[PATCH 0/2] Enable modem line status events on cp210x, add support for PPS on RI pin

[Brian Kloppenborg <bkloppenborg@gmail.com>]

Dear Johan,

This is my first patch to the Linux kernel.

Patch 1 enables support for modem line status changes to the cp210x driver. This is required to receive pulse-per-second (PPS) signals from GPS receivers. Support for this feature exists in the FTDI driver, but is not present in cp210x. The patch is implemented through (1) enabling the device's event mode by default when the port is opened or closed, and (2) registering the CTS, DSR, RI, and DCD changes with the kernel through conventional means.

Patch 2 enables support for GPS PPS signals on the RI pin. While most GPS devices typically expose this signal on the DCD pin, the Adafruit Ultimate GPS with USB-C placed it on the RI pin instead. So this patch is highly focused on that specific device. From what I can tell, the usb_serial_handle_dcd_change function is used exclusively to register PPS signals with the kernel, so calling it from the RI block shouldn't result in unexpected behavior.

Please let me know if you require any further information.

Regards

Brian Kloppenborg

Signed-off-by: Brian Kloppenborg <brian@kloppenborg.net>

Brian Kloppenborg (2):
  Make cp210x respond to modem status changes (CTS, DSR, RI, DCD) by
    default.
  Make cp210x register GPS PPS signals on the RI pin.

 drivers/usb/serial/cp210x.c | 71 +++++++++++++++++++++++++++++++------
 1 file changed, 60 insertions(+), 11 deletions(-)

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2.34.1