Date:   Thu, 27 Apr 2017 19:09:18 +0200
From:   Mike Looijmans <mike.looijmans@...ic.nl>
To:     Lars-Peter Clausen <lars@...afoo.de>,
        Jonathan Cameron <jic23@...nel.org>,
        <linux-iio@...r.kernel.org>
CC:     <linux-kernel@...r.kernel.org>, <Michael.Hennerich@...log.com>,
        <knaack.h@....de>, <pmeerw@...erw.net>
Subject: Re: [PATCH] iio:ad5064: Add support for ltc2633 and similar devices

On 27-04-17 11:16, Lars-Peter Clausen wrote:
> On 04/27/2017 07:52 AM, Jonathan Cameron wrote:
>> On 26/04/17 10:44, Mike Looijmans wrote:
>>> The Linear Technology LTC2631, LTC2633 and LTC2635 are very similar
>>> to the AD5064 device, in particular the LTC2627.
>>>
>>> This patch adds support for those devices. Only the LTC2633 has been
>>> tested, which is the 2-channel variant. The LTC2631 is the 1-channel,
>>> and the LTC2635 the 4-channel version. The actual DAC resolution depends
>>> on the exact chip type and can be 12, 10 or 8 bits, using the upper bits
>>> so this has no effect on the register map. The internal reference is set
>>> to 2.5V on "L" versions, and it's 4.096V for "H" versions.
>>>
>>> Datasheets:
>>>     LTC2631: http://www.linear.com/docs/26553
>>>     LTC2633: http://www.linear.com/docs/39529
>>>     LTC2635: http://www.linear.com/docs/28754
>>>
>>> Signed-off-by: Mike Looijmans <mike.looijmans@...ic.nl>
>
> Ah, its always good if somebody manages to clear an item from your TODO list
> before you :)

Glad to be able to reverse the roles this time :)

>> Looks fine to me, but I'd like to give time for Lars to take a look
>> as it is his driver.
>
> Patch looks good, but I'd prefer it if we had different entries in the
> device table for different resolutions. So you don't have to manually shift
> the output value by 12 when you are using the 8-bit version. This is how it
> has been done for other DAC drivers and it would be good to stay consistent.

Doing so would add 18 entries (3 channels, 2 ranges, 3 resolutions) 
instead of a mere 6. That's why I refrained from it.

>
> Maybe even include the reset-to-midscale/reset-to-gnd designator of the part
> number in the compatible string.
>
> http://cds.linear.com/docs/en/datasheet/2631fc.pdf#page=3

And that would make the number of entries to add 36. I think if we go 
that path, we should make things parameterizable, e.g. have channel 
count, bit resolution, reset state and range as devicetree parameters, 
so that the "compatible" string needn't hold all information. It would 
impact existing trees though.


