linux-kernel - Re: [PATCH 1/2] staging: iio: vcnl4000: Add IR current adjust support

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Message-ID: <d785baed-5688-c5ff-8217-2a5516954a88@kernel.org>
Date:	Sun, 24 Jul 2016 11:17:17 +0100
From:	Jonathan Cameron <jic23@...nel.org>
To:	Pratik Prajapati <pratik.prajapati12@...il.com>,
	Hartmut Knaack <knaack.h@....de>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Peter Meerwald-Stadler <pmeerw@...erw.net>
Cc:	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] staging: iio: vcnl4000: Add IR current adjust support

On 21/07/16 15:41, Pratik Prajapati wrote:
> Signed-off-by: Pratik Prajapati <pratik.prajapati12@...il.com>
Various bits and pieces in line.  Mostly little tidy ups.

Also, please always check that an ABI is in the Documentation
of the ABI.  This can even include standard combinations we simply
have seen before.  Here the LED stuff needs to be in there.

As there are wild cards, it's not trivial to grep those files, but
people do...

Also they are used as the basis for userspace libraries as they
can't be expected to track every new bit of ABI we sneak in somewhere
deep in a driver :)

Jonathan
> ---
>  drivers/iio/light/vcnl4000.c | 78 ++++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 72 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iio/light/vcnl4000.c b/drivers/iio/light/vcnl4000.c
> index 360b6e9..1378175 100644
> --- a/drivers/iio/light/vcnl4000.c
> +++ b/drivers/iio/light/vcnl4000.c
> @@ -11,7 +11,6 @@
>   * IIO driver for VCNL4000 (7-bit I2C slave address 0x13)
>   *
>   * TODO:
> - *   allow to adjust IR current
>   *   proximity threshold and event handling
>   *   periodic ALS/proximity measurement (VCNL4010/20)
>   *   interrupts (VCNL4010/20)
> @@ -46,6 +45,10 @@
>  #define VCNL4000_AL_OD		BIT(4) /* start on-demand ALS measurement */
>  #define VCNL4000_PS_OD		BIT(3) /* start on-demand proximity measurement */
>  
> +/* Bit mask for LED_CURRENT register */
> +#define VCNL4000_LED_CURRENT_MASK	0x3F
> +#define VCNL4000_LED_CURRENT_MAX	20
> +
>  struct vcnl4000_data {
>  	struct i2c_client *client;
>  	struct mutex lock;
> @@ -111,9 +114,42 @@ static const struct iio_chan_spec vcnl4000_channels[] = {
>  	}, {
>  		.type = IIO_PROXIMITY,
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> -	}
> +	}, {
> +		.type = IIO_CURRENT,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +			BIT(IIO_CHAN_INFO_SCALE),
> +		.extend_name = "led",
Please sanity check this extended form (which is fine I think)
is in the ABI docs.
Documentation/ABI/testing/sysfs-bus-iio

People need to be able to grep that document to find all forms of
the ABI so you'll need both an entry for raw and scale (just
add them to the relevant long lists.  Maybe a foot note
in the description to state the obvious that this controls
the current to an LED :)
> +		.output = 1,
> +		.scan_index = -1,
> +	},
>  };
>  
> +static int vcnl4000_write_led_current_raw(struct vcnl4000_data *data, int val)
> +{
> +	int ret;
> +
> +	if (val < 0 || val > VCNL4000_LED_CURRENT_MAX)
> +		return -ERANGE;
> +	mutex_lock(&data->lock);
> +	ret = i2c_smbus_write_byte_data(data->client, VCNL4000_LED_CURRENT,
> +			val);
> +	mutex_unlock(&data->lock);
blank line before simple returns is pretty much standard kernel syntax.
Hence a blank line here and in similar places ideally.
> +	return ret;
> +}
> +
> +static int vcnl4000_read_led_current_raw(struct vcnl4000_data *data)
> +{
> +	int ret;
> +
> +	mutex_lock(&data->lock);
> +	ret = i2c_smbus_read_byte_data(data->client, VCNL4000_LED_CURRENT);
> +	mutex_unlock(&data->lock);
> +	if (ret < 0)
> +		return ret;
> +	ret &= VCNL4000_LED_CURRENT_MASK;
> +	return ret;
Maybe roll these last two lines together? 
return ret & VCNL4000_LED_CURRENT_MASK;

Doesn't really effect readability so might as well shorten the code
a touch!
> +}
> +
>  static int vcnl4000_read_raw(struct iio_dev *indio_dev,
>  				struct iio_chan_spec const *chan,
>  				int *val, int *val2, long mask)
> @@ -138,23 +174,53 @@ static int vcnl4000_read_raw(struct iio_dev *indio_dev,
>  			if (ret < 0)
>  				return ret;
>  			return IIO_VAL_INT;
> +		case IIO_CURRENT:
> +			ret = vcnl4000_read_led_current_raw(data);
> +			if (ret < 0)
> +				return ret;
> +			*val = ret;
> +			return IIO_VAL_INT;
>  		default:
>  			return -EINVAL;
>  		}
> +
>  	case IIO_CHAN_INFO_SCALE:
> -		if (chan->type != IIO_LIGHT)
> +		switch (chan->type) {
> +		case IIO_LIGHT:
> +			*val = 0;
> +			*val2 = 250000;
> +			return IIO_VAL_INT_PLUS_MICRO;
> +		case IIO_CURRENT:
> +			/* Output register is in 10s of milliamps */
> +			*val = 10;
> +			return IIO_VAL_INT;
> +		default:
>  			return -EINVAL;
> +		}
>  
> -		*val = 0;
> -		*val2 = 250000;
> -		return IIO_VAL_INT_PLUS_MICRO;
>  	default:
>  		return -EINVAL;
>  	}
Can't get here...  So drop this return.
> +	return -EINVAL;
> +}
> +
> +static int vcnl4000_write_raw(struct iio_dev *indio_dev,
> +					struct iio_chan_spec const *chan,
> +					int val, int val2, long mask)
> +{
> +	struct vcnl4000_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	if (mask == IIO_CHAN_INFO_RAW && chan->type == IIO_CURRENT) {
> +		ret = vcnl4000_write_led_current_raw(data, val);
> +		return ret;
Drop the local variable and have
return vcnl4000...

> +	}
> +	return -EINVAL;
>  }
>  
>  static const struct iio_info vcnl4000_info = {
>  	.read_raw = vcnl4000_read_raw,
> +	.write_raw = vcnl4000_write_raw,
>  	.driver_module = THIS_MODULE,
>  };
>  
>