[PATCH 3/8] clk: imx27: retain early UART clocks during kernel init

[Lucas Stach]

Make sure to keep UART clocks enabled during kernel init if
earlyprintk or earlycon are active.

Signed-off-by: Lucas Stach <l.stach at pengutronix.de>
---
 drivers/clk/imx/clk-imx27.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/clk/imx/clk-imx27.c b/drivers/clk/imx/clk-imx27.c
index d9d50d54ef2a..54fb783123a9 100644
--- a/drivers/clk/imx/clk-imx27.c
+++ b/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 void __init imx27_uart_disable_cb(void)
+{
+	clk_disable_unprepare(clk[IMX27_CLK_PER1_GATE]);
+	clk_disable_unprepare(clk[IMX27_CLK_UART1_IPG_GATE]);
+	clk_disable_unprepare(clk[IMX27_CLK_UART2_IPG_GATE]);
+	clk_disable_unprepare(clk[IMX27_CLK_UART3_IPG_GATE]);
+	clk_disable_unprepare(clk[IMX27_CLK_UART4_IPG_GATE]);
+	clk_disable_unprepare(clk[IMX27_CLK_UART5_IPG_GATE]);
+	clk_disable_unprepare(clk[IMX27_CLK_UART6_IPG_GATE]);
+}
+
 static void __init _mx27_clocks_init(unsigned long fref)
 {
 	BUG_ON(!ccm);
@@ -163,6 +174,17 @@ static void __init _mx27_clocks_init(unsigned long fref)
 
 	clk_prepare_enable(clk[IMX27_CLK_EMI_AHB_GATE]);
 
+	if (imx_clk_keep_uart()) {
+		clk_prepare_enable(clk[IMX27_CLK_PER1_GATE]);
+		clk_prepare_enable(clk[IMX27_CLK_UART1_IPG_GATE]);
+		clk_prepare_enable(clk[IMX27_CLK_UART2_IPG_GATE]);
+		clk_prepare_enable(clk[IMX27_CLK_UART3_IPG_GATE]);
+		clk_prepare_enable(clk[IMX27_CLK_UART4_IPG_GATE]);
+		clk_prepare_enable(clk[IMX27_CLK_UART5_IPG_GATE]);
+		clk_prepare_enable(clk[IMX27_CLK_UART6_IPG_GATE]);
+		imx_clk_set_uart_disable_callback(imx27_uart_disable_cb);
+	}
+
 	imx_print_silicon_rev("i.MX27", mx27_revision());
 }
 
-- 
2.5.0