[PATCH RFC net-next 1/7] net: stmmac: provide generic transmit clock configuration hook

[Thierry Reding]

On Tue, Feb 18, 2025 at 11:14:39AM +0000, Russell King (Oracle) wrote:
> Several stmmac sub-drivers which support RGMII follow the same pattern.
> They calculate the transmit clock, and then call the clk API to set a
> clock to that rate.
> 
> Analysis of documentation suggests that the platform is responsible for
> providing the transmit clock to the DWMAC core (clk_tx_i). The expected
> rates are:
> 
> 	10Mbps	100Mbps	1Gbps
> MII	2.5MHz	25MHz
> GMII			125MHz
> RGMI	2.5MHz	25MHz	125MHz
> RMII	2.5MHz	25MHz
> 
> It seems some platforms require this clock to be manually configured,
> but there are outputs from the MAC core that indicate the speed, so a
> platform may use these to automatically configure the clock. Thus, we
> can't just provide one solution to configuring the clock.
> 
> Moreover, the clock may need to be derived from one of several sources
> depending on the interface mode.
> 
> Provide a platform hook that is passed the interface mode, speed, and
> transmit clock.
> 
> Signed-off-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 11 +++++++++++
>  include/linux/stmmac.h                            |  4 ++++
>  2 files changed, 15 insertions(+)

Reviewed-by: Thierry Reding <treding at nvidia.com>
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