The current phase API doesn't look into the actual hardware to get the phase
value, but will rather get it from a variable only set by the set_phase
function.
This will cause issue when the client driver will never call the set_phase
function, where we can end up having a reported phase that will not match what
the hardware has been programmed to by the bootloader or what phase is
programmed out of reset.
Add a new get_phase function for the drivers to implement so that we can get
this value.
Signed-off-by: Maxime Ripard <maxime.rip...@free-electrons.com>
---
drivers/clk/clk.c | 10 ++++++++++
include/linux/clk-provider.h | 5 +++++
2 files changed, 15 insertions(+)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index d87661af0c72..113d75db371d 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1934,6 +1934,16 @@ int __clk_init(struct device *dev, struct clk *clk)
clk->accuracy = 0;
/*
+ * Set clk's phase.
+ * Since a phase is by definition relative to its parent, just
+ * query the current clock phase, or just assume it's in phase.
+ */
+ if (clk->ops->get_phase)
+ clk->phase = clk->ops->get_phase(clk->hw);
+ else
+ clk->phase = 0;
+
+ /*
* Set clk's rate. The preferred method is to use .recalc_rate. For
* simple clocks and lazy developers the default fallback is to use the
* parent's rate. If a clock doesn't have a parent (or is orphaned)
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 69b20d4c1e1a..abec961092a7 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -130,6 +130,10 @@ struct dentry;
* set then clock accuracy will be initialized to parent accuracy
* or 0 (perfect clock) if clock has no parent.
*
+ * @get_phase: Queries the hardware to get the current phase of a clock.
+ * Returned values are 0-359 degrees on success, negative
+ * error codes on failure.
+ *
* @set_phase: Shift the phase this clock signal in degrees specified
* by the second argument. Valid values for degrees are
* 0-359. Return 0 on success, otherwise -EERROR.
@@ -182,6 +186,7 @@ struct clk_ops {
unsigned long parent_rate, u8 index);
unsigned long (*recalc_accuracy)(struct clk_hw *hw,
unsigned long parent_accuracy);
+ int (*get_phase)(struct clk_hw *hw);
int (*set_phase)(struct clk_hw *hw, int degrees);
void (*init)(struct clk_hw *hw);
int (*debug_init)(struct clk_hw *hw, struct dentry *dentry);
--
2.1.0
--
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