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authorMike Turquette <mturquette@linaro.org>2012-12-04 23:00:35 +0400
committerMike Turquette <mturquette@linaro.org>2012-12-11 10:35:02 +0400
commit7c045a55c97fb83a2e5e9c6c857162c4866cc602 (patch)
treee8c5a171b9b9085e86541aaccf9b85e3ec52298e
parent2630b17b6ee47ac79b4f5120ac49105027f644ea (diff)
downloadlinux-7c045a55c97fb83a2e5e9c6c857162c4866cc602.tar.xz
clk: introduce optional disable_unused callback
Some gate clocks have special needs which must be handled during the disable-unused clocks sequence. These needs might be driven by software due to the fact that we're disabling a clock outside of the normal clk_disable path and a clk's enable_count will not be accurate. On the other hand a specific hardware programming sequence might need to be followed for this corner case. This change is needed for the upcoming OMAP port to the common clock framework. Specifically, it is undesirable to treat the disable-unused path identically to the normal clk_disable path since other software layers are involved. In this case OMAP's clockdomain code throws WARNs and bails early due to the clock's enable_count being set to zero. A custom callback mitigates this problem nicely. Cc: Paul Walmsley <paul@pwsan.com> Acked-by: Ulf Hansson <ulf.hansson@linaro.org> Acked-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Mike Turquette <mturquette@linaro.org>
-rw-r--r--drivers/clk/clk.c13
-rw-r--r--include/linux/clk-provider.h6
2 files changed, 17 insertions, 2 deletions
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 9955ad7e786e..251e45d6024d 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -219,8 +219,17 @@ static void clk_disable_unused_subtree(struct clk *clk)
if (clk->flags & CLK_IGNORE_UNUSED)
goto unlock_out;
- if (__clk_is_enabled(clk) && clk->ops->disable)
- clk->ops->disable(clk->hw);
+ /*
+ * some gate clocks have special needs during the disable-unused
+ * sequence. call .disable_unused if available, otherwise fall
+ * back to .disable
+ */
+ if (__clk_is_enabled(clk)) {
+ if (clk->ops->disable_unused)
+ clk->ops->disable_unused(clk->hw);
+ else if (clk->ops->disable)
+ clk->ops->disable(clk->hw);
+ }
unlock_out:
spin_unlock_irqrestore(&enable_lock, flags);
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 3593a3ce3f0d..1c94d18514e2 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -57,6 +57,11 @@ struct clk_hw;
* This function must not sleep. Optional, if this op is not
* set then the enable count will be used.
*
+ * @disable_unused: Disable the clock atomically. Only called from
+ * clk_disable_unused for gate clocks with special needs.
+ * Called with enable_lock held. This function must not
+ * sleep.
+ *
* @recalc_rate Recalculate the rate of this clock, by querying hardware. The
* parent rate is an input parameter. It is up to the caller to
* ensure that the prepare_mutex is held across this call.
@@ -106,6 +111,7 @@ struct clk_ops {
int (*enable)(struct clk_hw *hw);
void (*disable)(struct clk_hw *hw);
int (*is_enabled)(struct clk_hw *hw);
+ void (*disable_unused)(struct clk_hw *hw);
unsigned long (*recalc_rate)(struct clk_hw *hw,
unsigned long parent_rate);
long (*round_rate)(struct clk_hw *hw, unsigned long,