clk: Allow clocks to be marked as CRITICAL

Critical clocks are those which must not be gated, else undefined
or catastrophic failure would occur.  Here we have chosen to
ensure the prepare/enable counts are correctly incremented, so as
not to confuse users with enabled clocks with no visible users.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Michael Turquette <mturquette@baylibre.com>
Link: lkml.kernel.org/r/1455225554-13267-2-git-send-email-mturquette@baylibre.com

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index fb74dc1f7520503d72f024b596dc72d002851e4c..275201fd7b016466c16afc16609cd7623d02ceb6 100644 (file)
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2397,6 +2397,11 @@ static int __clk_core_init(struct clk_core *core)
        if (core->ops->init)
                core->ops->init(core->hw);
 
+       if (core->flags & CLK_IS_CRITICAL) {
+               clk_core_prepare(core);
+               clk_core_enable(core);
+       }
+
        kref_init(&core->ref);
 out:
        clk_prepare_unlock();

diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index da95258127aace556dc32810c0b483bcda95198f..0638b41545022c9bef5e93f4c38af1c78f1971f6 100644 (file)
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -32,6 +32,7 @@
 #define CLK_GET_ACCURACY_NOCACHE BIT(8) /* do not use the cached clk accuracy */
 #define CLK_RECALC_NEW_RATES   BIT(9) /* recalc rates after notifications */
 #define CLK_SET_RATE_UNGATE    BIT(10) /* clock needs to run to set rate */
+#define CLK_IS_CRITICAL                BIT(11) /* do not gate, ever */
 
 struct clk;
 struct clk_hw;