linux-kernel - Re: [PATCH v4 2/2] iio: (bma400) add driver for the BMA400

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Message-ID: <487efd2c-b453-6c8b-eaac-7ba168bb4d77@infradead.org>
Date:   Thu, 17 Oct 2019 21:25:37 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Dan Robertson <dan@...obertson.com>,
        Jonathan Cameron <jic23@...nel.org>, linux-iio@...r.kernel.org,
        Peter Meerwald-Stadler <pmeerw@...erw.net>
Cc:     Andy Shevchenko <andy.shevchenko@...il.com>,
        devicetree@...r.kernel.org, Hartmut Knaack <knaack.h@....de>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/2] iio: (bma400) add driver for the BMA400

On 10/17/19 8:18 PM, Dan Robertson wrote:
> Add a IIO driver for the Bosch BMA400 3-axes ultra-low power accelerometer.
> The driver supports reading from the acceleration and temperature
> registers. The driver also supports reading and configuring the output data
> rate, oversampling ratio, and scale.
> 
> Signed-off-by: Dan Robertson <dan@...obertson.com>

Hi,
I'm repeating some comments from my V2 review.

> ---
>  drivers/iio/accel/Kconfig       |  18 +
>  drivers/iio/accel/Makefile      |   2 +
>  drivers/iio/accel/bma400.h      |  85 ++++
>  drivers/iio/accel/bma400_core.c | 796 ++++++++++++++++++++++++++++++++
>  drivers/iio/accel/bma400_i2c.c  |  60 +++
>  5 files changed, 961 insertions(+)
>  create mode 100644 drivers/iio/accel/bma400.h
>  create mode 100644 drivers/iio/accel/bma400_core.c
>  create mode 100644 drivers/iio/accel/bma400_i2c.c
> 
> diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
> index 9b9656ce37e6..a1081b902d16 100644
> --- a/drivers/iio/accel/Kconfig
> +++ b/drivers/iio/accel/Kconfig
> @@ -112,6 +112,24 @@ config BMA220
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called bma220_spi.
>  
> +config BMA400
> +	tristate "Bosch BMA400 3-Axis Accelerometer Driver"
> +	depends on I2C
> +	select REGMAP
> +	select BMA400_I2C if (I2C)

Since BMA400 already depends on I2C, the "if (I2C)" above is
redundant so it's not needed.

> +	help
> +	  Say Y here if you want to build a driver for the Bosch BMA400
> +	  triaxial acceleration sensor.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called bma400_core and you will also get
> +	  bma400_i2c for I2C.
> +
> +config BMA400_I2C
> +	tristate
> +	depends on BMA400
> +	select REGMAP_I2C
> +
>  config BMC150_ACCEL
>  	tristate "Bosch BMC150 Accelerometer Driver"
>  	select IIO_BUFFER


> diff --git a/drivers/iio/accel/bma400_core.c b/drivers/iio/accel/bma400_core.c
> new file mode 100644
> index 000000000000..80f1ee6713fa
> --- /dev/null
> +++ b/drivers/iio/accel/bma400_core.c
> @@ -0,0 +1,796 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * bma400_core.c - Core IIO driver for Bosch BMA400 triaxial acceleration
> + *                 sensor. Used by bma400-i2c.
> + *
> + * Copyright 2019 Dan Robertson <dan@...obertson.com>
> + *
> + * TODO:
> + *  - Support for power management
> + *  - Support events and interrupts
> + *  - Create channel the step count
> + *  - Create channel for sensor time
> + */
> +
> +#include <linux/device.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include <linux/bitops.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +
> +#include "bma400.h"
> +
> +/*
> + * The G-range selection may be one of 2g, 4g, 8, or 16g. The scale may
> + * be selected with the acc_range bits of the ACC_CONFIG1 register.
> + */
> +static const int bma400_scale_table[] = {
> +	0, 38344,
> +	0, 76590,
> +	0, 153277,
> +	0, 306457
> +};
> +
> +static const int bma400_osr_table[] = { 0, 1, 3 };
> +
> +/* See the ACC_CONFIG1 section of the datasheet */
> +static const int bma400_sample_freqs[] = {
> +	12,  500000,
> +	25,  0,
> +	50,  0,
> +	100, 0,
> +	200, 0,
> +	400, 0,
> +	800, 0,
> +};
> +
> +/* See the ACC_CONFIG0 section of the datasheet */
> +enum bma400_power_mode {
> +	POWER_MODE_SLEEP   = 0x00,
> +	POWER_MODE_LOW     = 0x01,
> +	POWER_MODE_NORMAL  = 0x02,
> +	POWER_MODE_INVALID = 0x03,
> +};
> +
> +struct bma400_sample_freq {
> +	int hz;
> +	int uhz;
> +};
> +
> +struct bma400_data {
> +	struct device *dev;
> +	struct mutex mutex; /* data register lock */

needs #include <linux/mutex.h>

> +	struct iio_mount_matrix orientation;
> +	struct regmap *regmap;
> +	enum bma400_power_mode power_mode;
> +	struct bma400_sample_freq sample_freq;
> +	int oversampling_ratio;
> +	int scale;
> +};
> +

[snip]

> +static int bma400_get_accel_scale_idx(struct bma400_data *data, int val)
> +{
> +	int i;
> +
> +	for (i = 1; i < ARRAY_SIZE(bma400_scale_table); i += 2) {

needs #include <linux/kernel.h>
for ARRAY_SIZE()

> +		if (bma400_scale_table[i] == val)
> +			return i - 1;
> +	}
> +	return -EINVAL;
> +}

[snip]

Thanks.

-- 
~Randy
See Documentation/process/submit-checklist.rst, especially Rule #1.