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Commit 30962d9d authored by Paul Walmsley's avatar Paul Walmsley
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OMAP2+ clock: revise omap2_clk_{disable,enable}() 



Simplify the code in the omap2_clk_disable() and omap2_clk_enable()
functions, reducing levels of indentation.  This makes the code easier
to read.  Add some additional debugging pr_debug()s here also to help
others understand what is going on.

Revise the omap2_clk_disable() logic so that it now attempts to
disable the clock's clockdomain before recursing up the clock tree.
Simultaneously, ensure that omap2_clk_enable() is called on parent
clocks first, before enabling the clockdomain.  This ensures that a
parent clock's clockdomain is enabled before the child clock's
clockdomain.  These sequences should be the inverse of each other.

Revise the omap2_clk_enable() logic so that it now cleans up after
itself upon encountering an error.  Previously, an error enabling a
parent clock could have resulted in inconsistent usecounts on the
enclosing clockdomain.

Remove the trivial _omap2_clk_disable() and _omap2_clk_enable() static
functions, and replace it with the clkops calls that they were
executing.

For all this to work, the clockdomain omap2_clkdm_clk_enable() and
omap2_clkdm_clk_disable() code must not return an error on clockdomains
without CLKSTCTRL registers; so modify those functions to simply return 0
in that case.

While here, add some basic kerneldoc documentation on both functions,
and get rid of some old non-CodingStyle-compliant comments that have
existed since the dawn of time (at least, the OMAP clock framework's
time).

Signed-off-by: default avatarPaul Walmsley <paul@pwsan.com>
Cc: Richard Woodruff <r-woodruff2@ti.com>
Cc: Rajendra Nayak <rnayak@ti.com>
parent 4d30e82c

arch/arm/mach-omap2/clock.c

+91 −44
Original line number Diff line number Diff line
@@ -37,9 +37,9 @@ 


u8 cpu_mask;



/*-------------------------------------------------------------------------

 * OMAP2/3/4 specific clock functions

 *-------------------------------------------------------------------------*/

/*

 * OMAP2+ specific clock functions

 */



/* Private functions */
@@ -71,20 +71,6 @@ static void _omap2_module_wait_ready(struct clk *clk) 
			     clk->name);

}



/* Enables clock without considering parent dependencies or use count

 * REVISIT: Maybe change this to use clk->enable like on omap1?

 */

static int _omap2_clk_enable(struct clk *clk)

{

	return clk->ops->enable(clk);

}



/* Disables clock without considering parent dependencies or use count */

static void _omap2_clk_disable(struct clk *clk)

{

	clk->ops->disable(clk);

}



/* Public functions */



/**
@@ -245,46 +231,106 @@ const struct clkops clkops_omap2_dflt = { 
	.disable	= omap2_dflt_clk_disable,

};



/**

 * omap2_clk_disable - disable a clock, if the system is not using it

 * @clk: struct clk * to disable

 *

 * Decrements the usecount on struct clk @clk.  If there are no users

 * left, call the clkops-specific clock disable function to disable it

 * in hardware.  If the clock is part of a clockdomain (which they all

 * should be), request that the clockdomain be disabled.  (It too has

 * a usecount, and so will not be disabled in the hardware until it no

 * longer has any users.)  If the clock has a parent clock (most of

 * them do), then call ourselves, recursing on the parent clock.  This

 * can cause an entire branch of the clock tree to be powered off by

 * simply disabling one clock.  Intended to be called with the clockfw_lock

 * spinlock held.  No return value.

 */

void omap2_clk_disable(struct clk *clk)

{

	if (clk->usecount > 0 && !(--clk->usecount)) {

		_omap2_clk_disable(clk);

		if (clk->parent)

			omap2_clk_disable(clk->parent);

	if (clk->usecount == 0) {

		WARN(1, "clock: %s: omap2_clk_disable() called, but usecount "

		     "already 0?", clk->name);

		return;

	}



	pr_debug("clock: %s: decrementing usecount\n", clk->name);



	clk->usecount--;



	if (clk->usecount > 0)

		return;



	pr_debug("clock: %s: disabling in hardware\n", clk->name);



	clk->ops->disable(clk);



	if (clk->clkdm)

		omap2_clkdm_clk_disable(clk->clkdm, clk);



	}

	if (clk->parent)

		omap2_clk_disable(clk->parent);

}



/**

 * omap2_clk_enable - request that the system enable a clock

 * @clk: struct clk * to enable

 *

 * Increments the usecount on struct clk @clk.  If there were no users

 * previously, then recurse up the clock tree, enabling all of the

 * clock's parents and all of the parent clockdomains, and finally,

 * enabling @clk's clockdomain, and @clk itself.  Intended to be

 * called with the clockfw_lock spinlock held.  Returns 0 upon success

 * or a negative error code upon failure.

