Re: [PATCH v7 7/7] input: joystick: Add ADC attached joystick driver.

Andy Shevchenko
2020-05-19T20:44:02Z

On Sun, May 17, 2020 at 10:49 PM Artur Rojek <contact@artur-rojek.eu> wrote:
>
> Add a driver for joystick devices connected to ADC controllers
> supporting the Industrial I/O subsystem.

...

> +static int adc_joystick_handle(const void *data, void *private)
> +{
> + struct adc_joystick *joy = private;
> + enum iio_endian endianness;
> + int bytes, msb, val, i;
> + bool sign;
> +
> + bytes = joy->chans[0].channel->scan_type.storagebits >> 3;
> +
> + for (i = 0; i < joy->num_chans; ++i) {
> + endianness = joy->chans[i].channel->scan_type.endianness;
> + msb = joy->chans[i].channel->scan_type.realbits - 1;

> + sign = (tolower(joy->chans[i].channel->scan_type.sign) == 's');

Do we need tolower()?

> +
> + switch (bytes) {
> + case 1:
> + val = ((const u8 *)data)[i];
> + break;
> + case 2:
> + if (endianness == IIO_BE)

> + val = be16_to_cpu(((const u16 *)data)[i]);

Yeah, you have to provide bitwise types to satisfy sparse.
Maybe using *_to_cpup() will cure this.

> + else if (endianness == IIO_LE)
> + val = le16_to_cpu(((const u16 *)data)[i]);
> + else /* IIO_CPU */
> + val = ((const u16 *)data)[i];
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + val >>= joy->chans[i].channel->scan_type.shift;
> + if (sign)
> + val = sign_extend32(val, msb);
> + else
> + val &= GENMASK(msb, 0);
> + input_report_abs(joy->input, joy->axes[i].code, val);
> + }
> +
> + input_sync(joy->input);
> +
> + return 0;
> +}

...

> + /* Count how many channels we got. NULL terminated. */
> + while (joy->chans[joy->num_chans].indio_dev)
> + joy->num_chans++;

I don't see how useful this is. Why not simple do below...

> + bits = joy->chans[0].channel->scan_type.storagebits;
> + if (!bits || (bits > 16)) {
> + dev_err(dev, "Unsupported channel storage size");
> + return -EINVAL;
> + }
> + for (i = 1; i < joy->num_chans; ++i)
> + if (joy->chans[i].channel->scan_type.storagebits != bits) {
> + dev_err(dev, "Channels must have equal storage size");
> + return -EINVAL;
> + }

...something like

for (i = 0; joy->chans[i].indio_dev; i++) {
bits = joy->chans[i].channel->scan_type.storagebits;
if (bits ...) {
...error handling...
}
if (bits != joy->chans[0].channel->scan_type.storagebits) {
...second level of error handling...
}
}

...

> +static const struct of_device_id adc_joystick_of_match[] = {
> + { .compatible = "adc-joystick", },

> + { },

No need comma.

> +};

--
With Best Regards,
Andy Shevchenko