AArch32: Add support to PSCI lib

This patch adds AArch32 support to PSCI library, as follows :

* The `psci_helpers.S` is implemented for AArch32.

* AArch32 version of internal helper function `psci_get_ns_ep_info()` is
  defined.

* The PSCI Library is responsible for the Non Secure context initialization.
  Hence a library interface `psci_prepare_next_non_secure_ctx()` is introduced
  to enable EL3 runtime firmware to initialize the non secure context without
  invoking context management library APIs.

Change-Id: I25595b0cc2dbfdf39dbf7c589b875cba33317b9d

4 files changed, 249 insertions, 6 deletions

diff --git a/lib/psci/aarch32/psci_helpers.S b/lib/psci/aarch32/psci_helpers.S
new file mode 100644
index 00000000..36d5d7d9
--- /dev/null
+++ b/lib/psci/aarch32/psci_helpers.S
@@ -0,0 +1,180 @@
+/*
+ * Copyright (c) 2016, 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 <asm_macros.S>
+#include <platform_def.h>
+#include <psci.h>
+
+	.globl	psci_do_pwrdown_cache_maintenance
+	.globl	psci_do_pwrup_cache_maintenance
+	.globl	psci_power_down_wfi
+
+/* -----------------------------------------------------------------------
+ * void psci_do_pwrdown_cache_maintenance(unsigned int power level);
+ *
+ * This function performs cache maintenance for the specified power
+ * level. The levels of cache affected are determined by the power
+ * level which is passed as the argument i.e. level 0 results
+ * in a flush of the L1 cache. Both the L1 and L2 caches are flushed
+ * for a higher power level.
+ *
+ * Additionally, this function also ensures that stack memory is correctly
+ * flushed out to avoid coherency issues due to a change in its memory
+ * attributes after the data cache is disabled.
+ * -----------------------------------------------------------------------
+ */
+func psci_do_pwrdown_cache_maintenance
+	push	{r4, lr}
+
+	/* ----------------------------------------------
+	 * Turn OFF cache and do stack maintenance
+	 * prior to cpu operations . This sequence is
+	 * different from AArch64 because in AArch32 the
+	 * assembler routines for cpu operations utilize
+	 * the stack whereas in AArch64 it doesn't.
+	 * ----------------------------------------------
+	 */
+	mov	r4, r0
+	bl	do_stack_maintenance
+
+	/* ---------------------------------------------
+	 * Determine how many levels of cache will be
+	 * subject to cache maintenance. Power level
+	 * 0 implies that only the cpu is being powered
+	 * down. Only the L1 data cache needs to be
+	 * flushed to the PoU in this case. For a higher
+	 * power level we are assuming that a flush
+	 * of L1 data and L2 unified cache is enough.
+	 * This information should be provided by the
+	 * platform.
+	 * ---------------------------------------------
+	 */
+	cmp	r4, #PSCI_CPU_PWR_LVL
+	pop	{r4,lr}
+
+	beq	prepare_core_pwr_dwn
+	b	prepare_cluster_pwr_dwn
+endfunc psci_do_pwrdown_cache_maintenance
+
+
+/* -----------------------------------------------------------------------
+ * void psci_do_pwrup_cache_maintenance(void);
+ *
+ * This function performs cache maintenance after this cpu is powered up.
+ * Currently, this involves managing the used stack memory before turning
+ * on the data cache.
+ * -----------------------------------------------------------------------
+ */
+func psci_do_pwrup_cache_maintenance
+	push	{lr}
+
+	/* ---------------------------------------------
+	 * Ensure any inflight stack writes have made it
+	 * to main memory.
+	 * ---------------------------------------------
+	 */
+	dmb	st
+
+	/* ---------------------------------------------
+	 * Calculate and store the size of the used
+	 * stack memory in r1. Calculate and store the
+	 * stack base address in r0.
+	 * ---------------------------------------------
+	 */
+	bl	plat_get_my_stack
+	mov	r1, sp
+	sub	r1, r0, r1
+	mov	r0, sp
+	bl	inv_dcache_range
+
+	/* ---------------------------------------------
+	 * Enable the data cache.
+	 * ---------------------------------------------
+	 */
+	ldcopr	r0, SCTLR
+	orr	r0, r0, #SCTLR_C_BIT
+	stcopr	r0, SCTLR
+	isb
+
+	pop	{pc}
+endfunc psci_do_pwrup_cache_maintenance
+
+	/* ---------------------------------------------
+	 * void do_stack_maintenance(void)
+	 * Do stack maintenance by flushing the used
+	 * stack to the main memory and invalidating the
+	 * remainder.
+	 * ---------------------------------------------
+	 */
+func do_stack_maintenance
+	push	{r4, lr}
+	bl	plat_get_my_stack
+
+	/* Turn off the D-cache */
+	ldcopr	r1, SCTLR
+	bic	r1, #SCTLR_C_BIT
+	stcopr	r1, SCTLR
+	isb
+
+	/* ---------------------------------------------
+	 * Calculate and store the size of the used
+	 * stack memory in r1.
+	 * ---------------------------------------------
+	 */
+	mov	r4, r0
+	mov	r1, sp
+	sub	r1, r0, r1
+	mov	r0, sp
+	bl	flush_dcache_range
+
+	/* ---------------------------------------------
+	 * Calculate and store the size of the unused
+	 * stack memory in r1. Calculate and store the
+	 * stack base address in r0.
+	 * ---------------------------------------------
+	 */
+	sub	r0, r4, #PLATFORM_STACK_SIZE
+	sub	r1, sp, r0
+	bl	inv_dcache_range
+
+	pop	{r4, pc}
+endfunc do_stack_maintenance
+
+/* -----------------------------------------------------------------------
+ * This function is called to indicate to the power controller that it
+ * is safe to power down this cpu. It should not exit the wfi and will
+ * be released from reset upon power up.
+ * -----------------------------------------------------------------------
+ */
+func psci_power_down_wfi
+	dsb	sy		// ensure write buffer empty
+	wfi
+	bl	plat_panic_handler
+endfunc psci_power_down_wfi
diff --git a/lib/psci/psci_common.c b/lib/psci/psci_common.c
index e87e8c05..68cdd6eb 100644
--- a/lib/psci/psci_common.c
+++ b/lib/psci/psci_common.c
@@ -592,6 +592,53 @@ int psci_validate_mpidr(u_register_t mpidr)
  * This function determines the full entrypoint information for the requested
  * PSCI entrypoint on power on/resume and returns it.
  ******************************************************************************/
+#ifdef AARCH32
+static int psci_get_ns_ep_info(entry_point_info_t *ep,
+			       uintptr_t entrypoint,
+			       u_register_t context_id)
+{
+	u_register_t ep_attr;
+	unsigned int aif, ee, mode;
+	u_register_t scr = read_scr();
+	u_register_t ns_sctlr, sctlr;
+
+	/* Switch to non secure state */
+	write_scr(scr | SCR_NS_BIT);
+	isb();
+	ns_sctlr = read_sctlr();
+
+	sctlr = scr & SCR_HCE_BIT ? read_hsctlr() : ns_sctlr;
+
+	/* Return to original state */
+	write_scr(scr);
+	isb();
+	ee = 0;
+
+	ep_attr = NON_SECURE | EP_ST_DISABLE;
+	if (sctlr & SCTLR_EE_BIT) {
+		ep_attr |= EP_EE_BIG;
+		ee = 1;
+	}
+	SET_PARAM_HEAD(ep, PARAM_EP, VERSION_1, ep_attr);
+
+	ep->pc = entrypoint;
+	memset(&ep->args, 0, sizeof(ep->args));
+	ep->args.arg0 = context_id;
+
+	mode = scr & SCR_HCE_BIT ? MODE32_hyp : MODE32_svc;
+
+	/*
+	 * TODO: Choose async. exception bits if HYP mode is not
+	 * implemented according to the values of SCR.{AW, FW} bits
+	 */
+	aif = SPSR_ABT_BIT | SPSR_IRQ_BIT | SPSR_FIQ_BIT;
+
+	ep->spsr = SPSR_MODE32(mode, entrypoint & 0x1, ee, aif);
+
+	return PSCI_E_SUCCESS;
+}
+
+#else
 static int psci_get_ns_ep_info(entry_point_info_t *ep,
 			       uintptr_t entrypoint,
 			       u_register_t context_id)
@@ -646,6 +693,7 @@ static int psci_get_ns_ep_info(entry_point_info_t *ep,
 
