clk: imx31: retain early UART clocks during kernel init

Make sure to keep UART clocks enabled during kernel init if
earlyprintk or earlycon are active.
Signed-off-by: NLucas Stach <l.stach@pengutronix.de>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>

drivers/clk/imx/clk-imx31.c

@@ -62,6 +62,16 @@ enum mx31_clks {
 static struct clk *clk[clk_max];
 static struct clk_onecell_data clk_data;
 
+static struct clk ** const uart_clks[] __initconst = {
+	&clk[ipg],
+	&clk[uart1_gate],
+	&clk[uart2_gate],
+	&clk[uart3_gate],
+	&clk[uart4_gate],
+	&clk[uart5_gate],
+	NULL
+};
+
 int __init mx31_clocks_init(unsigned long fref)
 {
 	void __iomem *base;
@@ -200,6 +210,8 @@ int __init mx31_clocks_init(unsigned long fref)
 	mx31_revision();
 	clk_disable_unprepare(clk[iim_gate]);
 
+	imx_register_uart_clocks(uart_clks);
+
 	mxc_timer_init(MX31_GPT1_BASE_ADDR, MX31_INT_GPT, GPT_TYPE_IMX31);
 
 	return 0;