[U-Boot-Users] dynamic setting of CONFIG_SYS_CLK_FREQ

VanBaren, Gerald (AGRE) Gerald.VanBaren at smiths-aerospace.com
Thu Apr 22 19:52:01 CEST 2004


The simplest way for shortcutting...

#define CONFIG_SYS_CLK_FREQ   get_clock_freq()

(writing of an acceptable get_clock_freq()is left as an exercize for the reader)

gvb


> -----Original Message-----
> From: u-boot-users-admin at lists.sourceforge.net
> [mailto:u-boot-users-admin at lists.sourceforge.net]On Behalf Of Wolfgang
> Denk
> Sent: Thursday, April 22, 2004 1:15 PM
> To: Kumar Gala
> Cc: U-Boot mailing list
> Subject: Re: [U-Boot-Users] dynamic setting of CONFIG_SYS_CLK_FREQ
>
>
> In message
> <66FC73FC-9476-11D8-A48D-000393DBC2E8 at motorola.com> you wrote:
> > I was wondering if there where an examples in the current
> u-boot source
> > tree in which CONFIG_SYS_CLK_FREQ was determined
> dynamically.  I have a
>
> Not exactly for CONFIG_SYS_CLK_FREQ - but the TQM8xxL boards  contain
> code to measure the input clock against the (known) 32kHz clock.
>
> > system in which I can read a config register on the board to let me
> > know if the CONFIG_SYS_CLK_FREQ is 66Mhz or 33Mhz.  I was hoping to
> > have the 16550 uart (and anything else) that needed
> CONFIG_SYS_CLK_FREQ
> > grab it from a variable instead.
>
> If you provide a suitable init fuction which sets the  value  in  the
> global  data  section eraly enough, you can probably shortcut the use
> of CONFIG_SYS_CLK_FREQ.
>
> > This is on an MPC85xx platform system.
>
> ...or any other.
>
>
> 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
> "There are three principal ways to lose money: wine, women, and engi-
> neers. While the first two are more pleasant, the third is by far the
> more certain."                           - Baron Rothschild, ca. 1800
>
>
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