[PATCH 6/8] OMAP2+: hwmod: upgrade per-hwmod mutex to a spinlock
Paul Walmsley
paul at pwsan.com
Tue Nov 16 05:18:10 EST 2010
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 at deeprootsystems.com> originally proposed this
patch - thanks Kevin.
Signed-off-by: Paul Walmsley <paul at pwsan.com>
Cc: Kevin Hilman <khilman at deeprootsystems.com>
Cc: Benoît Cousson <b-cousson at ti.com>
---
arch/arm/mach-omap2/omap_hwmod.c | 105 +++++++++++++++-----------
arch/arm/mach-omap2/serial.c | 9 --
arch/arm/plat-omap/include/plat/omap_hwmod.h | 6 +
3 files changed, 64 insertions(+), 56 deletions(-)
diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
index 0e85278..589c282 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>
@@ -1193,17 +1194,14 @@ static int _reset(struct omap_hwmod *oh)
}
/**
- * _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;
@@ -1250,16 +1248,14 @@ int _omap_hwmod_enable(struct omap_hwmod *oh)
}
/**
- * _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 "
@@ -1305,11 +1301,11 @@ static int _shutdown(struct omap_hwmod *oh)
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;
}
}
@@ -1382,7 +1378,7 @@ static int _setup(struct omap_hwmod *oh, void *data)
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);
@@ -1394,7 +1390,7 @@ static int _setup(struct omap_hwmod *oh, void *data)
/*
* 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) {
@@ -1416,7 +1412,7 @@ static int _setup(struct omap_hwmod *oh, void *data)
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)
@@ -1522,7 +1518,7 @@ int omap_hwmod_register(struct omap_hwmod *oh)
list_add_tail(&oh->node, &omap_hwmod_list);
- mutex_init(&oh->_mutex);
+ spin_lock_init(&oh->_lock);
oh->_state = _HWMOD_STATE_REGISTERED;
@@ -1682,18 +1678,18 @@ int omap_hwmod_unregister(struct omap_hwmod *oh)
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 *
@@ -1703,12 +1699,14 @@ int omap_hwmod_enable(struct omap_hwmod *oh)
*/
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;
}
@@ -1723,12 +1721,14 @@ int omap_hwmod_idle(struct omap_hwmod *oh)
*/
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;
}
@@ -1741,9 +1741,11 @@ int omap_hwmod_shutdown(struct omap_hwmod *oh)
*/
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;
}
@@ -1756,9 +1758,11 @@ int omap_hwmod_enable_clocks(struct omap_hwmod *oh)
*/
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;
}
@@ -1802,13 +1806,14 @@ void omap_hwmod_ocp_barrier(struct omap_hwmod *oh)
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;
}
@@ -2005,13 +2010,15 @@ int omap_hwmod_del_initiator_dep(struct omap_hwmod *oh,
*/
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;
}
@@ -2030,13 +2037,15 @@ int omap_hwmod_enable_wakeup(struct omap_hwmod *oh)
*/
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;
}
@@ -2056,13 +2065,14 @@ int omap_hwmod_disable_wakeup(struct omap_hwmod *oh)
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;
}
@@ -2082,13 +2092,14 @@ int omap_hwmod_assert_hardreset(struct omap_hwmod *oh, const char *name)
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;
}
@@ -2107,13 +2118,14 @@ int omap_hwmod_deassert_hardreset(struct omap_hwmod *oh, const char *name)
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;
}
@@ -2181,6 +2193,7 @@ int omap_hwmod_for_each_by_class(const char *classname,
int omap_hwmod_set_postsetup_state(struct omap_hwmod *oh, u8 state)
{
int ret;
+ unsigned long flags;
if (!oh)
return -EINVAL;
@@ -2190,7 +2203,7 @@ int omap_hwmod_set_postsetup_state(struct omap_hwmod *oh, u8 state)
state != _HWMOD_STATE_IDLE)
return -EINVAL;
- mutex_lock(&oh->_mutex);
+ spin_lock_irqsave(&oh->_lock, flags);
if (oh->_state != _HWMOD_STATE_REGISTERED) {
ret = -EINVAL;
@@ -2201,7 +2214,7 @@ int omap_hwmod_set_postsetup_state(struct omap_hwmod *oh, u8 state)
ret = 0;
ohsps_unlock:
- mutex_unlock(&oh->_mutex);
+ spin_unlock_irqrestore(&oh->_lock, flags);
return ret;
}
diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
index becf0e3..1be0031 100644
--- a/arch/arm/mach-omap2/serial.c
+++ b/arch/arm/mach-omap2/serial.c
@@ -105,21 +105,16 @@ struct omap_uart_state {
static LIST_HEAD(uart_list);
static u8 num_uarts;
-/*
- * Since these idle/enable hooks are used in the idle path itself
- * which has interrupts disabled, use the non-locking versions of
- * the hwmod enable/disable functions.
- */
static int uart_idle_hwmod(struct omap_device *od)
{
- _omap_hwmod_idle(od->hwmods[0]);
+ omap_hwmod_idle(od->hwmods[0]);
return 0;
}
static int uart_enable_hwmod(struct omap_device *od)
{
- _omap_hwmod_enable(od->hwmods[0]);
+ omap_hwmod_enable(od->hwmods[0]);
return 0;
}
diff --git a/arch/arm/plat-omap/include/plat/omap_hwmod.h b/arch/arm/plat-omap/include/plat/omap_hwmod.h
index e4c4fd4..b588f47 100644
--- a/arch/arm/plat-omap/include/plat/omap_hwmod.h
+++ b/arch/arm/plat-omap/include/plat/omap_hwmod.h
@@ -32,7 +32,7 @@
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/ioport.h>
-#include <linux/mutex.h>
+#include <linux/spinlock.h>
#include <plat/cpu.h>
struct omap_device;
@@ -472,7 +472,7 @@ struct omap_hwmod_class {
* @_postsetup_state: internal-use state to leave the hwmod in after _setup()
* @flags: hwmod flags (documented below)
* @omap_chip: OMAP chips this hwmod is present on
- * @_mutex: mutex serializing operations on this hwmod
+ * @_lock: spinlock serializing operations on this hwmod
* @node: list node for hwmod list (internal use)
*
* @main_clk refers to this module's "main clock," which for our
@@ -502,7 +502,7 @@ struct omap_hwmod {
void *dev_attr;
u32 _sysc_cache;
void __iomem *_mpu_rt_va;
- struct mutex _mutex;
+ spinlock_t _lock;
struct list_head node;
u16 flags;
u8 _mpu_port_index;
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