 	return PSCI_E_SUCCESS;
 }
+#endif
 
 /*******************************************************************************
  * This function validates the entrypoint with the platform layer if the
diff --git a/lib/psci/psci_lib.mk b/lib/psci/psci_lib.mk
index 3a5833ba..8daa8318 100644
--- a/lib/psci/psci_lib.mk
+++ b/lib/psci/psci_lib.mk
@@ -29,11 +29,10 @@
 #
 
 PSCI_LIB_SOURCES	:=	lib/el3_runtime/cpu_data_array.c	\
-				lib/el3_runtime/aarch64/context.S	\
-				lib/el3_runtime/aarch64/cpu_data.S	\
-				lib/el3_runtime/aarch64/context_mgmt.c	\
-				lib/cpus/aarch64/cpu_helpers.S		\
-				lib/locks/exclusive/aarch64/spinlock.S	\
+				lib/el3_runtime/${ARCH}/cpu_data.S	\
+				lib/el3_runtime/${ARCH}/context_mgmt.c	\
+				lib/cpus/${ARCH}/cpu_helpers.S		\
+				lib/locks/exclusive/${ARCH}/spinlock.S	\
 				lib/psci/psci_off.c			\
 				lib/psci/psci_on.c			\
 				lib/psci/psci_suspend.c			\
@@ -41,7 +40,11 @@ PSCI_LIB_SOURCES	:=	lib/el3_runtime/cpu_data_array.c	\
 				lib/psci/psci_main.c			\
 				lib/psci/psci_setup.c			\
 				lib/psci/psci_system_off.c		\
-				lib/psci/aarch64/psci_helpers.S
+				lib/psci/${ARCH}/psci_helpers.S
+
+ifeq (${ARCH}, aarch64)
+PSCI_LIB_SOURCES	+=	lib/el3_runtime/aarch64/context.S
+endif
 
 ifeq (${USE_COHERENT_MEM}, 1)
 PSCI_LIB_SOURCES		+=	lib/locks/bakery/bakery_lock_coherent.c
diff --git a/lib/psci/psci_setup.c b/lib/psci/psci_setup.c
index d35e0001..20d06352 100644
--- a/lib/psci/psci_setup.c
+++ b/lib/psci/psci_setup.c
@@ -278,3 +278,15 @@ void psci_arch_setup(void)
 	/* Initialize the cpu_ops pointer. */
 	init_cpu_ops();
 }
+
+/******************************************************************************
+ * PSCI Library interface to initialize the cpu context for the next non
+ * secure image during cold boot. The relevant registers in the cpu context
+ * need to be retrieved and programmed on return from this interface.
+ *****************************************************************************/
+void psci_prepare_next_non_secure_ctx(entry_point_info_t *next_image_info)
+{
+	assert(GET_SECURITY_STATE(next_image_info->h.attr) == NON_SECURE);
+	cm_init_my_context(next_image_info);
+	cm_prepare_el3_exit(NON_SECURE);
+}