Noralf pointed me at fixed-factor-clock, and that works in our (downstream) environment:

�� soc: soc {�� ...�� uart1: uart@7e215040 {�� compatible = "brcm,bcm2835-aux-uart", "ns16550";�� reg = <0x7e215040 0x40>;�� interrupts = <1 29>;�� clocks = <&clk_uart1>;�� reg-shift = <2>;�� no-loopback-test;�� status = "disabled";�� };�� };�� clocks: clocks {�� ... �� clk_core: clock@2 { �� compatible = "fixed-clock"; �� reg = <2>; �� #clock-cells = <0>; �� clock-output-names = "core"; �� clock-frequency = <250000000>; �� }; �� ...�� clk_uart1: clock@6 {�� compatible = "fixed-factor-clock";�� clocks = <&clk_core>;�� #clock-cells = <0>;�� clock-div = <1>;�� clock-mult = <2>;�� };�� };Phil

On 10/09/2015 16:57, Martin Sperl wrote:

On 10.09.2015, at 17:48, Noralf Tr�nnes <noralf@tronnes.org> wrote:

This looks interesting.
But there's a challenge with the uart1 and the 8250 driver.

Phil Elwell has this to say:
This means that that UART1 isn't an exact clone of a 8250 UART.
In a particular, the clock divisor is calculated differently.
A standard 8250 derives the baud rate as clock/(divisor16),
whereas the BCM2835 mini UART uses clock/(divisor8). This means
that if you want to use the standard driver then you need to lie
about the clock frequency, providing a value is twice the real
value, in order for a suitable divisor to be calculated.

Ref: https://github.com/raspberrypi/linux/pull/1008#issuecomment-139234607

So either we need a new uart1 driver or a doubled clock freq. somehow.

Found out the same thing and communicated it to Eric - not 
knowing about the different divider�

Martin