Use secure timer to generate S-EL1 interrupts

This patch adds support in the TSP to program the secure physical
generic timer to generate a EL-1 interrupt every half second. It also
adds support for maintaining the timer state across power management
operations. The TSPD ensures that S-EL1 can access the timer by
programming the SCR_EL3.ST bit.

This patch does not actually enable the timer. This will be done in a
subsequent patch once the complete framework for handling S-EL1
interrupts is in place.

Change-Id: I1b3985cfb50262f60824be3a51c6314ce90571bc

2 files changed, 108 insertions, 1 deletions

diff --git a/bl32/tsp/tsp.mk b/bl32/tsp/tsp.mk
index c478b435..07bd9c64 100644
--- a/bl32/tsp/tsp.mk
+++ b/bl32/tsp/tsp.mk
@@ -32,7 +32,8 @@ BL32_SOURCES		+=	bl32/tsp/tsp_main.c			\
 				bl32/tsp/aarch64/tsp_entrypoint.S	\
 				bl32/tsp/aarch64/tsp_request.S		\
 				common/aarch64/early_exceptions.S	\
-				lib/locks/exclusive/spinlock.S
+				lib/locks/exclusive/spinlock.S		\
+				bl32/tsp/tsp_timer.c
 
 BL32_LINKERFILE		:=	bl32/tsp/tsp.ld.S
 
diff --git a/bl32/tsp/tsp_timer.c b/bl32/tsp/tsp_timer.c
new file mode 100644
index 00000000..f66ff9fa
--- /dev/null
+++ b/bl32/tsp/tsp_timer.c
@@ -0,0 +1,106 @@
+/*
+ * 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 <arch_helpers.h>
+#include <assert.h>
+#include <tsp.h>
+
+/*******************************************************************************
+ * Data structure to keep track of per-cpu secure generic timer context across
+ * power management operations.
+ ******************************************************************************/
+typedef struct timer_context {
+	uint64_t cval;
+	uint32_t ctl;
+} timer_context_t;
+
+static timer_context_t pcpu_timer_context[PLATFORM_CORE_COUNT];
+
+/*******************************************************************************
+ * This function initializes the generic timer to fire every 0.5 second
+ ******************************************************************************/
+void tsp_generic_timer_start()
+{
+	uint64_t cval;
+	uint32_t ctl = 0;
+
+	/* The timer will fire every 0.5 second */
+	cval = read_cntpct_el0() + (read_cntfrq_el0() >> 1);
+	write_cntps_cval_el1(cval);
+
+	/* Enable the secure physical timer */
+	set_cntp_ctl_enable(ctl);
+	write_cntps_ctl_el1(ctl);
+}
+
+/*******************************************************************************
+ * This function deasserts the timer interrupt and sets it up again
+ ******************************************************************************/
+void tsp_generic_timer_handler()
+{
+	/* Ensure that the timer did assert the interrupt */
+	assert(get_cntp_ctl_istatus(read_cntps_ctl_el1()));
+
+	/* Disable the timer and reprogram it */
+	write_cntps_ctl_el1(0);
+	tsp_generic_timer_start();
+}
+
+/*******************************************************************************
+ * This function deasserts the timer interrupt prior to cpu power down
+ ******************************************************************************/
+void tsp_generic_timer_stop()
+{
+	/* Disable the timer */
+	write_cntps_ctl_el1(0);
+}
+
+/*******************************************************************************
+ * This function saves the timer context prior to cpu suspension
+ ******************************************************************************/
+void tsp_generic_timer_save()
+{
+	uint32_t linear_id = platform_get_core_pos(read_mpidr());
+
+	pcpu_timer_context[linear_id].cval = read_cntps_cval_el1();
+	pcpu_timer_context[linear_id].ctl = read_cntps_ctl_el1();
+	flush_dcache_range((uint64_t) &pcpu_timer_context[linear_id],
+			   sizeof(pcpu_timer_context[linear_id]));
+}
+
+/*******************************************************************************
+ * This function restores the timer context post cpu resummption
+ ******************************************************************************/
+void tsp_generic_timer_restore()
+{
+	uint32_t linear_id = platform_get_core_pos(read_mpidr());
+
+	write_cntps_cval_el1(pcpu_timer_context[linear_id].cval);
+	write_cntps_ctl_el1(pcpu_timer_context[linear_id].ctl);
+}