In TI K3 SoCs, I/O daisy chaining is used to allow wakeup from UART when the
UART controller is off. Set UART device as wakeup capable using out-of-band
wakeup if the 'wakeup' pinctrl state exists and the device may wakeup.

Reviewed-by: Dhruva Gole <d-gole@ti.com>
Signed-off-by: Kendall Willis <k-willis@ti.com>
---
Testing
-------
Tested on a AM62P SK EVM board. Suspend/resume verified with the Main UART
wakeup source by entering a keypress on the console.

This github branch has all the necessary patches to test the patch
using Main UART as a wakeup source:
https://github.com/kwillis01/linux/tree/v6.19/uart-daisy-chain/all
---
Changes in v2:
- Remove extraneous information about patches that need to be
  implemented to allow Main UART wakeup on K3 TI SoCs.
- Link to v1: https://lore.kernel.org/r/20251230-uart-wakeup-v1-1-13f1bb905f14@ti.com
---
 drivers/tty/serial/8250/8250_omap.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index 9e49ef48b851bf6cd3b04a77a4d0d7b4e064dc5f..6a5722b722650c1710e79fb76fc1a01cdeccc68f 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -1363,6 +1363,8 @@ static int omap8250_select_wakeup_pinctrl(struct device *dev,
 	if (!device_may_wakeup(dev))
 		return 0;
 
+	device_set_out_band_wakeup(dev);
+
 	return pinctrl_select_state(priv->pinctrl, priv->pinctrl_wakeup);
 }
 

---
base-commit: 46fe65a2c28ecf5df1a7475aba1f08ccf4c0ac1b
change-id: 20251230-uart-wakeup-00faeac7c994

Best regards,
-- 
Kendall Willis <k-willis@ti.com>

Kendall Willis <k-willis@ti.com> writes:

> In TI K3 SoCs, I/O daisy chaining is used to allow wakeup from UART when the
> UART controller is off. Set UART device as wakeup capable using out-of-band
> wakeup if the 'wakeup' pinctrl state exists and the device may wakeup.
>
> Reviewed-by: Dhruva Gole <d-gole@ti.com>
> Signed-off-by: Kendall Willis <k-willis@ti.com>

Reviewed-by: Kevin Hilman <khilman@baylibre.com>