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

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

quoted

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

quoted

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!

quoted

+       /*
+        * 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?

quoted

+        */

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

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

quoted

+       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.

quoted

+               "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":

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

quoted

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

So these seem correct too.

quoted

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

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

This is GPIO based.

quoted

+               "", "", "", "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.

Regards
ChenYu

quoted

+               "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