Revision 36a8032d77649430f5ef11fbf0df2bb026be0b04 authored by Linus Torvalds on 26 April 2015, 20:36:02 UTC, committed by Linus Torvalds on 26 April 2015, 20:36:02 UTC
Pull chrome platform updates from Olof Johansson: "Here's a set of updates to the Chrome OS platform drivers for this merge window. Main new things this cycle is: - Driver changes to expose the lightbar to users. With this, you can make your own blinkenlights on Chromebook Pixels. - Changes in the way that the atmel_mxt trackpads are probed. The laptop driver is trying to be smart and not instantiate the devices that don't answer to probe. For the trackpad that can come up in two modes (bootloader or regular), this gets complicated since the driver already knows how to handle the two modes including the actual addresses used. So now the laptop driver needs to know more too, instantiating the regular address even if the bootloader one is the probe that passed. - mfd driver improvements by Javier Martines Canillas, and a few bugfixes from him, kbuild and myself" * tag 'chrome-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/olof/chrome-platform: platform/chrome: chromeos_laptop - instantiate Atmel at primary address platform/chrome: cros_ec_lpc - Depend on X86 || COMPILE_TEST platform/chrome: cros_ec_lpc - Include linux/io.h header file platform/chrome: fix platform_no_drv_owner.cocci warnings platform/chrome: cros_ec_lightbar - fix duplicate const warning platform/chrome: cros_ec_dev - fix Unknown escape '%' warning platform/chrome: Expose Chrome OS Lightbar to users platform/chrome: Create sysfs attributes for the ChromeOS EC mfd: cros_ec: Instantiate ChromeOS EC character device platform/chrome: Add Chrome OS EC userspace device interface platform/chrome: Add cros_ec_lpc driver for x86 devices mfd: cros_ec: Add char dev and virtual dev pointers mfd: cros_ec: Use fixed size arrays to transfer data with the EC
lockref.c
#include <linux/export.h>
#include <linux/lockref.h>
#if USE_CMPXCHG_LOCKREF
/*
* Allow weakly-ordered memory architectures to provide barrier-less
* cmpxchg semantics for lockref updates.
*/
#ifndef cmpxchg64_relaxed
# define cmpxchg64_relaxed cmpxchg64
#endif
/*
* Note that the "cmpxchg()" reloads the "old" value for the
* failure case.
*/
#define CMPXCHG_LOOP(CODE, SUCCESS) do { \
struct lockref old; \
BUILD_BUG_ON(sizeof(old) != 8); \
old.lock_count = READ_ONCE(lockref->lock_count); \
while (likely(arch_spin_value_unlocked(old.lock.rlock.raw_lock))) { \
struct lockref new = old, prev = old; \
CODE \
old.lock_count = cmpxchg64_relaxed(&lockref->lock_count, \
old.lock_count, \
new.lock_count); \
if (likely(old.lock_count == prev.lock_count)) { \
SUCCESS; \
} \
cpu_relax_lowlatency(); \
} \
} while (0)
#else
#define CMPXCHG_LOOP(CODE, SUCCESS) do { } while (0)
#endif
/**
* lockref_get - Increments reference count unconditionally
* @lockref: pointer to lockref structure
*
* This operation is only valid if you already hold a reference
* to the object, so you know the count cannot be zero.
*/
void lockref_get(struct lockref *lockref)
{
CMPXCHG_LOOP(
new.count++;
,
return;
);
spin_lock(&lockref->lock);
lockref->count++;
spin_unlock(&lockref->lock);
}
EXPORT_SYMBOL(lockref_get);
/**
* lockref_get_not_zero - Increments count unless the count is 0 or dead
* @lockref: pointer to lockref structure
* Return: 1 if count updated successfully or 0 if count was zero
*/
int lockref_get_not_zero(struct lockref *lockref)
{
int retval;
CMPXCHG_LOOP(
new.count++;
if (old.count <= 0)
return 0;
,
return 1;
);
spin_lock(&lockref->lock);
retval = 0;
if (lockref->count > 0) {
lockref->count++;
retval = 1;
}
spin_unlock(&lockref->lock);
return retval;
}
EXPORT_SYMBOL(lockref_get_not_zero);
/**
* lockref_get_or_lock - Increments count unless the count is 0 or dead
* @lockref: pointer to lockref structure
* Return: 1 if count updated successfully or 0 if count was zero
* and we got the lock instead.
*/
int lockref_get_or_lock(struct lockref *lockref)
{
CMPXCHG_LOOP(
new.count++;
if (old.count <= 0)
break;
,
return 1;
);
spin_lock(&lockref->lock);
if (lockref->count <= 0)
return 0;
lockref->count++;
spin_unlock(&lockref->lock);
return 1;
}
EXPORT_SYMBOL(lockref_get_or_lock);
/**
* lockref_put_return - Decrement reference count if possible
* @lockref: pointer to lockref structure
*
* Decrement the reference count and return the new value.
* If the lockref was dead or locked, return an error.
*/
int lockref_put_return(struct lockref *lockref)
{
CMPXCHG_LOOP(
new.count--;
if (old.count <= 0)
return -1;
,
return new.count;
);
return -1;
}
EXPORT_SYMBOL(lockref_put_return);
/**
* lockref_put_or_lock - decrements count unless count <= 1 before decrement
* @lockref: pointer to lockref structure
* Return: 1 if count updated successfully or 0 if count <= 1 and lock taken
*/
int lockref_put_or_lock(struct lockref *lockref)
{
CMPXCHG_LOOP(
new.count--;
if (old.count <= 1)
break;
,
return 1;
);
spin_lock(&lockref->lock);
if (lockref->count <= 1)
return 0;
lockref->count--;
spin_unlock(&lockref->lock);
return 1;
}
EXPORT_SYMBOL(lockref_put_or_lock);
/**
* lockref_mark_dead - mark lockref dead
* @lockref: pointer to lockref structure
*/
void lockref_mark_dead(struct lockref *lockref)
{
assert_spin_locked(&lockref->lock);
lockref->count = -128;
}
EXPORT_SYMBOL(lockref_mark_dead);
/**
* lockref_get_not_dead - Increments count unless the ref is dead
* @lockref: pointer to lockref structure
* Return: 1 if count updated successfully or 0 if lockref was dead
*/
int lockref_get_not_dead(struct lockref *lockref)
{
int retval;
CMPXCHG_LOOP(
new.count++;
if (old.count < 0)
return 0;
,
return 1;
);
spin_lock(&lockref->lock);
retval = 0;
if (lockref->count >= 0) {
lockref->count++;
retval = 1;
}
spin_unlock(&lockref->lock);
return retval;
}
EXPORT_SYMBOL(lockref_get_not_dead);
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