Re: [PATCH v2 1/2] ti-adc081c: Add support for adc101c* and adc121c*

[Jonathan Cameron <jic23@kernel.org>]

On 04/04/16 19:21, Crestez Dan Leonard wrote:
> These chips has an almost identical interface but a deal with a
> different number of value bits. Datasheet links for comparison:
> 
>  * http://www.ti.com/lit/ds/symlink/adc081c021.pdf
>  * http://www.ti.com/lit/ds/symlink/adc101c021.pdf
>  * http://www.ti.com/lit/ds/symlink/adc121c021.pdf
> 
> Signed-off-by: Crestez Dan Leonard <leonard.crestez@intel.com>
A trivial little request inline to move over to an array of structures
describing the different parts and use an enum indexing that instead of pointers in the
i2c_device_id tables.

Otherwise looks good.
> ---
>  drivers/iio/adc/Kconfig      |  6 +++---
>  drivers/iio/adc/ti-adc081c.c | 42 ++++++++++++++++++++++++++++++++++++++----
>  2 files changed, 41 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 9ddcd5d..a2d0db5 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -378,11 +378,11 @@ config ROCKCHIP_SARADC
>  	  module will be called rockchip_saradc.
>  
>  config TI_ADC081C
> -	tristate "Texas Instruments ADC081C021/027"
> +	tristate "Texas Instruments ADC081C/ADC101C/ADC121C family"
>  	depends on I2C
>  	help
> -	  If you say yes here you get support for Texas Instruments ADC081C021
> -	  and ADC081C027 ADC chips.
> +	  If you say yes here you get support for Texas Instruments ADC081C,
> +	  ADC101C and ADC121C ADC chips.
>  
>  	  This driver can also be built as a module. If so, the module will be
>  	  called ti-adc081c.
> diff --git a/drivers/iio/adc/ti-adc081c.c b/drivers/iio/adc/ti-adc081c.c
> index ecbc121..3b3c656 100644
> --- a/drivers/iio/adc/ti-adc081c.c
> +++ b/drivers/iio/adc/ti-adc081c.c
> @@ -1,9 +1,21 @@
>  /*
> + * TI ADC081C/ADC101C/ADC121C 8/10/12-bit ADC driver
> + *
>   * Copyright (C) 2012 Avionic Design GmbH
> + * Copyright (C) 2016 Intel
>   *
>   * This program is free software; you can redistribute it and/or modify
>   * it under the terms of the GNU General Public License version 2 as
>   * published by the Free Software Foundation.
> + *
> + * Datasheets:
> + *	http://www.ti.com/lit/ds/symlink/adc081c021.pdf
> + *	http://www.ti.com/lit/ds/symlink/adc101c021.pdf
> + *	http://www.ti.com/lit/ds/symlink/adc121c021.pdf
> + *
> + * The devices have a very similar interface and differ mostly in the number of
> + * bits handled. For the 8-bit and 10-bit models the least-significant 4 or 2
> + * bits of value registers are reserved.
>   */
>  
>  #include <linux/err.h>
> @@ -17,6 +29,9 @@
>  struct adc081c {
>  	struct i2c_client *i2c;
>  	struct regulator *ref;
> +
> +	/* 8, 10 or 12 */
> +	int bits;
>  };
>  
>  #define REG_CONV_RES 0x00
> @@ -34,7 +49,7 @@ static int adc081c_read_raw(struct iio_dev *iio,
>  		if (err < 0)
>  			return err;
>  
> -		*value = (err >> 4) & 0xff;
> +		*value = (err & 0xFFF) >> (12 - adc->bits);
>  		return IIO_VAL_INT;
>  
>  	case IIO_CHAN_INFO_SCALE:
> @@ -43,7 +58,7 @@ static int adc081c_read_raw(struct iio_dev *iio,
>  			return err;
>  
>  		*value = err / 1000;
> -		*shift = 8;
> +		*shift = adc->bits;
>  
>  		return IIO_VAL_FRACTIONAL_LOG2;
>  
> @@ -60,6 +75,19 @@ static const struct iio_chan_spec adc081c_channel = {
>  	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
>  };
>  
> +struct adcxx1c_model {
> +	int bits;
> +};
> +
> +#define DEFINE_ADCxx1C_MODEL(_name, _bits)				\
> +	static const struct adcxx1c_model _name ## _model = {		\
> +		.bits = (_bits),					\
> +	}
> +
> +DEFINE_ADCxx1C_MODEL(adc081c,  8);
> +DEFINE_ADCxx1C_MODEL(adc101c, 10);
> +DEFINE_ADCxx1C_MODEL(adc121c, 12);
As suggested below, I'd prefer these were elements of an array of such structures
as it tends to lead to cleaner / more obvious code in my view.
> +
>  static const struct iio_info adc081c_info = {
>  	.read_raw = adc081c_read_raw,
>  	.driver_module = THIS_MODULE,
> @@ -70,6 +98,7 @@ static int adc081c_probe(struct i2c_client *client,
>  {
>  	struct iio_dev *iio;
>  	struct adc081c *adc;
> +	struct adcxx1c_model *model = (struct adcxx1c_model*)id->driver_data;
>  	int err;
>  
>  	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
> @@ -81,6 +110,7 @@ static int adc081c_probe(struct i2c_client *client,
>  
>  	adc = iio_priv(iio);
>  	adc->i2c = client;
> +	adc->bits = model->bits;
>  
>  	adc->ref = devm_regulator_get(&client->dev, "vref");
>  	if (IS_ERR(adc->ref))
> @@ -124,7 +154,9 @@ static int adc081c_remove(struct i2c_client *client)
>  }
>  
>  static const struct i2c_device_id adc081c_id[] = {
> -	{ "adc081c", 0 },
> +	{ "adc081c", (long)&adc081c_model },
> +	{ "adc101c", (long)&adc101c_model },
> +	{ "adc121c", (long)&adc121c_model },
It's often cleaner to use an enum instead of direct pointers.  Avoids some nasty
casting like you have needed to do here.  The enum can then be used to reference
into an array of model description structures.
>  	{ }
>  };
>  MODULE_DEVICE_TABLE(i2c, adc081c_id);
> @@ -132,6 +164,8 @@ MODULE_DEVICE_TABLE(i2c, adc081c_id);
>  #ifdef CONFIG_OF
>  static const struct of_device_id adc081c_of_match[] = {
>  	{ .compatible = "ti,adc081c" },
> +	{ .compatible = "ti,adc101c" },
> +	{ .compatible = "ti,adc121c" },
>  	{ }
>  };
>  MODULE_DEVICE_TABLE(of, adc081c_of_match);
> @@ -149,5 +183,5 @@ static struct i2c_driver adc081c_driver = {
>  module_i2c_driver(adc081c_driver);
>  
>  MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
> -MODULE_DESCRIPTION("Texas Instruments ADC081C021/027 driver");
> +MODULE_DESCRIPTION("Texas Instruments ADC081C/ADC101C/ADC121C driver");
>  MODULE_LICENSE("GPL v2");
>