Add a new PIN_CONFIG_BIAS_BUS_HOLD pin configuration for a bus holder pin mode (also known as bus keeper, or repeater). This is a weak latch which drives the last value on a tristate bus. Another device on the bus can drive the bus high or low before going tristate to change the value driven by the pin.
Signed-off-by: James Hogan <[email protected]> Cc: Linus Walleij <[email protected]> --- Changes in v2: - add BIAS_BUS_HOLD generic pinconf (patch 5) drivers/pinctrl/pinconf-generic.c | 1 + include/linux/pinctrl/pinconf-generic.h | 6 ++++++ 2 files changed, 7 insertions(+) diff --git a/drivers/pinctrl/pinconf-generic.c b/drivers/pinctrl/pinconf-generic.c index 33a5392..ba465b3 100644 --- a/drivers/pinctrl/pinconf-generic.c +++ b/drivers/pinctrl/pinconf-generic.c @@ -37,6 +37,7 @@ struct pin_config_item { static struct pin_config_item conf_items[] = { PCONFDUMP(PIN_CONFIG_BIAS_DISABLE, "input bias disabled", NULL), PCONFDUMP(PIN_CONFIG_BIAS_HIGH_IMPEDANCE, "input bias high impedance", NULL), + PCONFDUMP(PIN_CONFIG_BIAS_BUS_HOLD, "input bias bus hold", NULL), PCONFDUMP(PIN_CONFIG_BIAS_PULL_UP, "input bias pull up", NULL), PCONFDUMP(PIN_CONFIG_BIAS_PULL_DOWN, "input bias pull down", NULL), PCONFDUMP(PIN_CONFIG_DRIVE_PUSH_PULL, "output drive push pull", NULL), diff --git a/include/linux/pinctrl/pinconf-generic.h b/include/linux/pinctrl/pinconf-generic.h index 6aa2380..ac05b3c 100644 --- a/include/linux/pinctrl/pinconf-generic.h +++ b/include/linux/pinctrl/pinconf-generic.h @@ -29,6 +29,11 @@ * if for example some other pin is going to drive the signal connected * to it for a while. Pins used for input are usually always high * impedance. + * @PIN_CONFIG_BIAS_BUS_HOLD: the pin will be set to weakly latch so that it + * weakly drives the last value on a tristate bus, also known as a "bus + * holder", "bus keeper" or "repeater". This allows another device on the + * bus to change the value by driving the bus high or low and switching to + * tristate. The argument is ignored. * @PIN_CONFIG_BIAS_PULL_UP: the pin will be pulled up (usually with high * impedance to VDD). If the argument is != 0 pull-up is enabled, * if it is 0, pull-up is disabled. @@ -78,6 +83,7 @@ enum pin_config_param { PIN_CONFIG_BIAS_DISABLE, PIN_CONFIG_BIAS_HIGH_IMPEDANCE, + PIN_CONFIG_BIAS_BUS_HOLD, PIN_CONFIG_BIAS_PULL_UP, PIN_CONFIG_BIAS_PULL_DOWN, PIN_CONFIG_DRIVE_PUSH_PULL, -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
