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Message-ID: <20191207112623.31ac5288@archlinux>
Date:   Sat, 7 Dec 2019 11:26:23 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Daniel Junho <djunho@...il.com>
Cc:     Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Stefan Popa <stefan.popa@...log.com>,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        lkcamp@...ts.libreplanetbr.org
Subject: Re: [PATCH] iio:adc:ad7923: Add support for the
 ad7908/ad7918/ad7928

On Thu,  5 Dec 2019 12:58:21 -0300
Daniel Junho <djunho@...il.com> wrote:

> The ad7928 is software compatible with the ad7923. The ad7908 and ad7918 are the
> 8 and 10 bit version of the ad7928.
> 
> Signed-off-by: Daniel Junho <djunho@...il.com>
Hi Daniel,

Code itself looks good to me, but please be very careful to separate out 
non function cleanup from a patch adding something new.  It makes
reviewing harder.  We'd much rather see a series with the cleanup all clearly
marked as such (and getting a most a few seconds review) and the real code
being just that.

Thanks,

Jonathan

> ---
>  drivers/iio/adc/Kconfig  |  3 +-
>  drivers/iio/adc/ad7923.c | 96 +++++++++++++++++++++++++++++++---------
>  2 files changed, 78 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 976567d4dbef..40aa05fbf85e 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -205,7 +205,8 @@ config AD7923
>  	select IIO_TRIGGERED_BUFFER
>  	help
>  	  Say yes here to build support for Analog Devices
> -	  AD7904, AD7914, AD7923, AD7924 4 Channel ADCs.
> +	  AD7904, AD7914, AD7923, AD7924 4 Channel ADCs, and
> +	  AD7908, AD7918, AD7928 8 Channels ADCs.
>  
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called ad7923.
> diff --git a/drivers/iio/adc/ad7923.c b/drivers/iio/adc/ad7923.c
> index 3212eb4c0f25..f08a5218dad1 100644
> --- a/drivers/iio/adc/ad7923.c
> +++ b/drivers/iio/adc/ad7923.c
> @@ -1,6 +1,6 @@
>  // SPDX-License-Identifier: GPL-2.0-only
>  /*
> - * AD7904/AD7914/AD7923/AD7924 SPI ADC driver
> + * AD7904/AD7914/AD7923/AD7924/AD7908/AD7918/AD7928 SPI ADC driver
>   *
>   * Copyright 2011 Analog Devices Inc (from AD7923 Driver)
>   * Copyright 2012 CS Systemes d'Information
> @@ -26,23 +26,32 @@
>  #define AD7923_WRITE_CR		BIT(11)		/* write control register */
>  #define AD7923_RANGE		BIT(1)		/* range to REFin */
>  #define AD7923_CODING		BIT(0)		/* coding is straight binary */
> +

No white space changes in a patch doing real changes to the driver.

>  #define AD7923_PM_MODE_AS	(1)		/* auto shutdown */
>  #define AD7923_PM_MODE_FS	(2)		/* full shutdown */
>  #define AD7923_PM_MODE_OPS	(3)		/* normal operation */
> +
>  #define AD7923_CHANNEL_0	(0)		/* analog input 0 */
>  #define AD7923_CHANNEL_1	(1)		/* analog input 1 */
>  #define AD7923_CHANNEL_2	(2)		/* analog input 2 */
>  #define AD7923_CHANNEL_3	(3)		/* analog input 3 */
> -#define AD7923_SEQUENCE_OFF	(0)		/* no sequence fonction */
> -#define AD7923_SEQUENCE_PROTECT	(2)		/* no interrupt write cycle */
> -#define AD7923_SEQUENCE_ON	(3)		/* continuous sequence */
> -
> -#define AD7923_MAX_CHAN		4
> +#define AD7923_CHANNEL_4	(4)		/* analog input 4 */
> +#define AD7923_CHANNEL_5	(5)		/* analog input 5 */
> +#define AD7923_CHANNEL_6	(6)		/* analog input 6 */
> +#define AD7923_CHANNEL_7	(7)		/* analog input 7 */
These made me wonder.  Seems they aren't actually used in the driver anyway.
Ideally add a precursor to your main patch just dropping these particular
defines entirely.


