From 5e47f9535f53fd4cc05f32fb6166870f976fbb4e Mon Sep 17 00:00:00 2001 From: Stefan Roese Date: Mon, 19 Oct 2009 14:06:23 +0200 Subject: ppc4xx: Add function to check and dynamically change PCI sync clock PPC440EP(x)/PPC440GR(x): In asynchronous PCI mode, the synchronous PCI clock must meet certain requirements. The following equation describes the relationship that must be maintained between the asynchronous PCI clock and synchronous PCI clock. Select an appropriate PCI:PLB ratio to maintain the relationship: AsyncPCIClk - 1MHz <= SyncPCIclock <= (2 * AsyncPCIClk) - 1MHz This patch now adds a function to check and reconfigure the sync PCI clock to meet this requirement. This is in preparation for some AMCC boards (Sequoia/Rainier and Yosemite/Yellowstone) using this function to not violate the PCI clocking rules. Signed-off-by: Stefan Roese --- include/ppc4xx.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/ppc4xx.h') diff --git a/include/ppc4xx.h b/include/ppc4xx.h index 3bff00a55..5024db447 100644 --- a/include/ppc4xx.h +++ b/include/ppc4xx.h @@ -221,6 +221,8 @@ static inline void set_mcsr(u32 val) asm volatile("mtspr 0x23c, %0" : "=r" (val) :); } +int ppc4xx_pci_sync_clock_config(u32 async); + #endif /* __ASSEMBLY__ */ /* for multi-cpu support */ -- cgit v1.2.3