[ARM SMP] Add Realview MPcore SMP support

Add SMP support for the MPcore tile fitted to the Realview ARM
platform.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-realview/Makefile

@@ -4,3 +4,4 @@
 
 obj-y					:= core.o clock.o
 obj-$(CONFIG_MACH_REALVIEW_EB)		+= realview_eb.o
+obj-$(CONFIG_SMP)			+= platsmp.o headsmp.o

arch/arm/mach-realview/headsmp.S

+/*
+ *  linux/arch/arm/mach-realview/headsmp.S
+ *
+ *  Copyright (c) 2003 ARM Limited
+ *  All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/linkage.h>
+#include <linux/init.h>
+
+	__INIT
+
+/*
+ * Realview specific entry point for secondary CPUs.  This provides
+ * a "holding pen" into which all secondary cores are held until we're
+ * ready for them to initialise.
+ */
+ENTRY(realview_secondary_startup)
+	mrc	p15, 0, r0, c0, c0, 5
+	and	r0, r0, #15
+	adr	r4, 1f
+	ldmia	r4, {r5, r6}
+	sub	r4, r4, r5
+	add	r6, r6, r4
+pen:	ldr	r7, [r6]
+	cmp	r7, r0
+	bne	pen
+
+	/*
+	 * we've been released from the holding pen: secondary_stack
+	 * should now contain the SVC stack for this core
+	 */
+	b	secondary_startup
+
+1:	.long	.
+	.long	pen_release

arch/arm/mach-realview/platsmp.c

+/*
+ *  linux/arch/arm/mach-realview/platsmp.c
+ *
+ *  Copyright (C) 2002 ARM Ltd.
+ *  All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/smp.h>
+
+#include <asm/cacheflush.h>
+#include <asm/hardware/arm_scu.h>
+#include <asm/hardware.h>
+
+#include "core.h"
+
+extern void realview_secondary_startup(void);
+
+/*
+ * control for which core is the next to come out of the secondary
+ * boot "holding pen"
+ */
+volatile int __cpuinitdata pen_release = -1;
+
+static unsigned int __init get_core_count(void)
+{
+	unsigned int ncores;
+
+	ncores = __raw_readl(IO_ADDRESS(REALVIEW_MPCORE_SCU_BASE) + SCU_CONFIG);
+
+	return (ncores & 0x03) + 1;
+}
+
+static DEFINE_SPINLOCK(boot_lock);
+
+void __cpuinit platform_secondary_init(unsigned int cpu)
+{
+	/*
+	 * the primary core may have used a "cross call" soft interrupt
+	 * to get this processor out of WFI in the BootMonitor - make
+	 * sure that we are no longer being sent this soft interrupt
+	 */
+	smp_cross_call_done(cpumask_of_cpu(cpu));
+
+	/*
+	 * if any interrupts are already enabled for the primary
+	 * core (e.g. timer irq), then they will not have been enabled
+	 * for us: do so
+	 */
+	gic_cpu_init(__io_address(REALVIEW_GIC_CPU_BASE));
+
+	/*
+	 * let the primary processor know we're out of the
+	 * pen, then head off into the C entry point
+	 */
+	pen_release = -1;
+
+	/*
+	 * Synchronise with the boot thread.
+	 */
+	spin_lock(&boot_lock);
+	spin_unlock(&boot_lock);
+}
+
+int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
+{
+	unsigned long timeout;
+
+	/*
+	 * set synchronisation state between this boot processor
+	 * and the secondary one
+	 */
+	spin_lock(&boot_lock);
+
+	/*
+	 * The secondary processor is waiting to be released from
+	 * the holding pen - release it, then wait for it to flag
+	 * that it has been released by resetting pen_release.
+	 *
+	 * Note that "pen_release" is the hardware CPU ID, whereas
+	 * "cpu" is Linux's internal ID.
+	 */
+	pen_release = cpu;
+	flush_cache_all();
+
+	/*
+	 * XXX
+	 *
+	 * This is a later addition to the booting protocol: the
+	 * bootMonitor now puts secondary cores into WFI, so
+	 * poke_milo() no longer gets the cores moving; we need
+	 * to send a soft interrupt to wake the secondary core.
+	 * Use smp_cross_call() for this, since there's little
+	 * point duplicating the code here
+	 */
+	smp_cross_call(cpumask_of_cpu(cpu));
+
+	timeout = jiffies + (1 * HZ);
+	while (time_before(jiffies, timeout)) {
+		if (pen_release == -1)
+			break;
+
+		udelay(10);
+	}
+
+	/*
+	 * now the secondary core is starting up let it run its
+	 * calibrations, then wait for it to finish
+	 */
+	spin_unlock(&boot_lock);
+
+	return pen_release != -1 ? -ENOSYS : 0;
+}
+
+static void __init poke_milo(void)
+{
+	extern void secondary_startup(void);
+
+	/* nobody is to be released from the pen yet */
+	pen_release = -1;
+
+	/*
+	 * write the address of secondary startup into the system-wide
+	 * flags register, then clear the bottom two bits, which is what
+	 * BootMonitor is waiting for
+	 */
+#if 1
+#define REALVIEW_SYS_FLAGSS_OFFSET 0x30
+	__raw_writel(virt_to_phys(realview_secondary_startup),
+		     (IO_ADDRESS(REALVIEW_SYS_BASE) +
+		      REALVIEW_SYS_FLAGSS_OFFSET));
+#define REALVIEW_SYS_FLAGSC_OFFSET 0x34
+	__raw_writel(3,
+		     (IO_ADDRESS(REALVIEW_SYS_BASE) +
+		      REALVIEW_SYS_FLAGSC_OFFSET));
+#endif
+
+	mb();
+}
+
+void __init smp_prepare_cpus(unsigned int max_cpus)
+{
+	unsigned int ncores = get_core_count();
+	unsigned int cpu = smp_processor_id();
+	int i;
+
+	/* sanity check */
+	if (ncores == 0) {
+		printk(KERN_ERR
+		       "Realview: strange CM count of 0? Default to 1\n");
+
+		ncores = 1;
+	}
+
+	if (ncores > NR_CPUS) {
+		printk(KERN_WARNING
+		       "Realview: no. of cores (%d) greater than configured "
+		       "maximum of %d - clipping\n",
+		       ncores, NR_CPUS);
+		ncores = NR_CPUS;
+	}
+
+	smp_store_cpu_info(cpu);
+
+	/*
+	 * are we trying to boot more cores than exist?
+	 */
+	if (max_cpus > ncores)
+		max_cpus = ncores;
+
+	/*
+	 * Initialise the possible/present maps.
+	 * cpu_possible_map describes the set of CPUs which may be present
+	 * cpu_present_map describes the set of CPUs populated
+	 */
+	for (i = 0; i < max_cpus; i++) {
+		cpu_set(i, cpu_possible_map);
+		cpu_set(i, cpu_present_map);
+	}
+
+	/*
+	 * Do we need any more CPUs? If so, then let them know where
+	 * to start. Note that, on modern versions of MILO, the "poke"
+	 * doesn't actually do anything until each individual core is
+	 * sent a soft interrupt to get it out of WFI
+	 */
+	if (max_cpus > 1)
+		poke_milo();
+}

