PSCI: Use a single mailbox for warm reset for FVP and Juno

Since there is a unique warm reset entry point, the FVP and Juno
port can use a single mailbox instead of maintaining one per core.
The mailbox gets programmed only once when plat_setup_psci_ops()
is invoked during PSCI initialization. This means mailbox is not
zeroed out during wakeup.

Change-Id: Ieba032a90b43650f970f197340ebb0ce5548d432

3 files changed, 44 insertions, 68 deletions

diff --git a/plat/arm/board/fvp/aarch64/fvp_helpers.S b/plat/arm/board/fvp/aarch64/fvp_helpers.S
index 2787ee67..9cf3c73c 100644
--- a/plat/arm/board/fvp/aarch64/fvp_helpers.S
+++ b/plat/arm/board/fvp/aarch64/fvp_helpers.S
@@ -96,29 +96,30 @@ cb_panic:
 	b	cb_panic
 endfunc plat_secondary_cold_boot_setup
 
-
-	/* -----------------------------------------------------
+	/* ---------------------------------------------------------------------
 	 * unsigned long plat_get_my_entrypoint (void);
 	 *
-	 * Main job of this routine is to distinguish between
-	 * a cold and warm boot on the current CPU.
-	 * On a cold boot the secondaries first wait for the
-	 * platform to be initialized after which they are
-	 * hotplugged in. The primary proceeds to perform the
-	 * platform initialization.
-	 * On a warm boot, each cpu jumps to the address in its
-	 * mailbox.
+	 * Main job of this routine is to distinguish between a cold and warm
+	 * boot. On FVP, this information can be queried from the power
+	 * controller. The Power Control SYS Status Register (PSYSR) indicates
+	 * the wake-up reason for the CPU.
+	 *
+	 * For a cold boot, return 0.
+	 * For a warm boot, read the mailbox and return the address it contains.
 	 *
-	 * TODO: Not a good idea to save lr in a temp reg
 	 * TODO: PSYSR is a common register and should be
 	 * 	accessed using locks. Since its not possible
 	 * 	to use locks immediately after a cold reset
 	 * 	we are relying on the fact that after a cold
 	 * 	reset all cpus will read the same WK field
-	 * -----------------------------------------------------
+	 * ---------------------------------------------------------------------
 	 */
 func plat_get_my_entrypoint
-	mov	x9, x30 // lr
+	/* ---------------------------------------------------------------------
+	 * When bit PSYSR.WK indicates either "Wake by PPONR" or "Wake by GIC
+	 * WakeRequest signal" then it is a warm boot.
+	 * ---------------------------------------------------------------------
+	 */
 	mrs	x2, mpidr_el1
 	ldr	x1, =PWRC_BASE
 	str	w2, [x1, #PSYSR_OFF]
@@ -128,46 +129,41 @@ func plat_get_my_entrypoint
 	beq	warm_reset
 	cmp	w2, #WKUP_GICREQ
 	beq	warm_reset
+
+	/* Cold reset */
 	mov	x0, #0
-	b	exit
+	ret
+
 warm_reset:
-	/* ---------------------------------------------
-	 * A per-cpu mailbox is maintained in the tru-
-	 * sted DRAM. Its flushed out of the caches
-	 * after every update using normal memory so
-	 * its safe to read it here with SO attributes
-	 * ---------------------------------------------
+	/* ---------------------------------------------------------------------
+	 * A mailbox is maintained in the trusted SRAM. It is flushed out of the
+	 * caches after every update using normal memory so it is safe to read
+	 * it here with SO attributes.
+	 * ---------------------------------------------------------------------
 	 */
-	ldr	x10, =MBOX_BASE
-	bl	plat_my_core_pos
-	lsl	x0, x0, #ARM_CACHE_WRITEBACK_SHIFT
-	ldr	x0, [x10, x0]
+	mov_imm	x0, MBOX_BASE
+	ldr	x0, [x0]
 	cbz	x0, _panic
-exit:
-	ret	x9
-_panic:	b	_panic
+	ret
+
+	/* ---------------------------------------------------------------------
+	 * The power controller indicates this is a warm reset but the mailbox
+	 * is empty. This should never happen!
+	 * ---------------------------------------------------------------------
+	 */
+_panic:
+	b	_panic
 endfunc plat_get_my_entrypoint
 
