Events: Introduce AcpiMaskGpe() to implement GPE masking mechanism

There is a facility in Linux, developers can control the enabling/disabling
of a GPE via /sys/firmware/acpi/interrupts/gpexx. This is mainly for
debugging purposes.

But many users expect to use this facility to implement quirks to mask a
specific GPE when there is a gap in Linux causing this GPE to flood. This
is not working correctly because currently this facility invokes
enabling/disabling counting based GPE driver APIs:
 AcpiEnableGpe()/AcpiDisableGpe()
and the GPE drivers can still affect the count to mess up the GPE
masking purposes.

However, most of the IRQ chip designs allow masking/unmasking IRQs via a
masking bit which is different from the enabled bit to achieve the same
purpose. But the GPE hardware doesn't contain such a feature, this brings
the trouble.

In this patch, we introduce a software mechanism to implement the GPE
masking feature, and AcpiMaskGpe() are provided to the OSPMs to
mask/unmask GPEs in the above mentioned situation instead of
AcpiEnableGpe()/AcpiDisableGpe(). ACPICA BZ 1102. Lv Zheng.

Link: https://bugs.acpica.org/show_bug.cgi?id=1102
Signed-off-by: Lv Zheng <lv.zheng@intel.com>

source/components/events/evgpe.c

@@ -219,6 +219,70 @@ AcpiEvEnableGpe (
 }
 
 
+/*******************************************************************************
+ *
+ * FUNCTION:    AcpiEvMaskGpe
+ *
+ * PARAMETERS:  GpeEventInfo            - GPE to be blocked/unblocked
+ *              IsMasked                - Whether the GPE is masked or not
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Unconditionally mask/unmask a GPE during runtime.
+ *
+ ******************************************************************************/
+
+ACPI_STATUS
+AcpiEvMaskGpe (
+    ACPI_GPE_EVENT_INFO     *GpeEventInfo,
+    BOOLEAN                 IsMasked)
+{
+    ACPI_GPE_REGISTER_INFO  *GpeRegisterInfo;
+    UINT32                  RegisterBit;
+
+
+    ACPI_FUNCTION_TRACE (EvMaskGpe);
+
+
+    GpeRegisterInfo = GpeEventInfo->RegisterInfo;
+    if (!GpeRegisterInfo)
+    {
+        return_ACPI_STATUS (AE_NOT_EXIST);
+    }
+
+    RegisterBit = AcpiHwGetGpeRegisterBit (GpeEventInfo);
+
+    /* Perform the action */
+
+    if (IsMasked)
+    {
+        if (RegisterBit & GpeRegisterInfo->MaskForRun)
+        {
+            return_ACPI_STATUS (AE_BAD_PARAMETER);
+        }
+
+        (void) AcpiHwLowSetGpe (GpeEventInfo, ACPI_GPE_DISABLE);
+        ACPI_SET_BIT (GpeRegisterInfo->MaskForRun, (UINT8) RegisterBit);
+    }
+    else
+    {
+        if (!(RegisterBit & GpeRegisterInfo->MaskForRun))
+        {
+            return_ACPI_STATUS (AE_BAD_PARAMETER);
+        }
+
+        ACPI_CLEAR_BIT (GpeRegisterInfo->MaskForRun, (UINT8) RegisterBit);
+        if (GpeEventInfo->RuntimeCount &&
+            !GpeEventInfo->DisableForDispatch)
+        {
+            (void) AcpiHwLowSetGpe (GpeEventInfo, ACPI_GPE_ENABLE);
+        }
+    }
+
+    return_ACPI_STATUS (AE_OK);
+}
+
+
 /*******************************************************************************
  *
  * FUNCTION:    AcpiEvAddGpeReference
@@ -787,6 +851,7 @@ AcpiEvFinishGpe (
      * in the EventInfo.
      */
     (void) AcpiHwLowSetGpe (GpeEventInfo, ACPI_GPE_CONDITIONAL_ENABLE);
+    GpeEventInfo->DisableForDispatch = FALSE;
     return (AE_OK);
 }
 
