Commit dc6d1cda authored by Paul Walmsley's avatar Paul Walmsley
Browse files

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
84824022 - 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: default avatarPaul Walmsley <paul@pwsan.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Benoît Cousson <b-cousson@ti.com>
parent bd36179e

arch/arm/mach-omap2/omap_hwmod.c

+59 −46
Original line number Diff line number Diff line
@@ -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 @@ 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;
@@ -1249,16 +1247,14 @@ 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 "
@@ -1304,11 +1300,11 @@ 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;

		}

	}
@@ -1381,7 +1377,7 @@ 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);
@@ -1393,7 +1389,7 @@ 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) {
@@ -1415,7 +1411,7 @@ 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)
@@ -1521,7 +1517,7 @@ 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;
@@ -1681,18 +1677,18 @@ 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 *
@@ -1702,12 +1698,14 @@ 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;

}
@@ -1722,12 +1720,14 @@ 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;

}
@@ -1740,9 +1740,11 @@ 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;

}
@@ -1755,9 +1757,11 @@ 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;

}
@@ -1801,13 +1805,14 @@ 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;

}
@@ -2004,13 +2009,15 @@ 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;

}
@@ -2029,13 +2036,15 @@ 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;

}
@@ -2055,13 +2064,14 @@ 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;

}
@@ -2081,13 +2091,14 @@ 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;

}
@@ -2106,13 +2117,14 @@ 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;

}
@@ -2180,6 +2192,7 @@ 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;
@@ -2189,7 +2202,7 @@ 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;
@@ -2200,7 +2213,7 @@ 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;

}

arch/arm/mach-omap2/serial.c

+2 −7
Original line number Diff line number Diff line
@@ -106,21 +106,16 @@ 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;

}

arch/arm/plat-omap/include/plat/omap_hwmod.h

+3 −3
Original line number Diff line number Diff line
@@ -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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