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Date: Tue, 2 Jan 2024 16:39:42 +0800
From: ChiYuan Huang <cy_huang@richtek.com>
To: Jonathan Cameron <jic23@kernel.org>
CC: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley
	<conor+dt@kernel.org>, Lars-Peter Clausen <lars@metafoo.de>, Rob Herring
	<robh+dt@kernel.org>, Uwe =?iso-8859-1?Q?Kleine-K=F6nig?=
	<u.kleine-koenig@pengutronix.de>, <linux-iio@vger.kernel.org>,
	<devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 2/2] iio: adc: rtq6056: Add support for the whole
 RTQ6056 family
Message-ID: <20240102083942.GA14725@linuxcarl2.richtek.com>
References: <cover.1703762557.git.cy_huang@richtek.com>
 <74db15583a9a68701dbff5a1a967c0d987d6dfb6.1703762557.git.cy_huang@richtek.com>
 <20231230120347.0816bd09@jic23-huawei>
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In-Reply-To: <20231230120347.0816bd09@jic23-huawei>
User-Agent: Mutt/1.5.21 (2010-09-15)

On Sat, Dec 30, 2023 at 12:03:47PM +0000, Jonathan Cameron wrote:
> On Thu, 28 Dec 2023 19:29:35 +0800
> <cy_huang@richtek.com> wrote:
> 
> > From: ChiYuan Huang <cy_huang@richtek.com>
> > 
> > RTQ6053 and RTQ6059 are the same series of RTQ6056.
> > 
> > The respective differences with RTQ6056 are listed below
> > RTQ6053
> > - chip package type
> > 
> > RTQ6059
> > - Reduce the pinout for vbus sensing pin
> > - Some internal ADC scaling change
> > 
> > Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
> Hi ChiYuan,
> 
> Some comments inline, most focus on not mixing device specific features
> across code and data.  You always want them to be fully specified by
> the the device specific const struct directly not by code using an
> ID from there.  It ends up more readable and more flexible to have it
> all done via data or callbacks where things are a too complex for data.
> 
> Thanks,
> 
> Jonathan
> 
> > ---
> > v2
> > - Remove rtq6053 in DT match table and make rtq6053 fallback compatible
> >   with rtq6056
> > ---
> >  drivers/iio/adc/rtq6056.c | 264 ++++++++++++++++++++++++++++++++++++--
> >  1 file changed, 250 insertions(+), 14 deletions(-)
> > 
> > diff --git a/drivers/iio/adc/rtq6056.c b/drivers/iio/adc/rtq6056.c
> > index ad4cea6839b2..5587178cea83 100644
> > --- a/drivers/iio/adc/rtq6056.c
> > +++ b/drivers/iio/adc/rtq6056.c
> > @@ -39,6 +39,16 @@
> >  #define RTQ6056_DEFAULT_CONFIG	0x4127
> >  #define RTQ6056_CONT_ALLON	7
> >  
> > +#define RTQ6059_DEFAULT_CONFIG	0x3C47
> > +#define RTQ6059_VBUS_LSB_OFFSET	3
> > +#define RTQ6059_AVG_BASE	8
> > +
> > +enum {
> > +	RICHTEK_DEV_RTQ6056 = 0,
> > +	RICHTEK_DEV_RTQ6059,
> > +	RICHTEK_DEV_MAX
> > +};
> > +
> >  enum {
> >  	RTQ6056_CH_VSHUNT = 0,
> >  	RTQ6056_CH_VBUS,
> > @@ -50,16 +60,29 @@ enum {
> >  enum {
> >  	F_OPMODE = 0,
> >  	F_VSHUNTCT,
> > +	F_SADC = F_VSHUNTCT,
> 
> If the devices have different register fields, better to have different enums
> for them as well as that should result in less confusing code.
> 
> 
> >  	F_VBUSCT,
> > +	F_BADC = F_VBUSCT,
> >  	F_AVG,
> > +	F_PGA = F_AVG,
> >  	F_RESET,
> >  	F_MAX_FIELDS
> >  };
> >  
> > +struct richtek_dev_data {
> > +	int dev_id;
> 
> It almost always turns out to be a bad idea to use a mixture of
> 'data' in a structure like this and a device id plus special casing int he
> code.  Better to add more data to this structure or callbacks specific
> to the individual devices types.  So I shouldn't see a dev_id field in
> here at all.
> 
> > +	int default_conv_time;
> > +	unsigned int default_config;
> > +	unsigned int calib_coefficient;
> > +	const struct reg_field *reg_fields;
> > +	const struct iio_chan_spec *channels;
> > +};
> 
> ...
