hwspinlock: qcom: Lock #7 is special lock, uses dynamic proc_id

Message ID 1430499992-47944-1-git-send-email-lina.iyer@linaro.org
State New
Headers show

Commit Message

Lina Iyer May 1, 2015, 5:06 p.m.
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 <jhugo@codeaurora.org>
Cc: Bjorn Andersson <bjorn.andersson@sonymobile.com>
Cc: Andy Gross <agross@codeaurora.org>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 drivers/hwspinlock/qcom_hwspinlock.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

Comments

Lina Iyer May 1, 2015, 5:31 p.m. | #1
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
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Patch

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);
 	}