Re: [PATCH v3 2/4] thermal: k3: Add support for bandgap sensors

[Keerthy]

On 19/02/20 1:20 pm, Randy Dunlap wrote:
> On 2/18/20 11:43 PM, Keerthy wrote:
> > The bandgap provides current and voltage reference for its internal
> > circuits and other analog IP blocks. The analog-to-digital
> > converter (ADC) produces an output value that is proportional
> > to the silicon temperature.
> >
> > Currently reading temperatures and trend computing is supported
> > as there are no active/passive cooling agent supported.
> >
> > Signed-off-by: Keerthy <j-keerthy@xxxxxx>
> > ---
> >   drivers/thermal/Kconfig      |  12 ++
> >   drivers/thermal/Makefile     |   1 +
> >   drivers/thermal/k3_bandgap.c | 342 +++++++++++++++++++++++++++++++++++
> >   3 files changed, 355 insertions(+)
> >   create mode 100644 drivers/thermal/k3_bandgap.c
> >
> > diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> > index 5a05db5438d6..fa598eddc7ac 100644
> > --- a/drivers/thermal/Kconfig
> > +++ b/drivers/thermal/Kconfig
> > @@ -251,6 +251,18 @@ config IMX_THERMAL
> >   	  cpufreq is used as the cooling device to throttle CPUs when the
> >   	  passive trip is crossed.
> >   
> > +config K3_THERMAL
> > +	bool "Texas Instruments K3 thermal support"
>
> Hi,
> Why is this bool and not tristate?

Definitely can work as tristate. I will fix it next version.

> > +	depends on THERMAL
> > +	depends on ARCH_K3 || COMPILE_TEST
> > +	help
> > +	  If you say yes here you get thermal support for the Texas Instruments
> > +	  K3 SoC family. The current chip supported is:
> > +	   - AM654
> > +
> > +	  This includes temperature reading functionality and also trend
> > +	  computation.
> > +
> >   config MAX77620_THERMAL
> >   	tristate "Temperature sensor driver for Maxim MAX77620 PMIC"
> >   	depends on MFD_MAX77620
>
> > diff --git a/drivers/thermal/k3_bandgap.c b/drivers/thermal/k3_bandgap.c
> > new file mode 100644
> > index 000000000000..35d904eb9857
> > --- /dev/null
> > +++ b/drivers/thermal/k3_bandgap.c
> > @@ -0,0 +1,342 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * TI Bandgap temperature sensor driver for K3 SoC Family
> > + *
> > + * Copyright (C) 2020 Texas Instruments Incorporated - http://www.ti.com/
> > + */
>
> > +static int k3_bgp_read_temp(struct k3_thermal_data *devdata,
> > +			    int *temp)
> > +{
> > +	struct k3_bandgap *bgp;
> > +	unsigned int dtemp, s0, s1, s2;
> > +
> > +	bgp = devdata->bgp;
> > +	/**
>
> "/**" is used to indicate kernel-doc notation in the Linux kernel source files,
> but this comment is not kernel-doc notation, so please just use "/*".

Okay

> > +	 * Errata is applicable for am654 pg 1.0 silicon. There
> > +	 * is a variation of the order for 8-10 degree centigrade.
> > +	 * Work around that by getting the average of two closest
> > +	 * readings out of three readings everytime we want to
> > +	 * report temperatures.
> > +	 *
> > +	 * Errata workaround.
> > +	 */
> thanks.

Thanks for the review.

- Keerthy
>