[U-Boot-Users] Question about setting the sys clk freq based on a pull up on io.

Wolfgang Denk wd at denx.de
Wed Nov 19 09:59:06 CET 2003

Dear Conn,

in message <3FBACF35.4020006 at esteem.com> you wrote:
> 	My problem is how do I go about this without severly modifying U-Boots 
> structure. In analyzing how to do this I determined that the 
> configuration and reading of the IO pin sould be done in a 
> board_pre_init function. This rases the issue of passing values between 
> the init functions called by board_init_f. My second issue is how do I 

You can store the cpu_clk / bus_clk in the global_data structure.

> deal with the two frquencies since only one can be defined as 
> CONFIG_SYS_CLK_FREQ(which is used in several places) without sticking 
> lots of nasty board specific ifdefs through out the code.

I don't see the need for #ifdef's.

> (Note I didn't look at them all). We realy don't want to have to specify 
> at compile time what frequency we intend on using. This may become an 

I see no need that CONFIG_SYS_CLK_FREQ must be a constant. Instead of

	#define CONFIG_SYS_CLK_FREQ     33333333

you can - for example - use

	#define CONFIG_SYS_CLK_FREQ     my_function_to_read_clocks()

Best regards,

Wolfgang Denk

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
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