linux-kernel - [PATCH] serial: 8250: omap: set out-of-band wakeup if wakeup pinctrl exists

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Message-ID: <20251230-uart-wakeup-v1-1-13f1bb905f14@ti.com>
Date: Tue, 30 Dec 2025 15:24:51 -0600
From: Kendall Willis <k-willis@...com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Jiri Slaby
	<jirislaby@...nel.org>
CC: <d-gole@...com>, <vishalm@...com>, <sebin.francis@...com>,
	<msp@...libre.com>, <khilman@...libre.com>, <a-kaur@...com>,
	<s-kochidanadu@...com>, <linux-kernel@...r.kernel.org>,
	<linux-serial@...r.kernel.org>, Kendall Willis <k-willis@...com>
Subject: [PATCH] serial: 8250: omap: set out-of-band wakeup if wakeup
 pinctrl exists

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.

Signed-off-by: Kendall Willis <k-willis@...com>
---
Implementation
--------------
This patch is intended to be implemented along with the following
series. This patch has no dependencies on any of the other series:

1. "pmdomain: ti_sci: handle wakeup constraint for out-of-band wakeup":
   Skips setting constraints for wakeup sources that have out-of-band
   wakeup capability.
   https://github.com/kwillis01/linux/commits/v6.19/uart-daisy-chain/pmdomain

2. "serial: 8250: omap: set out-of-band wakeup if wakeup pinctrl exists"
   (this patch): Implements out-of-band wakeup from the UARTs for TI K3
   SoCs
   https://github.com/kwillis01/linux/tree/v6.19/uart-daisy-chain/uart-wakeup

3. "arm64: dts: ti: k3-am62: Support Main UART wakeup": Implements the
   functionality to wakeup the system from the Main UART
   https://github.com/kwillis01/linux/tree/b4/uart-daisy-chain-dts

Testing
-------
Tested on a AM62P SK EVM board with all series and dependencies
implemented. 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 series
using v6.19-rc1:
https://github.com/kwillis01/linux/tree/v6.19/uart-daisy-chain/all
---
 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: f8f9c1f4d0c7a64600e2ca312dec824a0bc2f1da
change-id: 20251230-uart-wakeup-00faeac7c994

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