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Message-ID: <CAL_JsqKEXtL0hvEgFALKaCgW2Go==wj14_dDomdK_hPU23oXLQ@mail.gmail.com>
Date: Tue, 30 Jan 2018 08:41:25 -0600
From: Rob Herring <robh@...nel.org>
To: Denis OSTERLAND <denis.osterland@...hl.com>
Cc: "m.grzeschik@...gutronix.de" <m.grzeschik@...gutronix.de>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux@...ck-us.net" <linux@...ck-us.net>,
"a.zummo@...ertech.it" <a.zummo@...ertech.it>,
"jdelvare@...e.com" <jdelvare@...e.com>,
"alexandre.belloni@...e-electrons.com"
<alexandre.belloni@...e-electrons.com>,
"linux-rtc@...r.kernel.org" <linux-rtc@...r.kernel.org>,
"kernel@...gutronix.de" <kernel@...gutronix.de>
Subject: Re: [PATCH 4/4] rtc: isl1208: add support for isl1219 with hwmon for
tamper detection
On Tue, Jan 30, 2018 at 2:56 AM, Denis OSTERLAND
<denis.osterland@...hl.com> wrote:
> Am Montag, den 29.01.2018, 17:41 -0600 schrieb Rob Herring:
>> On Tue, Jan 23, 2018 at 01:18:01PM +0100, Michael Grzeschik wrote:
>> >
>> > We add support for the ISL1219 chip that got an integrated tamper
>> > detection function. This patch implements the feature by using an hwmon
>> > interface.
>> >
>> > The ISL1219 can also describe the timestamp of the intrusion
>> > event. For this we add the documentation of the new interface
>> > intrusion[0-*]_timestamp.
>> >
>> > The devicetree documentation for the ISL1219 device tree
>> > binding is added with an short example.
>> >
>> > Signed-off-by: Michael Grzeschik <m.grzeschik@...gutronix.de>
>> > Signed-off-by: Denis Osterland <Denis.Osterland@...hl.com>
>> > ---
>> > .../rtc/{intersil,isl1208.txt => isil,isl1208.txt} | 18 +-
>> > Documentation/hwmon/sysfs-interface | 7 +
>> > drivers/rtc/rtc-isl1208.c | 190 +++++++++++++++++++--
>> > 3 files changed, 201 insertions(+), 14 deletions(-)
>> > rename Documentation/devicetree/bindings/rtc/{intersil,isl1208.txt => isil,isl1208.txt} (57%)
>> >
>> > diff --git a/Documentation/devicetree/bindings/rtc/intersil,isl1208.txt b/Documentation/devicetree/bindings/rtc/isil,isl1208.txt
>> > similarity index 57%
>> > rename from Documentation/devicetree/bindings/rtc/intersil,isl1208.txt
>> > rename to Documentation/devicetree/bindings/rtc/isil,isl1208.txt
>> > index a54e99feae1ca..d549699e1cfc4 100644
>> > --- a/Documentation/devicetree/bindings/rtc/intersil,isl1208.txt
>> > +++ b/Documentation/devicetree/bindings/rtc/isil,isl1208.txt
>> > @@ -1,14 +1,21 @@
>> > -Intersil ISL1208, ISL1218 I2C RTC/Alarm chip
>> > +Intersil ISL1208, ISL1218, ISL1219 I2C RTC/Alarm chip
>> >
>> > ISL1208 is a trivial I2C device (it has simple device tree bindings,
>> > consisting of a compatible field, an address and possibly an interrupt
>> > line).
>> >
>> > +ISL1219 supports tamper detection user space representation through
>> > +case intrusion hwmon sensor.
>> User space and hwmon are Linux details not relevant to the binding. Just
>> describe the h/w.
> OK.
>>
>> >
>> > +ISL1219 has additional pins EVIN and #EVDET for tamper detection.
>> > +I2C devices support only one irq. #IRQ and #EVDET are open-drain active low,
>> > +so it is possible layout them to one SoC pin with pull-up.
>> > +
>> > Required properties supported by the device:
>> >
>> > - "compatible": must be one of
>> > "isil,isl1208"
>> > "isil,isl1218"
>> > + "isil,isl1219"
>> > - "reg": I2C bus address of the device
>> >
>> > Optional properties:
>> > @@ -33,3 +40,12 @@ Example isl1208 node with #IRQ pin connected to SoC gpio1 pin 12:
>> > interrupt-parent = <&gpio1>;
>> > interrupts = <12 IRQ_TYPE_EDGE_FALLING>;
>> > };
>> > +
>> > +Example isl1219 node with #IRQ pin and #EVDET pin connected to SoC gpio1 pin 12:
>> > +
>> > + isl1219: isl1219@68 {
>> > + compatible = "intersil,isl1219";
>> > + reg = <0x68>;
>> > + interrupts-extended = <&gpio1 12 IRQ_TYPE_EDGE_FALLING>;
>> With 2 interrupts, you should have 2 values. If they are connected
>> together, just repeat the connection. Otherwise, you can't tell if EVDET
>> is a no connect.
> If I got you right, you suggest an additional IRQ entry to parse.
Yes.
> A short example, #IRQ pin connected to gpio1 pin 12 and
> #EVDET pin connected to gpio2 pin 24:
>
> isl1219: rtc@68 {
> compatible = "intersil,isl1219";
> reg = <0x68>;
> interrupt-names = "irq", "evdet";
> interrupts-extended = <&gpio1 12 IRQ_TYPE_EDGE_FALLING>,
> <&gpio2 24 IRQ_TYPE_EDGE_FALLING>;
> };
>
> In driver implementation we need only one interrupt, because we can
> determinate action to take based on value of status register.
That's fine. The binding describes the hardware. Drivers can support
as much or as little as they like.
> In current implementation there was no need to do some additional
> OF parsing, everything is done by I2C generic code.
> I guess, it is not much additional work to do so, but I am not sure
> if it´s worthwhile.
If you don't care about the 2nd interrupt, I don't think you'd have to
change anything.
>>
>> There's not much point in having an example for every compatible. This
>> binding is simple enough, one should be enough.
> Shell we remove the example without an interrupt?
The existing example has a single interrupt, right? That should be
enough. You just need to document for the interrupts property which
devices have 2 interrupts and what the order is.
Rob
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