ACPICA: Misc comments to minimize code divergence

Modify/add some comments to minimize ACPICA/linux GPE code divergence.

Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

6 files changed, 81 insertions, 46 deletions

diff --git a/drivers/acpi/acpica/achware.h b/drivers/acpi/acpica/achware.h
index 167470ad2d21..258d628793ea 100644
--- a/drivers/acpi/acpica/achware.h
+++ b/drivers/acpi/acpica/achware.h
@@ -94,7 +94,7 @@ u32 acpi_hw_get_gpe_register_bit(struct acpi_gpe_event_info *gpe_event_info,
                              struct acpi_gpe_register_info *gpe_register_info);
 
 acpi_status
-acpi_hw_low_set_gpe(struct acpi_gpe_event_info *gpe_event_info, u8 action);
+acpi_hw_low_set_gpe(struct acpi_gpe_event_info *gpe_event_info, u32 action);
 
 acpi_status
 acpi_hw_disable_gpe_block(struct acpi_gpe_xrupt_info *gpe_xrupt_info,
diff --git a/drivers/acpi/acpica/evgpe.c b/drivers/acpi/acpica/evgpe.c
index 3bcf5ef74c62..7c339d34ab42 100644
--- a/drivers/acpi/acpica/evgpe.c
+++ b/drivers/acpi/acpica/evgpe.c
@@ -104,7 +104,7 @@ acpi_ev_update_gpe_enable_mask(struct acpi_gpe_event_info *gpe_event_info)
  *
  * RETURN:      Status
  *
- * DESCRIPTION: Clear the given GPE from stale events and enable it.
+ * DESCRIPTION: Clear a GPE of stale events and enable it.
  *
  ******************************************************************************/
 acpi_status
@@ -142,7 +142,7 @@ acpi_ev_enable_gpe(struct acpi_gpe_event_info *gpe_event_info)
  *
  * FUNCTION:    acpi_ev_add_gpe_reference
  *
- * PARAMETERS:  gpe_event_info  - GPE to enable
+ * PARAMETERS:  gpe_event_info          - Add a reference to this GPE
  *
  * RETURN:      Status
  *
@@ -163,6 +163,9 @@ acpi_status acpi_ev_add_gpe_reference(struct acpi_gpe_event_info *gpe_event_info
 
         gpe_event_info->runtime_count++;
         if (gpe_event_info->runtime_count == 1) {
+
+                /* Enable on first reference */
+
                 status = acpi_ev_update_gpe_enable_mask(gpe_event_info);
                 if (ACPI_SUCCESS(status)) {
                         status = acpi_ev_enable_gpe(gpe_event_info);
@@ -180,7 +183,7 @@ acpi_status acpi_ev_add_gpe_reference(struct acpi_gpe_event_info *gpe_event_info
  *
  * FUNCTION:    acpi_ev_remove_gpe_reference
  *
- * PARAMETERS:  gpe_event_info  - GPE to disable
+ * PARAMETERS:  gpe_event_info          - Remove a reference to this GPE
  *
  * RETURN:      Status
  *
@@ -201,6 +204,9 @@ acpi_status acpi_ev_remove_gpe_reference(struct acpi_gpe_event_info *gpe_event_i
 
         gpe_event_info->runtime_count--;
         if (!gpe_event_info->runtime_count) {
+
+                /* Disable on last reference */
+
                 status = acpi_ev_update_gpe_enable_mask(gpe_event_info);
                 if (ACPI_SUCCESS(status)) {
                         status = acpi_hw_low_set_gpe(gpe_event_info,
@@ -386,7 +392,7 @@ u32 acpi_ev_gpe_detect(struct acpi_gpe_xrupt_info * gpe_xrupt_list)
                         }
 
                         ACPI_DEBUG_PRINT((ACPI_DB_INTERRUPTS,
-                                          "Read GPE Register at GPE%X: Status=%02X, Enable=%02X\n",
+                                          "Read GPE Register at GPE%02X: Status=%02X, Enable=%02X\n",
                                           gpe_register_info->base_gpe_number,
                                           status_reg, enable_reg));
 
