[PATCH 3/3] clk: sunxi: protect core clocks from accidental shutdown

Emilio López
2013-09-21T01:03:12Z

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 L?pez <emilio@elopez.com.ar>
---
drivers/clk/sunxi/clk-sunxi.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)

diff --git a/drivers/clk/sunxi/clk-sunxi.c b/drivers/clk/sunxi/clk-sunxi.c
index 34ee69f..83d3eac 100644
--- 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();
}
--
1.8.4