> 
> >  static int rtq6056_adc_read_channel(struct rtq6056_priv *priv,
> >  				    struct iio_chan_spec const *ch,
> >  				    int *val)
> >  {
> > +	const struct richtek_dev_data *devdata = priv->devdata;
> >  	struct device *dev = priv->dev;
> >  	unsigned int addr = ch->address;
> >  	unsigned int regval;
> > @@ -168,10 +282,18 @@ static int rtq6056_adc_read_channel(struct rtq6056_priv *priv,
> >  		return ret;
> >  
> >  	/* Power and VBUS is unsigned 16-bit, others are signed 16-bit */
> > -	if (addr == RTQ6056_REG_BUSVOLT || addr == RTQ6056_REG_POWER)
> > +	switch (addr) {
> > +	case RTQ6056_REG_BUSVOLT:
> > +		if (devdata->dev_id == RICHTEK_DEV_RTQ6059)
> > +			regval >>= RTQ6059_VBUS_LSB_OFFSET;
> 
> Store the offset as for other case below and apply it unconditionally. If it is
> zero then this is a noop.
> 
> > +		fallthrough;
> > +	case RTQ6056_REG_POWER:
> >  		*val = regval;
> > -	else
> > +		break;
> > +	default:
> >  		*val = sign_extend32(regval, 16);
> 
> Fallthrough stuff is harder to read so only use it when there is significant saving
> in code.  here just repeat the sign_extend32() in both cases.
> 
> > +		break;
> > +	}
> >  
> >  	return IIO_VAL_INT;
> >  }
> > @@ -199,6 +321,28 @@ static int rtq6056_adc_read_scale(struct iio_chan_spec const *ch, int *val,
> >  	}
> >  }
> >  
> 
> >  static int rtq6056_adc_get_sample_freq(struct rtq6056_priv *priv,
> >  				       struct iio_chan_spec const *ch, int *val)
> >  {
> > @@ -292,11 +464,15 @@ static int rtq6056_adc_read_raw(struct iio_dev *indio_dev,
> >  				int *val2, long mask)
> >  {
> >  	struct rtq6056_priv *priv = iio_priv(indio_dev);
> > +	const struct richtek_dev_data *devdata = priv->devdata;
> >  
> >  	switch (mask) {
> >  	case IIO_CHAN_INFO_RAW:
> >  		return rtq6056_adc_read_channel(priv, chan, val);
> >  	case IIO_CHAN_INFO_SCALE:
> > +		if (devdata->dev_id == RICHTEK_DEV_RTQ6059)
> > +			return rtq6059_adc_read_scale(chan, val, val2);
> 
> Provide a callback for this as for other examples below.
> 
> > +
> >  		return rtq6056_adc_read_scale(chan, val, val2);
> >  	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> >  		*val = priv->avg_sample;
> > @@ -313,16 +489,28 @@ static int rtq6056_adc_read_avail(struct iio_dev *indio_dev,
> >  				  const int **vals, int *type, int *length,
> >  				  long mask)
> >  {
> > +	struct rtq6056_priv *priv = iio_priv(indio_dev);
> > +	const struct richtek_dev_data *devdata = priv->devdata;
> > +
> >  	switch (mask) {
> >  	case IIO_CHAN_INFO_SAMP_FREQ:
> > +		if (devdata->dev_id == RICHTEK_DEV_RTQ6059)
> > +			return -EINVAL;
> 
> Shouldn't need this protection as the channels won't have relevant
> bitmap bit set and this will never be called.
> 
> > +
> >  		*vals = rtq6056_samp_freq_list;
> >  		*type = IIO_VAL_INT;
> >  		*length = ARRAY_SIZE(rtq6056_samp_freq_list);
> >  		return IIO_AVAIL_LIST;
> >  	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> > -		*vals = rtq6056_avg_sample_list;
> > +		if (devdata->dev_id == RICHTEK_DEV_RTQ6059) {
> > +			*vals = rtq6059_avg_sample_list;
> > +			*length = ARRAY_SIZE(rtq6059_avg_sample_list);
> Store all this in devdata.
