arm64: mvebu: a8k: Add support for NAND clock get

Implement mvebu_get_nand_clock call for A8K family.
This function is used by PXA3XX NAND driver.

Signed-off-by: Konstantin Porotchkin <kostap@marvell.com>
Cc: Stefan Roese <sr@denx.de>
Cc: Igal Liberman <igall@marvell.com>
Cc: Nadav Haklai <nadavh@marvell.com>
Reviewed-by: Stefan Roese <sr@denx.de>

arch/arm/mach-mvebu/armada8k/cpu.c

@@ -110,3 +110,21 @@ void reset_cpu(ulong ignored)
 	reg &= ~(1 << RFU_SW_RESET_OFFSET);
 	writel(reg, RFU_GLOBAL_SW_RST);
 }
+
+/*
+ * TODO - implement this functionality using platform
+ *        clock driver once it gets available
+ * Return NAND clock in Hz
+ */
+u32 mvebu_get_nand_clock(void)
+{
+	unsigned long NAND_FLASH_CLK_CTRL = 0xF2440700UL;
+	unsigned long NF_CLOCK_SEL_MASK = 0x1;
+	u32 reg;
+
+	reg = readl(NAND_FLASH_CLK_CTRL);
+	if (reg & NF_CLOCK_SEL_MASK)
+		return 400 * 1000000;
+	else
+		return 250 * 1000000;
+}