lkml.org 
[lkml]   [2019]   [Dec]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v6 2/2] iio: (bma400) add driver for the BMA400
On Wed, Dec 11, 2019 at 3:20 AM Dan Robertson <dan@dlrobertson.com> 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.

> +#define BMA400_LP_OSR_SHIFT 0x05
> +#define BMA400_NP_OSR_SHIFT 0x04
> +#define BMA400_SCALE_SHIFT 0x06

I'm not sure why this is being defined as hex number instead of plain decimal...

> +#define BMA400_TWO_BITS_MASK GENMASK(1, 0)
> +#define BMA400_LP_OSR_MASK GENMASK(6, BMA400_LP_OSR_SHIFT)
> +#define BMA400_NP_OSR_MASK GENMASK(5, BMA400_NP_OSR_SHIFT)
> +#define BMA400_ACC_ODR_MASK GENMASK(3, 0)
> +#define BMA400_ACC_SCALE_MASK GENMASK(7, BMA400_SCALE_SHIFT)

And here simple better to put same numbers. It will help to read.

...

> +extern const struct regmap_config bma400_regmap_config;

> +const struct regmap_config bma400_regmap_config = {
> + .reg_bits = 8,
> + .val_bits = 8,
> + .max_register = BMA400_CMD_REG,
> + .cache_type = REGCACHE_RBTREE,
> + .writeable_reg = bma400_is_writable_reg,
> + .volatile_reg = bma400_is_volatile_reg,
> +};
> +EXPORT_SYMBOL(bma400_regmap_config);

I'm not sure I got the idea why this one is being exported.

...

> + if (odr < BMA400_ACC_ODR_MIN_RAW ||
> + odr > BMA400_ACC_ODR_MAX_RAW) {

One line?

> + ret = -EINVAL;
> + goto error;
> + }

...

> + if (uhz || hz % BMA400_ACC_ODR_MIN_WHOLE_HZ)
> + return -EINVAL;
> +
> + val = hz / BMA400_ACC_ODR_MIN_WHOLE_HZ;
> + idx = __ffs(val);
> +

> + if (val ^ BIT(idx))

Seems like funny way of checking is_power_of_2(). But it's up to maintainers.
And your variant may even be better here (in code generation perspective)...

However, the whole idea here is, IIUC, to have something like

hz = 2^idx * BMA400_ACC_ODR_MIN_WHOLE_HZ

I think you may do it without divisions, i.e. call __ffs() first and then do
idx = __ffs(...);
val = hz >> idx;
if (val != BMA400_ACC_ODR_MIN_WHOLE_HZ)
return -EINVAL;

or something like above.

> + return -EINVAL;

...

> + odr = (~BMA400_ACC_ODR_MASK & val) | idx;

I'm wondering why Yoda style is being used here.

...

> +static void bma400_accel_scale_from_raw(int raw, unsigned int *val)
> +{
> + *val = BMA400_SCALE_MIN * (1 << raw);

Isn't it the same as
*val = BMA400_SCALE_MIN << raw;
?

> +}

...

> + if (val % BMA400_SCALE_MIN || scale ^ BIT(raw))

Similar comment as above about divisions, is_power_of_2(), etc.

> + return -EINVAL;

...

> + ret = regmap_read(data->regmap, BMA400_ACC_CONFIG0_REG, &val);
> + if (ret < 0)

I'm wondering if in all of these regmap_read()...

> + return ret;

> + ret = regmap_write(data->regmap, BMA400_ACC_CONFIG0_REG,
> + mode | (val & ~BMA400_TWO_BITS_MASK));
> + if (ret < 0) {

...and regmap_write() calls you ever can get a positive returned code.

> + dev_err(data->dev, "Failed to write to power-mode\n");
> + return ret;
> + }

...

> + regmap = devm_regmap_init_i2c(client, &bma400_regmap_config);

> +

Redundant blank line.

> + if (IS_ERR(regmap)) {
> + dev_err(&client->dev, "failed to create regmap\n");
> + return PTR_ERR(regmap);
> + }

--
With Best Regards,
Andy Shevchenko

\
 
 \ /
  Last update: 2019-12-11 14:22    [W:0.077 / U:0.184 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site