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clk: Add a function to retrieve phase

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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.ripard@free-electrons.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Hans de Goede <hdegoede@redhat.com>
This commit is contained in:
Maxime Ripard 2014-07-14 13:53:27 +02:00
parent 355bb165cd
commit 9824cf73c3
2 changed files with 15 additions and 0 deletions
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10
drivers/clk/clk.c
View File

@ -1933,6 +1933,16 @@ int __clk_init(struct device *dev, struct clk *clk)
else else
clk->accuracy = 0; 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 * 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 * simple clocks and lazy developers the default fallback is to use the

5
include/linux/clk-provider.h
View File

@ -130,6 +130,10 @@ struct dentry;
* set then clock accuracy will be initialized to parent accuracy * set then clock accuracy will be initialized to parent accuracy
* or 0 (perfect clock) if clock has no parent. * 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 * @set_phase: Shift the phase this clock signal in degrees specified
* by the second argument. Valid values for degrees are * by the second argument. Valid values for degrees are
* 0-359. Return 0 on success, otherwise -EERROR. * 0-359. Return 0 on success, otherwise -EERROR.
@ -182,6 +186,7 @@ struct clk_ops {
unsigned long parent_rate, u8 index); unsigned long parent_rate, u8 index);
unsigned long (*recalc_accuracy)(struct clk_hw *hw, unsigned long (*recalc_accuracy)(struct clk_hw *hw,
unsigned long parent_accuracy); unsigned long parent_accuracy);
int (*get_phase)(struct clk_hw *hw);
int (*set_phase)(struct clk_hw *hw, int degrees); int (*set_phase)(struct clk_hw *hw, int degrees);
void (*init)(struct clk_hw *hw); void (*init)(struct clk_hw *hw);
int (*debug_init)(struct clk_hw *hw, struct dentry *dentry); int (*debug_init)(struct clk_hw *hw, struct dentry *dentry);