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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: Paul Walmsley <paul@pwsan.com>
Cc: Richard Woodruff <r-woodruff2@ti.com>
Cc: Rajendra Nayak <rnayak@ti.com>
hifive-unleashed-5.1
Paul Walmsley 2010-02-22 22:09:38 -07:00
parent 4d30e82c26
commit 30962d9d0c
2 changed files with 105 additions and 52 deletions
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147
arch/arm/mach-omap2/clock.c
View File

@ -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->clkdm)
omap2_clkdm_clk_disable(clk->clkdm, clk);
if (clk->usecount == 0) {
WARN(1, "clock: %s: omap2_clk_disable() called, but usecount "
"already 0?", clk->name);
return;
}
}
int omap2_clk_enable(struct clk *clk)
{
int ret = 0;
pr_debug("clock: %s: decrementing usecount\n", clk->name);
if (clk->usecount++ == 0) {
if (clk->clkdm)
omap2_clkdm_clk_enable(clk->clkdm, clk);
clk->usecount--;
if (clk->parent) {
ret = omap2_clk_enable(clk->parent);
if (ret)
goto err;
}
if (clk->usecount > 0)
return;
ret = _omap2_clk_enable(clk);
if (ret) {
if (clk->parent)
omap2_clk_disable(clk->parent);
pr_debug("clock: %s: disabling in hardware\n", clk->name);
goto err;
}
}
return ret;
clk->ops->disable(clk);
err:
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;
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) {
WARN(1, "clock: %s: could not enable parent %s: %d\n",
clk->name, clk->parent->name, ret);
goto oce_err1;
}
}
if (clk->clkdm) {
ret = omap2_clkdm_clk_enable(clk->clkdm, clk);
if (ret) {
WARN(1, "clock: %s: could not enable clockdomain %s: "
"%d\n", clk->name, clk->clkdm->name, ret);
goto oce_err2;
}
}
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);
}

10
arch/arm/mach-omap2/clockdomain.c
View File

@ -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) ||