 */

int omap2_clk_enable(struct clk *clk)

{

	int ret = 0;

	int ret;



	if (clk->usecount++ == 0) {

		if (clk->clkdm)

			omap2_clkdm_clk_enable(clk->clkdm, clk);

	pr_debug("clock: %s: incrementing usecount\n", clk->name);



	clk->usecount++;



	if (clk->usecount > 1)

		return 0;



	pr_debug("clock: %s: enabling in hardware\n", clk->name);



	if (clk->parent) {

		ret = omap2_clk_enable(clk->parent);

			if (ret)

				goto err;

		if (ret) {

			WARN(1, "clock: %s: could not enable parent %s: %d\n",

			     clk->name, clk->parent->name, ret);

			goto oce_err1;

		}

	}



		ret = _omap2_clk_enable(clk);

	if (clk->clkdm) {

		ret = omap2_clkdm_clk_enable(clk->clkdm, clk);

		if (ret) {

			if (clk->parent)

				omap2_clk_disable(clk->parent);



			goto err;

			WARN(1, "clock: %s: could not enable clockdomain %s: "

			     "%d\n", clk->name, clk->clkdm->name, ret);

			goto oce_err2;

		}

	}

	return ret;



err:

	ret = clk->ops->enable(clk);

	if (ret) {

		WARN(1, "clock: %s: could not enable: %d\n", clk->name, ret);

		goto oce_err3;

	}



	return 0;



oce_err3:

	if (clk->clkdm)

		omap2_clkdm_clk_disable(clk->clkdm, clk);

oce_err2:

	if (clk->parent)

		omap2_clk_disable(clk->parent);

oce_err1:

	clk->usecount--;



	return ret;

}
@@ -325,9 +371,9 @@ const struct clkops clkops_omap3_noncore_dpll_ops = { 
#endif





/*-------------------------------------------------------------------------

 * Omap2 clock reset and init functions

 *-------------------------------------------------------------------------*/

/*

 * OMAP2+ clock reset and init functions

 */



#ifdef CONFIG_OMAP_RESET_CLOCKS

void omap2_clk_disable_unused(struct clk *clk)
@@ -344,8 +390,9 @@ void omap2_clk_disable_unused(struct clk *clk) 
	if (cpu_is_omap34xx()) {

		omap2_clk_enable(clk);

		omap2_clk_disable(clk);

	} else

		_omap2_clk_disable(clk);

	} else {

		clk->ops->disable(clk);

	}

	if (clk->clkdm != NULL)

		pwrdm_clkdm_state_switch(clk->clkdm);

}

arch/arm/mach-omap2/clockdomain.c

+8 −2
Original line number Diff line number Diff line
@@ -978,7 +978,7 @@ int omap2_clkdm_clk_enable(struct clockdomain *clkdm, struct clk *clk) 
	 * downstream clocks for debugging purposes?

	 */



	if (!clkdm || !clk || !clkdm->clkstctrl_reg)

	if (!clkdm || !clk)

		return -EINVAL;



	if (atomic_inc_return(&clkdm->usecount) > 1)
@@ -989,6 +989,9 @@ int omap2_clkdm_clk_enable(struct clockdomain *clkdm, struct clk *clk) 
	pr_debug("clockdomain: clkdm %s: clk %s now enabled\n", clkdm->name,

		 clk->name);



	if (!clkdm->clkstctrl_reg)

		return 0;



	v = omap2_clkdm_clktrctrl_read(clkdm);



	if ((cpu_is_omap34xx() && v == OMAP34XX_CLKSTCTRL_ENABLE_AUTO) ||
@@ -1030,7 +1033,7 @@ int omap2_clkdm_clk_disable(struct clockdomain *clkdm, struct clk *clk) 
	 * downstream clocks for debugging purposes?

	 */



	if (!clkdm || !clk || !clkdm->clkstctrl_reg)

	if (!clkdm || !clk)

		return -EINVAL;



#ifdef DEBUG
@@ -1048,6 +1051,9 @@ int omap2_clkdm_clk_disable(struct clockdomain *clkdm, struct clk *clk) 
	pr_debug("clockdomain: clkdm %s: clk %s now disabled\n", clkdm->name,

		 clk->name);



	if (!clkdm->clkstctrl_reg)

		return 0;



	v = omap2_clkdm_clktrctrl_read(clkdm);



	if ((cpu_is_omap34xx() && v == OMAP34XX_CLKSTCTRL_ENABLE_AUTO) ||