On 22.07.2016 17:47, Chen-Yu Tsai wrote:

On Fri, Jul 22, 2016 at 10:55 PM, Linus Walleij
[off-list ref] wrote:

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On Thu, Jul 14, 2016 at 1:47 PM, Oleksij Rempel [off-list ref] wrote:

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This names the GPIO lines on the Banana Pi board in accordance with
the A20_Banana_Pi v1.4 Specification.

This will make these line names reflect through to userspace
so that they can easily be identified and used with the new
character device ABI.

Some care has been taken to name all lines, not just those used
by the external connectors, also lines that are muxed into some
other function than GPIO: these are named "[FOO]" so that users
can see with lsgpio what all lines are used for.

Ps: most of the text was taken from Linux Wallej patch.

LinuS

oops... :)

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Cc: devicetree at vger.kernel.org
Cc: Linus Walleij <redacted>
Cc: linux-arm-kernel at lists.infradead.org
Cc: Chen-Yu Tsai <redacted>
Signed-off-by: Oleksij Rempel <redacted>

Nice usecase!

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+       /*
+        * Legend: proper name = the GPIO line is used as GPIO
+        *         NC = not connected (not routed from the SoC)
+        *         "[PER]" = pin is muxed for peripheral (not GPIO)
+        *         "" = no idea, schematic doesn't say, could be
+        *              unrouted (not connected to any external pin)
+        *         LSEC = Low Speed External Connector
+        *         HSEC = High Speed External Connector

I don't see LSEC/HSEC used anywhere?

ok, will remove it. Probably it will be better to have it in common
place some where by the Docs?

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+        */

So maybe we should make this naming convention a suggested
standard. People seem to like it.

Why should i invent some thing new, some Docs with suggested names will
be good.

One question about this whole thing: how extensively should we add
the names? Only for exposed pins? Or every pin that's routed/used?

Depends on HW. Even on production system i had cases where i need to
jump in and use some random pin for debugging. So, hawing it in
devicetree can help to reduce time later.

But i would prefer to have some kind of merged names: Names provided by
SoC descriptor (real pin names or locations) and names provided by board
design.

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+       gpio-line-names =
+               /* PA */
+               "[ERXD3]", "[ERXD2]", "[ERXD1]", "[ERXD0]", "[ETXD3]",
+                       "[ETXD2]", "[ETXD1]", "[ETXD0]",
+               "[ERXCK]", "[ERXERR]", "[ERXDV]", "[EMDC]", "[EMDIO]",
+                       "[ETXEN]", "[ETXCK]", "[ECRS]",
+               "[ECOL]", "[ETXERR]", "", "", "", "", "", "",
+               "", "", "", "", "", "", "", "",
+               /* PB */
+               "[PMU-SCK]", "[PMU-SDA]", "", "", "", "NC", "NC", "NC",
+               "NC", "[USB0-DRV]", "NC", "NC", "NC", "NC", "", "",
+               "", "", "", "", "SCL", "SDA", "", "",

Are these bit-banged SCL and SDA for doing I2C with
GPIO? Otherwise you probably want to name them "[SCL]" and "[SDA]"

There's an actual I2C controller backing them.

Ok, i will fix it.

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+               "TXD0", "RXD0", "IO-1", "PH3", "[USB0-IDDET]", "PH5", "", "",

Same here. You probably want "[TXD0]" etc unless you're bit-banging
the serial port. "IO-1" sounds like a real GPIO though and should
probably be named like that without [] and "PH3" what is that really?
A device-muxed pin or some kind of GPIO?

PH3 is actually the pin name. The vendor uses "IO-7" and "IO-8" as function
names for PH3 and PH5, but actually names them "NC":

Not in:
https://linux-sunxi.org/images/9/9d/A20_Bananapi_Schematic.pdf

which was used for this patch.

    http://www.bananapi.org/p/product.html

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+               "", "", "[SD0-DET]", "", "", "", "", "",
+               "NC", "", "", "", "IO-4", "IO-5", "NC", "[EMAC-PWR-EN]",

So these seem correct too.

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+               "[LED1]", "NC", "NC", "NC", "", "", "", "",

"LED1" seems like the right name, if this is a GPIO used to drive
a LED.

This is GPIO based.

This was not clear to me, marking GPIO pin as peripheral, at moment of
writing and testing it was a allocated by led driver. Bit for example
IO-GCLK was free to use for GPIO :).. so do [] actually make sense?

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+               "", "", "", "IO-GCLK", "NC", "NC", "NC", "NC",

WHat is IO-GCLK? A real GPIO line used for toggling a clock?
Or a hardware clock signal? In the first case it it correctly named,
in the other case it should be "[IO-GCLK]".

According to the schematics this is a PWM output.

there are two names:
SoC name: PWM1
Connector name: IO-GCLK

Which should be used. IMO it was user friendly to use connector name.

Regards
ChenYu

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+               "NC", "NC", "[SPI-CE0]", "[SPI-CLK]", "[SPI-MOSI]",
+                       "[SPI-MISO]", "[SPI-CE1]", "NC",
+               "IO-6", "IO-3", "IO-2", "IO-0", "", "", "", "",

Looks right.

Yours,
Linus Walleij