| ------------ barebox timekeeping ------------- |
| |
| In barebox we use the clocksource mechanism from the Linux Kernel. This makes |
| it fairly easy to add timer functionality for a new board or architecture. |
| Apart from initialization there is only one function required: |
| clocksource_read(). This function returns the current value of a free running |
| counter. Other functions like udelay() and get_time_ns() are derived from this |
| function. The only thing you have to implement is a clocksource driver. See |
| cpu/arm920t/imx/interrupts.c for an example. clocksource drivers from the |
| Linux Kernel can be used nearly 1:1, except for the register accesses. |
| |
| for clocksources the __lshrdi3 symbol is needed. You can find the function for |
| your architecture in the Linux Kernel or a libc of your choice. |
