Message-ID: <20200925132840.513bf214@archlinux>
Date:   Fri, 25 Sep 2020 13:28:40 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Gene Chen <gene.chen.richtek@...il.com>
Cc:     robh+dt@...nel.org, matthias.bgg@...il.com, knaack.h@....de,
        lars@...afoo.de, pmeerw@...erw.net, devicetree@...r.kernel.org,
        linux-iio@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        gene_chen@...htek.com, Wilma.Wu@...iatek.com,
        shufan_lee@...htek.com, cy_huang@...htek.com,
        benjamin.chao@...iatek.com
Subject: Re: [PATCH v5 3/3] iio: adc: mt6360: Add ADC driver for MT6360

On Mon, 21 Sep 2020 19:24:02 +0800
Gene Chen <gene.chen.richtek@...il.com> wrote:

> From: Gene Chen <gene_chen@...htek.com>
> 
> Add MT6360 ADC driver include Charger Current, Voltage, and
> Temperature.
> 
> Signed-off-by: Gene Chen <gene_chen@...htek.com>

Hi Gene,

A few things inline that need fixing or tidying up.

Looking good otherwise.

Jonathan
> ---
>  drivers/iio/adc/Kconfig      |  11 ++
>  drivers/iio/adc/Makefile     |   1 +
>  drivers/iio/adc/mt6360-adc.c | 363 +++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 375 insertions(+)
>  create mode 100644 drivers/iio/adc/mt6360-adc.c
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index d94dc80..a135ada 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -703,6 +703,17 @@ config MCP3911
>  	  This driver can also be built as a module. If so, the module will be
>  	  called mcp3911.
>  
> +config MEDIATEK_MT6360_ADC
> +	tristate "Mediatek MT6360 ADC driver"
> +	depends on MFD_MT6360
> +	select IIO_BUFFER
> +	select IIO_TRIGGERED_BUFFER
> +	help
> +	  Say Y here to enable MT6360 ADC support.
> +	  Integrated for System Monitoring includes
> +	  is used in smartphones and tablets and supports a 11 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 90f94ad..5fca90a 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -65,6 +65,7 @@ obj-$(CONFIG_MAX9611) += max9611.o
>  obj-$(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_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/mt6360-adc.c b/drivers/iio/adc/mt6360-adc.c
> new file mode 100644
> index 0000000..a1a01e5
> --- /dev/null
> +++ b/drivers/iio/adc/mt6360-adc.c
> @@ -0,0 +1,363 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <linux/delay.h>
> +#include <linux/irq.h>
> +#include <linux/kernel.h>
> +#include <linux/ktime.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/iio/triggered_buffer.h>
> +
> +#define MT6360_REG_PMUCHGCTRL3	0x313
> +#define MT6360_REG_PMUADCCFG	0x356
> +#define MT6360_REG_PMUADCIDLET	0x358
> +#define MT6360_REG_PMUADCRPT1	0x35A
> +
> +/* PMUCHGCTRL3 0x313 */
> +#define MT6360_AICR_MASK	GENMASK(7, 2)
> +#define MT6360_AICR_SHFT	2
> +#define MT6360_AICR_400MA	0x6
> +/* PMUADCCFG 0x356 */
> +#define MT6360_ADCEN_MASK	0x8000
> +/* PMUADCRPT1 0x35A */
> +#define MT6360_PREFERCH_MASK	GENMASK(7, 4)
> +#define MT6360_PREFERCH_SHFT	4
> +#define MT6360_RPTCH_MASK	GENMASK(3, 0)
> +#define MT6360_NO_PREFER	15
> +
> +/* Time in ms */
> +#define ADC_WAIT_TIME_MS	25
> +
> +enum {
> +	MT6360_CHAN_USBID = 0,
> +	MT6360_CHAN_VBUSDIV5,
> +	MT6360_CHAN_VBUSDIV2,
> +	MT6360_CHAN_VSYS,
> +	MT6360_CHAN_VBAT,
> +	MT6360_CHAN_IBUS,
> +	MT6360_CHAN_IBAT,
> +	MT6360_CHAN_CHG_VDDP,
> +	MT6360_CHAN_TEMP_JC,
> +	MT6360_CHAN_VREF_TS,
> +	MT6360_CHAN_TS,
> +	MT6360_CHAN_MAX
> +};
> +
> +struct mt6360_adc_data {
> +	struct device *dev;
> +	struct regmap *regmap;
> +	/* Due to only one set of ADC control, this lock is used to prevent the race condition */
> +	struct mutex adc_lock;
> +	ktime_t last_off_timestamps[MT6360_CHAN_MAX];
> +};
> +
> +static int mt6360_adc_read_channel(struct mt6360_adc_data *mad, int channel, int *val)
> +{
> +	__be16 adc_enable;
> +	u8 rpt[3];
> +	ktime_t start_t, predict_end_t;
> +	unsigned int pre_wait_time;
> +	int ret;
> +
> +	mutex_lock(&mad->adc_lock);
> +
> +	/* Select the preferred ADC channel */
> +	ret = regmap_update_bits(mad->regmap, MT6360_REG_PMUADCRPT1, MT6360_PREFERCH_MASK,
> +				 channel << MT6360_PREFERCH_SHFT);
> +	if (ret)
> +		goto out_adc_lock;
> +
> +	adc_enable = cpu_to_be16(MT6360_ADCEN_MASK | BIT(channel));
