Hi York,
On Tue, Feb 2, 2016 at 11:11 AM, york sun york.sun@nxp.com wrote:
On 02/01/2016 04:05 PM, Simon Glass wrote:
<snip> >> >> I will take this chance to convert P2020DS to use DM. Need some guidance here. >> For NS16550, it needs the clock. To keep it simple, let's presume platform data >> is used. My trouble is the clock is not unknown at compiling time. It needs to >> be updated by checking the board/soc configuration after power up. The clock is >> only available after get_clocks() is called in init_sequance. Is there a way I >> can update the clocks before the driver is initialized? >> >> York > > See this commit: > > 858530a8 dm: tegra: Enable driver model for serial > > It sets up its own clock.
Simon,
Thanks for the pointer. I actually noticed this commit but it adds some confusion to me. Take your code as an example
U_BOOT_DRIVER(serial_ns16550) = { .name = "serial_tegra20", .id = UCLASS_SERIAL, .of_match = tegra_serial_ids, .ofdata_to_platdata = tegra_serial_ofdata_to_platdata, .platdata_auto_alloc_size = sizeof(struct ns16550_platdata), .priv_auto_alloc_size = sizeof(struct NS16550), .probe = ns16550_serial_probe, .ops = &ns16550_serial_ops, };
The name "serial_ns16550" is not directly used anywhere. So I guess you didn't have to name it as "serial_ns16550", right?
The commit Simon gave was an old one. Now all ns16550 driver has been unified into one.
One step forward, if I want to create a new driver, say "fsl_ns16550", I will have to use ofdata_to_platdata to fill in plat->clock. But for majority powerpc SoCs, we don't use device tree. We may start to use device tree on new products. But it is probably not a good idea to force every platform to change.
Please do not create a new driver for FSL chipset. Does FSL have any plan to continue maintaining all these PowerPC SoCs in U-Boot? If yes, I believe the intention is to bring driver model and device tree to these boards.
Is there another way to update plat->clock?
You can define CONFIG_SYS_NS16550_CLK to a routine that gets the correct clock freq at runtime: eg: get_serial_clock()
Regards, Bin