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

From: Jonathan Cameron
Date: Sun Apr 03 2016 - 05:16:43 EST


On 31/03/16 18:20, 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@xxxxxxxxx>
Just one query inline.

J
> ---
> drivers/iio/adc/Kconfig | 6 +++---
> drivers/iio/adc/ti-adc081c.c | 31 +++++++++++++++++++++++++++----
> 2 files changed, 30 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..9b2f26f 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;
>
> @@ -72,6 +87,9 @@ static int adc081c_probe(struct i2c_client *client,
> struct adc081c *adc;
> int err;
>
> + if (id->driver_data != 8 && id->driver_data != 10 && id->driver_data != 12)
> + return -EINVAL;
How could this condition occur? The driver won't be probed if we don't have
a match on one of the items in the id table and they all obey this rull?

On Peter's comment, it would be future proofing to use an index into a
information structure array, but I'd prefer that to be added when needed and
am reasonably happy with how you have it here.
> +
> if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
> return -EOPNOTSUPP;
>
> @@ -81,6 +99,7 @@ static int adc081c_probe(struct i2c_client *client,
>
> adc = iio_priv(iio);
> adc->i2c = client;
> + adc->bits = id->driver_data;
>
> adc->ref = devm_regulator_get(&client->dev, "vref");
> if (IS_ERR(adc->ref))
> @@ -124,7 +143,9 @@ static int adc081c_remove(struct i2c_client *client)
> }
>
> static const struct i2c_device_id adc081c_id[] = {
> - { "adc081c", 0 },
> + { "adc081c", 8 },
> + { "adc101c", 10 },
> + { "adc121c", 12 },
> { }
> };
> MODULE_DEVICE_TABLE(i2c, adc081c_id);
> @@ -132,6 +153,8 @@ 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 +172,5 @@ static struct i2c_driver adc081c_driver = {
> module_i2c_driver(adc081c_driver);
>
> MODULE_AUTHOR("Thierry Reding <thierry.reding@xxxxxxxxxxxxxxxxx>");
> -MODULE_DESCRIPTION("Texas Instruments ADC081C021/027 driver");
> +MODULE_DESCRIPTION("Texas Instruments ADC081C/ADC101C/ADC121C driver");
> MODULE_LICENSE("GPL v2");
>