> wrote:
>
> > MCP3911 is a dual channel Analog Front End (AFE) containing two
> > synchronous sampling delta-sigma Analog-to-Digital Converters (ADC).
> >
> > Signed-off-by: Marcus Folkesson <marcus.folkesson@xxxxxxxxx>
> > Signed-off-by: Kent Gustavsson <kent@xxxxxxxxxx>
> Hi
>
> I think you missed cleaning up the clock enable in the remove.
> If it is safe to not do so it should also be safe in the error path
> of probe.

I've actually noticed this and had it prepared in v4 :-)

>
> A couple of trivial other things jumped out at me whilst reading.

Thank you so much, I will fix these.
>
> Thanks,
>
> Jonathan
> > ---
> >
> > Notes:
> > v2:
> > - cleanups and bugfixes (thanks Peter Meerwald-Stadler)
> > - drop hardware gain
> > - use the presence or lack of regulator to indicate if we go for internal or external voltage reference
> > - do not store device node in private struct
> > - drop support to set width in devicetree
> > - use the presence or lack of clock to indicate if we go for internal or external clock
> >
> > drivers/iio/adc/Kconfig | 10 ++
> > drivers/iio/adc/Makefile | 1 +
> > drivers/iio/adc/mcp3911.c | 366 ++++++++++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 377 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..29aa39930ead
> > --- /dev/null
> > +++ b/drivers/iio/adc/mcp3911.c
> > @@ -0,0 +1,366 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Driver for Microchip MCP3911, Two-channel Analog Front End
> > + *
> > + * Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@xxxxxxxxx>
> > + * Copyright (C) 2018 Kent Gustavsson <kent@xxxxxxxxxx>
> > + *
> > + */
> > +#include <linux/clk.h>
> > +#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_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)
> > +
> > +/* Internal voltage reference in uV */
> > +#define MCP3911_INT_VREF_UV 1200000
> > +
> > +#define MCP3911_REG_READ(reg, id) ((((reg) << 1) | ((id) << 5) | (1 << 0)) & 0xff)
> > +#define MCP3911_REG_WRITE(reg, id) ((((reg) << 1) | ((id) << 5) | (0 << 0)) & 0xff)
> > +
> > +#define MCP3911_NUM_CHANNELS 2
> > +
> > +struct mcp3911 {
> > + struct spi_device *spi;
> > + struct mutex lock;
> > + struct regulator *vref;
> > + struct clk *adc_clk;
> > + u32 dev_addr;
> > +};
> > +
> > +static int mcp3911_read(struct mcp3911 *adc, u8 reg, u32 *val, u8 len)
> > +{
> > + int ret;
> > +
> > + reg = MCP3911_REG_READ(reg, adc->dev_addr);
> > + ret = spi_write_then_read(adc->spi, &reg, 1, val, len);
> > + if (ret < 0)
> > + return ret;
> > +
> > + be32_to_cpus(val);
> > + *val >>= ((4 - len) * 8);
> > + 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);
> > +
> > + val <<= (3 - len) * 8;
> > + cpu_to_be32s(&val);
> > + val |= MCP3911_REG_WRITE(reg, adc->dev_addr);
> > +
> > + return spi_write(adc->spi, &val, len+1);
>
> Spaces around operators needed everywhere. Please check the
> kernel coding style docs.
>
> > +}
> > +
> > +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_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_SCALE:
> > + if (adc->vref) {
> > + ret = regulator_get_voltage(adc->vref);
> > + if (ret < 0) {
> > + dev_err(indio_dev->dev.parent,
> > + "failed to get vref voltage: %d\n",
> > + ret);
> > + goto out;
> > + }
> > +
> > + *val = ret / 1000;
> > + } else {
> > + *val = MCP3911_INT_VREF_UV;
> > + }
> > +
> > + *val2 = 24;
