[PATCH 3/4] bcm2835-gpio-exp: Driver for GPIO expander via mailbox service

[Stefan Wahren]

Hi Baruch,

> Baruch Siach <baruch at tkos.co.il> hat am 9. Januar 2018 um 14:41 geschrieben:
> 
> 
> Hi Stefan,
> 
> On Tue, Jan 02, 2018 at 07:49:44PM +0100, Stefan Wahren wrote:
> 
> [...]
> 
> > > +	ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_GET_GPIO_CONFIG,
> > > +				    &get, sizeof(get));
> > > +	if (ret) {
> > > +		dev_err(gpio->dev,
> > > +			"Failed to get GPIO %u config (%d)\n", off, ret);
> > > +		return ret;
> > > +	}
> > 
> > Shouldn't we also check the in-bound status at get.gpio?
> 
> What is the in-bound status value? May you refer me to the documentation?

unfortunately this mailbox property isn't documented here [1]. So please refer to Phil's explanation [2].

I assume gpio_get_config.gpio of the response would be 0x80000000 in case of an invalid request. But i didn't test it yet.

This was my solution [3] for the RPI_FIRMWARE_GET_CUSTOMER_OTP. But it hadn't been reviewed yet.

Stefan

[1] - https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface
[2] - http://lists.infradead.org/pipermail/linux-rpi-kernel/2018-January/007237.html
[3] - https://github.com/lategoodbye/rpi-zero/blob/bcm2835-otp/drivers/nvmem/raspberrypi-otp.c#L61

> 
> > And in all the other gpio ops?
> 
> Thanks,
> baruch
> 
> -- 
>      http://baruch.siach.name/blog/                  ~. .~   Tk Open Systems
> =}------------------------------------------------ooO--U--Ooo------------{=
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