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drivers: serial: Smartbond: add support DTR line wakeup

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This change allows to use DTR line driven from external serial port
that when active (low) will prevent UART device from going to sleep.
It will also wake up platform when DTR line becomes active.

DTR line is often activated in serial port connected to host computer
when operating system opens serial device like COMx for Windows
or /dev/ttyACMx /dev/ttyUSBx for Linux based systems.

DTR line (specified in device tree) will be used by WAKEUP and PDC
controllers (via GPIO driver) to handle DTR line changes.

Signed-off-by: Jerzy Kasenberg <jerzy.kasenberg@codecoup.pl>
This commit is contained in:
Jerzy Kasenberg 2023-08-22 15:27:20 +02:00 • committed by Anas Nashif
commit 961959fc5f
2 changed files with 51 additions and 0 deletions
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12
dts/bindings/serial/renesas,smartbond-uart.yaml
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@ -47,3 +47,15 @@ properties:
type: int
description: |
Time to prevent UART entering sleep mode after receiving data (ms)
dtr-gpios:
type: phandle-array
description: |
DTR pin specification. DTR pin when active tells that the driver that there
is active client on the other side of serial line.
The device driver does not use DTR for hardware flow control.
When device is connected to computer serial converter usually asserts DTR
line when serial port is opened and ready for communication.
This line can be used in Smartbond(tm) driver to detect remote client presence.
If client is not present the device can disable UART, allowing for
power system management to enter more efficient power levels.