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OMAP2+: hwmod: upgrade per-hwmod mutex to a spinlock

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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
848240223c - 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>
This commit is contained in:
Paul Walmsley 2010-12-14 12:42:35 -07:00
parent bd36179eec
commit dc6d1cda04
3 changed files with 64 additions and 56 deletions
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6
arch/arm/plat-omap/include/plat/omap_hwmod.h
View file

@ -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;