On 03/22/2016 10:57 AM, Linus Walleij wrote:
Some GPIO controllers has a special hardware bit we can flip
to support open drain / source. This means that on these hardwares
we do not need to emulate OD/OS by setting the line to input
instead of actively driving it high/low. Add an optional vtable
callback to the driver set_single_ended() so that driver can
implement this in hardware if they have it.
We may need a pinctrl_gpio_set_config() call at some point to
propagate this down to a backing pin control device on systems
with split GPIO/pin control.
Reported-by: Michael Hennerich <michael.hennerich@xxxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
Michael, please have a look at this and consider testing it with
your hardware and adding a .set_single_ended() callback in your
driver to see if it does what you want. I'm ready to merge this
if at least one driver make use of it.
Hi Linus,
I think the patch looks good.
Unfortunately it only applies against your gpio/for-next branch.
for some reason on that 4.5 kernel the SDHCI interface on my test board
doesn't work any more.
So I can't really fully test it at the moment.
diff --git a/drivers/iio/dac/ad5592r-base.c b/drivers/iio/dac/ad5592r-base.c
index 4019e44..efb7442 100644
--- a/drivers/iio/dac/ad5592r-base.c
+++ b/drivers/iio/dac/ad5592r-base.c
@@ -127,6 +127,38 @@ static int ad5592r_gpio_request(struct gpio_chip
*chip, unsigned offset)
return 0;
}
+static int ad5592r_gpio_set_single_ended(struct gpio_chip *chip,
+ unsigned offset,
+ enum single_ended_mode mode)
+{
+ struct ad5592r_state *st = gpiochip_get_data(chip);
+ int ret = 0;
+
+ mutex_lock(&st->gpio_lock);
+
+ switch (mode) {
+ case LINE_MODE_PUSH_PULL:
+ st->gpio_opendrain &= ~BIT(offset);
+ break;
+
+ case LINE_MODE_OPEN_DRAIN:
+ st->gpio_opendrain |= BIT(offset);
+ break;
+
+ case LINE_MODE_OPEN_SOURCE:
+ default:
+ ret = -ENOTSUPP;
+ }
+
+ mutex_unlock(&st->gpio_lock);
+
+ if (ret)
+ return ret;
+
+ return st->ops->reg_write(st, AD5592R_REG_OPEN_DRAIN,
+ st->gpio_opendrain);
+}
+
static int ad5592r_gpio_init(struct ad5592r_state *st)
{
if (!st->gpio_map)
@@ -139,6 +171,7 @@ static int ad5592r_gpio_init(struct ad5592r_state *st)
st->gpiochip.can_sleep = true;
st->gpiochip.direction_input = ad5592r_gpio_direction_input;
st->gpiochip.direction_output = ad5592r_gpio_direction_output;
+ st->gpiochip.set_single_ended = ad5592r_gpio_set_single_ended;
st->gpiochip.get = ad5592r_gpio_get;
st->gpiochip.set = ad5592r_gpio_set;
st->gpiochip.request = ad5592r_gpio_request;
diff --git a/drivers/iio/dac/ad5592r-base.h b/drivers/iio/dac/ad5592r-base.h
index 2753385..09d545b 100644
--- a/drivers/iio/dac/ad5592r-base.h
+++ b/drivers/iio/dac/ad5592r-base.h
@@ -66,6 +66,7 @@ struct ad5592r_state {
u8 gpio_out;
u8 gpio_in;
u8 gpio_val;
+ u8 gpio_opendrain;
__be16 spi_msg ____cacheline_aligned;
__be16 spi_msg_nop;
--
Greetings,
Michael
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