[RFC PATCH] pinctrl: pinmux: Introduce API to check if a pin is requested

[Prabhakar <prabhakar.csengg@xxxxxxxxx>]

From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>

Introduce `pin_requestesd` API to check if a pin is currently requested.
This API allows pinctrl drivers to verify whether a pin is requested or
not by checking if the pin is owned by either `gpio_owner` or `mux_owner`.

GPIO pins used as interrupts through the `interrupts` DT property do not
follow the usual `gpio_request`/`pin_request` path, unlike GPIO pins used
as interrupts via the `gpios` property. As a result, such pins were
reported as `UNCLAIMED` in the `pinmux-pins` sysfs file, even though they
were in use as interrupts.

With the newly introduced API, pinctrl drivers can check if a pin is
already requested by the pinctrl core and ensure that pin is requested
during when using as irq. This helps to ensure that the `pinmux-pins`
sysfs file reflects the correct status of the pin.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
---
 drivers/pinctrl/pinmux.c | 14 ++++++++++++++
 drivers/pinctrl/pinmux.h |  5 +++++
 2 files changed, 19 insertions(+)

diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
index 02033ea1c643..19c68e174c36 100644
--- a/drivers/pinctrl/pinmux.c
+++ b/drivers/pinctrl/pinmux.c
@@ -99,6 +99,20 @@ bool pinmux_can_be_used_for_gpio(struct pinctrl_dev *pctldev, unsigned int pin)
 	return !(ops->strict && !!desc->gpio_owner);
 }
 
+bool pin_requestesd(struct pinctrl_dev *pctldev, int pin)
+{
+	struct pin_desc *desc;
+
+	desc = pin_desc_get(pctldev, pin);
+	if (!desc)
+		return false;
+
+	if (!desc->gpio_owner && !desc->mux_owner)
+		return false;
+
+	return true;
+}
+
 /**
  * pin_request() - request a single pin to be muxed in, typically for GPIO
  * @pctldev: the associated pin controller device
diff --git a/drivers/pinctrl/pinmux.h b/drivers/pinctrl/pinmux.h
index 2965ec20b77f..550cb3b4c068 100644
--- a/drivers/pinctrl/pinmux.h
+++ b/drivers/pinctrl/pinmux.h
@@ -42,6 +42,7 @@ int pinmux_map_to_setting(const struct pinctrl_map *map,
 void pinmux_free_setting(const struct pinctrl_setting *setting);
 int pinmux_enable_setting(const struct pinctrl_setting *setting);
 void pinmux_disable_setting(const struct pinctrl_setting *setting);
+bool pin_requestesd(struct pinctrl_dev *pctldev, int pin);
 
 #else
 
@@ -100,6 +101,10 @@ static inline void pinmux_disable_setting(const struct pinctrl_setting *setting)
 {
 }
 
+bool pin_requestesd(struct pinctrl_dev *pctldev, int pin)
+{
+	return false;
+}
 #endif
 
 #if defined(CONFIG_PINMUX) && defined(CONFIG_DEBUG_FS)
-- 
2.43.0