@@ -660,8 +666,7 @@ acpi_ev_gpe_dispatch(struct acpi_namespace_node *gpe_device,
                 status = acpi_hw_clear_gpe(gpe_event_info);
                 if (ACPI_FAILURE(status)) {
                         ACPI_EXCEPTION((AE_INFO, status,
-                                        "Unable to clear GPE[0x%2X]",
-                                        gpe_number));
+                                        "Unable to clear GPE%02X", gpe_number));
                         return_UINT32(ACPI_INTERRUPT_NOT_HANDLED);
                 }
         }
@@ -720,7 +725,7 @@ acpi_ev_gpe_dispatch(struct acpi_namespace_node *gpe_device,
                                          gpe_event_info);
                 if (ACPI_FAILURE(status)) {
                         ACPI_EXCEPTION((AE_INFO, status,
-                                        "Unable to queue handler for GPE[0x%2X] - event disabled",
+                                        "Unable to queue handler for GPE%2X - event disabled",
                                         gpe_number));
                 }
                 break;
@@ -733,7 +738,7 @@ acpi_ev_gpe_dispatch(struct acpi_namespace_node *gpe_device,
                  * a GPE to be enabled if it has no handler or method.
                  */
                 ACPI_ERROR((AE_INFO,
-                            "No handler or method for GPE[0x%2X], disabling event",
+                            "No handler or method for GPE%02X, disabling event",
                             gpe_number));
 
                 break;
diff --git a/drivers/acpi/acpica/evgpeblk.c b/drivers/acpi/acpica/evgpeblk.c
index e2e8164bb811..9acb86958c09 100644
--- a/drivers/acpi/acpica/evgpeblk.c
+++ b/drivers/acpi/acpica/evgpeblk.c
@@ -361,9 +361,9 @@ acpi_ev_create_gpe_block(struct acpi_namespace_node *gpe_device,
 
         gpe_block->node = gpe_device;
         gpe_block->gpe_count = (u16)(register_count * ACPI_GPE_REGISTER_WIDTH);
+        gpe_block->initialized = FALSE;
         gpe_block->register_count = register_count;
         gpe_block->block_base_number = gpe_block_base_number;
-        gpe_block->initialized = FALSE;
 
         ACPI_MEMCPY(&gpe_block->block_address, gpe_block_address,
                     sizeof(struct acpi_generic_address));
@@ -423,14 +423,12 @@ acpi_ev_create_gpe_block(struct acpi_namespace_node *gpe_device,
  *
  * FUNCTION:    acpi_ev_initialize_gpe_block
  *
- * PARAMETERS:  gpe_device          - Handle to the parent GPE block
- *              gpe_block           - Gpe Block info
+ * PARAMETERS:  acpi_gpe_callback
  *
  * RETURN:      Status
  *
- * DESCRIPTION: Initialize and enable a GPE block. First find and run any
- *              _PRT methods associated with the block, then enable the
- *              appropriate GPEs.
+ * DESCRIPTION: Initialize and enable a GPE block. Enable GPEs that have
+ *              associated methods.
  *              Note: Assumes namespace is locked.
  *
  ******************************************************************************/
@@ -450,8 +448,8 @@ acpi_ev_initialize_gpe_block(struct acpi_gpe_xrupt_info *gpe_xrupt_info,
         ACPI_FUNCTION_TRACE(ev_initialize_gpe_block);
 
         /*
-         * Ignore a null GPE block (e.g., if no GPE block 1 exists) and
-         * GPE blocks that have been initialized already.
+         * Ignore a null GPE block (e.g., if no GPE block 1 exists), and
+         * any GPE blocks that have been initialized already.
          */
         if (!gpe_block || gpe_block->initialized) {
                 return_ACPI_STATUS(AE_OK);
@@ -459,8 +457,8 @@ acpi_ev_initialize_gpe_block(struct acpi_gpe_xrupt_info *gpe_xrupt_info,
 
         /*
          * Enable all GPEs that have a corresponding method and have the
-         * ACPI_GPE_CAN_WAKE flag unset.  Any other GPEs within this block must
-         * be enabled via the acpi_enable_gpe() interface.
+         * ACPI_GPE_CAN_WAKE flag unset. Any other GPEs within this block
+         * must be enabled via the acpi_enable_gpe() interface.
          */
         gpe_enabled_count = 0;
 
diff --git a/drivers/acpi/acpica/evgpeinit.c b/drivers/acpi/acpica/evgpeinit.c
index 734a494bd705..c59dc2340593 100644
--- a/drivers/acpi/acpica/evgpeinit.c
+++ b/drivers/acpi/acpica/evgpeinit.c
@@ -45,11 +45,27 @@
 #include "accommon.h"
 #include "acevents.h"
 #include "acnamesp.h"
-#include "acinterp.h"
 
 #define _COMPONENT          ACPI_EVENTS
 ACPI_MODULE_NAME("evgpeinit")
 
