msm: clock: Add hardware gating support to branch clocks
Add support for hardware clock gating on branch clocks. Do this
in a few steps:
o At clock registration time, check to see if the branch is not
in hardware gated mode and fix up the branch data structure
as appropriate
o When a clk_reset() is asserted take the branch out of
hardware control so the reset can propagate if the clock
is enabled
o When a clk_reset() is deasserted put the branch back into
hardware control
Add three new ops to the clk_ops structure to support the above.
void (*enable_hwcg)(struct clk *clk);
void (*disable_hwcg)(struct clk *clk);
int (*in_hwcg_mode)(struct clk *clk);
{enable,disable}_hwcg() should enable and disable hardware clock
gating if possible. in_hwcg_mode() should return either a
non-zero value or a zero indicating whether the clock is
currently in hardware gating mode or not in hardware gating mode
respectively.
Use in_hwcg_mode() to detect when to skip the halt checks for a
branch and when to disable/enable hardware gating mode while
measuring clocks. This is particularly important for measurement
because we don't want to put a clock into hardware gating mode
accidentally after we measure the clock if the clock wasn't in
hardware gating mode to begin with.
Also expose a debugfs node indicating whether or not this clock
supports hardware gating. This should aid in debugging problems
due to hardware gating.
Change-Id: Id9b2d83adcc6dabe2544f48ef0b4d752d9a5c5c1
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
diff --git a/arch/arm/mach-msm/clock-debug.c b/arch/arm/mach-msm/clock-debug.c
index 4990c81..411a272 100644
--- a/arch/arm/mach-msm/clock-debug.c
+++ b/arch/arm/mach-msm/clock-debug.c
@@ -54,12 +54,31 @@
static int clock_debug_measure_get(void *data, u64 *val)
{
- int ret;
struct clk *clock = data;
+ int ret, is_hw_gated;
+
+ /* Check to see if the clock is in hardware gating mode */
+ if (clock->flags & CLKFLAG_HWCG)
+ is_hw_gated = clock->ops->in_hwcg_mode(clock);
+ else
+ is_hw_gated = 0;
ret = clk_set_parent(measure, clock);
- if (!ret)
+ if (!ret) {
+ /*
+ * Disable hw gating to get accurate rate measurements. Only do
+ * this if the clock is explictly enabled by software. This
+ * allows us to detect errors where clocks are on even though
+ * software is not requesting them to be on due to broken
+ * hardware gating signals.
+ */
+ if (is_hw_gated && clock->count)
+ clock->ops->disable_hwcg(clock);
*val = clk_get_rate(measure);
+ /* Reenable hwgating if it was disabled */
+ if (is_hw_gated && clock->count)
+ clock->ops->enable_hwcg(clock);
+ }
return ret;
}
@@ -109,6 +128,16 @@
DEFINE_SIMPLE_ATTRIBUTE(clock_local_fops, clock_debug_local_get,
NULL, "%llu\n");
+static int clock_debug_hwcg_get(void *data, u64 *val)
+{
+ struct clk *clock = data;
+ *val = !!(clock->flags & CLKFLAG_HWCG);
+ return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(clock_hwcg_fops, clock_debug_hwcg_get,
+ NULL, "%llu\n");
+
static struct dentry *debugfs_base;
static u32 debug_suspend;
static struct clk_lookup *msm_clocks;
@@ -239,6 +268,10 @@
&clock_local_fops))
goto error;
+ if (!debugfs_create_file("has_hw_gating", S_IRUGO, clk_dir, clock,
+ &clock_hwcg_fops))
+ goto error;
+
if (measure &&
!clk_set_parent(measure, clock) &&
!debugfs_create_file("measure", S_IRUGO, clk_dir, clock,