Re: [RESEND 10/14] iio: adc: mt6370: Add Mediatek MT6370 support

From: Jonathan Cameron
Date: Tue May 31 2022 - 09:21:20 EST

On Tue, 31 May 2022 19:18:56 +0800
ChiaEn Wu <peterwu.pub@xxxxxxxxx> wrote:

> From: ChiaEn Wu <chiaen_wu@xxxxxxxxxxx>
>
> Add Mediatek MT6370 ADC support.
>
> Signed-off-by: ChiaEn Wu <chiaen_wu@xxxxxxxxxxx>

Hi ChiaEn,

A few comments inline.

Thanks,

Jonathan

> ---
> drivers/iio/adc/Kconfig | 9 ++
> drivers/iio/adc/Makefile | 1 +
> drivers/iio/adc/mt6370-adc.c | 257 +++++++++++++++++++++++++++++++++++
> 3 files changed, 267 insertions(+)
> create mode 100644 drivers/iio/adc/mt6370-adc.c
>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 71ab0a06aa82..d7932dd9b773 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -737,6 +737,15 @@ config MEDIATEK_MT6360_ADC
> is used in smartphones and tablets and supports a 11 channel
> general purpose ADC.
>
> +config MEDIATEK_MT6370_ADC
> + tristate "Mediatek MT6370 ADC driver"
> + depends on MFD_MT6370
> + help
> + Say Y here to enable MT6370 ADC support.
> + Integrated for System Monitoring includes

The wrapping of this text needs cleaning up.

> + is used in smartphones and tablets and supports a 9 channel
> + general purpose ADC.
> +
> 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 39d806f6d457..0ce285c7e2d0 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -68,6 +68,7 @@ obj-$(CONFIG_MCP320X) += mcp320x.o
> obj-$(CONFIG_MCP3422) += mcp3422.o
> obj-$(CONFIG_MCP3911) += mcp3911.o
> obj-$(CONFIG_MEDIATEK_MT6360_ADC) += mt6360-adc.o
> +obj-$(CONFIG_MEDIATEK_MT6370_ADC) += mt6370-adc.o
> obj-$(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/mt6370-adc.c b/drivers/iio/adc/mt6370-adc.c
> new file mode 100644
> index 000000000000..3320ebca17ad
> --- /dev/null
> +++ b/drivers/iio/adc/mt6370-adc.c
> @@ -0,0 +1,257 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <dt-bindings/iio/adc/mediatek,mt6370_adc.h>
> +#include <linux/bits.h>
> +#include <linux/bitfield.h>
> +#include <linux/iio/iio.h>
> +#include <linux/irq.h>

Not seeing any interrupt support in here.


> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +#define MT6370_REG_CHG_CTRL3 0x113 /* AICR */
> +#define MT6370_REG_CHG_CTRL7 0x117 /* ICHG */
> +#define MT6370_REG_CHG_ADC 0x121
> +#define MT6370_REG_ADC_DATA_H 0x14C
> +
> +#define MT6370_ADC_START_MASK BIT(0)
> +#define MT6370_ADC_IN_SEL_MASK GENMASK(7, 4)
> +#define MT6370_AICR_ICHG_MASK GENMASK(7, 2)
> +
> +#define MT6370_ADC_CHAN_SHIFT 4

Prefer using a mask and then FIELD_PREP

> +
> +#define MT6370_AICR_400MA 0x6
> +#define MT6370_ICHG_500MA 0x4
> +#define MT6370_ICHG_900MA 0x8
> +
> +#define ADC_CONV_TIME_US 35000
> +#define ADC_CONV_POLLING_TIME 1000
> +
> +struct mt6370_adc_data {
> + struct device *dev;
> + struct regmap *regmap;
> + struct mutex lock;

All locks need documentation. What is the scope of the lock?
Looks like it protects device state when doing setup, wait for read, read
cycles.

> +};
> +
> +static int mt6370_adc_read_channel(struct mt6370_adc_data *priv, int chan,
> + unsigned long addr, int *val)
> +{
> + __be16 be_val;
> + unsigned int reg_val;
> + int ret;
> +
> + mutex_lock(&priv->lock);
> +
> + reg_val = MT6370_ADC_START_MASK | (addr << MT6370_ADC_CHAN_SHIFT);

FIELD_PREP for that shift?

