Re: [RFC/PATCH 1/2] dt-binding: mfd: Add Maxim/Dallas DS1374 MFD device binding

From: Rob Herring
Date: Fri May 12 2017 - 20:00:44 EST


On Tue, May 09, 2017 at 11:20:20AM -0700, Moritz Fischer wrote:
> This adds a binding for the Maxim/Dallas DS1374 MFD.
>
> Signed-off-by: Moritz Fischer <mdf@xxxxxxxxxx>
> ---
>
> Hi all,
>
> I'm not entirely sure aobut the binding, does anyone
> have a better suggestion for the remap-wdt-reset property?
>
> Thanks,
>
> Moritz
>
> ---
> Documentation/devicetree/bindings/mfd/ds1374.txt | 63 ++++++++++++++++++++++
> .../devicetree/bindings/trivial-devices.txt | 1 -
> drivers/rtc/Kconfig | 2 +
> 3 files changed, 65 insertions(+), 1 deletion(-)
> create mode 100644 Documentation/devicetree/bindings/mfd/ds1374.txt
>
> diff --git a/Documentation/devicetree/bindings/mfd/ds1374.txt b/Documentation/devicetree/bindings/mfd/ds1374.txt
> new file mode 100644
> index 0000000..b22396f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mfd/ds1374.txt
> @@ -0,0 +1,63 @@
> +* Device tree bindings for Maxim/Dallas DS1374 Multi Function Device (MFD)
> +
> +The Maxim/Dallas DS1374 is a multi function device that combines rtc,
> +watchdog or alarm, as well as trickle charger.
> +
> +The DS1374 is connected via I2C.
> +
> +Required properties:
> +- compatible: "dallas,ds1374"
> +- reg: I2C slave address
> +- dallas,ds1374-mode: Should be one of the following values:

Just "dallas,mode" is sufficient.

> + <0> for RTC
> + <1> for RTC + Alarm (Interrupt)
> + <2> for RTC + Watchdog
> +
> +Required child:
> +A single available child device of type matching the "dallas,ds1374-mode"
> +property.
> +
> +Optional properties (watchdog):
> +- dallas,ds1374-remap-wdt-reset: Boolean describing whether the INT pin
> + on the device is used as interrupt for
> + the alarm

Isn't presence of the interrupt property or not enough? It would be
kind of useless to have no interrupt and also not do anything on
timeout.

> +
> +See ../watchdog/* for generic watchdog bindings.
> +
> +Optional properties (real time clock):
> +- interrupt: phandle to interrupt cell for the rtc's alarm feature
> +
> +See ../rtc/* for generic rtc bindings.
> +
> +Optional properties (trickle-charger):
> +- dallas,trickle-resistor-ohms : Selected resistor for trickle charger
> + Values usable for ds1374 are 250, 2000, 4000
> + Should be given if trickle charger should be enabled
> +- dallas,trickle-diode-disable : Do not use internal trickle charger diode
> + Should be given if internal trickle charger diode should be disabled
> +
> +Example for rtc with alarm mode and interrupt:
> +
> +i2c@12ca0000 {
> + rtc@68 {
> + compatible = "ds1374";
> + reg = <0x68>;
> + interrupts = <&gpio0 62>;
> + dallas,ds1374-mode = <2>
> +
> + dallas,trickle-resistor-ohms = <250>;
> + dallas,trickle-diode-disable;
> + };
> +};
> +
> +Example for rtc with watchdog and reset on timeout, with reset remapped
> +to the INT pin:
> +
> +i2c@12ca0000 {
> + rtc@68 {
> + compatible = "ds1374";
> + reg = <0x68>;
> + dallas,ds1374-mode = <2>
> + dallas,ds1374-remap-wdt-reset;
> + };
> +};
> diff --git a/Documentation/devicetree/bindings/trivial-devices.txt b/Documentation/devicetree/bindings/trivial-devices.txt
> index 3e0a34c..f7a50e5 100644
> --- a/Documentation/devicetree/bindings/trivial-devices.txt
> +++ b/Documentation/devicetree/bindings/trivial-devices.txt
> @@ -29,7 +29,6 @@ cirrus,cs42l51 Cirrus Logic CS42L51 audio codec
> dallas,ds1307 64 x 8, Serial, I2C Real-Time Clock
> dallas,ds1338 I2C RTC with 56-Byte NV RAM
> dallas,ds1340 I2C RTC with Trickle Charger
> -dallas,ds1374 I2C, 32-Bit Binary Counter Watchdog RTC with Trickle Charger and Reset Input/Output
> dallas,ds1631 High-Precision Digital Thermometer
> dallas,ds1682 Total-Elapsed-Time Recorder with Alarm
> dallas,ds1775 Tiny Digital Thermometer and Thermostat
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 8d3b957..e6763fe 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -250,6 +250,8 @@ config RTC_DRV_DS1307_CENTURY
>
> config RTC_DRV_DS1374
> tristate "Dallas/Maxim DS1374"
> + depends on MFD_DS1374
> + depends on REGMAP_I2C
> help
> If you say yes here you get support for Dallas Semiconductor
> DS1374 real-time clock chips. If an interrupt is associated
> --
> 2.7.4
>