Thanks for all the great feedback. I have incorporated a lot of it, though not all ... partly because there was not yet unanimity on some issues. Big changes: - children of a uart are no longer automatically managed. The driver for the child device must register with the tty after which it will be told when the tty is opened or closed. The driver can then do whatever it likes, which may involve powering the device on. - I am now only providing a single drivers: serial-power-manager. It can be used for devices which only want power management. Currently it can provide this using a regulator and/or a toggle GPIO. This one driver supports both of my devices. non-changes: - The interface functionality is still provided by the 'tty' layer, not the 'serial' layer. I have no strong feelings on this and doubt that I would have until some other user appeared for this functionality. That would help show if the current arrangement was helpful or inconvenient. - We still treat any child node of a tty device which has a 'compatible' field gets allocated a device. If there is no platform driver which supports that 'compatible' value, then the device will be inactive. Specific action will only be taken if there is a child node with a 'compatible' field for which there is a supporting driver. small changes: - proper 'compatible' names are used - switch to use 'gpiod' instead of 'gpio' - no longer misuse the 'tty_' prefix. Comments and suggestions always welcome, Thanks, NeilBrown --- NeilBrown (2): TTY: add support for "tty slave" devices. misc: add a driver to power on/off UART attached devices. .../devicetree/bindings/misc/wi2wi,w2cbw003.txt | 19 + .../devicetree/bindings/misc/wi2wi,w2sg0004.txt | 37 + .../devicetree/bindings/serial/of-serial.txt | 4 .../devicetree/bindings/vendor-prefixes.txt | 1 drivers/misc/Kconfig | 12 drivers/misc/Makefile | 1 drivers/misc/serial-power-manager.c | 494 ++++++++++++++++++++ drivers/tty/tty_io.c | 73 +++ include/linux/tty.h | 16 + 9 files changed, 654 insertions(+), 3 deletions(-) create mode 100644 Documentation/devicetree/bindings/misc/wi2wi,w2cbw003.txt create mode 100644 Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt create mode 100644 drivers/misc/serial-power-manager.c -- Signature -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html