> > + 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:
> > + if (val2 != 0) {
> > + ret = -EINVAL;
> > + goto out;
> > + }
> > +
> > + /* 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);
> > + break;
> > + }
> > +
> > +out:
> > + mutex_unlock(&adc->lock);
> > + return ret;
> > +}
> > +
> > +#define MCP3911_CHAN(idx) { \
> > + .type = IIO_VOLTAGE, \
> > + .indexed = 1, \
> > + .channel = idx, \
> > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> > + BIT(IIO_CHAN_INFO_OFFSET) | \
> > + BIT(IIO_CHAN_INFO_SCALE), \
> > +}
> > +
> > +static const struct iio_chan_spec mcp3911_channels[] = {
> > + MCP3911_CHAN(0),
> > + MCP3911_CHAN(1),
> > +};
> > +
> > +static const struct iio_info mcp3911_info = {
> > + .read_raw = mcp3911_read_raw,
> > + .write_raw = mcp3911_write_raw,
> > +};
> > +
> > +static int mcp3911_config(struct mcp3911 *adc, struct device_node *of_node)
> > +{
> > + u32 configreg;
> > + int ret;
> > +
> > + of_property_read_u32(of_node, "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;
> > +
> > + if (adc->vref) {
> > + dev_dbg(&adc->spi->dev, "use external voltage reference\n");
> > + configreg |= MCP3911_CONFIG_VREFEXT;
> > +
> The blank line here is inconsistent with other near by blocks (nitpick ;)
> > + } else {
> > + dev_dbg(&adc->spi->dev, "use internal voltage reference (1.2V)\n");
> > + configreg &= ~MCP3911_CONFIG_VREFEXT;
> > + }
> > +
> > + if (adc->adc_clk) {
> > + 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;
> > + }
> > +
> > + return mcp3911_write(adc, MCP3911_REG_CONFIG, configreg, 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->vref = devm_regulator_get_optional(&adc->spi->dev, "vref");
> > + if (IS_ERR(adc->vref)) {
> > +
> > + if (PTR_ERR(adc->vref) == -ENODEV) {
> > + adc->vref = NULL;
> > + } else {
> > + dev_err(&adc->spi->dev,
> > + "failed to get regulator (%ld)\n",
> > + PTR_ERR(adc->vref));
> > + return PTR_ERR(adc->vref);
> > + }
> > +
> > + } else {
> > + ret = regulator_enable(adc->vref);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > + adc->adc_clk = devm_clk_get(&adc->spi->dev, "adc_clk");
> > + if (IS_ERR(adc->adc_clk)) {
> > + if (PTR_ERR(adc->adc_clk) == -ENOENT) {
> > + adc->adc_clk = NULL;
> > + } else {
> > + dev_err(&adc->spi->dev,
> > + "failed to get adc clk (%ld)\n",
> > + PTR_ERR(adc->adc_clk));
> > + ret = PTR_ERR(adc->adc_clk);
> > + goto reg_disable;
> > + }
> > + } else {
> > + ret = clk_prepare_enable(adc->adc_clk);
> > + if (ret < 0) {
> > + dev_err(&adc->spi->dev,
> > + "Failed to enable adc_clk: %d\n", ret);
> > + goto reg_disable;
> > + }
> > + }
> > +
> > + ret = mcp3911_config(adc, spi->dev.of_node);
> > + if (ret)
> > + goto clk_disable;
> > +
> > + 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 clk_disable;
> > +
> > + return ret;
> > +
> > +clk_disable:
> > + if (adc->adc_clk)
> > + clk_disable_unprepare(adc->adc_clk);
> > +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);
> > +
>
> You need to also disable_unprepare the clock in remove as well.
>
> > + 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@xxxxxxxxx>");
> > +MODULE_AUTHOR("Kent Gustavsson <kent@xxxxxxxxxx>");
> > +MODULE_DESCRIPTION("Microchip Technology MCP3911");
> > +MODULE_LICENSE("GPL v2");
>

Best regards
Marcus Folkesson

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