linux-kernel - Re: [PATCH 3/3] iio: adc: Add support for PMIC7 ADC

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Message-ID: <CAHp75Vfk1DZ+bz6h_prm6Tp7kXos6jio5JCpg6=wvGRmDPTBsw@mail.gmail.com>
Date:   Tue, 24 Mar 2020 18:33:31 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Jishnu Prakash <jprakash@...eaurora.org>
Cc:     agross@...nel.org, Bjorn Andersson <bjorn.andersson@...aro.org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        smohanad@...eaurora.org, kgunda@...eaurora.org,
        aghayal@...eaurora.org, Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-arm-msm@...r.kernel.org,
        linux-iio <linux-iio@...r.kernel.org>,
        linux-arm-msm-owner@...r.kernel.org
Subject: Re: [PATCH 3/3] iio: adc: Add support for PMIC7 ADC

On Tue, Mar 24, 2020 at 5:46 PM Jishnu Prakash <jprakash@...eaurora.org> wrote:
>
> The ADC architecture on PMIC7 is changed as compared to PMIC5. The
> major change from PMIC5 is that all SW communication to ADC goes through
> PMK8350, which communicates with other PMICs through PBS when the ADC
> on PMK8350 works in master mode. The SID register is used to identify the
> PMICs with which the PBS needs to communicate. Add support for the same.
>
> In addition, add definitions for ADC channels and virtual channel
> definitions per PMIC, to be used by ADC clients for PMIC7.

...

> +#define ADC_CHANNEL_OFFSET                     0x8
> +#define ADC_CHANNEL_MASK                       0xff

GENMASK()

...

> +#define ADC_APP_SID                            0x40
> +#define ADC_APP_SID_MASK                       0xf

GENMASK()

> +#define ADC7_CONV_TIMEOUT                      msecs_to_jiffies(10)

Useless.

...

> +       buf[1] &= (u8) ~ADC5_USR_FAST_AVG_CTL_SAMPLES_MASK;

Use '0xFF ^ _MASK' instead of casting.

...

> +       buf[3] &= (u8) ~ADC5_USR_HW_SETTLE_DELAY_MASK;

Ditto.

...

> +       ret = adc5_write(adc, ADC5_USR_CONV_REQ, &conv_req, 1);
> +
> +       return ret;

return adc5_write(...);

...

> +               pr_err("ADC configure failed with %d\n", ret);

Use dev_*() instead everywhere.

...

> +       /* No support for polling mode at present*/
> +       wait_for_completion_timeout(&adc->complete,
> +                                       ADC7_CONV_TIMEOUT);

One line. The limit is 80 and it can be bend in some cases a little bit.

...

> +               v_channel = ((adc->chan_props[i].sid << ADC_CHANNEL_OFFSET) |
> +                       adc->chan_props[i].channel);

Too many parentheses.

...

> +               sid = (chan >> ADC_CHANNEL_OFFSET);
> +               chan = (chan & ADC_CHANNEL_MASK);

Ditto.

...

> +                       (adc->is_pmic7))

Ditto.

...

> +       if (of_device_is_compatible(node, "qcom,spmi-adc7")) {
> +               indio_dev->info = &adc7_info;
> +               adc->is_pmic7 = true;
> +       } else {
> +               indio_dev->info = &adc5_info;
> +       }

Hmm... I would rather put this as driver_data in ID structure(s).

...

> +static int adc5_exit(struct platform_device *pdev)
> +{
> +       struct adc5_chip *adc = platform_get_drvdata(pdev);
> +

> +       mutex_destroy(&adc->lock);

Are you sure you will have no race conditions? Does this driver use IRQs?

> +       return 0;
> +}

...

> +       s64 resistance = 0;

= adc_code  // or sign extended variant if needed.

> +       /* (ADC code * R_PULLUP (100Kohm)) / (full_scale_code - ADC code)*/

> +       resistance = (s64) adc_code * R_PU_100K;
> +       resistance = div64_s64(resistance, (RATIO_MAX_ADC7 - adc_code));

 resistance *= R_PU_100K;
 resistance = div64_s64(resistance, RATIO_MAX_ADC7 - adc_code);

...

> +       int voltage, vtemp0, temp, i = 0;

> +       while (i < ARRAY_SIZE(adcmap7_die_temp)) {
> +               if (adcmap7_die_temp[i].x > voltage)
> +                       break;
> +               i++;
> +       }

for loop (one line less, more explicit initial value assignment)?

-- 
With Best Regards,
Andy Shevchenko