> + ret = regmap_write(priv->regmap, MT6370_REG_CHG_ADC, reg_val);
> + if (ret)
> + goto adc_unlock;
> +
> + msleep(ADC_CONV_TIME_US / 1000);
> +
> + ret = regmap_read_poll_timeout(priv->regmap,
> + MT6370_REG_CHG_ADC, reg_val,
> + !(reg_val & MT6370_ADC_START_MASK),
> + ADC_CONV_POLLING_TIME,
> + ADC_CONV_TIME_US * 3);
> + if (ret) {
> + if (ret == -ETIMEDOUT)
> + dev_err(priv->dev, "Failed to wait adc conversion\n");
> + goto adc_unlock;
> + }
> +
> + ret = regmap_raw_read(priv->regmap, MT6370_REG_ADC_DATA_H,
> + &be_val, sizeof(be_val));
> + if (ret)
> + goto adc_unlock;
> +
> + *val = be16_to_cpu(be_val);
> + ret = IIO_VAL_INT;
> +
> +adc_unlock:
> + mutex_unlock(&priv->lock);
> +
> + return ret;
> +}
> +
> +static int mt6370_adc_read_scale(struct mt6370_adc_data *priv,
> + int chan, int *val1, int *val2)
> +{
> + unsigned int reg_val;
> + int ret;
> +
> + switch (chan) {
> + case MT6370_CHAN_VBAT:
> + case MT6370_CHAN_VSYS:
> + case MT6370_CHAN_CHG_VDDP:
> + *val1 = 5000;

This seems very large. Voltages are in millivolts
as per Documentation/ABI/testing/sysfs-bus-iio
and this means each step is 5 volts.

So value in mv is currently 5 * _raw



> + return IIO_VAL_INT;
> + case MT6370_CHAN_IBUS:
> + ret = regmap_read(priv->regmap, MT6370_REG_CHG_CTRL3, &reg_val);
> + if (ret)
> + return ret;
> +
> + reg_val = FIELD_GET(MT6370_AICR_ICHG_MASK, reg_val);
> + if (reg_val < MT6370_AICR_400MA)
> + *val1 = 33500;
> + else
> + *val1 = 50000;
> +
> + return IIO_VAL_INT;
> + case MT6370_CHAN_IBAT:
> + ret = regmap_read(priv->regmap, MT6370_REG_CHG_CTRL7, &reg_val);
> + if (ret)
> + return ret;
> +
> + reg_val = FIELD_GET(MT6370_AICR_ICHG_MASK, reg_val);
> + if (reg_val < MT6370_ICHG_500MA)
> + *val1 = 23750;
> + else if (reg_val >= MT6370_ICHG_500MA &&
> + reg_val < MT6370_ICHG_900MA)
> + *val1 = 26800;
> + else
> + *val1 = 50000;
> +
> + return IIO_VAL_INT;
> + case MT6370_CHAN_VBUSDIV5:
> + *val1 = 25000;
> + return IIO_VAL_INT;
> + case MT6370_CHAN_VBUSDIV2:
> + *val1 = 50000;
> + return IIO_VAL_INT;
> + case MT6370_CHAN_TS_BAT:
> + *val1 = 25;
> + *val2 = 10000;
> + return IIO_VAL_FRACTIONAL;
> + case MT6370_CHAN_TEMP_JC:
> + *val1 = 2;
> + return IIO_VAL_INT;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static int mt6370_adc_read_offset(struct mt6370_adc_data *priv,
> + int chan, int *val)
> +{
> + *val = (chan == MT6370_CHAN_TEMP_JC) ? -20 : 0;

Offset default is 0, so for channels where it doesn't apply don't
provide the offset attribute at all.

> + return IIO_VAL_INT;
> +}
> +
> +static int mt6370_adc_read_raw(struct iio_dev *iio_dev,
> + const struct iio_chan_spec *chan,
> + int *val, int *val2, long mask)
> +{
> + struct mt6370_adc_data *priv = iio_priv(iio_dev);
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + return mt6370_adc_read_channel(priv, chan->channel,
> + chan->address, val);
> + case IIO_CHAN_INFO_SCALE:
> + return mt6370_adc_read_scale(priv, chan->channel, val, val2);
> + case IIO_CHAN_INFO_OFFSET:
> + return mt6370_adc_read_offset(priv, chan->channel, val);
> + }
> +
> + return -EINVAL;
> +}
> +
> +static const char * const mt6370_channel_labels[MT6370_CHAN_MAX] = {

