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From: Linus Walleij <linus.walleij@linaro.org>
To: Andrew Jeffery <andrew@aj.id.au>
Cc: Hongwei Zhang <hongweiz@ami.com>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	Joel Stanley <joel@jms.id.au>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
	linux-aspeed <linux-aspeed@lists.ozlabs.org>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [v5 1/2] dt-bindings: gpio: aspeed: Add SGPIO support
Date: Mon, 29 Jul 2019 23:57:16 +0200	[thread overview]
Message-ID: <CACRpkdZcLNe+oM1jWPpva0LECc-P48ab3H-kG7eabMmSvmvioA@mail.gmail.com> (raw)
In-Reply-To: <f2875111-9ba9-43b7-b2a4-d00c8725f5a0@www.fastmail.com>

On Mon, Jul 29, 2019 at 2:19 AM Andrew Jeffery <andrew@aj.id.au> wrote:

> The behaviour is to periodically emit the state of all enabled GPIOs
> (i.e. the ngpios value), one per bus clock cycle. There's no explicit
> addressing scheme, the protocol encodes the value for a given GPIO
> by its position in the data stream relative to a pulse on the "load data"
> (LD) line, whose envelope covers the clock cycle for the last GPIO in
> the sequence. Similar to SPI the bus has both out and in lines, which
> cater to output/input GPIOs.
>
> A rough timing diagram for a 16-GPIO configuration looks like what
> I've pasted here:
>
> https://gist.github.com/amboar/c9543af1957854474b8c05ab357f0675

OK that is complex. I agree we need to keep this driver together.

Yours,
Linus Walleij

WARNING: multiple messages have this Message-ID (diff)
From: Linus Walleij <linus.walleij@linaro.org>
To: Andrew Jeffery <andrew@aj.id.au>
Cc: Mark Rutland <mark.rutland@arm.com>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
	<devicetree@vger.kernel.org>,
	linux-aspeed <linux-aspeed@lists.ozlabs.org>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	Rob Herring <robh+dt@kernel.org>, Joel Stanley <joel@jms.id.au>,
	Hongwei Zhang <hongweiz@ami.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [v5 1/2] dt-bindings: gpio: aspeed: Add SGPIO support
Date: Mon, 29 Jul 2019 23:57:16 +0200	[thread overview]
Message-ID: <CACRpkdZcLNe+oM1jWPpva0LECc-P48ab3H-kG7eabMmSvmvioA@mail.gmail.com> (raw)
In-Reply-To: <f2875111-9ba9-43b7-b2a4-d00c8725f5a0@www.fastmail.com>

On Mon, Jul 29, 2019 at 2:19 AM Andrew Jeffery <andrew@aj.id.au> wrote:

> The behaviour is to periodically emit the state of all enabled GPIOs
> (i.e. the ngpios value), one per bus clock cycle. There's no explicit
> addressing scheme, the protocol encodes the value for a given GPIO
> by its position in the data stream relative to a pulse on the "load data"
> (LD) line, whose envelope covers the clock cycle for the last GPIO in
> the sequence. Similar to SPI the bus has both out and in lines, which
> cater to output/input GPIOs.
>
> A rough timing diagram for a 16-GPIO configuration looks like what
> I've pasted here:
>
> https://gist.github.com/amboar/c9543af1957854474b8c05ab357f0675

OK that is complex. I agree we need to keep this driver together.

Yours,
Linus Walleij

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2019-07-29 21:57 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-19 19:24 [v5 0/2] gpio: aspeed: Add SGPIO driver Hongwei Zhang
2019-07-19 19:24 ` Hongwei Zhang
2019-07-19 19:24 ` Hongwei Zhang
2019-07-19 19:24 ` [v5 1/2] dt-bindings: gpio: aspeed: Add SGPIO support Hongwei Zhang
2019-07-19 19:24   ` Hongwei Zhang
2019-07-19 19:24   ` Hongwei Zhang
2019-07-20  8:12   ` Linus Walleij
2019-07-20  8:12     ` Linus Walleij
2019-07-20  8:12     ` Linus Walleij
2019-07-22  1:42     ` Andrew Jeffery
2019-07-22  1:42       ` Andrew Jeffery
2019-07-22  1:42       ` Andrew Jeffery
2019-07-28 23:34       ` Linus Walleij
2019-07-28 23:34         ` Linus Walleij
2019-07-28 23:34         ` Linus Walleij
2019-07-29  0:19         ` Andrew Jeffery
2019-07-29  0:19           ` Andrew Jeffery
2019-07-29  0:19           ` Andrew Jeffery
2019-07-29 21:57           ` Linus Walleij [this message]
2019-07-29 21:57             ` Linus Walleij
2019-07-29 21:57             ` Linus Walleij
2019-07-30 19:25   ` Hongwei Zhang
2019-07-30 19:25     ` Hongwei Zhang
2019-07-30 19:25     ` Hongwei Zhang
2019-07-19 19:24 ` [v5 2/2] gpio: aspeed: Add SGPIO driver Hongwei Zhang
2019-07-19 19:24   ` Hongwei Zhang
2019-07-20  7:36   ` Linus Walleij
2019-07-20  7:36     ` Linus Walleij
2019-07-22 20:36   ` Hongwei Zhang
2019-07-22 20:36     ` Hongwei Zhang
2019-07-28 23:37     ` Linus Walleij
2019-07-28 23:37       ` Linus Walleij
2019-07-29 20:29   ` [v6 " Hongwei Zhang
2019-07-29 20:29     ` Hongwei Zhang
2019-07-29 20:29     ` Hongwei Zhang
2019-07-29 20:43   ` Hongwei Zhang
2019-07-29 20:43     ` Hongwei Zhang
2019-07-29 20:43     ` Hongwei Zhang
2019-07-29 20:56   ` [v5 " Hongwei Zhang
2019-07-29 20:56     ` Hongwei Zhang
2019-07-29 20:56     ` Hongwei Zhang

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