Commit 19bdc9d0 authored by Magnus Damm's avatar Magnus Damm Committed by Paul Mundt
Browse files

clocksource: sh_cmt clocksource support 



Add clocksource support to the sh_cmt driver. With this in
place we can do tickless with a single CMT channel.

Signed-off-by: default avatarMagnus Damm <damm@igel.co.jp>
Signed-off-by: default avatarPaul Mundt <lethal@linux-sh.org>
parent 99ce567b

drivers/clocksource/sh_cmt.c

+66 −0
Original line number Diff line number Diff line
@@ -47,6 +47,7 @@ struct sh_cmt_priv { 
	unsigned long rate;

	spinlock_t lock;

	struct clock_event_device ced;

	struct clocksource cs;

	unsigned long total_cycles;

};
@@ -376,6 +377,68 @@ static void sh_cmt_stop(struct sh_cmt_priv *p, unsigned long flag) 
	spin_unlock_irqrestore(&p->lock, flags);

}



static struct sh_cmt_priv *cs_to_sh_cmt(struct clocksource *cs)

{

	return container_of(cs, struct sh_cmt_priv, cs);

}



static cycle_t sh_cmt_clocksource_read(struct clocksource *cs)

{

	struct sh_cmt_priv *p = cs_to_sh_cmt(cs);

	unsigned long flags, raw;

	unsigned long value;

	int has_wrapped;



	spin_lock_irqsave(&p->lock, flags);

	value = p->total_cycles;

	raw = sh_cmt_get_counter(p, &has_wrapped);



	if (unlikely(has_wrapped))

		raw = p->match_value;

	spin_unlock_irqrestore(&p->lock, flags);



	return value + raw;

}



static int sh_cmt_clocksource_enable(struct clocksource *cs)

{

	struct sh_cmt_priv *p = cs_to_sh_cmt(cs);

	int ret;



	p->total_cycles = 0;



	ret = sh_cmt_start(p, FLAG_CLOCKSOURCE);

	if (ret)

		return ret;



	/* TODO: calculate good shift from rate and counter bit width */

	cs->shift = 0;

	cs->mult = clocksource_hz2mult(p->rate, cs->shift);

	return 0;

}



static void sh_cmt_clocksource_disable(struct clocksource *cs)

{

	sh_cmt_stop(cs_to_sh_cmt(cs), FLAG_CLOCKSOURCE);

}



static int sh_cmt_register_clocksource(struct sh_cmt_priv *p,

				       char *name, unsigned long rating)

{

	struct clocksource *cs = &p->cs;



	cs->name = name;

	cs->rating = rating;

	cs->read = sh_cmt_clocksource_read;

	cs->enable = sh_cmt_clocksource_enable;

	cs->disable = sh_cmt_clocksource_disable;

	cs->mask = CLOCKSOURCE_MASK(sizeof(unsigned long) * 8);

	cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;

	pr_info("sh_cmt: %s used as clock source\n", cs->name);

	clocksource_register(cs);

	return 0;

}



static struct sh_cmt_priv *ced_to_sh_cmt(struct clock_event_device *ced)

{

	return container_of(ced, struct sh_cmt_priv, ced);
@@ -483,6 +546,9 @@ int sh_cmt_register(struct sh_cmt_priv *p, char *name, 
	if (clockevent_rating)

		sh_cmt_register_clockevent(p, name, clockevent_rating);



	if (clocksource_rating)

		sh_cmt_register_clocksource(p, name, clocksource_rating);



	return 0;

}