linux-kernel - Re: [PATCH v5 00/10] ASPEED sgpio driver enhancement.

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Date:   Thu, 10 Jun 2021 16:39:32 +0800
From:   Steven Lee <steven_lee@...eedtech.com>
To:     Linus Walleij <linus.walleij@...aro.org>
CC:     Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Rob Herring <robh+dt@...nel.org>,
        Joel Stanley <joel@....id.au>,
        Andrew Jeffery <andrew@...id.au>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "moderated list:ARM/ASPEED MACHINE SUPPORT" 
        <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:ARM/ASPEED MACHINE SUPPORT" 
        <linux-aspeed@...ts.ozlabs.org>,
        open list <linux-kernel@...r.kernel.org>,
        Hongwei Zhang <Hongweiz@....com>,
        Ryan Chen <ryan_chen@...eedtech.com>,
        Billy Tsai <billy_tsai@...eedtech.com>
Subject: Re: [PATCH v5 00/10] ASPEED sgpio driver enhancement.

The 06/10/2021 15:50, Linus Walleij wrote:
> On Thu, Jun 10, 2021 at 4:24 AM Steven Lee <steven_lee@...eedtech.com> wrote:
> 
> > Per the comment in the following mail
> > https://lkml.org/lkml/2021/6/9/317
> >
> > I was wondering if I should prepare v6 for the currnet solution or
> > I should drop this patch series then prepare another patch for the
> > new solution(piar GPIO input/output) which breaks userspace but is
> > better than the current solution.
> 
> I would say just go ahead with the new solution. AFAIK Aspeed
> has pretty tight control over what kind of userspace run on these
> systems.
> 
> BTW please influence Aspeed to use the GPIO character device
> and ligpiod
> https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git/
> if you are doing any kind of userspace GPIO control (which I
> suspect that you do).
> 

We currently use gpioset and gpioget that provided by libgpiod to test
aspeed gpio and sgpio drivers.

For the current solution on AST2600,
the valid range of input pins  is 0 ~ 127,
the valid range of output pins is 128 ~ 255.
So we access input pins by the following command

```
gpioget $chipId 0 1 2 3 4 ... 127
```

and access output pins by the following command

```
gpioset $chipId 128=1 129=0 130=1 131=1 ... 255=1

```


The new solution will change the gpio id order as follows
Input:
```
gpioget $chipId 0 2 4 6 8 ... 254

```

Output:

```
gpioset $chipId 1=1 3=0 5=1 7=1 ... 255=1

```

Thanks,
Steven

> Yours,
> Linus Walleij