>> Jonathan
>>> ---
>>>  drivers/iio/dac/Kconfig  |  3 ++-
>>>  drivers/iio/dac/ad5064.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++--
>>>  2 files changed, 58 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
>>> index d3084028..31ffb67 100644
>>> --- a/drivers/iio/dac/Kconfig
>>> +++ b/drivers/iio/dac/Kconfig
>>> @@ -13,7 +13,8 @@ config AD5064
>>>  	  AD5045, AD5064, AD5064-1, AD5065, AD5625, AD5625R, AD5627, AD5627R,
>>>  	  AD5628, AD5629R, AD5645R, AD5647R, AD5648, AD5665, AD5665R, AD5666,
>>>  	  AD5667, AD5667R, AD5668, AD5669R, LTC2606, LTC2607, LTC2609, LTC2616,
>>> -	  LTC2617, LTC2619, LTC2626, LTC2627, LTC2629 Digital to Analog Converter.
>>> +	  LTC2617, LTC2619, LTC2626, LTC2627, LTC2629, LTC2631, LTC2633, LTC2635
>>> +	  Digital to Analog Converter.
>>>
>>>  	  To compile this driver as a module, choose M here: the
>>>  	  module will be called ad5064.
>>> diff --git a/drivers/iio/dac/ad5064.c b/drivers/iio/dac/ad5064.c
>>> index 6803e4a..b440180 100644
>>> --- a/drivers/iio/dac/ad5064.c
>>> +++ b/drivers/iio/dac/ad5064.c
>>> @@ -2,8 +2,8 @@
>>>   * AD5024, AD5025, AD5044, AD5045, AD5064, AD5064-1, AD5065, AD5625, AD5625R,
>>>   * AD5627, AD5627R, AD5628, AD5629R, AD5645R, AD5647R, AD5648, AD5665, AD5665R,
>>>   * AD5666, AD5667, AD5667R, AD5668, AD5669R, LTC2606, LTC2607, LTC2609, LTC2616,
>>> - * LTC2617, LTC2619, LTC2626, LTC2627, LTC2629 Digital to analog converters
>>> - * driver
>>> + * LTC2617, LTC2619, LTC2626, LTC2627, LTC2629, LTC2631, LTC2633, LTC2635
>>> + * Digital to analog converters driver
>>>   *
>>>   * Copyright 2011 Analog Devices Inc.
>>>   *
>>> @@ -168,6 +168,12 @@ enum ad5064_type {
>>>  	ID_LTC2626,
>>>  	ID_LTC2627,
>>>  	ID_LTC2629,
>>> +	ID_LTC2631_L,
>>> +	ID_LTC2631_H,
>>> +	ID_LTC2633_L,
>>> +	ID_LTC2633_H,
>>> +	ID_LTC2635_L,
>>> +	ID_LTC2635_H,
>>>  };
>>>
>>>  static int ad5064_write(struct ad5064_state *st, unsigned int cmd,
>>> @@ -724,6 +730,48 @@ static int ad5064_write_raw(struct iio_dev *indio_dev,
>>>  		.num_channels = 4,
>>>  		.regmap_type = AD5064_REGMAP_LTC,
>>>  	},
>>> +	[ID_LTC2631_L] = {
>>> +		.shared_vref = true,
>>> +		.internal_vref = 2500000,
>>> +		.channels = ltc2627_channels,
>>> +		.num_channels = 1,
>>> +		.regmap_type = AD5064_REGMAP_LTC,
>>> +	},
>>> +	[ID_LTC2631_H] = {
>>> +		.shared_vref = true,
>>> +		.internal_vref = 4096000,
>>> +		.channels = ltc2627_channels,
>>> +		.num_channels = 1,
>>> +		.regmap_type = AD5064_REGMAP_LTC,
>>> +	},
>>> +	[ID_LTC2633_L] = {
>>> +		.shared_vref = true,
>>> +		.internal_vref = 2500000,
>>> +		.channels = ltc2627_channels,
>>> +		.num_channels = 2,
>>> +		.regmap_type = AD5064_REGMAP_LTC,
>>> +	},
>>> +	[ID_LTC2633_H] = {
>>> +		.shared_vref = true,
>>> +		.internal_vref = 4096000,
>>> +		.channels = ltc2627_channels,
>>> +		.num_channels = 2,
>>> +		.regmap_type = AD5064_REGMAP_LTC,
>>> +	},
>>> +	[ID_LTC2635_L] = {
>>> +		.shared_vref = true,
>>> +		.internal_vref = 2500000,
>>> +		.channels = ltc2627_channels,
>>> +		.num_channels = 4,
>>> +		.regmap_type = AD5064_REGMAP_LTC,
>>> +	},
>>> +	[ID_LTC2635_H] = {
>>> +		.shared_vref = true,
>>> +		.internal_vref = 4096000,
>>> +		.channels = ltc2627_channels,
>>> +		.num_channels = 4,
>>> +		.regmap_type = AD5064_REGMAP_LTC,
>>> +	},
>>>  };
>>>
>>>  static inline unsigned int ad5064_num_vref(struct ad5064_state *st)
>>> @@ -982,6 +1030,12 @@ static int ad5064_i2c_remove(struct i2c_client *i2c)
>>>  	{"ltc2626", ID_LTC2626},
>>>  	{"ltc2627", ID_LTC2627},
>>>  	{"ltc2629", ID_LTC2629},
>>> +	{"ltc2631-l", ID_LTC2631_L},
>>> +	{"ltc2631-h", ID_LTC2631_H},
>>> +	{"ltc2633-l", ID_LTC2633_L},
>>> +	{"ltc2633-h", ID_LTC2633_H},
>>> +	{"ltc2635-l", ID_LTC2635_L},
>>> +	{"ltc2635-h", ID_LTC2635_H},
>>>  	{}
>>>  };
>>>  MODULE_DEVICE_TABLE(i2c, ad5064_i2c_ids);
>>>
>>
>


-- 
Mike Looijmans


Kind regards,

Mike Looijmans
System Expert

TOPIC Products
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Postbus 440, NL-5680 AK Best
Telefoon: +31 (0) 499 33 69 79
E-mail: mike.looijmans@...icproducts.com
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