+/*
+ * Initialize the PLL. We need to know the frequency of the reference clock
+ * to calculate the optimal multiplier. For PCI we assume 66MHz, since that
+ * allows us to operate without the risk of overclocking the chip. If it
+ * actually uses 33MHz, the chip will operate at half the speed, this can be
+ * overriden by specifying the frequency as module parameter (pci33).
+ *
+ * Unfortunately the PCI clock is not very suitable since the HIFN needs a
+ * stable clock and the PCI clock frequency may vary, so the default is the
+ * external clock. There is no way to find out its frequency, we default to
+ * 66MHz since according to Mike Ham of HiFn, almost every board in existence
+ * has an external crystal populated at 66MHz.
+ */
+static void hifn_init_pll(struct hifn_device *dev)
+{
+ unsigned int freq, m;
+ u32 pllcfg;
+
+ pllcfg = HIFN_1_PLL | HIFN_PLL_RESERVED_1;
+
+ if (strncmp(hifn_pll_ref, "ext", 3) == 0)
+ pllcfg |= HIFN_PLL_REF_CLK_PLL;
+ else
+ pllcfg |= HIFN_PLL_REF_CLK_HBI;
+
+ if (hifn_pll_ref[3] != '\0')
+ freq = simple_strtoul(hifn_pll_ref + 3, NULL, 10);
+ else {
+ freq = 66;
+ printk(KERN_INFO "hifn795x: assuming %uMHz clock speed, "
+ "override with hifn_pll_ref=%.3s<frequency>\n",
+ freq, hifn_pll_ref);
+ }
+
+ m = HIFN_PLL_FCK_MAX / freq;
+
+ pllcfg |= (m / 2 - 1) << HIFN_PLL_ND_SHIFT;
+ if (m <= 8)
+ pllcfg |= HIFN_PLL_IS_1_8;
+ else
+ pllcfg |= HIFN_PLL_IS_9_12;
+
+ /* Select clock source and enable clock bypass */
+ hifn_write_1(dev, HIFN_1_PLL, pllcfg |
+ HIFN_PLL_PK_CLK_HBI | HIFN_PLL_PE_CLK_HBI | HIFN_PLL_BP);
+
+ /* Let the chip lock to the input clock */
+ mdelay(10);
+
+ /* Disable clock bypass */
+ hifn_write_1(dev, HIFN_1_PLL, pllcfg |
+ HIFN_PLL_PK_CLK_HBI | HIFN_PLL_PE_CLK_HBI);
+
+ /* Switch the engines to the PLL */
+ hifn_write_1(dev, HIFN_1_PLL, pllcfg |
+ HIFN_PLL_PK_CLK_PLL | HIFN_PLL_PE_CLK_PLL);
+
+ /*
+ * The Fpk_clk runs at half the total speed. Its frequency is needed to
+ * calculate the minimum time between two reads of the rng. Since 33MHz
+ * is actually 33.333... we overestimate the frequency here, resulting
+ * in slightly larger intervals.
+ */
+ dev->pk_clk_freq = 1000000 * (freq + 1) * m / 2;
+}
+