> +	ret = regmap_raw_write(mad->regmap, MT6360_REG_PMUADCCFG, &adc_enable, sizeof(adc_enable));
> +	if (ret)
> +		goto out_adc_lock;
> +
> +	start_t = ktime_get();
> +	predict_end_t = ktime_add_ms(mad->last_off_timestamps[channel], 2 * ADC_WAIT_TIME_MS);
> +
> +	if (ktime_after(start_t, predict_end_t))
> +		pre_wait_time = ADC_WAIT_TIME_MS;
> +	else
> +		pre_wait_time = 3 * ADC_WAIT_TIME_MS;
> +
> +	msleep(pre_wait_time);
> +
> +	while (true) {
> +		ret = regmap_raw_read(mad->regmap, MT6360_REG_PMUADCRPT1, rpt, sizeof(rpt));
> +		if (ret)
> +			goto out_adc_conv;
> +
> +		/*
> +		 * There are two functions, ZCV and TypeC OTP, running ADC VBAT and TS in
> +		 * background, and ADC samples are taken on a fixed frequency no matter read the
> +		 * previous one or not.
> +		 * To avoid conflict, We set minimum time threshold after enable ADC and
> +		 * check report channel is the same.
> +		 * The worst case is run the same ADC twice and background function is also running,
> +		 * ADC conversion sequence is desire channel before start ADC, background ADC,
> +		 * desire channel after start ADC.
> +		 * So the minimum correct data is three times of typical conversion time.
> +		 */
> +		if ((rpt[0] & MT6360_RPTCH_MASK) == channel)
> +			break;
> +
> +		msleep(ADC_WAIT_TIME_MS);
> +	}
> +
> +	/* rpt[1]: ADC_HI_BYTE, rpt[2]: ADC_LOW_BYTE */
> +	*val = rpt[1] << 8 | rpt[2];
> +	ret = IIO_VAL_INT;
> +
> +out_adc_conv:
> +	/* Only keep ADC enable */
> +	adc_enable = cpu_to_be16(MT6360_ADCEN_MASK);
> +	regmap_raw_write(mad->regmap, MT6360_REG_PMUADCCFG, &adc_enable, sizeof(adc_enable));
> +	mad->last_off_timestamps[channel] = ktime_get();
> +	/* Config prefer channel to NO_PREFER */
> +	regmap_update_bits(mad->regmap, MT6360_REG_PMUADCRPT1, MT6360_PREFERCH_MASK,
> +			   MT6360_NO_PREFER << MT6360_PREFERCH_SHFT);
> +out_adc_lock:
> +	mutex_unlock(&mad->adc_lock);
> +
> +	return ret;
> +}
> +
> +static int mt6360_adc_read_scale(struct mt6360_adc_data *mad, int channel, int *val, int *val2)
> +{
> +	unsigned int regval;
> +	int ret;
> +
> +	switch (channel) {
> +	case MT6360_CHAN_USBID:
> +	case MT6360_CHAN_VSYS:
> +	case MT6360_CHAN_VBAT:
> +	case MT6360_CHAN_CHG_VDDP:
> +	case MT6360_CHAN_VREF_TS:
> +	case MT6360_CHAN_TS:
> +		*val = 1250;
> +		return IIO_VAL_INT;
> +	case MT6360_CHAN_VBUSDIV5:
> +		*val = 6250;
> +		return IIO_VAL_INT;
> +	case MT6360_CHAN_VBUSDIV2:
> +	case MT6360_CHAN_IBUS:
> +	case MT6360_CHAN_IBAT:
> +		*val = 2500;
> +
> +		if (channel == MT6360_CHAN_IBUS) {
> +			/* IBUS will be affected by input current limit for the different Ron */
> +			/* Check whether the config is <400mA or not */
> +			ret = regmap_read(mad->regmap, MT6360_REG_PMUCHGCTRL3, &regval);
> +			if (ret)
> +				return ret;
> +
> +			regval = (regval & MT6360_AICR_MASK) >> MT6360_AICR_SHFT;
> +			if (regval < MT6360_AICR_400MA)
> +				*val = 1900;
> +		}
> +
> +		return IIO_VAL_INT;
> +	case MT6360_CHAN_TEMP_JC:
> +		*val = 105;
> +		*val2 = 100;
> +		return IIO_VAL_FRACTIONAL;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int mt6360_adc_read_offset(struct mt6360_adc_data *mad, int channel, int *val)
> +{
> +	*val = (channel == MT6360_CHAN_TEMP_JC) ? -80 : 0;
> +	return IIO_VAL_INT;
> +
> +}
> +
> +static int mt6360_adc_read_raw(struct iio_dev *iio_dev, const struct iio_chan_spec *chan,
> +			       int *val, int *val2, long mask)
> +{
> +	struct mt6360_adc_data *mad = iio_priv(iio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		return mt6360_adc_read_channel(mad, chan->channel, val);
> +	case IIO_CHAN_INFO_SCALE:
> +		return mt6360_adc_read_scale(mad, chan->channel, val, val2);
> +	case IIO_CHAN_INFO_OFFSET:
> +		return mt6360_adc_read_offset(mad, chan->channel, val);
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static const char *mt6360_channel_labels[MT6360_CHAN_MAX] = {
> +	"usbid", "vbusdiv5", "vbusdiv2", "vsys", "vbat", "ibus", "ibat", "chg_vddp", "temp_jc",
> +	"vref_ts", "ts"
> +};
> +
> +static int mt6360_adc_read_label(struct iio_dev *iio_dev, const struct iio_chan_spec *chan,
> +				 char *label)
> +{
> +	return snprintf(label, PAGE_SIZE, "%s\n", mt6360_channel_labels[chan->channel]);
> +}

