clk: sunxi: protect core clocks from accidental shutdown

Some important clocks may get disabled as a side effect of another clock
being disabled, because they have no consumers. This patch implements a
mechanism so those clocks can be claimed by the driver and therefore
remain enabled at all times.

Signed-off-by: Emilio López <emilio@elopez.com.ar>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

diff --git a/drivers/clk/sunxi/clk-sunxi.c b/drivers/clk/sunxi/clk-sunxi.c
index 34ee69f4d50c5bd574ceeed4893b0bb9f67a3686..83d3eace3ebc718716fea5d5bc6848f162d82fec 100644 (file)
--- a/drivers/clk/sunxi/clk-sunxi.c
+++ b/drivers/clk/sunxi/clk-sunxi.c
@@ -617,6 +617,31 @@ static void __init of_sunxi_table_clock_setup(const struct of_device_id *clk_mat
        }
 }
 
+/**
+ * System clock protection
+ *
+ * By enabling these critical clocks, we prevent their accidental gating
+ * by the framework
+ */
+static void __init sunxi_clock_protect(void)
+{
+       struct clk *clk;
+
+       /* memory bus clock - sun5i+ */
+       clk = clk_get(NULL, "mbus");
+       if (!IS_ERR(clk)) {
+               clk_prepare_enable(clk);
+               clk_put(clk);
+       }
+
+       /* DDR clock - sun4i+ */
+       clk = clk_get(NULL, "pll5_ddr");
+       if (!IS_ERR(clk)) {
+               clk_prepare_enable(clk);
+               clk_put(clk);
+       }
+}
+
 void __init sunxi_init_clocks(void)
 {
        /* Register all the simple and basic clocks on DT */
@@ -633,4 +658,7 @@ void __init sunxi_init_clocks(void)
 
        /* Register gate clocks */
        of_sunxi_table_clock_setup(clk_gates_match, sunxi_gates_clk_setup);
+
+       /* Enable core system clocks */
+       sunxi_clock_protect();
 }