+/*
+ * Note: History of _PRW support in ACPICA
+ *
+ * Originally (2000 - 2010), the GPE initialization code performed a walk of
+ * the entire namespace to execute the _PRW methods and detect all GPEs
+ * capable of waking the system.
+ *
+ * As of 10/2010, the _PRW method execution has been removed since it is
+ * actually unnecessary. The host OS must in fact execute all _PRW methods
+ * in order to identify the device/power-resource dependencies. We now put
+ * the onus on the host OS to identify the wake GPEs as part of this process
+ * and to inform ACPICA of these GPEs via the acpi_setup_gpe_for_wake interface. This
+ * not only reduces the complexity of the ACPICA initialization code, but in
+ * some cases (on systems with very large namespaces) it should reduce the
+ * kernel boot time as well.
+ */
+
 /*******************************************************************************
  *
  * FUNCTION:    acpi_ev_gpe_initialize
@@ -222,7 +238,7 @@ void acpi_ev_update_gpes(acpi_owner_id table_owner_id)
         acpi_status status = AE_OK;
 
         /*
-         * 2) Find any _Lxx/_Exx GPE methods that have just been loaded.
+         * Find any _Lxx/_Exx GPE methods that have just been loaded.
          *
          * Any GPEs that correspond to new _Lxx/_Exx methods are immediately
          * enabled.
@@ -235,9 +251,9 @@ void acpi_ev_update_gpes(acpi_owner_id table_owner_id)
                 return;
         }
 
+        walk_info.count = 0;
         walk_info.owner_id = table_owner_id;
         walk_info.execute_by_owner_id = TRUE;
-        walk_info.count = 0;
 
         /* Walk the interrupt level descriptor list */
 
@@ -298,7 +314,7 @@ void acpi_ev_update_gpes(acpi_owner_id table_owner_id)
  *                  xx     - is the GPE number [in HEX]
  *
  * If walk_info->execute_by_owner_id is TRUE, we only execute examine GPE methods
- *    with that owner.
+ * with that owner.
  *
  ******************************************************************************/
 
diff --git a/drivers/acpi/acpica/evxfgpe.c b/drivers/acpi/acpica/evxfgpe.c
index fcf4a5cdc9a4..416845bc9c1f 100644
--- a/drivers/acpi/acpica/evxfgpe.c
+++ b/drivers/acpi/acpica/evxfgpe.c
@@ -55,13 +55,19 @@ ACPI_MODULE_NAME("evxfgpe")
  *
  * PARAMETERS:  None
  *
- * RETURN:      None
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Complete GPE initialization and enable all GPEs that have
+ *              associated _Lxx or _Exx methods and are not pointed to by any
+ *              device _PRW methods (this indicates that these GPEs are
+ *              generally intended for system or device wakeup. Such GPEs
+ *              have to be enabled directly when the devices whose _PRW
+ *              methods point to them are set up for wakeup signaling.)
  *
- * DESCRIPTION: Enable all GPEs that have associated _Lxx or _Exx methods and
- *              are not pointed to by any device _PRW methods indicating that
- *              these GPEs are generally intended for system or device wakeup
- *              (such GPEs have to be enabled directly when the devices whose
- *              _PRW methods point to them are set up for wakeup signaling).
+ * NOTE: Should be called after any GPEs are added to the system. Primarily,
+ * after the system _PRW methods have been run, but also after a GPE Block
+ * Device has been added or if any new GPE methods have been added via a
+ * dynamic table load.
  *
  ******************************************************************************/
 
@@ -252,7 +258,8 @@ ACPI_EXPORT_SYMBOL(acpi_setup_gpe_for_wake)
  *
  * RETURN:      Status
  *
- * DESCRIPTION: Set or clear the GPE's wakeup enable mask bit.
+ * DESCRIPTION: Set or clear the GPE's wakeup enable mask bit. The GPE must
+ *              already be marked as a WAKE GPE.
  *
  ******************************************************************************/
 
@@ -268,8 +275,10 @@ acpi_status acpi_set_gpe_wake_mask(acpi_handle gpe_device, u32 gpe_number, u8 ac
 
         flags = acpi_os_acquire_lock(acpi_gbl_gpe_lock);
 
