MIPS: BCM63xx: Add SMP support to prom.c

This involves two changes to the BSP code:

1) register_smp_ops() for BMIPS SMP

2) The CPU1 boot vector on some of the BCM63xx platforms conflicts with
the special interrupt vector (IV).  Move it to 0x8000_0380 at boot time,
to resolve the conflict.
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
[jogo@openwrt.org: moved SMP ops registration into ifdef guard,
 changed ifdef guards to if (IS_ENABLED())]
Signed-off-by: Jonas Gorski <jogo@openwrt.org>
Cc: linux-mips@linux-mips.org
Cc: John Crispin <blogic@openwrt.org>
Cc: Maxime Bizon <mbizon@freebox.fr>
Cc: Florian Fainelli <florian@openwrt.org>
Patchwork: https://patchwork.linux-mips.org/patch/5489/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/bcm63xx/prom.c

@@ -8,7 +8,11 @@
 
 #include <linux/init.h>
 #include <linux/bootmem.h>
+#include <linux/smp.h>
 #include <asm/bootinfo.h>
+#include <asm/bmips.h>
+#include <asm/smp-ops.h>
+#include <asm/mipsregs.h>
 #include <bcm63xx_board.h>
 #include <bcm63xx_cpu.h>
 #include <bcm63xx_io.h>
@@ -54,6 +58,43 @@ void __init prom_init(void)
 
 	/* do low level board init */
 	board_prom_init();
+
+	if (IS_ENABLED(CONFIG_CPU_BMIPS4350) && IS_ENABLED(CONFIG_SMP)) {
+		/* set up SMP */
+		register_smp_ops(&bmips_smp_ops);
+
+		/*
+		 * BCM6328 might not have its second CPU enabled, while BCM6358
+		 * needs special handling for its shared TLB, so disable SMP
+		 * for now.
+		 */
+		if (BCMCPU_IS_6328()) {
+			bmips_smp_enabled = 0;
+		} else if (BCMCPU_IS_6358()) {
+			bmips_smp_enabled = 0;
+		}
+
+		if (!bmips_smp_enabled)
+			return;
+
+		/*
+		 * The bootloader has set up the CPU1 reset vector at
+		 * 0xa000_0200.
+		 * This conflicts with the special interrupt vector (IV).
+		 * The bootloader has also set up CPU1 to respond to the wrong
+		 * IPI interrupt.
+		 * Here we will start up CPU1 in the background and ask it to
+		 * reconfigure itself then go back to sleep.
+		 */
+		memcpy((void *)0xa0000200, &bmips_smp_movevec, 0x20);
+		__sync();
+		set_c0_cause(C_SW0);
+		cpumask_set_cpu(1, &bmips_booted_mask);
+
+		/*
+		 * FIXME: we really should have some sort of hazard barrier here
+		 */
+	}
 }
 
 void __init prom_free_prom_memory(void)