Introduce interrupt registration framework in BL3-1

This patch introduces a framework for registering interrupts routed to
EL3. The interrupt routing model is governed by the SCR_EL3.IRQ and
FIQ bits and the security state an interrupt is generated in. The
framework recognizes three type of interrupts depending upon which
exception level and security state they should be handled in
i.e. Secure EL1 interrupts, Non-secure interrupts and EL3
interrupts. It provides an API and macros that allow a runtime service
to register an handler for a type of interrupt and specify the routing
model. The framework validates the routing model and uses the context
management framework to ensure that it is applied to the SCR_EL3 prior
to entry into the target security state. It saves the handler in
internal data structures. An API is provided to retrieve the handler
when an interrupt of a particular type is asserted. Registration is
expected to be done once by the primary CPU. The same handler and
routing model is used for all CPUs.

Support for EL3 interrupts will be added to the framework in the
future. A makefile flag has been added to allow the FVP port choose
between ARM GIC v2 and v3 support in EL3. The latter version is
currently unsupported.

A framework for handling interrupts in BL3-1 will be introduced in
subsequent patches. The default routing model in the absence of any
handlers expects no interrupts to be routed to EL3.

Change-Id: Idf7c023b34fcd4800a5980f2bef85e4b5c29e649

1 files changed, 206 insertions, 0 deletions

diff --git a/bl31/interrupt_mgmt.c b/bl31/interrupt_mgmt.c
new file mode 100644
index 00000000..2b0c7970
--- /dev/null
+++ b/bl31/interrupt_mgmt.c
@@ -0,0 +1,206 @@
+/*
+ * Copyright (c) 2014, ARM Limited and Contributors. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of ARM nor the names of its contributors may be used
+ * to endorse or promote products derived from this software without specific
+ * prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <assert.h>
+#include <bl_common.h>
+#include <context_mgmt.h>
+#include <errno.h>
+#include <interrupt_mgmt.h>
+#include <platform.h>
+#include <stdio.h>
+
+/*******************************************************************************
+ * Local structure and corresponding array to keep track of the state of the
+ * registered interrupt handlers for each interrupt type.
+ * The field descriptions are:
+ *
+ * 'flags' : Bit[0], Routing model for this interrupt type when execution is
+ *                   not in EL3 in the secure state. '1' implies that this
+ *                   interrupt will be routed to EL3. '0' implies that this
+ *                   interrupt will be routed to the current exception level.
+ *
+ *           Bit[1], Routing model for this interrupt type when execution is
+ *                   not in EL3 in the non-secure state. '1' implies that this
+ *                   interrupt will be routed to EL3. '0' implies that this
+ *                   interrupt will be routed to the current exception level.
+ *
+ *           All other bits are reserved and SBZ.
+ *
+ * 'scr_el3[2]'  : Mapping of the routing model in the 'flags' field to the
+ *                 value of the SCR_EL3.IRQ or FIQ bit for each security state.
+ *                 There are two instances of this field corresponding to the
+ *                 two security states.
+ ******************************************************************************/
+typedef struct intr_type_desc {
+	interrupt_type_handler_t handler;
+	uint32_t flags;
+	uint32_t scr_el3[2];
+} intr_type_desc_t;
+
+static intr_type_desc_t intr_type_descs[MAX_INTR_TYPES];
+
+/*******************************************************************************
+ * This function validates the interrupt type. EL3 interrupts are currently not
+ * supported.
+ ******************************************************************************/
+static int32_t validate_interrupt_type(uint32_t type)
+{
+	if (type == INTR_TYPE_EL3)
+		return -ENOTSUP;
+
+	if (type != INTR_TYPE_S_EL1 && type != INTR_TYPE_NS)
+		return -EINVAL;
+
+	return 0;
+}
+
+/*******************************************************************************
+* This function validates the routing model for this type of interrupt