arch/arm/mm/proc-v6.S

@@ -12,6 +12,7 @@
 #include <linux/linkage.h>
 #include <asm/assembler.h>
 #include <asm/asm-offsets.h>
+#include <asm/hardware/arm_scu.h>
 #include <asm/procinfo.h>
 #include <asm/pgtable.h>
 
@@ -194,6 +195,23 @@ cpu_v6_name:
  *	- cache type register is implemented
  */
 __v6_setup:
+#ifdef CONFIG_SMP
+	/* Set up the SCU on core 0 only */
+	mrc	p15, 0, r0, c0, c0, 5		@ CPU core number
+	ands	r0, r0, #15
+	moveq	r0, #0x10000000 @ SCU_BASE
+	orreq	r0, r0, #0x00100000
+	ldreq	r5, [r0, #SCU_CTRL]
+	orreq	r5, r5, #1
+	streq	r5, [r0, #SCU_CTRL]
+
+#ifndef CONFIG_CPU_DCACHE_DISABLE
+	mrc	p15, 0, r0, c1, c0, 1		@ Enable SMP/nAMP mode
+	orr	r0, r0, #0x20
+	mcr	p15, 0, r0, c1, c0, 1
+#endif
+#endif
+
 	mov	r0, #0
 	mcr	p15, 0, r0, c7, c14, 0		@ clean+invalidate D cache
 	mcr	p15, 0, r0, c7, c5, 0		@ invalidate I cache

include/asm-arm/arch-realview/entry-macro.S

@@ -47,3 +47,17 @@
 		cmpcs	\irqnr, \irqnr
 
 		.endm
+
+		/* We assume that irqstat (the raw value of the IRQ acknowledge
+		 * register) is preserved from the macro above.
+		 * If there is an IPI, we immediately signal end of interrupt on the
+		 * controller, since this requires the original irqstat value which
+		 * we won't easily be able to recreate later.
+		 */
+
+		.macro test_for_ipi, irqnr, irqstat, base, tmp
+		bic	\irqnr, \irqstat, #0x1c00
+		cmp	\irqnr, #16
+		strcc	\irqstat, [\base, #GIC_CPU_EOI]
+		cmpcs	\irqnr, \irqnr
+		.endm

include/asm-arm/arch-realview/platform.h

@@ -207,6 +207,7 @@
 #define REALVIEW_GIC_CPU_BASE         0x10040000	/* Generic interrupt controller CPU interface */
 #define REALVIEW_GIC_DIST_BASE        0x10041000	/* Generic interrupt controller distributor */
 #else
+#define REALVIEW_MPCORE_SCU_BASE	0x10100000	/*  SCU registers */
 #define REALVIEW_GIC_CPU_BASE		0x10100100	/* Generic interrupt controller CPU interface */
 #define REALVIEW_GIC_DIST_BASE		0x10101000	/* Generic interrupt controller distributor */
 #endif

include/asm-arm/arch-realview/smp.h

+#ifndef ASMARM_ARCH_SMP_H
+#define ASMARM_ARCH_SMP_H
+
+#include <linux/config.h>
+
+#include <asm/hardware/gic.h>
+
+#define hard_smp_processor_id()			\
+	({						\
+		unsigned int cpunum;			\
+		__asm__("mrc p15, 0, %0, c0, c0, 5"	\
+			: "=r" (cpunum));		\
+		cpunum &= 0x0F;				\
+	})
+
+/*
+ * We use IRQ1 as the IPI
+ */
+static inline void smp_cross_call(cpumask_t callmap)
+{
+	gic_raise_softirq(callmap, 1);
+}
+
+/*
+ * Do nothing on MPcore.
+ */
+static inline void smp_cross_call_done(cpumask_t callmap)
+{
+}
+
+#endif

include/asm-arm/hardware/arm_scu.h

+#ifndef ASMARM_HARDWARE_ARM_SCU_H
+#define ASMARM_HARDWARE_ARM_SCU_H
+
+/*
+ * SCU registers
+ */
+#define SCU_CTRL		0x00
+#define SCU_CONFIG		0x04
+#define SCU_CPU_STATUS		0x08
+#define SCU_INVALIDATE		0x0c
+#define SCU_FPGA_REVISION	0x10
+
+#endif