@@ -856,6 +921,8 @@ AcpiEvGpeDispatch (
         }
     }
 
+    GpeEventInfo->DisableForDispatch = TRUE;
+
     /*
      * Dispatch the GPE to either an installed handler or the control
      * method associated with this GPE (_Lxx or _Exx). If a handler

source/components/events/evxfgpe.c

@@ -343,11 +343,13 @@ AcpiSetGpe (
     case ACPI_GPE_ENABLE:
 
         Status = AcpiHwLowSetGpe (GpeEventInfo, ACPI_GPE_ENABLE);
+        GpeEventInfo->DisableForDispatch = FALSE;
         break;
 
     case ACPI_GPE_DISABLE:
 
         Status = AcpiHwLowSetGpe (GpeEventInfo, ACPI_GPE_DISABLE);
+        GpeEventInfo->DisableForDispatch = TRUE;
         break;
 
     default:
@@ -364,6 +366,56 @@ AcpiSetGpe (
 ACPI_EXPORT_SYMBOL (AcpiSetGpe)
 
 
+/*******************************************************************************
+ *
+ * FUNCTION:    AcpiMaskGpe
+ *
+ * PARAMETERS:  GpeDevice           - Parent GPE Device. NULL for GPE0/GPE1
+ *              GpeNumber           - GPE level within the GPE block
+ *              IsMasked            - Whether the GPE is masked or not
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Unconditionally mask/unmask the an individual GPE, ex., to
+ *              prevent a GPE flooding.
+ *
+ ******************************************************************************/
+
+ACPI_STATUS
+AcpiMaskGpe (
+    ACPI_HANDLE             GpeDevice,
+    UINT32                  GpeNumber,
+    BOOLEAN                 IsMasked)
+{
+    ACPI_GPE_EVENT_INFO     *GpeEventInfo;
+    ACPI_STATUS             Status;
+    ACPI_CPU_FLAGS          Flags;
+
+
+    ACPI_FUNCTION_TRACE (AcpiMaskGpe);
+
+
+    Flags = AcpiOsAcquireLock (AcpiGbl_GpeLock);
+
+    /* Ensure that we have a valid GPE number */
+
+    GpeEventInfo = AcpiEvGetGpeEventInfo (GpeDevice, GpeNumber);
+    if (!GpeEventInfo)
+    {
+        Status = AE_BAD_PARAMETER;
+        goto UnlockAndExit;
+    }
+
+    Status = AcpiEvMaskGpe (GpeEventInfo, IsMasked);
+
+UnlockAndExit:
+    AcpiOsReleaseLock (AcpiGbl_GpeLock, Flags);
+    return_ACPI_STATUS (Status);
+}
+
+ACPI_EXPORT_SYMBOL (AcpiMaskGpe)
+
+
 /*******************************************************************************
  *
  * FUNCTION:    AcpiMarkGpeForWake

source/components/hardware/hwgpe.c

@@ -180,7 +180,7 @@ AcpiHwLowSetGpe (
     UINT32                  Action)
 {
     ACPI_GPE_REGISTER_INFO  *GpeRegisterInfo;
-    ACPI_STATUS             Status;
+    ACPI_STATUS             Status = AE_OK;
     UINT32                  EnableMask;
     UINT32                  RegisterBit;
 
@@ -236,9 +236,12 @@ AcpiHwLowSetGpe (
         return (AE_BAD_PARAMETER);
     }
 
-    /* Write the updated enable mask */
+    if (!(RegisterBit & GpeRegisterInfo->MaskForRun))
+    {
+        /* Write the updated enable mask */
 
