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 exports serial8250_do_set_divisor() patch3 implements the fractional divisor support for Synopsys DW 8250. Since v5: - Add Andy's Reviewed-by tag to all patches. Since v4: - use tmp to save baud * 16 rather than calculate every time in dw8250_get_divisor() Since v3: - simplify the dw8250_get_divisor() implementation again. Since v2: - rebase to tty-next branch, since I need one patch from Andy which is in tty-next - drop the patch "serial: 8250: let serial8250_get_divisor() get uart_port * as param" since it's in tty-next now. - add a new patch to export serial8250_do_set_divisor(), and reuse it to complete dw8250_set_divisor(). - remove DW 8250 version check, since the DLF register always exists and if fractional divisor isn't supported, the register read as 0 - add comments to explain how dw8250_get_divisor() get quot and frac. - the frac calcuation is simplified with well implemented GENMASK - Add Andy's Reviewed-by tag to patch1. Since v1: - add an extra patch to let serial8250_get_divisor() get uart_port * as param - take Andy's suggestions to "integrates hooks in the same way like it's done for the rest of 8250 ones". Many thanks to Andy. Jisheng Zhang (3): serial: 8250: introduce get_divisor() and set_divisor() hook serial: 8250: export serial8250_do_set_divisor() serial: 8250_dw: add fractional divisor support drivers/tty/serial/8250/8250_core.c | 4 +++ drivers/tty/serial/8250/8250_dw.c | 45 +++++++++++++++++++++++++++++ drivers/tty/serial/8250/8250_port.c | 30 +++++++++++++++---- include/linux/serial_8250.h | 3 ++ include/linux/serial_core.h | 7 +++++ 5 files changed, 84 insertions(+), 5 deletions(-) -- 2.18.0 -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
