linux-kernel - Re: [PATCH v2 2/2] thermal: thermal-generic-adc: add temperature sensor channel

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <CAPVz0n3gs_1wUncJ8w5kpSLiDpJEzPUQ_qaaR2TAhHJHtTR5EA@mail.gmail.com>
Date: Mon, 3 Mar 2025 13:08:31 +0200
From: Svyatoslav Ryhel <clamor95@...il.com>
To: Lukasz Luba <lukasz.luba@....com>
Cc: linux-pm@...r.kernel.org, Conor Dooley <conor+dt@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Rob Herring <robh@...nel.org>, devicetree@...r.kernel.org, 
	Zhang Rui <rui.zhang@...el.com>, Daniel Lezcano <daniel.lezcano@...aro.org>, 
	"Rafael J. Wysocki" <rafael@...nel.org>, Laxman Dewangan <ldewangan@...dia.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] thermal: thermal-generic-adc: add temperature
 sensor channel

пн, 3 бер. 2025 р. о 12:53 Lukasz Luba <lukasz.luba@....com> пише:
>
>
>
> On 2/28/25 13:22, Svyatoslav Ryhel wrote:
> > пт, 28 лют. 2025 р. о 15:11 Lukasz Luba <lukasz.luba@....com> пише:
> >>
> >> Hi Svyatoslav,
> >>
> >> On 2/19/25 08:28, Svyatoslav Ryhel wrote:
> >>> Add IIO sensor channel along with existing thermal sensor cell. This
> >>> would benefit devices that use adc sensors to detect temperature and
> >>> need a custom conversion table.
> >>>
> >>> Signed-off-by: Svyatoslav Ryhel <clamor95@...il.com>
> >>> ---
> >>>    drivers/thermal/thermal-generic-adc.c | 54 ++++++++++++++++++++++++++-
> >>>    1 file changed, 53 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/thermal/thermal-generic-adc.c b/drivers/thermal/thermal-generic-adc.c
> >>> index ee3d0aa31406..a8f3b965b39b 100644
> >>> --- a/drivers/thermal/thermal-generic-adc.c
> >>> +++ b/drivers/thermal/thermal-generic-adc.c
> >>> @@ -7,6 +7,7 @@
> >>>     * Author: Laxman Dewangan <ldewangan@...dia.com>
> >>>     */
> >>>    #include <linux/iio/consumer.h>
> >>> +#include <linux/iio/iio.h>
> >>>    #include <linux/kernel.h>
> >>>    #include <linux/module.h>
> >>>    #include <linux/platform_device.h>
> >>> @@ -73,6 +74,57 @@ static const struct thermal_zone_device_ops gadc_thermal_ops = {
> >>>        .get_temp = gadc_thermal_get_temp,
> >>>    };
> >>>
> >>> +static const struct iio_chan_spec gadc_thermal_iio_channel[] = {
> >>> +     {
> >>> +             .type = IIO_TEMP,
> >>> +             .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> >>> +     }
> >>> +};
> >>> +
> >>> +static int gadc_thermal_read_raw(struct iio_dev *indio_dev,
> >>> +                              struct iio_chan_spec const *chan,
> >>> +                              int *temp, int *val2, long mask)
> >>> +{
> >>> +     struct gadc_thermal_info *gtinfo = iio_priv(indio_dev);
> >>> +     int ret;
> >>> +
> >>> +     if (mask != IIO_CHAN_INFO_PROCESSED)
> >>> +             return -EINVAL;
> >>> +
> >>> +     ret = gadc_thermal_get_temp(gtinfo->tz_dev, temp);
> >>> +     if (ret < 0)
> >>> +             return ret;
> >>> +
> >>> +     *temp /= 1000;
> >>> +
> >>> +     return IIO_VAL_INT;
> >>> +}
> >>> +
> >>> +static const struct iio_info gadc_thermal_iio_info = {
> >>> +     .read_raw = gadc_thermal_read_raw,
> >>> +};
> >>> +
> >>> +static int gadc_iio_register(struct device *dev, struct gadc_thermal_info *gti)
> >>> +{
> >>> +     struct gadc_thermal_info *gtinfo;
> >>> +     struct iio_dev *indio_dev;
> >>> +
> >>> +     indio_dev = devm_iio_device_alloc(dev, sizeof(struct gadc_thermal_info));
> >>> +     if (!indio_dev)
> >>> +             return -ENOMEM;
> >>> +
> >>> +     gtinfo = iio_priv(indio_dev);
> >>> +     memcpy(gtinfo, gti, sizeof(struct gadc_thermal_info));
> >>> +
> >>> +     indio_dev->name = dev_name(dev);
> >>> +     indio_dev->info = &gadc_thermal_iio_info;
> >>> +     indio_dev->modes = INDIO_DIRECT_MODE;
> >>> +     indio_dev->channels = gadc_thermal_iio_channel;
> >>> +     indio_dev->num_channels = ARRAY_SIZE(gadc_thermal_iio_channel);
> >>> +
> >>> +     return devm_iio_device_register(dev, indio_dev);
> >>
> >> I don't get the idea why we need iio device, while we already have the
> >> hwmon.
> >>
> >
> > Idea behind this is to be able to convert adc iio channel into temp
> > iio channel without introducing a new sensor which will duplicate
> > behavior of existing one (by this I mean conversion table use). Not
> > all devices can or have to use hwmon and some may require iio channel
> > hooked up.
> >
> > Real life example. I own a device (LG P985) which has a fuel gauge
> > that does not support battery thermal readings. Vendor provided a
> > dedicated adc sensor and one of its channels is used as thermal sensor
> > with device specific conversion table. Fuel gauge on the other hand
> > supports linking in a dedicated temp iio channel to get thermal
> > readings.
>
> Thanks. IMO you can add these two sentences into the patch header.
> It's telling more about the need of this change.
>

Sure, will do

> BTW, I would like to see later how you use it in your battery driver
> (please add me on CC, because I'm curious).
>

It is already present in the kernel. Here is the schema
https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/power/supply/maxim,max17040.yaml?h=v6.14-rc5

> The code looks good, so please resend with better patch header
> and I'll review the whole patch