-    Status = AcpiHwWrite (EnableMask, &GpeRegisterInfo->EnableAddress);
+        Status = AcpiHwWrite (EnableMask, &GpeRegisterInfo->EnableAddress);
+    }
     return (Status);
 }
 
@@ -341,6 +344,13 @@ AcpiHwGetGpeStatus (
         LocalEventStatus |= ACPI_EVENT_FLAG_ENABLED;
     }
 
+    /* GPE currently masked? (masked for runtime?) */
+
+    if (RegisterBit & GpeRegisterInfo->MaskForRun)
+    {
+        LocalEventStatus |= ACPI_EVENT_FLAG_MASKED;
+    }
+
     /* GPE enabled for wake? */
 
     if (RegisterBit & GpeRegisterInfo->EnableForWake)
@@ -512,6 +522,7 @@ AcpiHwEnableRuntimeGpeBlock (
     UINT32                  i;
     ACPI_STATUS             Status;
     ACPI_GPE_REGISTER_INFO  *GpeRegisterInfo;
+    UINT32                  EnableMask;
 
 
     /* NOTE: assumes that all GPEs are currently disabled */
@@ -528,8 +539,9 @@ AcpiHwEnableRuntimeGpeBlock (
 
         /* Enable all "runtime" GPEs in this register */
 
-        Status = AcpiHwGpeEnableWrite (GpeRegisterInfo->EnableForRun,
-            GpeRegisterInfo);
+        EnableMask = GpeRegisterInfo->EnableForRun &
+            ~GpeRegisterInfo->MaskForRun;
+        Status = AcpiHwGpeEnableWrite (EnableMask, GpeRegisterInfo);
         if (ACPI_FAILURE (Status))
         {
             return (Status);

source/include/acevents.h

@@ -187,6 +187,11 @@ ACPI_STATUS
 AcpiEvEnableGpe (
     ACPI_GPE_EVENT_INFO     *GpeEventInfo);
 
+ACPI_STATUS
+AcpiEvMaskGpe (
+    ACPI_GPE_EVENT_INFO     *GpeEventInfo,
+    BOOLEAN                 IsMasked);
+
 ACPI_STATUS
 AcpiEvAddGpeReference (
     ACPI_GPE_EVENT_INFO     *GpeEventInfo);

source/include/aclocal.h

@@ -622,11 +622,12 @@ typedef union acpi_gpe_dispatch_info
  */
 typedef struct acpi_gpe_event_info
 {
-    union acpi_gpe_dispatch_info    Dispatch;       /* Either Method, Handler, or NotifyList */
-    struct acpi_gpe_register_info   *RegisterInfo;  /* Backpointer to register info */
-    UINT8                           Flags;          /* Misc info about this GPE */
-    UINT8                           GpeNumber;      /* This GPE */
-    UINT8                           RuntimeCount;   /* References to a run GPE */
+    union acpi_gpe_dispatch_info    Dispatch;           /* Either Method, Handler, or NotifyList */
+    struct acpi_gpe_register_info   *RegisterInfo;      /* Backpointer to register info */
+    UINT8                           Flags;              /* Misc info about this GPE */
+    UINT8                           GpeNumber;          /* This GPE */
+    UINT8                           RuntimeCount;       /* References to a run GPE */
+    BOOLEAN                         DisableForDispatch; /* Masked during dispatching */
 
 } ACPI_GPE_EVENT_INFO;
 
@@ -639,6 +640,7 @@ typedef struct acpi_gpe_register_info
     UINT16                          BaseGpeNumber;  /* Base GPE number for this register */
     UINT8                           EnableForWake;  /* GPEs to keep enabled when sleeping */
     UINT8                           EnableForRun;   /* GPEs to keep enabled when running */
+    UINT8                           MaskForRun;     /* GPEs to keep masked when running */
     UINT8                           EnableMask;     /* Current mask of enabled GPEs */
 