> 
> 		*vals = devdata->avg_sample_list;
> 		*length = devdata->avg_sample_list_length;
> 
> > +		} else {
> > +			*vals = rtq6056_avg_sample_list;
> > +			*length = ARRAY_SIZE(rtq6056_avg_sample_list);
> > +		}
> > +
> >  		*type = IIO_VAL_INT;
> > -		*length = ARRAY_SIZE(rtq6056_avg_sample_list);
> >  		return IIO_AVAIL_LIST;
> >  	default:
> >  		return -EINVAL;
> > @@ -334,6 +522,7 @@ static int rtq6056_adc_write_raw(struct iio_dev *indio_dev,
> >  				 int val2, long mask)
> >  {
> >  	struct rtq6056_priv *priv = iio_priv(indio_dev);
> > +	const struct richtek_dev_data *devdata = priv->devdata;
> >  	int ret;
> >  
> >  	ret = iio_device_claim_direct_mode(indio_dev);
> > @@ -342,10 +531,16 @@ static int rtq6056_adc_write_raw(struct iio_dev *indio_dev,
> >  
> >  	switch (mask) {
> >  	case IIO_CHAN_INFO_SAMP_FREQ:
> > -		ret = rtq6056_adc_set_samp_freq(priv, chan, val);
> > +		if (devdata->dev_id == RICHTEK_DEV_RTQ6059)
> > +			ret = -EINVAL;
> > +		else
> > +			ret = rtq6056_adc_set_samp_freq(priv, chan, val);
> >  		break;
> >  	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> > -		ret = rtq6056_adc_set_average(priv, val);
> > +		if (devdata->dev_id == RICHTEK_DEV_RTQ6059)
> > +			ret = rtq6059_adc_set_average(priv, val);
> > +		else
> > +			ret = rtq6056_adc_set_average(priv, val);
> 
> Provide a callback in devdata so this becomes something like
> 		ret = devdata->set_averate(priv, val);
> 
> >  		break;
> >  	default:
> 
> > +static const struct iio_info rtq6059_info = {
> > +	.attrs = &rtq6056_attribute_group,
> 
> This is odd. you don't provide an access functions so you won't be able to read
> channels etc. It isn't used so I guess you should just get rid of it.
> 
> > +};
> > +
> >  static irqreturn_t rtq6056_buffer_trigger_handler(int irq, void *p)
> >  {
> >  	struct iio_poll_func *pf = p;
> >  	struct iio_dev *indio_dev = pf->indio_dev;
> >  	struct rtq6056_priv *priv = iio_priv(indio_dev);
> > +	const struct richtek_dev_data *devdata = priv->devdata;
> >  	struct device *dev = priv->dev;
> >  	struct {
> >  		u16 vals[RTQ6056_MAX_CHANNEL];
> > @@ -469,6 +670,10 @@ static irqreturn_t rtq6056_buffer_trigger_handler(int irq, void *p)
> >  		if (ret)
> >  			goto out;
> >  
> > +		if (devdata->dev_id == RICHTEK_DEV_RTQ6059 &&
> > +		    addr == RTQ6056_REG_BUSVOLT)
> 
> Store an offset in the devdata->dev_id and this becomes something like.
> 		if (addr == RTQ6056_REG_BUS_VOLT)
> 			raw >>= devdata->vbus_offset;
> 
> > +			raw >>= RTQ6059_VBUS_LSB_OFFSET;
> > +
> >  		data.vals[i++] = raw;
> >  	}
> >  
> > @@ -528,20 +733,26 @@ static int rtq6056_probe(struct i2c_client *i2c)
> >  	struct rtq6056_priv *priv;
> >  	struct device *dev = &i2c->dev;
> >  	struct regmap *regmap;
> > +	const struct richtek_dev_data *devdata;
> >  	unsigned int vendor_id, shunt_resistor_uohm;
> >  	int ret;
> >  
> >  	if (!i2c_check_functionality(i2c->adapter, I2C_FUNC_SMBUS_WORD_DATA))
> >  		return -EOPNOTSUPP;
> >  
> > +	devdata = device_get_match_data(dev);
> > +	if (!devdata)
> > +		return dev_err_probe(dev, -EINVAL, "Invalid dev data\n");
> > +
> >  	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
> >  	if (!indio_dev)
> >  		return -ENOMEM;
> >  
> >  	priv = iio_priv(indio_dev);
> >  	priv->dev = dev;
> > -	priv->vshuntct_us = priv->vbusct_us = 1037;
> > +	priv->vshuntct_us = priv->vbusct_us = devdata->default_conv_time;
> 
> I'd keep a _us postfix for default_conv_time to make the units of that
> self documenting as well.
> 
> >  	priv->avg_sample = 1;
> > +	priv->devdata = devdata;
> >  	i2c_set_clientdata(i2c, priv);
> >  
> >  	regmap = devm_regmap_init_i2c(i2c, &rtq6056_regmap_config);
> > @@ -556,20 +767,26 @@ static int rtq6056_probe(struct i2c_client *i2c)
> >  		return dev_err_probe(dev, ret,
> >  				     "Failed to get manufacturer info\n");
> >  
> > +	/* For RTQ6059, this vendor id value is meaningless */
> 
> If that is the case, why are you checking it?
