GIC: Introduce API to get interrupt ID
Acknowledging interrupt shall return a raw value from the interrupt
controller in which the actual interrupt ID may be encoded. Add a
platform API to extract the actual interrupt ID from the raw value
obtained from interrupt controller.
Document the new function. Also clarify the semantics of interrupt
acknowledge.
Change-Id: I818dad7be47661658b16f9807877d259eb127405
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
diff --git a/docs/platform-interrupt-controller-API.rst b/docs/platform-interrupt-controller-API.rst
index 795c085..c14f005 100644
--- a/docs/platform-interrupt-controller-API.rst
+++ b/docs/platform-interrupt-controller-API.rst
@@ -292,6 +292,22 @@
*Priority Mask Register*, and make sure memory updates are visible before
potential trigger due to mask update.
+Function: unsigned int plat_ic_get_interrupt_id(unsigned int raw); [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : unsigned int
+ Return : unsigned int
+
+This API should extract and return the interrupt number from the raw value
+obtained by the acknowledging the interrupt (read using
+``plat_ic_acknowledge_interrupt()``). If the interrupt ID is invalid, this API
+should return ``INTR_ID_UNAVAILABLE``.
+
+In case of ARM standard platforms using GIC, the implementation of the API
+masks out the interrupt ID field from the acknowledged value from GIC.
+
----
*Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.*
diff --git a/docs/porting-guide.rst b/docs/porting-guide.rst
index f0a8aaf..af933fd 100644
--- a/docs/porting-guide.rst
+++ b/docs/porting-guide.rst
@@ -2479,14 +2479,17 @@
Return : uint32_t
This API is used by the CPU to indicate to the platform IC that processing of
-the highest pending interrupt has begun. It should return the id of the
-interrupt which is being processed.
+the highest pending interrupt has begun. It should return the raw, unmodified
+value obtained from the interrupt controller when acknowledging an interrupt.
+The actual interrupt number shall be extracted from this raw value using the API
+`plat_ic_get_interrupt_id()`__.
+
+.. __: platform-interrupt-controller-API.rst#function-unsigned-int-plat-ic-get-interrupt-id-unsigned-int-raw-optional
This function in ARM standard platforms using GICv2, reads the *Interrupt
Acknowledge Register* (``GICC_IAR``). This changes the state of the highest
priority pending interrupt from pending to active in the interrupt controller.
-It returns the value read from the ``GICC_IAR``. This value is the id of the
-interrupt whose state has been changed.
+It returns the value read from the ``GICC_IAR``, unmodified.
In the case of ARM standard platforms using GICv3, if the API is invoked
from EL3, the function reads the system register ``ICC_IAR0_EL1``, *Interrupt
@@ -2494,7 +2497,7 @@
reads the system register ``ICC_IAR1_EL1``, *Interrupt Acknowledge Register
group 1*. The read changes the state of the highest pending interrupt from
pending to active in the interrupt controller. The value read is returned
-and is the id of the interrupt whose state has been changed.
+unmodified.
The TSP uses this API to start processing of the secure physical timer
interrupt.
diff --git a/include/drivers/arm/gicv3.h b/include/drivers/arm/gicv3.h
index b2e4d4c..f2a5371 100644
--- a/include/drivers/arm/gicv3.h
+++ b/include/drivers/arm/gicv3.h
@@ -245,6 +245,9 @@
#define GICR_NUM_REGS(reg_name) \
DIV_ROUND_UP_2EVAL(TOTAL_PCPU_INTR_NUM, (1 << reg_name ## _SHIFT))
+/* Interrupt ID mask for HPPIR, AHPPIR, IAR and AIAR CPU Interface registers */
+#define INT_ID_MASK 0xffffff
+
/*******************************************************************************
* This structure describes some of the implementation defined attributes of the
* GICv3 IP. It is used by the platform port to specify these attributes in order
diff --git a/include/plat/common/platform.h b/include/plat/common/platform.h
index 068d7aa..086e5e6 100644
--- a/include/plat/common/platform.h
+++ b/include/plat/common/platform.h
@@ -90,6 +90,7 @@
void plat_ic_set_interrupt_pending(unsigned int id);
void plat_ic_clear_interrupt_pending(unsigned int id);
unsigned int plat_ic_set_priority_mask(unsigned int mask);
+unsigned int plat_ic_get_interrupt_id(unsigned int raw);
/*******************************************************************************
* Optional common functions (may be overridden)
diff --git a/plat/common/plat_gicv2.c b/plat/common/plat_gicv2.c
index 05fabca..38e1a61 100644
--- a/plat/common/plat_gicv2.c
+++ b/plat/common/plat_gicv2.c
@@ -277,3 +277,13 @@
{
return gicv2_set_pmr(mask);
}
+
+unsigned int plat_ic_get_interrupt_id(unsigned int raw)
+{
+ unsigned int id = (raw & INT_ID_MASK);
+
+ if (id == GIC_SPURIOUS_INTERRUPT)
+ id = INTR_ID_UNAVAILABLE;
+
+ return id;
+}
diff --git a/plat/common/plat_gicv3.c b/plat/common/plat_gicv3.c
index 52ceb6a..030eea7 100644
--- a/plat/common/plat_gicv3.c
+++ b/plat/common/plat_gicv3.c
@@ -271,6 +271,14 @@
{
return gicv3_set_pmr(mask);
}
+
+unsigned int plat_ic_get_interrupt_id(unsigned int raw)
+{
+ unsigned int id = (raw & INT_ID_MASK);
+
+ return (gicv3_is_intr_id_special_identifier(id) ?
+ INTR_ID_UNAVAILABLE : id);
+}
#endif
#ifdef IMAGE_BL32