+ ******************************************************************************/
+static int32_t validate_routing_model(uint32_t type, uint32_t flags)
+{
+	flags >>= INTR_RM_FLAGS_SHIFT;
+	flags &= INTR_RM_FLAGS_MASK;
+
+	if (type == INTR_TYPE_S_EL1)
+		return validate_sel1_interrupt_rm(flags);
+
+	if (type == INTR_TYPE_NS)
+		return validate_ns_interrupt_rm(flags);
+
+	return -EINVAL;
+}
+
+/*******************************************************************************
+ * This function returns the cached copy of the SCR_EL3 which contains the
+ * routing model (expressed through the IRQ and FIQ bits) for a security state
+ * which was stored through a call to 'set_routing_model()' earlier.
+ ******************************************************************************/
+uint32_t get_scr_el3_from_routing_model(uint32_t security_state)
+{
+	uint32_t scr_el3;
+
+	assert(security_state <= NON_SECURE);
+	scr_el3 = intr_type_descs[INTR_TYPE_NS].scr_el3[security_state];
+	scr_el3 |= intr_type_descs[INTR_TYPE_S_EL1].scr_el3[security_state];
+	scr_el3 |= intr_type_descs[INTR_TYPE_EL3].scr_el3[security_state];
+	return scr_el3;
+}
+
+/*******************************************************************************
+ * This function uses the 'interrupt_type_flags' parameter to obtain the value
+ * of the trap bit (IRQ/FIQ) in the SCR_EL3 for a security state for this
+ * interrupt type. It uses it to update the SCR_EL3 in the cpu context and the
+ * 'intr_type_desc' for that security state.
+ ******************************************************************************/
+static void set_scr_el3_from_rm(uint32_t type,
+				uint32_t interrupt_type_flags,
+				uint32_t security_state)
+{
+	uint32_t flag, bit_pos;
+
+	flag = get_interrupt_rm_flag(interrupt_type_flags, security_state);
+	bit_pos = plat_interrupt_type_to_line(type, security_state);
+	intr_type_descs[type].scr_el3[security_state] = flag << bit_pos;
+	cm_write_scr_el3_bit(security_state, bit_pos, flag);
+}
+
+/*******************************************************************************
+ * This function validates the routing model specified in the 'flags' and
+ * updates internal data structures to reflect the new routing model. It also
+ * updates the copy of SCR_EL3 for each security state with the new routing
+ * model in the 'cpu_context' structure for this cpu.
+ ******************************************************************************/
+int32_t set_routing_model(uint32_t type, uint32_t flags)
+{
+	int32_t rc;
+
+	rc = validate_interrupt_type(type);
+	if (rc)
+		return rc;
+
+	rc = validate_routing_model(type, flags);
+	if (rc)
+		return rc;
+
+	/* Update the routing model in internal data structures */
+	intr_type_descs[type].flags = flags;
+	set_scr_el3_from_rm(type, flags, SECURE);
+	set_scr_el3_from_rm(type, flags, NON_SECURE);
+
+	return 0;
+}
+
+/*******************************************************************************
+ * This function registers a handler for the 'type' of interrupt specified. It
+ * also validates the routing model specified in the 'flags' for this type of
+ * interrupt.
+ ******************************************************************************/
+int32_t register_interrupt_type_handler(uint32_t type,
+					interrupt_type_handler_t handler,
+					uint32_t flags)
+{
+	int32_t rc;
+
+	/* Validate the 'handler' parameter */
+	if (!handler)
+		return -EINVAL;
+
+	/* Validate the 'flags' parameter */
+	if (flags & INTR_TYPE_FLAGS_MASK)
+		return -EINVAL;
+
+	/* Check if a handler has already been registered */
+	if (intr_type_descs[type].handler)
+		return -EALREADY;
+
+	rc = set_routing_model(type, flags);
+	if (rc)
+		return rc;
+
+	/* Save the handler */
+	intr_type_descs[type].handler = handler;
+
+	return 0;
+}
+
+/*******************************************************************************
+ * This function is called when an interrupt is generated and returns the
+ * handler for the interrupt type (if registered). It returns NULL if the
+ * interrupt type is not supported or its handler has not been registered.
+ ******************************************************************************/
+interrupt_type_handler_t get_interrupt_type_handler(uint32_t type)
+{
+	if (validate_interrupt_type(type))
+		return NULL;
+
+	return intr_type_descs[type].handler;
+}
+