On Tue, May 03, 2016 at 12:24:10AM +0200, Linus Walleij wrote: > Make it possible to name the producer side of a GPIO line using > a "gpio-line-names" property array, modeled on the > "clock-output-names" property from the clock bindings. > > This naming is especially useful for: > > - Debugging: lines are named after function, not just opaque > offset numbers. > > - Exploration: systems where some or all GPIO lines are available > to end users, such as prototyping, one-off's "makerspace usecases" > users are helped by the names of the GPIO lines when tinkering. > This usecase has been surfacing recently. > > The gpio-line-names attribute is completely optional. > > Example output from lsgpio on a patched Snowball tree: > > GPIO chip: gpiochip6, "8000e180.gpio", 32 GPIO lines > line 0: unnamed unused > line 1: "AP_GPIO161" "extkb3" [kernel] > line 2: "AP_GPIO162" "extkb4" [kernel] > line 3: "ACCELEROMETER_INT1_RDY" unused [kernel] > line 4: "ACCELEROMETER_INT2" unused > line 5: "MAG_DRDY" unused [kernel] > line 6: "GYRO_DRDY" unused [kernel] > line 7: "RSTn_MLC" unused > line 8: "RSTn_SLC" unused > line 9: "GYRO_INT" unused > line 10: "UART_WAKE" unused > line 11: "GBF_RESET" unused > line 12: unnamed unused > > Cc: Rob Herring <robh+dt@xxxxxxxxxx> > Cc: Grant Likely <grant.likely@xxxxxxxxxx> > Cc: Amit Kucheria <amit.kucheria@xxxxxxxxxx> > Cc: David Mandala <david.mandala@xxxxxxxxxx> > Cc: Lee Campbell <leecam@xxxxxxxxxx> > Cc: devicetree@xxxxxxxxxxxxxxx > Reviewed-by: Michael Welling <mwelling@xxxxxxxx> > Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx> > --- > ChangeLog v3->v4: > - Do not use the bool accessor to see if a line is there, use > the return value from counting the strings to bail out if > <= 0. > - Augment the naming loop to be smarter. > ChangeLog v2->v3: > - Swap "gpio-names" for "gpio-line-names" as "gpio-names" indicate > a consumer endpoint in DT terminology. > - Index to either: > (A) The end of the gpio-names array or > (B) ngpios > So we don't risk going out of bounds on either > ChangeLog v1->v2: > - Make the naming function return void: we continue at all times > and always return 0 anyway. > - Fix a return value check. > > This has been discussed at some length now. > > Why we are not using hogs: these are consumer side, not producer > side. The gpio-controller in DT (gpio_chip in Linux) is a > producer, not a consumer. > > This patch is not about assigning initial values to GPIO lines. > That is an orthogonal usecase. This is just about naming lines. > --- > Documentation/devicetree/bindings/gpio/gpio.txt | 19 ++++++++++ Acked-by: Rob Herring <robh@xxxxxxxxxx> > drivers/gpio/gpiolib-of.c | 49 +++++++++++++++++++++++++ > 2 files changed, 68 insertions(+) -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
