* Patch by Yuli Barcohen, 13 Jul 2004:
Allow clock setting on MPC866/MPC885 series chips according to
environment variable `cpuclk'
* Patch by Yuli Barcohen, 20 Apr 2004:
Remove unnecessary redefine of CPM_DATAONLY_SIZE for MPC826x
diff --git a/doc/README.MPC866 b/doc/README.MPC866
index 42abac8..c8256a1 100644
--- a/doc/README.MPC866
+++ b/doc/README.MPC866
@@ -1,12 +1,12 @@
The current implementation allows the user to specify the desired CPU
clock value, in MHz, via an environment variable "cpuclk".
-Three compile-time constants are used:
+Four compile-time constants are used:
- CFG_866_OSCCLK - input quartz clock
- CFG_866_CPUCLK_MIN - minimum allowed CPU clock
- CFG_866_CPUCLK_MAX - maximum allowed CPU clock
- CFG_866_CPUCLK_DEFAULT - default CPU clock value
+ CONFIG_8xx_OSCLK - input quartz clock
+ CFG_8xx_CPUCLK_MIN - minimum allowed CPU clock
+ CFG_8xx_CPUCLK_MAX - maximum allowed CPU clock
+ CONFIG_8xx_CPUCLK_DEFAULT - default CPU clock value
If the "cpuclk" environment variable value is within the CPUCLK_MIN /
CPUCLK_MAX limits, the specified value is used. Otherwise, the
@@ -16,8 +16,9 @@
the restrictions of your hardware (board, processor). For example,
ethernet will stop working for CPU clock frequencies below 25 MHz.
-Please note that for now the new clock-handling code has been enabled
-for the TQM866M board only, even though it should be pretty much
-common for other MPC859 / MPC866 based boards also. Our intention
-here was to move in small steps and not to break the existing code
-for other boards.
+Please note that the new clock-handling code is enabled if
+CONFIG_8xx_CPUCLK_DEFAULT is defined. Since this mechanism supports
+only MPC866 and newer CPUs, this constant MUST NOT be defined for
+MPC823/850/860/862 series. The clock generation algorithm for older
+chips is different and has not been implemented yet. If you need it,
+your patch is welcome.