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-rw-r--r--cpu/ppc4xx/cpu_init.c69
1 files changed, 69 insertions, 0 deletions
diff --git a/cpu/ppc4xx/cpu_init.c b/cpu/ppc4xx/cpu_init.c
index a00da40..ccd9993 100644
--- a/cpu/ppc4xx/cpu_init.c
+++ b/cpu/ppc4xx/cpu_init.c
@@ -330,3 +330,72 @@ int cpu_init_r (void)
return 0;
}
+
+#if defined(CONFIG_PCI) && \
+ (defined(CONFIG_440EP) || defined(CONFIG_440EPX) || \
+ defined(CONFIG_440GR) || defined(CONFIG_440GRX))
+/*
+ * 440EP(x)/GR(x) PCI async/sync clocking restriction:
+ *
+ * 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
+ */
+static int ppc4xx_pci_sync_clock_ok(u32 sync, u32 async)
+{
+ if (((async - 1000000) > sync) || (sync > ((2 * async) - 1000000)))
+ return 0;
+ else
+ return 1;
+}
+
+int ppc4xx_pci_sync_clock_config(u32 async)
+{
+ sys_info_t sys_info;
+ u32 sync;
+ int div;
+ u32 reg;
+ u32 spcid_val[] = {
+ CPR0_SPCID_SPCIDV0_DIV1, CPR0_SPCID_SPCIDV0_DIV2,
+ CPR0_SPCID_SPCIDV0_DIV3, CPR0_SPCID_SPCIDV0_DIV4 };
+
+ get_sys_info(&sys_info);
+ sync = sys_info.freqPCI;
+
+ /*
+ * First check if the equation above is met
+ */
+ if (!ppc4xx_pci_sync_clock_ok(sync, async)) {
+ /*
+ * Reconfigure PCI sync clock to meet the equation.
+ * Start with highest possible PCI sync frequency
+ * (divider 1).
+ */
+ for (div = 1; div <= 4; div++) {
+ sync = sys_info.freqPLB / div;
+ if (ppc4xx_pci_sync_clock_ok(sync, async))
+ break;
+ }
+
+ if (div <= 4) {
+ mtcpr(CPR0_SPCID, spcid_val[div]);
+
+ mfcpr(CPR0_ICFG, reg);
+ reg |= CPR0_ICFG_RLI_MASK;
+ mtcpr(CPR0_ICFG, reg);
+
+ /* do chip reset */
+ mtspr(SPRN_DBCR0, 0x20000000);
+ } else {
+ /* Impossible to configure the PCI sync clock */
+ return -1;
+ }
+ }
+
+ return 0;
+}
+#endif