Very nice.  The patch series adding this callback will hopefully be finalized
shortly.

> +
> +static const struct iio_info mt6360_adc_iio_info = {
> +	.read_raw = mt6360_adc_read_raw,
> +	.read_label = mt6360_adc_read_label,
> +};
> +
> +#define MT6360_ADC_CHAN(_idx, _type) {				\
> +	.type = _type,						\
> +	.channel = MT6360_CHAN_##_idx,				\
> +	.scan_index = MT6360_CHAN_##_idx,			\
> +	.datasheet_name = #_idx,				\
> +	.scan_type =  {						\
> +		.sign = 'u',					\
> +		.realbits = 16,					\
> +		.storagebits = 16,				\
> +		.endianness = IIO_CPU,				\
> +	},							\
> +	.indexed = 1,						\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
> +				BIT(IIO_CHAN_INFO_SCALE) |	\
> +				BIT(IIO_CHAN_INFO_OFFSET),	\
> +}
> +
> +static const struct iio_chan_spec mt6360_adc_channels[] = {
> +	MT6360_ADC_CHAN(USBID, IIO_VOLTAGE),
> +	MT6360_ADC_CHAN(VBUSDIV5, IIO_VOLTAGE),
> +	MT6360_ADC_CHAN(VBUSDIV2, IIO_VOLTAGE),
> +	MT6360_ADC_CHAN(VSYS, IIO_VOLTAGE),
> +	MT6360_ADC_CHAN(VBAT, IIO_VOLTAGE),
> +	MT6360_ADC_CHAN(IBUS, IIO_CURRENT),
> +	MT6360_ADC_CHAN(IBAT, IIO_CURRENT),
> +	MT6360_ADC_CHAN(CHG_VDDP, IIO_VOLTAGE),
> +	MT6360_ADC_CHAN(TEMP_JC, IIO_TEMP),
> +	MT6360_ADC_CHAN(VREF_TS, IIO_VOLTAGE),
> +	MT6360_ADC_CHAN(TS, IIO_VOLTAGE),
> +	IIO_CHAN_SOFT_TIMESTAMP(MT6360_CHAN_MAX),
> +};
> +
> +static irqreturn_t mt6360_adc_trigger_handler(int irq, void *p)
> +{
> +	struct iio_poll_func *pf = p;
> +	struct iio_dev *indio_dev = pf->indio_dev;
> +	struct mt6360_adc_data *mad = iio_priv(indio_dev);
> +	struct {
> +		u16 values[MT6360_CHAN_MAX];
> +		int64_t timestamp;
> +	} data __aligned(8) = {0};

I don't think that is sufficient to force the gap to be set to 0.
The c99 spec says in 6.7.8.21
"If there are fewer initializers in a brace-enclosed list than there are elements or members
of an aggregate, or fewer characters in a string literal used to initialize an array of known
size than there are elements in the array, the remainder of the aggregate shall be
initialized implicitly the same as objects that have static storage duration."

