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Commit e59c5371 authored by Mike Turquette's avatar Mike Turquette Committed by Maxime Ripard
Browse files

clk: introduce clk_set_phase function & callback 



A common operation for a clock signal generator is to shift the phase of
that signal. This patch introduces a new function to the clk.h API to
dynamically adjust the phase of a clock signal. Additionally this patch
introduces support for the new function in the common clock framework
via the .set_phase call back in struct clk_ops.

Signed-off-by: default avatarMike Turquette <mturquette@linaro.org>
Signed-off-by: default avatarMaxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: default avatarHeiko Stuebner <heiko@sntech.de>
Acked-by: default avatarHans de Goede <hdegoede@redhat.com>
parent cfe4c93b

drivers/clk/clk.c

+81 −4
Original line number Diff line number Diff line
@@ -117,11 +117,11 @@ static void clk_summary_show_one(struct seq_file *s, struct clk *c, int level) 
	if (!c)

		return;



	seq_printf(s, "%*s%-*s %11d %12d %11lu %10lu\n",

	seq_printf(s, "%*s%-*s %11d %12d %11lu %10lu %-3d\n",

		   level * 3 + 1, "",

		   30 - level * 3, c->name,

		   c->enable_count, c->prepare_count, clk_get_rate(c),

		   clk_get_accuracy(c));

		   clk_get_accuracy(c), clk_get_phase(c));

}



static void clk_summary_show_subtree(struct seq_file *s, struct clk *c,
@@ -143,8 +143,8 @@ static int clk_summary_show(struct seq_file *s, void *data) 
	struct clk *c;

	struct hlist_head **lists = (struct hlist_head **)s->private;



	seq_puts(s, "   clock                         enable_cnt  prepare_cnt        rate   accuracy\n");

	seq_puts(s, "--------------------------------------------------------------------------------\n");

	seq_puts(s, "   clock                         enable_cnt  prepare_cnt        rate   accuracy   phase\n");

	seq_puts(s, "----------------------------------------------------------------------------------------\n");



	clk_prepare_lock();
@@ -180,6 +180,7 @@ static void clk_dump_one(struct seq_file *s, struct clk *c, int level) 
	seq_printf(s, "\"prepare_count\": %d,", c->prepare_count);

	seq_printf(s, "\"rate\": %lu", clk_get_rate(c));

	seq_printf(s, "\"accuracy\": %lu", clk_get_accuracy(c));

	seq_printf(s, "\"phase\": %d", clk_get_phase(c));

}



static void clk_dump_subtree(struct seq_file *s, struct clk *c, int level)
@@ -264,6 +265,11 @@ static int clk_debug_create_one(struct clk *clk, struct dentry *pdentry) 
	if (!d)

		goto err_out;



	d = debugfs_create_u32("clk_phase", S_IRUGO, clk->dentry,

			(u32 *)&clk->phase);

	if (!d)

		goto err_out;



	d = debugfs_create_x32("clk_flags", S_IRUGO, clk->dentry,

			(u32 *)&clk->flags);

	if (!d)
@@ -1738,6 +1744,77 @@ int clk_set_parent(struct clk *clk, struct clk *parent) 
}

EXPORT_SYMBOL_GPL(clk_set_parent);



/**

 * clk_set_phase - adjust the phase shift of a clock signal

 * @clk: clock signal source

 * @degrees: number of degrees the signal is shifted

 *

 * Shifts the phase of a clock signal by the specified

 * degrees. Returns 0 on success, -EERROR otherwise.

 *

 * This function makes no distinction about the input or reference

 * signal that we adjust the clock signal phase against. For example

 * phase locked-loop clock signal generators we may shift phase with

 * respect to feedback clock signal input, but for other cases the

 * clock phase may be shifted with respect to some other, unspecified

 * signal.

 *

 * Additionally the concept of phase shift does not propagate through

 * the clock tree hierarchy, which sets it apart from clock rates and

 * clock accuracy. A parent clock phase attribute does not have an

 * impact on the phase attribute of a child clock.

 */

int clk_set_phase(struct clk *clk, int degrees)

{

	int ret = 0;



	if (!clk)

		goto out;



	/* sanity check degrees */

	degrees %= 360;

	if (degrees < 0)

		degrees += 360;



	clk_prepare_lock();



	if (!clk->ops->set_phase)

		goto out_unlock;



	ret = clk->ops->set_phase(clk->hw, degrees);



	if (!ret)

		clk->phase = degrees;



out_unlock:

	clk_prepare_unlock();



out:

	return ret;

}



/**

 * clk_get_phase - return the phase shift of a clock signal

 * @clk: clock signal source

 *

 * Returns the phase shift of a clock node in degrees, otherwise returns

 * -EERROR.

 */

int clk_get_phase(struct clk *clk)

{

	int ret = 0;



	if (!clk)

		goto out;



	clk_prepare_lock();

	ret = clk->phase;

	clk_prepare_unlock();



out:

	return ret;

}



/**

 * __clk_init - initialize the data structures in a struct clk

 * @dev:	device initializing this clk, placeholder for now

include/linux/clk-private.h

+1 −0
Original line number Diff line number Diff line
@@ -46,6 +46,7 @@ struct clk { 
	unsigned int		enable_count;

	unsigned int		prepare_count;

	unsigned long		accuracy;

	int			phase;

	struct hlist_head	children;

	struct hlist_node	child_node;

	unsigned int		notifier_count;

include/linux/clk-provider.h

+5 −0
Original line number Diff line number Diff line
@@ -129,6 +129,10 @@ struct dentry; 
 *		set then clock accuracy will be initialized to parent accuracy

 *		or 0 (perfect clock) if clock has no parent.

 *

 * @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.

 *

 * @init:	Perform platform-specific initialization magic.

 *		This is not not used by any of the basic clock types.

 *		Please consider other ways of solving initialization problems
@@ -177,6 +181,7 @@ struct clk_ops { 
				    unsigned long parent_rate, u8 index);

	unsigned long	(*recalc_accuracy)(struct clk_hw *hw,

					   unsigned long parent_accuracy);

	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);

};

include/linux/clk.h

+29 −0
Original line number Diff line number Diff line
@@ -106,6 +106,25 @@ int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb); 
 */

long clk_get_accuracy(struct clk *clk);



/**

 * clk_set_phase - adjust the phase shift of a clock signal

 * @clk: clock signal source

 * @degrees: number of degrees the signal is shifted

 *

 * Shifts the phase of a clock signal by the specified degrees. Returns 0 on

 * success, -EERROR otherwise.

 */

int clk_set_phase(struct clk *clk, int degrees);



/**

 * clk_get_phase - return the phase shift of a clock signal

 * @clk: clock signal source

 *

 * Returns the phase shift of a clock node in degrees, otherwise returns

 * -EERROR.

 */

int clk_get_phase(struct clk *clk);



#else



static inline long clk_get_accuracy(struct clk *clk)
@@ -113,6 +132,16 @@ static inline long clk_get_accuracy(struct clk *clk) 
	return -ENOTSUPP;

}



static inline long clk_set_phase(struct clk *clk, int phase)

{

	return -ENOTSUPP;

}



static inline long clk_get_phase(struct clk *clk)

{

	return -ENOTSUPP;

}



#endif



/**