如何复位Freescale Power Architecture系列处理中的PCIe控制器

在PCIe控制器出现一些不可恢复的错误时，复位PCIe控制器是让PCIe控制器走出这种错误状态的一个必要条件。下面给出复位Freescale Power Architecture系列处理器上的PCIe控制器的一种方法，该方法使用到的寄存器一般在处理器文档中并没有公开，属于内部寄存器。

Perform a PCI Express controller soft reset with the following sequence in order:

1. Save there return value for memory location "CCSRBAR + PCI Express controller block offset + 0xF00" to a temporary location, depending on the PCI Express controller in use.

2. OR the above temporary value with 0x0800_0000 and write it back to memory location"CCSRBAR + PCI Express controller block offset + 0xF00"

3. Wait for 1ms

4. AND the temporary value obtained in step 1 with 0xF7FF_FFFF and write it back to the memory location "CCSRBAR + PCI Express controller block offset +0xF00"

5. Poll the LTSSM register until the LTSSM status code returns 0x16 consistently to indicate that the link is up.