The static case is covered by 6.7.8.10
"If an object that has automatic storage duration is not initialized explicitly, its value is
indeterminate. If an object that has static storage duration is not initialized explicitly,
then:
— if it has pointer type, it is initialized to a null pointer;
— if it has arithmetic type, it is initialized to (positive or unsigned) zero;
— if it is an aggregate, every member is initialized (recursively) according to these rules;
— if it isaunion, the first named member is initialized (recursively) according to these
  rules
"
Structure is an aggregate,s every member is initialized.  Unfortunately that doesn't
have any impact on gaps.  So it 'might' zero it, but there are no guarantees.

As such, I think you need to use memset which will just fill the memory with zeros
without caring about the structure.
Or cheeky route is to add elements to fill the gap and just call them pad[] or similar.


> +	int i = 0, bit, val, ret;
> +
> +
> +	for_each_set_bit(bit, indio_dev->active_scan_mask, indio_dev->masklength) {
> +		ret = mt6360_adc_read_channel(mad, bit, &val);
> +		if (ret < 0) {
> +			dev_warn(&indio_dev->dev, "Failed to get channel %d conversion val\n", bit);
> +			goto out;
> +		}
> +
> +		data.values[i++] = val;
> +	}
> +	iio_push_to_buffers_with_timestamp(indio_dev, &data, iio_get_time_ns(indio_dev));
> +out:
> +	iio_trigger_notify_done(indio_dev->trig);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static inline int mt6360_adc_reset(struct mt6360_adc_data *info)
> +{
> +	__be16 adc_enable;
> +	ktime_t all_off_time;
> +	int i, ret;
> +
> +	/* Clear ADC idle wait time to 0 */
> +	ret = regmap_write(info->regmap, MT6360_REG_PMUADCIDLET, 0);
> +	if (ret)
> +		return ret;
> +
> +	/* Only keep ADC enable, but keep all channels off */
> +	adc_enable = cpu_to_be16(MT6360_ADCEN_MASK);
> +	ret = regmap_raw_write(info->regmap, MT6360_REG_PMUADCCFG, (void *)&adc_enable,
Why are we casting to a void *? That shouldn't be necessary. Am I missing something?

> +			       sizeof(__be16));

Slight preference for sizeof(adc_enable) as then I don't have to sanity checkit
is the right type whilst reviewing.

> +	if (ret)
> +		return ret;
> +
> +	/* Reset all channel off time to the current one */
> +	all_off_time = ktime_get();
> +	for (i = 0; i < MT6360_CHAN_MAX; i++)
> +		info->last_off_timestamps[i] = all_off_time;
> +
> +	return 0;
> +}
> +
> +static int mt6360_adc_probe(struct platform_device *pdev)
> +{
> +	struct mt6360_adc_data *mad;
> +	struct regmap *regmap;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	regmap = dev_get_regmap(pdev->dev.parent, NULL);
> +	if (!regmap) {
> +		dev_err(&pdev->dev, "Failed to get parent regmap\n");
> +		return -ENODEV;
> +	}
> +
> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*mad));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	mad = iio_priv(indio_dev);
> +	mad->dev = &pdev->dev;
> +	mad->regmap = regmap;
> +	mutex_init(&mad->adc_lock);
> +
> +	ret = mt6360_adc_reset(mad);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "Failed to reset adc\n");
> +		return ret;
> +	}
> +
> +	indio_dev->name = dev_name(&pdev->dev);
> +	indio_dev->dev.parent = &pdev->dev;
> +	indio_dev->info = &mt6360_adc_iio_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = mt6360_adc_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(mt6360_adc_channels);
> +
> +	ret = devm_iio_triggered_buffer_setup(&pdev->dev, indio_dev, NULL,
> +					      mt6360_adc_trigger_handler, NULL);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to allocate iio trigger buffer\n");
> +		return ret;
> +	}
> +
> +	return devm_iio_device_register(&pdev->dev, indio_dev);
> +}
> +
> +static const struct of_device_id __maybe_unused mt6360_adc_of_id[] = {
> +	{ .compatible = "mediatek,mt6360-adc", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, mt6360_adc_of_id);
> +
> +static struct platform_driver mt6360_adc_driver = {
> +	.driver = {
> +		.name = "mt6360-adc",
> +		.of_match_table = mt6360_adc_of_id,
> +	},
> +	.probe = mt6360_adc_probe,
> +};
> +module_platform_driver(mt6360_adc_driver);
> +
> +MODULE_AUTHOR("Gene Chen <gene_chen@...htek.com>");
> +MODULE_DESCRIPTION("MT6360 ADC Driver");
> +MODULE_LICENSE("GPL v2");

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