MIPS: Netlogic: Reduce size of reset code

Update thread wakeup function to use scratch registers for saving SP and
RA. Move the register restore code needed for thread 0 to the calling
function. This reduces the size of code copied to the reset vector.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6910/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/netlogic/common/reset.S

@@ -197,6 +197,9 @@ FEXPORT(nlm_reset_entry)
 EXPORT(nlm_boot_siblings)
 	/* core L1D flush before enable threads */
 	xlp_flush_l1_dcache
+	/* save ra and sp, will be used later (only for boot cpu) */
+	dmtc0	ra, $22, 6
+	dmtc0	sp, $22, 7
 	/* Enable hw threads by writing to MAP_THREADMODE of the core */
 	li	t0, CKSEG1ADDR(RESET_DATA_PHYS)
 	lw	t1, BOOT_THREAD_MODE(t0)	/* t1 <- thread mode */
@@ -238,14 +241,12 @@ EXPORT(nlm_boot_siblings)
 	nop
 
 	/*
-	 * For the boot CPU, we have to restore registers and
-	 * return
+	 * For the boot CPU, we have to restore ra and sp and return, rest
+	 * of the registers will be restored by the caller
 	 */
-4:	dmfc0	t0, $4, 2	/* restore SP from UserLocal */
-	li	t1, 0xfadebeef
-	dmtc0	t1, $4, 2	/* restore SP from UserLocal */
-	PTR_SUBU sp, t0, PT_SIZE
-	RESTORE_ALL
+4:
+	dmfc0	ra, $22, 6
+	dmfc0	sp, $22, 7
 	jr	ra
 	nop
 EXPORT(nlm_reset_entry_end)

arch/mips/netlogic/common/smpboot.S

@@ -54,8 +54,9 @@
 	.set	noat
 	.set	arch=xlr		/* for mfcr/mtcr, XLR is sufficient */
 
-FEXPORT(xlp_boot_core0_siblings)	/* "Master" cpu starts from here */
-	dmtc0	sp, $4, 2		/* SP saved in UserLocal */
+/* Called by the boot cpu to wake up its sibling threads */
+NESTED(xlp_boot_core0_siblings, PT_SIZE, sp)
+	/* CPU register contents lost when enabling threads, save them first */
 	SAVE_ALL
 	sync
 	/* find the location to which nlm_boot_siblings was relocated */
@@ -65,9 +66,12 @@ FEXPORT(xlp_boot_core0_siblings)	/* "Master" cpu starts from here */
 	dsubu	t2, t1
 	daddu	t2, t0
 	/* call it */
-	jr	t2
+	jalr	t2
 	nop
-	/* not reached */
+	RESTORE_ALL
+	jr	ra
+	nop
+END(xlp_boot_core0_siblings)
 
 NESTED(nlm_boot_secondary_cpus, 16, sp)
 	/* Initialize CP0 Status */