For Synopsys DesignWare 8250 uart which version >= 4.00a, there's a valid divisor latch fraction register. The fractional divisor width is 4bits ~ 6bits.
patch1 introduces necessary hooks to 8250 core. patch2 implement the fractional divisor support for Synopsys DW 8250. Jisheng Zhang (2): serial: 8250: introduce get_divisor() and set_divisor() hook serial: 8250_dw: add fractional divisor support drivers/tty/serial/8250/8250_core.c | 4 +++ drivers/tty/serial/8250/8250_dw.c | 54 +++++++++++++++++++++++++++++ drivers/tty/serial/8250/8250_port.c | 8 +++++ include/linux/serial_8250.h | 7 ++++ 4 files changed, 73 insertions(+) -- 2.18.0