-        /* Ensure that we have a valid GPE number */
-
+        /*
+         * Ensure that we have a valid GPE number and that this GPE is in
+         * fact a wake GPE
+         */
         gpe_event_info = acpi_ev_get_gpe_event_info(gpe_device, gpe_number);
         if (!gpe_event_info) {
                 status = AE_BAD_PARAMETER;
@@ -366,7 +375,7 @@ ACPI_EXPORT_SYMBOL(acpi_clear_gpe)
  *
  * RETURN:      Status
  *
- * DESCRIPTION: Get status of an event (general purpose)
+ * DESCRIPTION: Get the current status of a GPE (signalled/not_signalled)
  *
  ******************************************************************************/
 acpi_status
@@ -476,7 +485,8 @@ ACPI_EXPORT_SYMBOL(acpi_enable_all_runtime_gpes)
  *
  * RETURN:      Status
  *
- * DESCRIPTION: Create and Install a block of GPE registers
+ * DESCRIPTION: Create and Install a block of GPE registers. The GPEs are not
+ *              enabled here.
  *
  ******************************************************************************/
 acpi_status
diff --git a/drivers/acpi/acpica/hwgpe.c b/drivers/acpi/acpica/hwgpe.c
index 7c6d4858bb49..85c3cbd4304d 100644
--- a/drivers/acpi/acpica/hwgpe.c
+++ b/drivers/acpi/acpica/hwgpe.c
@@ -62,10 +62,10 @@ acpi_hw_enable_wakeup_gpe_block(struct acpi_gpe_xrupt_info *gpe_xrupt_info,
  * PARAMETERS:  gpe_event_info      - Info block for the GPE
  *              gpe_register_info   - Info block for the GPE register
  *
- * RETURN:      Status
+ * RETURN:      Register mask with a one in the GPE bit position
  *
- * DESCRIPTION: Compute GPE enable mask with one bit corresponding to the given
- *              GPE set.
+ * DESCRIPTION: Compute the register mask for this GPE. One bit is set in the
+ *              correct position for the input GPE.
  *
  ******************************************************************************/
 
@@ -85,12 +85,12 @@ u32 acpi_hw_get_gpe_register_bit(struct acpi_gpe_event_info *gpe_event_info,
  *
  * RETURN:      Status
  *
- * DESCRIPTION: Enable or disable a single GPE in its enable register.
+ * DESCRIPTION: Enable or disable a single GPE in the parent enable register.
  *
  ******************************************************************************/
 
 acpi_status
-acpi_hw_low_set_gpe(struct acpi_gpe_event_info *gpe_event_info, u8 action)
+acpi_hw_low_set_gpe(struct acpi_gpe_event_info *gpe_event_info, u32 action)
 {
         struct acpi_gpe_register_info *gpe_register_info;
         acpi_status status;
@@ -113,14 +113,20 @@ acpi_hw_low_set_gpe(struct acpi_gpe_event_info *gpe_event_info, u8 action)
                 return (status);
         }
 
-        /* Set ot clear just the bit that corresponds to this GPE */
+        /* Set or clear just the bit that corresponds to this GPE */
 
         register_bit = acpi_hw_get_gpe_register_bit(gpe_event_info,
                                                 gpe_register_info);
         switch (action) {
         case ACPI_GPE_CONDITIONAL_ENABLE:
-                if (!(register_bit & gpe_register_info->enable_for_run))
+
+                /* Only enable if the enable_for_run bit is set */
+
+                if (!(register_bit & gpe_register_info->enable_for_run)) {
                         return (AE_BAD_PARAMETER);
+                }
+
+                /*lint -fallthrough */
 
         case ACPI_GPE_ENABLE:
                 ACPI_SET_BIT(enable_mask, register_bit);
@@ -131,7 +137,7 @@ acpi_hw_low_set_gpe(struct acpi_gpe_event_info *gpe_event_info, u8 action)
                 break;
 
         default:
-                ACPI_ERROR((AE_INFO, "Invalid action\n"));
+                ACPI_ERROR((AE_INFO, "Invalid GPE Action, %u\n", action));
                 return (AE_BAD_PARAMETER);
         }
 
@@ -168,13 +174,13 @@ acpi_status acpi_hw_clear_gpe(struct acpi_gpe_event_info * gpe_event_info)
                 return (AE_NOT_EXIST);
         }
 
-        register_bit = acpi_hw_get_gpe_register_bit(gpe_event_info,
-                                                gpe_register_info);
-
         /*
          * Write a one to the appropriate bit in the status register to
          * clear this GPE.
          */
+        register_bit =
+            acpi_hw_get_gpe_register_bit(gpe_event_info, gpe_register_info);
+
         status = acpi_hw_write(register_bit,
                                &gpe_register_info->status_address);
 
@@ -201,8 +207,8 @@ acpi_hw_get_gpe_status(struct acpi_gpe_event_info * gpe_event_info,
         u32 in_byte;
         u32 register_bit;
         struct acpi_gpe_register_info *gpe_register_info;
-        acpi_status status;
         acpi_event_status local_event_status = 0;
+        acpi_status status;
 
         ACPI_FUNCTION_ENTRY();