[PATCH RFC 08/10] hwspinlock: qcom: Lock #7 is special lock, uses dynamic proc_id
From: Lina Iyer <hidden>
Date: 2015-08-05 16:32:44
Also in:
linux-arm-msm, linux-devicetree, linux-pm
Subsystem:
arm/qualcomm mailing list, hardware spinlock core, the rest · Maintainers:
Bjorn Andersson, Linus Torvalds
Possibly related (same subject, not in this thread)
- 2015-08-14 · Re: [PATCH RFC 08/10] hwspinlock: qcom: Lock #7 is special lock, uses dynamic proc_id · Lina Iyer <hidden>
- 2015-08-13 · Re: [PATCH RFC 08/10] hwspinlock: qcom: Lock #7 is special lock, uses dynamic proc_id · Bjorn Andersson <hidden>
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. Declare lock #7 as raw capable, so the hwspinlock framework would not enfore acquiring a s/w spinlock before acquiring the hwspinlock. Cc: Jeffrey Hugo <redacted> Cc: Bjorn Andersson <redacted> Cc: Andy Gross <redacted> Signed-off-by: Lina Iyer <redacted> --- drivers/hwspinlock/qcom_hwspinlock.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-)
diff --git a/drivers/hwspinlock/qcom_hwspinlock.c b/drivers/hwspinlock/qcom_hwspinlock.c
index c752447..573f0dd 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); }
@@ -129,6 +139,8 @@ static int qcom_hwspinlock_probe(struct platform_device *pdev) regmap, field); } + bank->lock[QCOM_CPUIDLE_LOCK].hwcaps = HWL_CAP_ALLOW_RAW; + pm_runtime_enable(&pdev->dev); ret = hwspin_lock_register(bank, &pdev->dev, &qcom_hwspinlock_ops,
--
2.1.4