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@xxxxxxxxx>
Cc: Richard Woodruff <r-woodruff2@xxxxxx>
Cc: Rajendra Nayak <rnayak@xxxxxx>
---
arch/arm/mach-omap2/clock.c | 135 +++++++++++++++++++++++++------------
arch/arm/mach-omap2/clockdomain.c | 10 ++-
2 files changed, 99 insertions(+), 46 deletions(-)
diff --git a/arch/arm/mach-omap2/clock.c b/arch/arm/mach-omap2/clock.c
index d1f115d..a6d0b34 100644
--- a/arch/arm/mach-omap2/clock.c
+++ b/arch/arm/mach-omap2/clock.c
@@ -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;
}
+
+ 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);
- if (clk->parent) {
- ret = omap2_clk_enable(clk->parent);
- if (ret)
- goto err;
- }
+ clk->usecount++;
+
+ if (clk->usecount > 1)
+ return 0;
- ret = _omap2_clk_enable(clk);
+ pr_debug("clock: %s: enabling in hardware\n", clk->name);
+
+ if (clk->parent) {
+ ret = omap2_clk_enable(clk->parent);
if (ret) {
- if (clk->parent)
- omap2_clk_disable(clk->parent);
+ WARN(1, "clock: %s: could not enable parent %s: %d\n",
+ clk->name, clk->parent->name, ret);
+ goto oce_err1;
+ }
+ }
- goto err;
+ 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;
}
}
- 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);
}
diff --git a/arch/arm/mach-omap2/clockdomain.c b/arch/arm/mach-omap2/clockdomain.c
index b26d30a..b87ad66 100644
--- a/arch/arm/mach-omap2/clockdomain.c
+++ b/arch/arm/mach-omap2/clockdomain.c
@@ -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) ||
--
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