 
-	/* -----------------------------------------------------
+	/* ---------------------------------------------------------------------
 	 * void platform_mem_init (void);
 	 *
-	 * Zero out the mailbox registers in the shared memory.
-	 * The mmu is turned off right now and only the primary can
-	 * ever execute this code. Secondaries will read the
-	 * mailboxes using SO accesses. In short, BL31 will
-	 * update the mailboxes after mapping the tzdram as
-	 * normal memory. It will flush its copy after update.
-	 * BL1 will always read the mailboxes with the MMU off
-	 * -----------------------------------------------------
+	 * Nothing to do on FVP, the Trusted SRAM is available straight away
+	 * after reset.
+	 * ---------------------------------------------------------------------
 	 */
 func platform_mem_init
-	ldr	x0, =MBOX_BASE
-	mov	w1, #PLATFORM_CORE_COUNT
-loop:
-	str	xzr, [x0], #CACHE_WRITEBACK_GRANULE
-	subs	w1, w1, #1
-	b.gt	loop
 	ret
 endfunc platform_mem_init
 
diff --git a/plat/arm/board/fvp/fvp_def.h b/plat/arm/board/fvp/fvp_def.h
index 842a287b..69294815 100644
--- a/plat/arm/board/fvp/fvp_def.h
+++ b/plat/arm/board/fvp/fvp_def.h
@@ -139,7 +139,6 @@
 
 /* Entrypoint mailboxes */
 #define MBOX_BASE			ARM_SHARED_RAM_BASE
-#define MBOX_SIZE			0x200
 
 
 #endif /* __FVP_DEF_H__ */
diff --git a/plat/arm/board/fvp/fvp_pm.c b/plat/arm/board/fvp/fvp_pm.c
index 56d65029..8be51054 100644
--- a/plat/arm/board/fvp/fvp_pm.c
+++ b/plat/arm/board/fvp/fvp_pm.c
@@ -43,11 +43,6 @@
 #include "fvp_def.h"
 #include "fvp_private.h"
 
-unsigned long wakeup_address;
-
-typedef volatile struct mailbox {
-	unsigned long value __aligned(CACHE_WRITEBACK_GRANULE);
-} mailbox_t;
 
 #if ARM_RECOM_STATE_ID_ENC
 /*
@@ -74,16 +69,11 @@ const unsigned int arm_pm_idle_states[] = {
  * Private FVP function to program the mailbox for a cpu before it is released
  * from reset.
  ******************************************************************************/
-static void fvp_program_mailbox(uint64_t mpidr, uint64_t address)
+static void fvp_program_mailbox(uintptr_t address)
 {
-	uint64_t linear_id;
-	mailbox_t *fvp_mboxes;
-
-	linear_id = plat_arm_calc_core_pos(mpidr);
-	fvp_mboxes = (mailbox_t *)MBOX_BASE;
-	fvp_mboxes[linear_id].value = address;
-	flush_dcache_range((unsigned long) &fvp_mboxes[linear_id],
-			   sizeof(unsigned long));
+	uintptr_t *mailbox = (void *) MBOX_BASE;
+	*mailbox = address;
+	flush_dcache_range((uintptr_t) mailbox, sizeof(*mailbox));
 }
 
 /*******************************************************************************
@@ -150,9 +140,7 @@ int fvp_pwr_domain_on(u_register_t mpidr)
 		psysr = fvp_pwrc_read_psysr(mpidr);
 	} while (psysr & PSYSR_AFF_L0);
 
-	fvp_program_mailbox(mpidr, wakeup_address);
 	fvp_pwrc_write_pponr(mpidr);
-
 	return rc;
 }
 
@@ -200,9 +188,6 @@ void fvp_pwr_domain_suspend(const psci_power_state_t *target_state)
 	/* Get the mpidr for this cpu */
 	mpidr = read_mpidr_el1();
 
-	/* Program the jump address for the this cpu */
-	fvp_program_mailbox(mpidr, wakeup_address);
-
 	/* Program the power controller to enable wakeup interrupts. */
 	fvp_pwrc_set_wen(mpidr);
 
@@ -254,9 +239,6 @@ void fvp_pwr_domain_on_finish(const psci_power_state_t *target_state)
 	 */
 	fvp_pwrc_clr_wen(mpidr);
 
-	/* Zero the jump address in the mailbox for this cpu */
-	fvp_program_mailbox(mpidr, 0);
-
 	/* Enable the gic cpu interface */
 	arm_gic_cpuif_setup();
 
@@ -332,9 +314,8 @@ int plat_setup_psci_ops(uintptr_t sec_entrypoint,
 				const plat_psci_ops_t **psci_ops)
 {
 	*psci_ops = &fvp_plat_psci_ops;
-	wakeup_address = sec_entrypoint;
 
-	flush_dcache_range((unsigned long)&wakeup_address,
-				sizeof(wakeup_address));
+	/* Program the jump address */
+	fvp_program_mailbox(sec_entrypoint);
 	return 0;
 }