Re: [PATCH v2 2/2] staging: iio: cdc: ad7746: use dt for capacitive channel setup.

Jonathan Cameron
2021-04-24T12:10:36Z

On Sun, 18 Apr 2021 19:50:10 -0300
Lucas Stankus <lucas.p.stankus@gmail.com> wrote:

> Ditch platform_data fields in favor of device tree properties for
> configuring EXCA and EXCB output pins and setting the capacitive channel
> excitation level.
>
> As this covers all current use cases for the platform_data struct, remove
> ad7746.h header file since it's no longer needed.
>
> Signed-off-by: Lucas Stankus <lucas.p.stankus@gmail.com>
Hi Lucas,

Just one comment which is that the permille to register value
is a bit opaque so I think I'd prefer a simple lookup table even though it
is a bit more code.

Otherwise looks good to me.

Thanks,

Jonathan
> ---
>
> Changes in v2:
> Previously this change set was composed of two patches, but it lead to
> regressions between the two. Merging them avoids the unwanted behaviour
> without having to deal with the special cases.
>
> drivers/staging/iio/cdc/ad7746.c | 42 +++++++++++++++-----------------
> drivers/staging/iio/cdc/ad7746.h | 28 ---------------------
> 2 files changed, 19 insertions(+), 51 deletions(-)
> delete mode 100644 drivers/staging/iio/cdc/ad7746.h
>
> diff --git a/drivers/staging/iio/cdc/ad7746.c b/drivers/staging/iio/cdc/ad7746.c
> index dfd71e99e872..c0e84c1cf4f1 100644
> --- a/drivers/staging/iio/cdc/ad7746.c
> +++ b/drivers/staging/iio/cdc/ad7746.c
> @@ -18,8 +18,6 @@
> #include <linux/iio/iio.h>
> #include <linux/iio/sysfs.h>
>
> -#include "ad7746.h"
> -
> /*
> * AD7746 Register Definition
> */
> @@ -66,7 +64,7 @@
> #define AD7746_EXCSETUP_NEXCB BIT(4)
> #define AD7746_EXCSETUP_EXCA BIT(3)
> #define AD7746_EXCSETUP_NEXCA BIT(2)
> -#define AD7746_EXCSETUP_EXCLVL(x) (((x) & 0x3) << 0)
> +#define AD7746_EXCSETUP_EXCLVL(x) (((x) >> 7) & 0x3)

I'd like a comment on this maths, or just use a lookup table instead so
we don't have to think about it and also enforce exact matches.
The rounding this results in is a bit odd

>
> /* Config Register Bit Designations (AD7746_REG_CFG) */
> #define AD7746_CONF_VTFS_SHIFT 6
> @@ -676,10 +674,11 @@ static const struct iio_info ad7746_info = {
> static int ad7746_probe(struct i2c_client *client,
> const struct i2c_device_id *id)
> {
> - struct ad7746_platform_data *pdata = client->dev.platform_data;
> + struct device *dev = &client->dev;
> struct ad7746_chip_info *chip;
> struct iio_dev *indio_dev;
> unsigned char regval = 0;
> + unsigned int vdd_permille;
> int ret = 0;
>
> indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
> @@ -703,28 +702,25 @@ static int ad7746_probe(struct i2c_client *client,
> indio_dev->num_channels = ARRAY_SIZE(ad7746_channels);
> indio_dev->modes = INDIO_DIRECT_MODE;
>
> - if (pdata) {
> - if (pdata->exca_en) {
> - if (pdata->exca_inv_en)
> - regval |= AD7746_EXCSETUP_NEXCA;
> - else
> - regval |= AD7746_EXCSETUP_EXCA;
> - }
> -
> - if (pdata->excb_en) {
> - if (pdata->excb_inv_en)
> - regval |= AD7746_EXCSETUP_NEXCB;
> - else
> - regval |= AD7746_EXCSETUP_EXCB;
> - }
> + if (device_property_read_bool(dev, "adi,exca-output-en")) {
> + if (device_property_read_bool(dev, "adi,exca-output-invert"))
> + regval |= AD7746_EXCSETUP_NEXCA;
> + else
> + regval |= AD7746_EXCSETUP_EXCA;
> + }
>
> - regval |= AD7746_EXCSETUP_EXCLVL(pdata->exclvl);
> - } else {
> - dev_warn(&client->dev, "No platform data? using default\n");
> - regval = AD7746_EXCSETUP_EXCA | AD7746_EXCSETUP_EXCB |
> - AD7746_EXCSETUP_EXCLVL(3);
> + if (device_property_read_bool(dev, "adi,excb-output-en")) {
> + if (device_property_read_bool(dev, "adi,excb-output-invert"))
> + regval |= AD7746_EXCSETUP_NEXCB;
> + else
> + regval |= AD7746_EXCSETUP_EXCB;
> }
>
> + ret = device_property_read_u32(dev, "adi,excitation-vdd-permille",
> + &vdd_permille);
> + if (!ret)
> + regval |= AD7746_EXCSETUP_EXCLVL(vdd_permille);
> +
> ret = i2c_smbus_write_byte_data(chip->client,
> AD7746_REG_EXC_SETUP, regval);
> if (ret < 0)
> diff --git a/drivers/staging/iio/cdc/ad7746.h b/drivers/staging/iio/cdc/ad7746.h
> deleted file mode 100644
> index 8bdbd732dbbd..000000000000
> --- a/drivers/staging/iio/cdc/ad7746.h
> +++ /dev/null
> @@ -1,28 +0,0 @@
> -/* SPDX-License-Identifier: GPL-2.0 */
> -/*
> - * AD7746 capacitive sensor driver supporting AD7745, AD7746 and AD7747
> - *
> - * Copyright 2011 Analog Devices Inc.
> - */
> -
> -#ifndef IIO_CDC_AD7746_H_
> -#define IIO_CDC_AD7746_H_
> -
> -/*
> - * TODO: struct ad7746_platform_data needs to go into include/linux/iio
> - */
> -
> -#define AD7466_EXCLVL_0 0 /* +-VDD/8 */
> -#define AD7466_EXCLVL_1 1 /* +-VDD/4 */
> -#define AD7466_EXCLVL_2 2 /* +-VDD * 3/8 */
> -#define AD7466_EXCLVL_3 3 /* +-VDD/2 */
> -
> -struct ad7746_platform_data {
> - unsigned char exclvl; /*Excitation Voltage Level */
> - bool exca_en; /* enables EXCA pin as the excitation output */
> - bool exca_inv_en; /* enables /EXCA pin as the excitation output */
> - bool excb_en; /* enables EXCB pin as the excitation output */
> - bool excb_inv_en; /* enables /EXCB pin as the excitation output */
> -};
> -
> -#endif /* IIO_CDC_AD7746_H_ */