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Message-ID: <CAL_JsqJgoWBmx8-Gcabo_d8R7wqS1pPAu1wauAqq8JRrWMFq3A@mail.gmail.com> Date: Thu, 26 Jan 2023 07:38:47 -0600 From: Rob Herring <robh@...nel.org> To: "Hawkins, Nick" <nick.hawkins@....com> Cc: "Verdun, Jean-Marie" <verdun@....com>, "krzysztof.kozlowski+dt@...aro.org" <krzysztof.kozlowski+dt@...aro.org>, "linux@...linux.org.uk" <linux@...linux.org.uk>, "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>, "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, "joel@....id.au" <joel@....id.au> Subject: Re: [PATCH v4 2/5] dt-bindings: i2c: Add hpe,gxp-i2c On Wed, Jan 25, 2023 at 3:32 PM Hawkins, Nick <nick.hawkins@....com> wrote: > > > > + hpe,sysreg: > > > + $ref: /schemas/types.yaml#/definitions/phandle > > > + description: > > > + Phandle to the global status and enable interrupt registers shared > > > + between each I2C engine controller instance. It enables the I2C > > > + engine controller to act as both a master or slave by being able to > > > + arm and respond to interrupts from its engine. Each bit in the > > > + registers represent the respective bit position. > > > > Each bit represents the bit position? > > Yes what I mean here is that bit 0 represents engine 0, bit 1 represents > engine 1 and so on. I will reword this how you have below. > > > AIUI, each I2C instance has a bit in it needs to control. How does the > > driver know what instance (and therefore the correct bit)? Typically you > > would have a 2nd cell here with that information. > > We are currently using the memory area designated reg to determine > which engine we are on. > > Here is a snippet from patch 1 of this patchset that introduces the driver: > /* Use physical memory address to determine which I2C engine this is. */ > + drvdata->engine = ((u32)drvdata->base & 0xf00) >> 8; > > This works because each engine is 0x100 apart. Ah, that works fine then. Reviewed-by: Rob Herring <robh@...nel.org>
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