OMAP2+: hwmod: upgrade per-hwmod mutex to a spinlock
Change the per-hwmod mutex to a spinlock. (The per-hwmod lock
serializes most post-initialization hwmod operations such as enable,
idle, and shutdown.) Spinlocks are needed, because in some cases,
hwmods must be enabled from timer interrupt disabled-context, such as
an ISR. The current use-case that is driving this is the OMAP GPIO
block ISR: it can trigger interrupts even with its clocks disabled,
but these clocks are needed for register accesses in the ISR to succeed.
This patch also effectively reverts commit
848240223c35fcc71c424ad51a8e8aef42d3879c - this patch makes
_omap_hwmod_enable() and _omap_hwmod_init() static, renames them back
to _enable() and _idle(), and changes their callers to call the
spinlocking versions. Previously, since omap_hwmod_{enable,init}()
attempted to take mutexes, these functions could not be called while
the timer interrupt was disabled; but now that the functions use
spinlocks and save and restore the IRQ state, it is appropriate to
call them directly.
Kevin Hilman <khilman@deeprootsystems.com> originally proposed this
patch - thanks Kevin.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Benoît Cousson <b-cousson@ti.com>
diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
index 12a0b9a..31990e9 100644
--- a/arch/arm/mach-omap2/omap_hwmod.c
+++ b/arch/arm/mach-omap2/omap_hwmod.c
@@ -135,6 +135,7 @@
#include <linux/err.h>
#include <linux/list.h>
#include <linux/mutex.h>
+#include <linux/spinlock.h>
#include <plat/common.h>
#include <plat/cpu.h>
@@ -1192,17 +1193,14 @@
}
/**
- * _omap_hwmod_enable - enable an omap_hwmod
+ * _enable - enable an omap_hwmod
* @oh: struct omap_hwmod *
*
* Enables an omap_hwmod @oh such that the MPU can access the hwmod's
- * register target. (This function has a full name --
- * _omap_hwmod_enable() rather than simply _enable() -- because it is
- * currently required by the pm34xx.c idle loop.) Returns -EINVAL if
- * the hwmod is in the wrong state or passes along the return value of
- * _wait_target_ready().
+ * register target. Returns -EINVAL if the hwmod is in the wrong
+ * state or passes along the return value of _wait_target_ready().
*/
-int _omap_hwmod_enable(struct omap_hwmod *oh)
+static int _enable(struct omap_hwmod *oh)
{
int r;
@@ -1249,16 +1247,14 @@
}
/**
- * _omap_hwmod_idle - idle an omap_hwmod
+ * _idle - idle an omap_hwmod
* @oh: struct omap_hwmod *
*
* Idles an omap_hwmod @oh. This should be called once the hwmod has
- * no further work. (This function has a full name --
- * _omap_hwmod_idle() rather than simply _idle() -- because it is
- * currently required by the pm34xx.c idle loop.) Returns -EINVAL if
- * the hwmod is in the wrong state or returns 0.
+ * no further work. Returns -EINVAL if the hwmod is in the wrong
+ * state or returns 0.
*/
-int _omap_hwmod_idle(struct omap_hwmod *oh)
+static int _idle(struct omap_hwmod *oh)
{
if (oh->_state != _HWMOD_STATE_ENABLED) {
WARN(1, "omap_hwmod: %s: idle state can only be entered from "
@@ -1304,11 +1300,11 @@
if (oh->class->pre_shutdown) {
prev_state = oh->_state;
if (oh->_state == _HWMOD_STATE_IDLE)
- _omap_hwmod_enable(oh);
+ _enable(oh);
ret = oh->class->pre_shutdown(oh);
if (ret) {
if (prev_state == _HWMOD_STATE_IDLE)
- _omap_hwmod_idle(oh);
+ _idle(oh);
return ret;
}
}
@@ -1381,7 +1377,7 @@
if ((oh->flags & HWMOD_INIT_NO_RESET) && oh->rst_lines_cnt == 1)
return 0;
- r = _omap_hwmod_enable(oh);
+ r = _enable(oh);
if (r) {
pr_warning("omap_hwmod: %s: cannot be enabled (%d)\n",
oh->name, oh->_state);
@@ -1393,7 +1389,7 @@
/*
* OCP_SYSCONFIG bits need to be reprogrammed after a softreset.
- * The _omap_hwmod_enable() function should be split to
+ * The _enable() function should be split to
* avoid the rewrite of the OCP_SYSCONFIG register.
