From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mslow1.mail.gandi.net (mslow1.mail.gandi.net [217.70.178.240]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 041DE2C82 for ; Wed, 1 Dec 2021 10:43:28 +0000 (UTC) Received: from relay2-d.mail.gandi.net (unknown [217.70.183.194]) by mslow1.mail.gandi.net (Postfix) with ESMTP id DDF09D95D6 for ; Wed, 1 Dec 2021 10:42:27 +0000 (UTC) Received: (Authenticated sender: foss@0leil.net) by relay2-d.mail.gandi.net (Postfix) with ESMTPSA id D299E40005; Wed, 1 Dec 2021 10:42:17 +0000 (UTC) Date: Wed, 1 Dec 2021 11:42:15 +0100 From: Quentin Schulz To: Evgeny Boger Cc: linux-iio@vger.kernel.org, devicetree@vger.kernel.org, Jonathan Cameron , Lars-Peter Clausen , Chen-Yu Tsai , Jernej Skrabec , Maxime Ripard , linux-sunxi@lists.linux.dev Subject: Re: [PATCH 1/2] iio:adc:axp20x: add support for NTC thermistor Message-ID: <20211201104215.usstwfbvrv7pamqp@fiqs> References: <20211118141233.247907-1-boger@wirenboard.com> <20211118141233.247907-2-boger@wirenboard.com> Precedence: bulk X-Mailing-List: linux-sunxi@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211118141233.247907-2-boger@wirenboard.com> Hi Evgeny, On Thu, Nov 18, 2021 at 05:12:32PM +0300, Evgeny Boger wrote: > Most AXPxxx-based reference designs place a 10k NTC thermistor on a > TS pin. When appropriately configured, AXP PMICs will inject fixed > current (80uA by default) into TS pin and measure the voltage across a > thermistor. The PMIC itself will by default compare this voltage with > predefined thresholds and disable battery charging whenever They actually are configurable, we just don't have the knobs for this in the kernel. "In the diagram above, VTH/VTL refers to the high temperature threshold and low temperature threshold, which is programmable via registers REG38H/39H/3CH/3DH respectively. " in AXP209 datasheet, section "Battery temperature detection". > the battery is too hot or too cold. > > Alternatively, the TS pin can be configured as general-purpose > ADC input. This mode is not supported by the driver. > > This patch allows reading the voltage on the TS pin. It can be then > either processed by userspace or used by kernel consumer like hwmon > ntc thermistor driver. > > Signed-off-by: Evgeny Boger > --- > drivers/iio/adc/axp20x_adc.c | 45 +++++++++++++++++++++++++++++++----- > 1 file changed, 39 insertions(+), 6 deletions(-) > > diff --git a/drivers/iio/adc/axp20x_adc.c b/drivers/iio/adc/axp20x_adc.c > index 3e0c0233b431..12d469a52cea 100644 > --- a/drivers/iio/adc/axp20x_adc.c > +++ b/drivers/iio/adc/axp20x_adc.c [...] > +static int axp22x_adc_scale_voltage(int channel, int *val, int *val2) > +{ > + switch (channel) { > + case AXP22X_BATT_V: > + /* 1.1 mV per LSB */ > + *val = 1; > + *val2 = 100000; > + return IIO_VAL_INT_PLUS_MICRO; > + > + case AXP22X_TS_IN: > + /* 0.8 mV per LSB */ > + *val = 0; > + *val2 = 800000; > + return IIO_VAL_INT_PLUS_MICRO; > + > + default: > + return -EINVAL; > + } > +} > static int axp813_adc_scale_voltage(int channel, int *val, int *val2) > { > switch (channel) { [...] > @@ -378,12 +415,7 @@ static int axp22x_adc_scale(struct iio_chan_spec const *chan, int *val, > { > switch (chan->type) { > case IIO_VOLTAGE: > - if (chan->channel != AXP22X_BATT_V) > - return -EINVAL; > - > - *val = 1; > - *val2 = 100000; > - return IIO_VAL_INT_PLUS_MICRO; > + return axp22x_adc_scale_voltage(chan->channel, val, val2); > I would have personally split the move to a separate axp22x_adc_scale_voltage function in a separate commit. I was a bit confused at first why in the diff above there was a AXP22X_BATT_V addition since this commit is about AXP22X_TS_IN. If the maintainers are ok with it, I don't mind too much. I don't have the HW to test this, but changes look ok. Reviewed-by: Quentin Schulz Thanks! Quentin