| 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: |
| |
| 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 |
| |
| If the "cpuclk" environment variable value is within the CPUCLK_MIN / |
| CPUCLK_MAX limits, the specified value is used. Otherwise, the |
| default CPU clock value is set. |
| |
| Please make sure you understand what you are doing, and understand |
| 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. |