 } ACPI_GPE_REGISTER_INFO;

source/include/acpixf.h

@@ -979,6 +979,13 @@ AcpiFinishGpe (
     ACPI_HANDLE             GpeDevice,
     UINT32                  GpeNumber))
 
+ACPI_HW_DEPENDENT_RETURN_STATUS (
+ACPI_STATUS
+AcpiMaskGpe (
+    ACPI_HANDLE             GpeDevice,
+    UINT32                  GpeNumber,
+    BOOLEAN                 IsMasked))
+
 ACPI_HW_DEPENDENT_RETURN_STATUS (
 ACPI_STATUS
 AcpiMarkGpeForWake (

source/include/actypes.h

@@ -817,16 +817,17 @@ typedef UINT32                          ACPI_EVENT_TYPE;
  * The encoding of ACPI_EVENT_STATUS is illustrated below.
  * Note that a set bit (1) indicates the property is TRUE
  * (e.g. if bit 0 is set then the event is enabled).
- * +-------------+-+-+-+-+-+
- * |   Bits 31:5 |4|3|2|1|0|
- * +-------------+-+-+-+-+-+
- *          |     | | | | |
- *          |     | | | | +- Enabled?
- *          |     | | | +--- Enabled for wake?
- *          |     | | +----- Status bit set?
- *          |     | +------- Enable bit set?
- *          |     +--------- Has a handler?
- *          +--------------- <Reserved>
+ * +-------------+-+-+-+-+-+-+
+ * |   Bits 31:6 |5|4|3|2|1|0|
+ * +-------------+-+-+-+-+-+-+
+ *          |     | | | | | |
+ *          |     | | | | | +- Enabled?
+ *          |     | | | | +--- Enabled for wake?
+ *          |     | | | +----- Status bit set?
+ *          |     | | +------- Enable bit set?
+ *          |     | +--------- Has a handler?
+ *          |     +----------- Masked?
+ *          +----------------- <Reserved>
  */
 typedef UINT32                          ACPI_EVENT_STATUS;
 
@@ -836,6 +837,7 @@ typedef UINT32                          ACPI_EVENT_STATUS;
 #define ACPI_EVENT_FLAG_STATUS_SET      (ACPI_EVENT_STATUS) 0x04
 #define ACPI_EVENT_FLAG_ENABLE_SET      (ACPI_EVENT_STATUS) 0x08
 #define ACPI_EVENT_FLAG_HAS_HANDLER     (ACPI_EVENT_STATUS) 0x10
+#define ACPI_EVENT_FLAG_MASKED          (ACPI_EVENT_STATUS) 0x20
 #define ACPI_EVENT_FLAG_SET             ACPI_EVENT_FLAG_STATUS_SET
 
 /* Actions for AcpiSetGpe, AcpiGpeWakeup, AcpiHwLowSetGpe */
@@ -846,14 +848,15 @@ typedef UINT32                          ACPI_EVENT_STATUS;
 
 /*
  * GPE info flags - Per GPE
- * +-------+-+-+---+
- * |  7:5  |4|3|2:0|
- * +-------+-+-+---+
- *     |    | |  |
- *     |    | |  +-- Type of dispatch:to method, handler, notify, or none
- *     |    | +----- Interrupt type: edge or level triggered
- *     |    +------- Is a Wake GPE
- *     +------------ <Reserved>
+ * +---+-+-+-+---+
+ * |7:6|5|4|3|2:0|
+ * +---+-+-+-+---+
+ *   |  | | |  |
+ *   |  | | |  +-- Type of dispatch:to method, handler, notify, or none
+ *   |  | | +----- Interrupt type: edge or level triggered
+ *   |  | +------- Is a Wake GPE
+ *   |  +--------- Is GPE masked by the software GPE masking machanism
+ *   +------------ <Reserved>
  */
 #define ACPI_GPE_DISPATCH_NONE          (UINT8) 0x00
 #define ACPI_GPE_DISPATCH_METHOD        (UINT8) 0x01