> +
> +#define AD7923_SEQUENCE_OFF	(0x00)		/* no sequence function */
> +#define AD7923_SEQUENCE_SHADOW	(0x01)		/* use the shadow register
> +						 * for programming
> +						 * (only AD7908/7918/7928)
> +						 */
> +#define AD7923_SEQUENCE_PROTECT	(0x10)		/* no interrupt write cycle */
> +#define AD7923_SEQUENCE_ON	(0x11)		/* continuous sequence */
>  
>  #define AD7923_PM_MODE_WRITE(mode)	((mode) << 4)	 /* write mode */
>  #define AD7923_CHANNEL_WRITE(channel)	((channel) << 6) /* write channel */
> -#define AD7923_SEQUENCE_WRITE(sequence)	((((sequence) & 1) << 3) \
> -					+ (((sequence) & 2) << 9))
> +#define AD7923_SEQUENCE_WRITE(sequence)	((((sequence) & 0x01) << 3) \
> +					+ (((sequence) & 0x10) << 9))

This change is interesting.  Was original code just buggy? we were masking
against 2nd bit, and now we are masking against the 4th?

>  						/* write sequence fonction */
>  /* left shift for CR : bit 11 transmit in first */
>  #define AD7923_SHIFT_REGISTER	4
> @@ -78,6 +87,9 @@ enum ad7923_id {
>  	AD7904,
>  	AD7914,
>  	AD7924,
> +	AD7908,
> +	AD7918,
> +	AD7928
>  };
>  
>  #define AD7923_V_CHAN(index, bits)					\
> @@ -97,7 +109,7 @@ enum ad7923_id {
>  		},							\
>  	}
>  
> -#define DECLARE_AD7923_CHANNELS(name, bits) \
> +#define DECLARE_AD7923_4CHANNELS(name, bits) \
>  const struct iio_chan_spec name ## _channels[] = { \
>  	AD7923_V_CHAN(0, bits), \
>  	AD7923_V_CHAN(1, bits), \
> @@ -106,9 +118,25 @@ const struct iio_chan_spec name ## _channels[] = { \
>  	IIO_CHAN_SOFT_TIMESTAMP(4), \
>  }
>  
> -static DECLARE_AD7923_CHANNELS(ad7904, 8);
> -static DECLARE_AD7923_CHANNELS(ad7914, 10);
> -static DECLARE_AD7923_CHANNELS(ad7924, 12);
> +#define DECLARE_AD7923_8CHANNELS(name, bits) \
> +const struct iio_chan_spec name ## _channels[] = { \
> +	AD7923_V_CHAN(0, bits), \
> +	AD7923_V_CHAN(1, bits), \
> +	AD7923_V_CHAN(2, bits), \
> +	AD7923_V_CHAN(3, bits), \
> +	AD7923_V_CHAN(4, bits), \
> +	AD7923_V_CHAN(5, bits), \
> +	AD7923_V_CHAN(6, bits), \
> +	AD7923_V_CHAN(7, bits), \
> +	IIO_CHAN_SOFT_TIMESTAMP(8), \
> +}
> +
> +static DECLARE_AD7923_4CHANNELS(ad7904, 8);
> +static DECLARE_AD7923_4CHANNELS(ad7914, 10);
> +static DECLARE_AD7923_4CHANNELS(ad7924, 12);
> +static DECLARE_AD7923_8CHANNELS(ad7908, 8);
> +static DECLARE_AD7923_8CHANNELS(ad7918, 10);
> +static DECLARE_AD7923_8CHANNELS(ad7928, 12);
>  
>  static const struct ad7923_chip_info ad7923_chip_info[] = {
>  	[AD7904] = {
> @@ -123,6 +151,18 @@ static const struct ad7923_chip_info ad7923_chip_info[] = {
>  		.channels = ad7924_channels,
>  		.num_channels = ARRAY_SIZE(ad7924_channels),
>  	},
> +	[AD7908] = {
> +		.channels = ad7908_channels,
> +		.num_channels = ARRAY_SIZE(ad7908_channels),
> +	},
> +	[AD7918] = {
> +		.channels = ad7918_channels,
> +		.num_channels = ARRAY_SIZE(ad7918_channels),
> +	},
> +	[AD7928] = {
> +		.channels = ad7928_channels,
> +		.num_channels = ARRAY_SIZE(ad7928_channels),
> +	},
>  };
>  
>  /**
> @@ -135,10 +175,10 @@ static int ad7923_update_scan_mode(struct iio_dev *indio_dev,
>  	int i, cmd, len;
>  
>  	len = 0;
> -	for_each_set_bit(i, active_scan_mask, AD7923_MAX_CHAN) {
> +	for_each_set_bit(i, active_scan_mask, indio_dev->num_channels - 1) {
>  		cmd = AD7923_WRITE_CR | AD7923_CHANNEL_WRITE(i) |
> -			AD7923_SEQUENCE_WRITE(AD7923_SEQUENCE_OFF) |
> -			st->settings;
> +		      AD7923_SEQUENCE_WRITE(AD7923_SEQUENCE_OFF) |
> +		      st->settings;
>  		cmd <<= AD7923_SHIFT_REGISTER;
>  		st->tx_buf[len++] = cpu_to_be16(cmd);
>  	}
> @@ -188,13 +228,13 @@ static irqreturn_t ad7923_trigger_handler(int irq, void *p)
>  	return IRQ_HANDLED;
>  }
>  
> -static int ad7923_scan_direct(struct ad7923_state *st, unsigned ch)
> +static int ad7923_scan_direct(struct ad7923_state *st, unsigned int ch)

