The uartlite device is a "soft" device and certain parameters (such as
data bits, parity, and baud) are configured at synthesis time, and
cannot be discovered at runtime. Fortunately, bindings for this device
typically include some of these parameters (especially baud rate).
Instead of silently letting Linux's termios drift away from what the
hardware is actually doing, make the termios reflect the hardware, and
prevent them from being changed. With this series applied, the user
recieves an error message the first time they try and change these
termios:
# stty parity
[ 7.221696] uartlite 84000000.serial: only 'n' parity supported
[ 7.222139] uartlite 84000000.serial: only 8 data bits supported
stty: standard input: cannot perform all requested operations
In addition, the configured baud/parity/bits/etc. are exposed through
the standard termios ioctls, instead of using the default termios for
unconfigured ttys.
Changes in v2:
- Compare the baud computed with uart_get_baud_rate to pdata->baud,
instead of just checking c_cflag. This will catch anything that messes
with ispeed and ospeed.
- Don't bother trying to set the initial termios. Instead, just skip
warning if old is NULL.
- Because we no longer use uart_set_options, just convert the devicetree
properties directly to clflags.
Sean Anderson (4):
dt-bindings: serial: uartlite: Convert to json-schema
dt-bindings: serial: uartlite: Add properties for synthesis-time
parameters
sh: j2: Update uartlite binding with data and parity properties
tty: serial: uartlite: Prevent changing fixed parameters
.../bindings/serial/xlnx,opb-uartlite.txt | 23 ----
.../bindings/serial/xlnx,opb-uartlite.yaml | 92 ++++++++++++++
arch/sh/boot/dts/j2_mimas_v2.dts | 2 +
drivers/tty/serial/uartlite.c | 120 ++++++++++++++++--
4 files changed, 203 insertions(+), 34 deletions(-)
delete mode 100644 Documentation/devicetree/bindings/serial/xlnx,opb-uartlite.txt
create mode 100644 Documentation/devicetree/bindings/serial/xlnx,opb-uartlite.yaml
--
2.25.1