*/
if (oh->class->sysc) {
@@ -1415,7 +1411,7 @@
postsetup_state = _HWMOD_STATE_ENABLED;
if (postsetup_state == _HWMOD_STATE_IDLE)
- _omap_hwmod_idle(oh);
+ _idle(oh);
else if (postsetup_state == _HWMOD_STATE_DISABLED)
_shutdown(oh);
else if (postsetup_state != _HWMOD_STATE_ENABLED)
@@ -1521,7 +1517,7 @@
list_add_tail(&oh->node, &omap_hwmod_list);
- mutex_init(&oh->_mutex);
+ spin_lock_init(&oh->_lock);
oh->_state = _HWMOD_STATE_REGISTERED;
@@ -1681,18 +1677,18 @@
int omap_hwmod_enable(struct omap_hwmod *oh)
{
int r;
+ unsigned long flags;
if (!oh)
return -EINVAL;
- mutex_lock(&oh->_mutex);
- r = _omap_hwmod_enable(oh);
- mutex_unlock(&oh->_mutex);
+ spin_lock_irqsave(&oh->_lock, flags);
+ r = _enable(oh);
+ spin_unlock_irqrestore(&oh->_lock, flags);
return r;
}
-
/**
* omap_hwmod_idle - idle an omap_hwmod
* @oh: struct omap_hwmod *
@@ -1702,12 +1698,14 @@
*/
int omap_hwmod_idle(struct omap_hwmod *oh)
{
+ unsigned long flags;
+
if (!oh)
return -EINVAL;
- mutex_lock(&oh->_mutex);
- _omap_hwmod_idle(oh);
- mutex_unlock(&oh->_mutex);
+ spin_lock_irqsave(&oh->_lock, flags);
+ _idle(oh);
+ spin_unlock_irqrestore(&oh->_lock, flags);
return 0;
}
@@ -1722,12 +1720,14 @@
*/
int omap_hwmod_shutdown(struct omap_hwmod *oh)
{
+ unsigned long flags;
+
if (!oh)
return -EINVAL;
- mutex_lock(&oh->_mutex);
+ spin_lock_irqsave(&oh->_lock, flags);
_shutdown(oh);
- mutex_unlock(&oh->_mutex);
+ spin_unlock_irqrestore(&oh->_lock, flags);
return 0;
}
@@ -1740,9 +1740,11 @@
*/
int omap_hwmod_enable_clocks(struct omap_hwmod *oh)
{
- mutex_lock(&oh->_mutex);
+ unsigned long flags;
+
+ spin_lock_irqsave(&oh->_lock, flags);
_enable_clocks(oh);
- mutex_unlock(&oh->_mutex);
+ spin_unlock_irqrestore(&oh->_lock, flags);
return 0;
}
@@ -1755,9 +1757,11 @@
*/
int omap_hwmod_disable_clocks(struct omap_hwmod *oh)
{
- mutex_lock(&oh->_mutex);
+ unsigned long flags;
+
+ spin_lock_irqsave(&oh->_lock, flags);
_disable_clocks(oh);
- mutex_unlock(&oh->_mutex);
+ spin_unlock_irqrestore(&oh->_lock, flags);
return 0;
}
@@ -1801,13 +1805,14 @@
int omap_hwmod_reset(struct omap_hwmod *oh)
{
int r;
+ unsigned long flags;
if (!oh)
return -EINVAL;
- mutex_lock(&oh->_mutex);
+ spin_lock_irqsave(&oh->_lock, flags);
r = _reset(oh);
- mutex_unlock(&oh->_mutex);
+ spin_unlock_irqrestore(&oh->_lock, flags);
return r;
}
@@ -2004,13 +2009,15 @@
*/
int omap_hwmod_enable_wakeup(struct omap_hwmod *oh)
{
+ unsigned long flags;
+
if (!oh->class->sysc ||
!(oh->class->sysc->sysc_flags & SYSC_HAS_ENAWAKEUP))
return -EINVAL;
- mutex_lock(&oh->_mutex);
+ spin_lock_irqsave(&oh->_lock, flags);
_enable_wakeup(oh);
- mutex_unlock(&oh->_mutex);
+ spin_unlock_irqrestore(&oh->_lock, flags);
return 0;
}
@@ -2029,13 +2036,15 @@
*/
int omap_hwmod_disable_wakeup(struct omap_hwmod *oh)
{
+ unsigned long flags;
+
if (!oh->class->sysc ||
!(oh->class->sysc->sysc_flags & SYSC_HAS_ENAWAKEUP))
return -EINVAL;
- mutex_lock(&oh->_mutex);
+ spin_lock_irqsave(&oh->_lock, flags);
_disable_wakeup(oh);
- mutex_unlock(&oh->_mutex);
+ spin_unlock_irqrestore(&oh->_lock, flags);
return 0;
}
@@ -2055,13 +2064,14 @@
int omap_hwmod_assert_hardreset(struct omap_hwmod *oh, const char *name)
{
int ret;
+ unsigned long flags;
if (!oh)
return -EINVAL;
- mutex_lock(&oh->_mutex);
+ spin_lock_irqsave(&oh->_lock, flags);
ret = _assert_hardreset(oh, name);
- mutex_unlock(&oh->_mutex);
+ spin_unlock_irqrestore(&oh->_lock, flags);
return ret;
}
@@ -2081,13 +2091,14 @@
int omap_hwmod_deassert_hardreset(struct omap_hwmod *oh, const char *name)
{
int ret;
+ unsigned long flags;
if (!oh)
return -EINVAL;
- mutex_lock(&oh->_mutex);
+ spin_lock_irqsave(&oh->_lock, flags);
ret = _deassert_hardreset(oh, name);
- mutex_unlock(&oh->_mutex);
+ spin_unlock_irqrestore(&oh->_lock, flags);
return ret;
}
@@ -2106,13 +2117,14 @@
int omap_hwmod_read_hardreset(struct omap_hwmod *oh, const char *name)
{
int ret;
+ unsigned long flags;
if (!oh)
return -EINVAL;
- mutex_lock(&oh->_mutex);
+ spin_lock_irqsave(&oh->_lock, flags);
ret = _read_hardreset(oh, name);
- mutex_unlock(&oh->_mutex);
+ spin_unlock_irqrestore(&oh->_lock, flags);
return ret;
}
@@ -2180,6 +2192,7 @@
int omap_hwmod_set_postsetup_state(struct omap_hwmod *oh, u8 state)
{
int ret;
+ unsigned long flags;
if (!oh)
return -EINVAL;
@@ -2189,7 +2202,7 @@
state != _HWMOD_STATE_IDLE)
return -EINVAL;
- mutex_lock(&oh->_mutex);
+ spin_lock_irqsave(&oh->_lock, flags);
if (oh->_state != _HWMOD_STATE_REGISTERED) {
ret = -EINVAL;
@@ -2200,7 +2213,7 @@
ret = 0;
ohsps_unlock:
- mutex_unlock(&oh->_mutex);
+ spin_unlock_irqrestore(&oh->_lock, flags);
return ret;
}