Should be in a precursor patch tidying this up.   Never mix new features
with cleanup as it's harder to review.

>  {
>  	int ret, cmd;
>  
>  	cmd = AD7923_WRITE_CR | AD7923_CHANNEL_WRITE(ch) |
> -		AD7923_SEQUENCE_WRITE(AD7923_SEQUENCE_OFF) |
> -		st->settings;
> +	      AD7923_SEQUENCE_WRITE(AD7923_SEQUENCE_OFF) |
> +	      st->settings;

Clean out this noise from the patch.  We just want to see
the new stuff rather than stare at a line to figure if it
is just whitespace, or if there is a real change ;)

>  	cmd <<= AD7923_SHIFT_REGISTER;
>  	st->tx_buf[0] = cpu_to_be16(cmd);
>  
> @@ -280,7 +320,7 @@ static int ad7923_probe(struct spi_device *spi)
>  
>  	st->spi = spi;
>  	st->settings = AD7923_CODING | AD7923_RANGE |
> -			AD7923_PM_MODE_WRITE(AD7923_PM_MODE_OPS);
> +		       AD7923_PM_MODE_WRITE(AD7923_PM_MODE_OPS);

Please clean out an noise like this bit of realignment.

>  
>  	info = &ad7923_chip_info[spi_get_device_id(spi)->driver_data];
>  
> @@ -348,13 +388,29 @@ static const struct spi_device_id ad7923_id[] = {
>  	{"ad7914", AD7914},
>  	{"ad7923", AD7924},
>  	{"ad7924", AD7924},
> +	{"ad7908", AD7908},
> +	{"ad7918", AD7918},
> +	{"ad7928", AD7928},
>  	{}
>  };
>  MODULE_DEVICE_TABLE(spi, ad7923_id);
>  
> +static const struct of_device_id ad7923_of_match[] = {
> +	{ .compatible = "adi,ad7904", },
> +	{ .compatible = "adi,ad7914", },
> +	{ .compatible = "adi,ad7923", },
> +	{ .compatible = "adi,ad7924", },
> +	{ .compatible = "adi,ad7908", },
> +	{ .compatible = "adi,ad7918", },
> +	{ .compatible = "adi,ad7928", },
> +	{ },
Really minor but I would have preferred a precursor patch
adding the of_device_id table for existing parts.

Makes a clear separation between new device support and tidying
up the fact that table should be there to allow the specific
adi,* matching.

> +};
> +MODULE_DEVICE_TABLE(of, ad7923_of_match);
> +
>  static struct spi_driver ad7923_driver = {
>  	.driver = {
>  		.name	= "ad7923",
> +		.of_match_table = ad7923_of_match,
>  	},
>  	.probe		= ad7923_probe,
>  	.remove		= ad7923_remove,
> @@ -364,5 +420,5 @@ module_spi_driver(ad7923_driver);
>  
>  MODULE_AUTHOR("Michael Hennerich <michael.hennerich@...log.com>");
>  MODULE_AUTHOR("Patrick Vasseur <patrick.vasseur@....fr>");
> -MODULE_DESCRIPTION("Analog Devices AD7904/AD7914/AD7923/AD7924 ADC");
> +MODULE_DESCRIPTION("Analog Devices AD7904/AD7914/AD7923/AD7924/AD7908/AD7918/AD7928 ADC");
>  MODULE_LICENSE("GPL v2");

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