Hwspinlocks are widely used between processors in an SoC, and also
between elevation levels within in the same processor. QCOM SoC's use
hwspinlock to serialize entry into a low power mode when the context
switches from Linux to secure monitor.
Lock #7 has been assigned for this purpose. In order to differentiate
between one cpu core holding a lock while another cpu is contending for
the same lock, the proc id written into the lock is (128 + cpu id). This
makes it unique value among the cpu cores and therefore when a core
locks the hwspinlock, other cores would wait for the lock to be released
since they would have a different proc id. This value is specific for
the lock #7 only.
Cc: Jeffrey Hugo <[email protected]>
Cc: Bjorn Andersson <[email protected]>
Cc: Andy Gross <[email protected]>
Signed-off-by: Lina Iyer <[email protected]>
---
drivers/hwspinlock/qcom_hwspinlock.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)
diff --git a/drivers/hwspinlock/qcom_hwspinlock.c b/drivers/hwspinlock/qcom_hwspinlock.c
index 93b62e0..043c62c 100644
--- a/drivers/hwspinlock/qcom_hwspinlock.c
+++ b/drivers/hwspinlock/qcom_hwspinlock.c
@@ -25,16 +25,26 @@
#include "hwspinlock_internal.h"
-#define QCOM_MUTEX_APPS_PROC_ID 1
-#define QCOM_MUTEX_NUM_LOCKS 32
+#define QCOM_MUTEX_APPS_PROC_ID 1
+#define QCOM_MUTEX_CPUIDLE_OFFSET 128
+#define QCOM_CPUIDLE_LOCK 7
+#define QCOM_MUTEX_NUM_LOCKS 32
+
+static inline u32 __qcom_get_proc_id(struct hwspinlock *lock)
+{
+ return hwspin_lock_get_id(lock) == QCOM_CPUIDLE_LOCK ?
+ (QCOM_MUTEX_CPUIDLE_OFFSET + smp_processor_id()) :
+ QCOM_MUTEX_APPS_PROC_ID;
+}
static int qcom_hwspinlock_trylock(struct hwspinlock *lock)
{
struct regmap_field *field = lock->priv;
u32 lock_owner;
int ret;
+ u32 proc_id = __qcom_get_proc_id(lock);
- ret = regmap_field_write(field, QCOM_MUTEX_APPS_PROC_ID);
+ ret = regmap_field_write(field, proc_id);
if (ret)
return ret;
@@ -42,7 +52,7 @@ static int qcom_hwspinlock_trylock(struct hwspinlock *lock)
if (ret)
return ret;
- return lock_owner == QCOM_MUTEX_APPS_PROC_ID;
+ return lock_owner == proc_id;
}
static void qcom_hwspinlock_unlock(struct hwspinlock *lock)
@@ -57,7 +67,7 @@ static void qcom_hwspinlock_unlock(struct hwspinlock *lock)
return;
}
- if (lock_owner != QCOM_MUTEX_APPS_PROC_ID) {
+ if (lock_owner != __qcom_get_proc_id(lock)) {
pr_err("%s: spinlock not owned by us (actual owner is %d)\n",
__func__, lock_owner);
}
--
2.1.4
On 5/1/2015 11:06 AM, Lina Iyer wrote:
> diff --git a/drivers/hwspinlock/qcom_hwspinlock.c b/drivers/hwspinlock/qcom_hwspinlock.c
> index 93b62e0..043c62c 100644
> --- a/drivers/hwspinlock/qcom_hwspinlock.c
> +++ b/drivers/hwspinlock/qcom_hwspinlock.c
> @@ -25,16 +25,26 @@
>
> #include "hwspinlock_internal.h"
>
> -#define QCOM_MUTEX_APPS_PROC_ID 1
> -#define QCOM_MUTEX_NUM_LOCKS 32
> +#define QCOM_MUTEX_APPS_PROC_ID 1
> +#define QCOM_MUTEX_CPUIDLE_OFFSET 128
> +#define QCOM_CPUIDLE_LOCK 7
> +#define QCOM_MUTEX_NUM_LOCKS 32
> +
This part of the diff doesn't look right. Why is it showing that
QCOM_MUTEX_APPS_PROC_ID and QCOM_MUTEX_NUM_LOCKS are deleted and added
lines? Shouldn't they be unchanged by this patch?
--
Jeffrey Hugo
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
Forum, a Linux Foundation Collaborative Project
On Fri, May 01 2015 at 11:27 -0600, Jeffrey Hugo wrote:
>On 5/1/2015 11:06 AM, Lina Iyer wrote:
>
>>diff --git a/drivers/hwspinlock/qcom_hwspinlock.c b/drivers/hwspinlock/qcom_hwspinlock.c
>>index 93b62e0..043c62c 100644
>>--- a/drivers/hwspinlock/qcom_hwspinlock.c
>>+++ b/drivers/hwspinlock/qcom_hwspinlock.c
>>@@ -25,16 +25,26 @@
>>
>> #include "hwspinlock_internal.h"
>>
>>-#define QCOM_MUTEX_APPS_PROC_ID 1
>>-#define QCOM_MUTEX_NUM_LOCKS 32
>>+#define QCOM_MUTEX_APPS_PROC_ID 1
>>+#define QCOM_MUTEX_CPUIDLE_OFFSET 128
>>+#define QCOM_CPUIDLE_LOCK 7
>>+#define QCOM_MUTEX_NUM_LOCKS 32
>>+
>
>This part of the diff doesn't look right. Why is it showing that
>QCOM_MUTEX_APPS_PROC_ID and QCOM_MUTEX_NUM_LOCKS are deleted and added
>lines? Shouldn't they be unchanged by this patch?
>
Sigh. I must have updated the tabs to play nice. Will fix in the next
spin.
Thanks for the review.
--Lina
>--
>Jeffrey Hugo
>Qualcomm Innovation Center, Inc.
>The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
>Forum, a Linux Foundation Collaborative Project