[PATCH v42 4/6] clk: per-user clk prepare & enable ref counts

From: Michael Turquette
Date: Thu Feb 11 2016 - 16:20:48 EST


This patch adds prepare and enable reference counts for the per-user
handles that clock consumers have for a clock node. This patch warns if
an imbalance occurs while trying to disable or unprepare a clock and
aborts, leaving the hardware unaffected.

Signed-off-by: Michael Turquette <mturquette@xxxxxxxxxxxx>
---
Changed in v2ish:
* Fixed locking bug (Thanks Maxime!)

drivers/clk/clk.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 5181a15..01183e3 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -85,6 +85,8 @@ struct clk {
unsigned long min_rate;
unsigned long max_rate;
struct hlist_node clks_node;
+ unsigned int enable_count;
+ unsigned int prepare_count;
};

/*** locking ***/
@@ -609,7 +611,11 @@ void clk_unprepare(struct clk *clk)
return;

clk_prepare_lock();
+ if (WARN_ON(clk->prepare_count == 0))
+ goto out;
+ clk->prepare_count--;
clk_core_unprepare(clk->core);
+out:
clk_prepare_unlock();
}
EXPORT_SYMBOL_GPL(clk_unprepare);
@@ -666,6 +672,7 @@ int clk_prepare(struct clk *clk)
return 0;

clk_prepare_lock();
+ clk->prepare_count++;
ret = clk_core_prepare(clk->core);
clk_prepare_unlock();

@@ -719,7 +726,11 @@ void clk_disable(struct clk *clk)
return;

flags = clk_enable_lock();
+ if (WARN_ON(clk->enable_count == 0))
+ goto out;
+ clk->enable_count--;
clk_core_disable(clk->core);
+out:
clk_enable_unlock(flags);
}
EXPORT_SYMBOL_GPL(clk_disable);
@@ -781,6 +792,7 @@ int clk_enable(struct clk *clk)
return 0;

flags = clk_enable_lock();
+ clk->enable_count++;
ret = clk_core_enable(clk->core);
clk_enable_unlock(flags);

--
2.1.4