clk: lpc18xx-ccu: fix potential system hang when disabling unused clocks
CCU branch clock register must only be accessed while the base
(parent) clock is running. Access with a disabled base clock
will cause the system to hang. Fix this issue by adding code
that check if the parent clock is running in the is_enabled
clk_ops callback.
This hang would occur when disabling unused clocks after AMBA
runtime pm had already disabled some of the clocks.
Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
diff --git a/drivers/clk/nxp/clk-lpc18xx-ccu.c b/drivers/clk/nxp/clk-lpc18xx-ccu.c
index eeaee97..13aabbb 100644
--- a/drivers/clk/nxp/clk-lpc18xx-ccu.c
+++ b/drivers/clk/nxp/clk-lpc18xx-ccu.c
@@ -179,9 +179,22 @@
static int lpc18xx_ccu_gate_is_enabled(struct clk_hw *hw)
{
- struct clk_gate *gate = to_clk_gate(hw);
+ const struct clk_hw *parent;
- return clk_readl(gate->reg) & LPC18XX_CCU_RUN;
+ /*
+ * The branch clock registers are only accessible
+ * if the base (parent) clock is enabled. Register
+ * access with a disabled base clock will hang the
+ * system.
+ */
+ parent = clk_hw_get_parent(hw);
+ if (!parent)
+ return 0;
+
+ if (!clk_hw_is_enabled(parent))
+ return 0;
+
+ return clk_gate_ops.is_enabled(hw);
}
static const struct clk_ops lpc18xx_ccu_gate_ops = {