> I'd read that comment as meaning this will fail for RTQ6059
>
This is my misunderstanding. That's due to the draft datasheet not said this register
exist.  After I contact the designer, that's all the same with RTQ6056.

So I'll remove the comment line. The check is still needed. RTQ6059 won't fail in this check.
> >  	if (vendor_id != RTQ6056_VENDOR_ID)
> >  		return dev_err_probe(dev, -ENODEV,
> >  				     "Invalid vendor id 0x%04x\n", vendor_id);
> >  
> >  	ret = devm_regmap_field_bulk_alloc(dev, regmap, priv->rm_fields,
> > -					   rtq6056_reg_fields, F_MAX_FIELDS);
> > +					   devdata->reg_fields, F_MAX_FIELDS);
> >  	if (ret)
> >  		return dev_err_probe(dev, ret, "Failed to init regmap field\n");
> >  
> >  	/*
> > +	 * RTQ6053 & RTQ6056:
> >  	 * By default, configure average sample as 1, bus and shunt conversion
> >  	 * time as 1037 microsecond, and operating mode to all on.
> > +	 *
> > +	 * RTQ6059:
> > +	 * By default, configure average sample as 1, bus and shunt conversion
> > +	 * time as 532 microsecond, and operating mode to all on.
> Move this documentation to where devdata->default_config is set. 
> It's device specific information, so put it in the device specific place not
> the main code flow.
> 
> >  	 */
> > -	ret = regmap_write(regmap, RTQ6056_REG_CONFIG, RTQ6056_DEFAULT_CONFIG);
> > +	ret = regmap_write(regmap, RTQ6056_REG_CONFIG, devdata->default_config);
> >  	if (ret)
> >  		return dev_err_probe(dev, ret,
> >  				     "Failed to enable continuous sensing\n");
> > @@ -598,8 +815,8 @@ static int rtq6056_probe(struct i2c_client *i2c)
> >  
> >  	indio_dev->name = "rtq6056";
> >  	indio_dev->modes = INDIO_DIRECT_MODE;
> > -	indio_dev->channels = rtq6056_channels;
> > -	indio_dev->num_channels = ARRAY_SIZE(rtq6056_channels);
> > +	indio_dev->channels = devdata->channels;
> > +	indio_dev->num_channels = RTQ6056_MAX_CHANNEL + 1;
> 
> I'd embed the number of channels in devdata as well then the ARRAY_SIZE() code
> that is obviously correct can still be used (just with different things being
> counted depending on which channels are being used). The gain in readability
> is worth the tiny bit of extra code and data.
> 
> >  	indio_dev->info = &rtq6056_info;
> >  
> >  	ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
> > @@ -640,8 +857,27 @@ static int rtq6056_runtime_resume(struct device *dev)
> >  static DEFINE_RUNTIME_DEV_PM_OPS(rtq6056_pm_ops, rtq6056_runtime_suspend,
> >  				 rtq6056_runtime_resume, NULL);
> >  
> > +static const struct richtek_dev_data rtq6056_devdata = {
> > +	.dev_id = RICHTEK_DEV_RTQ6056,
> > +	.default_conv_time = 1037,
> > +	.calib_coefficient = 5120000,
> > +	.default_config = RTQ6056_DEFAULT_CONFIG,
> > +	.reg_fields = rtq6056_reg_fields,
> > +	.channels = rtq6056_channels,
> > +};
> > +
> > +static const struct richtek_dev_data rtq6059_devdata = {
> > +	.dev_id = RICHTEK_DEV_RTQ6059,
> As mentioned above, this mix of data and a dev_id is not a good design pattern.
> It tends to end up as insufficiently flexible as support for more devices is
> added to a driver - plus it scatters the device type specific stuff all through
> the driver rather than having it all in one place.
> 
> > +	.default_conv_time = 532,
> > +	.calib_coefficient = 40960000,
> > +	.default_config = RTQ6059_DEFAULT_CONFIG,
> > +	.reg_fields = rtq6059_reg_fields,
> > +	.channels = rtq6059_channels,
> > +};
> > +
> >  static const struct of_device_id rtq6056_device_match[] = {
> > -	{ .compatible = "richtek,rtq6056" },
> > +	{ .compatible = "richtek,rtq6056", .data = &rtq6056_devdata },
> > +	{ .compatible = "richtek,rtq6059", .data = &rtq6059_devdata },
> >  	{}
> >  };
> >  MODULE_DEVICE_TABLE(of, rtq6056_device_match);
>