imx: mx6sl: Set the preclk clock source to OSC 24Mhz

For MX6SL, uses the OSC 24Mhz as the preclk source in CCM. Align the
preclk setting with kernel.
Signed-off-by: Ye.Li <B37916@freescale.com>

arch/arm/cpu/armv7/mx6/soc.c

@@ -239,6 +239,18 @@ static void clear_mmdc_ch_mask(void)
 	writel(0, &mxc_ccm->ccdr);
 }
 
+#ifdef CONFIG_MX6SL
+static void set_preclk_from_osc(void)
+{
+	struct mxc_ccm_reg *mxc_ccm = (struct mxc_ccm_reg *)CCM_BASE_ADDR;
+	u32 reg;
+
+	reg = readl(&mxc_ccm->cscmr1);
+	reg |= MXC_CCM_CSCMR1_PER_CLK_SEL_MASK;
+	writel(reg, &mxc_ccm->cscmr1);
+}
+#endif
+
 int arch_cpu_init(void)
 {
 	init_aips();
@@ -254,6 +266,11 @@ int arch_cpu_init(void)
 	if (mxc_get_clock(MXC_ARM_CLK) == 396000000)
 		set_ahb_rate(132000000);
 
+		/* Set perclk to source from OSC 24MHz */
+#if defined(CONFIG_MX6SL)
+	set_preclk_from_osc();
+#endif
+
 	imx_set_wdog_powerdown(false); /* Disable PDE bit of WMCR register */
 
 #ifdef CONFIG_APBH_DMA