[U-Boot-Users] arm 920 / integrator interrupts / flash / misc

Wolfgang Denk wd at denx.de
Fri Feb 28 10:34:15 CET 2003

In message <20030227155658.A22868 at europa.queda.net> you wrote:
> Thanks for your reply.  I am trying to ensure that the clock / timer stuff is
> working properly.  


> I had a question you might be able to answer:  For the Arm920 system in the
> file
> cpu/arm920t/speed.c
> I am unclear what the bus definitions are for the following:
> get_FCLK(), get_HCLK(), get_PCLK() and get_UCLK()
> Ie: what does F, H, P, U  represent?

See for example the documentation  for  the  Samsung  s3c2400/s3c2410

FCLK is used by ARM920T cpu core.

HCLK is used for AHB bus which is  used  by  ARM920T  cpu  core,  the
memory  controller, the interrupt controller, LCD controller, the DMA
and the USB host block.

PCLK is used for APB bus which is used by  the  peripherals  such  as
WDT,  IIS,  I2C,  PWM  timer, MMC interface, ADC, UART, GPIO, RTC and

UCLK is the output of the  USB  dedicated  PLL  (UPLL)  and  is  used
(obviously) for USB.

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
"Whoever undertakes to set himself up as a judge of Truth  and  Know-
ledge is shipwrecked by the laughter of the gods."  - Albert Einstein

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