Perhaps define an enum with which to index this and the chan spec
and hence ensure they end up matching.
[vbusdiv5] = "vbusdiv5", etc

> + "vbusdiv5", "vbusdiv2", "vsys", "vbat",
> + "ts_bat", "ibus", "ibat", "chg_vddp",
> + "temp_jc",
> +};
> +
> +static int mt6370_adc_read_label(struct iio_dev *iio_dev,
> + struct iio_chan_spec const *chan, char *label)
> +{
> + return snprintf(label, PAGE_SIZE, "%s\n",
> + mt6370_channel_labels[chan->channel]);
> +}
> +
> +static const struct iio_info mt6370_adc_iio_info = {
> + .read_raw = mt6370_adc_read_raw,
> + .read_label = mt6370_adc_read_label,
> +};
> +
> +#define MT6370_ADC_CHAN(_idx, _type, _addr) { \
> + .type = _type, \
> + .channel = MT6370_CHAN_##_idx, \
> + .address = _addr, \
> + .scan_index = MT6370_CHAN_##_idx, \
> + .indexed = 1, \
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> + BIT(IIO_CHAN_INFO_SCALE) | \
> + BIT(IIO_CHAN_INFO_OFFSET), \

See above. Only temp_jc channel should hav an offset.

> +}
> +
> +static const struct iio_chan_spec mt6370_adc_channels[] = {
> + MT6370_ADC_CHAN(VBUSDIV5, IIO_VOLTAGE, 1),
> + MT6370_ADC_CHAN(VBUSDIV2, IIO_VOLTAGE, 2),
> + MT6370_ADC_CHAN(VSYS, IIO_VOLTAGE, 3),
> + MT6370_ADC_CHAN(VBAT, IIO_VOLTAGE, 4),
> + MT6370_ADC_CHAN(TS_BAT, IIO_VOLTAGE, 6),
> + MT6370_ADC_CHAN(IBUS, IIO_CURRENT, 8),
> + MT6370_ADC_CHAN(IBAT, IIO_CURRENT, 9),
> + MT6370_ADC_CHAN(CHG_VDDP, IIO_VOLTAGE, 11),
> + MT6370_ADC_CHAN(TEMP_JC, IIO_TEMP, 12),
> +};
> +
> +static int mt6370_adc_probe(struct platform_device *pdev)
> +{
> + int ret;
> + struct mt6370_adc_data *priv;
> + struct regmap *regmap;
> + struct iio_dev *indio_dev;
> +
> + regmap = dev_get_regmap(pdev->dev.parent, NULL);
> + if (!regmap) {
> + dev_err(&pdev->dev, "Failed to get regmap\n");
> + return -ENODEV;
> + }
> +
> + indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*priv));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + priv = iio_priv(indio_dev);
> + priv->dev = &pdev->dev;
> + priv->regmap = regmap;
> + mutex_init(&priv->lock);
> +
> + ret = regmap_write(priv->regmap, MT6370_REG_CHG_ADC, 0);
> + if (ret) {
> + dev_err(&pdev->dev, "Failed to reset adc\n");
> + return ret;
> + }
> +
> + indio_dev->name = dev_name(&pdev->dev);

What does this end up as? It's used for userspace ABI and should
correspond to the part number, "mt6370-adc" probably
appropriate in this case (I think it'll end up as simply "adc.x"
currently?) Normally we just hard code this in the driver for
whatever devices the driver supports.

> + indio_dev->info = &mt6370_adc_iio_info;
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->channels = mt6370_adc_channels;
> + indio_dev->num_channels = ARRAY_SIZE(mt6370_adc_channels);
> +
> + return devm_iio_device_register(&pdev->dev, indio_dev);
> +}
> +
> +static const struct of_device_id mt6370_adc_of_id[] = {
> + { .compatible = "mediatek,mt6370-adc", },
> + {}
> +};
> +MODULE_DEVICE_TABLE(of, mt6370_adc_of_id);
> +
> +static struct platform_driver mt6370_adc_driver = {
> + .driver = {
> + .name = "mt6370-adc",
> + .of_match_table = mt6370_adc_of_id,
> + },
> + .probe = mt6370_adc_probe,
> +};
> +module_platform_driver(mt6370_adc_driver);
> +
> +MODULE_AUTHOR("ChiaEn Wu <chiaen_wu@xxxxxxxxxxx>");
> +MODULE_DESCRIPTION("MT6370 ADC Drvier");
> +MODULE_LICENSE("GPL v2");