clk: imx27: 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-imx27.c

@@ -47,6 +47,17 @@ static const char *ssi_sel_clks[] = { "spll_gate", "mpll", };
 static struct clk *clk[IMX27_CLK_MAX];
 static struct clk_onecell_data clk_data;
 
+static struct clk ** const uart_clks[] __initconst = {
+	&clk[IMX27_CLK_PER1_GATE],
+	&clk[IMX27_CLK_UART1_IPG_GATE],
+	&clk[IMX27_CLK_UART2_IPG_GATE],
+	&clk[IMX27_CLK_UART3_IPG_GATE],
+	&clk[IMX27_CLK_UART4_IPG_GATE],
+	&clk[IMX27_CLK_UART5_IPG_GATE],
+	&clk[IMX27_CLK_UART6_IPG_GATE],
+	NULL
+};
+
 static void __init _mx27_clocks_init(unsigned long fref)
 {
 	BUG_ON(!ccm);
@@ -163,6 +174,8 @@ static void __init _mx27_clocks_init(unsigned long fref)
 
 	clk_prepare_enable(clk[IMX27_CLK_EMI_AHB_GATE]);
 
+	imx_register_uart_clocks(uart_clks);
+
 	imx_print_silicon_rev("i.MX27", mx27_revision());
 }