smtc.c 32.4 KB
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/* Copyright (C) 2004 Mips Technologies, Inc */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/cpumask.h>
#include <linux/interrupt.h>
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#include <linux/module.h>
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#include <asm/cpu.h>
#include <asm/processor.h>
#include <asm/atomic.h>
#include <asm/system.h>
#include <asm/hardirq.h>
#include <asm/hazards.h>
#include <asm/mmu_context.h>
#include <asm/smp.h>
#include <asm/mipsregs.h>
#include <asm/cacheflush.h>
#include <asm/time.h>
#include <asm/addrspace.h>
#include <asm/smtc.h>
#include <asm/smtc_ipi.h>
#include <asm/smtc_proc.h>

/*
 * This file should be built into the kernel only if CONFIG_MIPS_MT_SMTC is set.
 */

#define MIPS_CPU_IPI_IRQ	1

#define LOCK_MT_PRA() \
	local_irq_save(flags); \
	mtflags = dmt()

#define UNLOCK_MT_PRA() \
	emt(mtflags); \
	local_irq_restore(flags)

#define LOCK_CORE_PRA() \
	local_irq_save(flags); \
	mtflags = dvpe()

#define UNLOCK_CORE_PRA() \
	evpe(mtflags); \
	local_irq_restore(flags)

/*
 * Data structures purely associated with SMTC parallelism
 */


/*
 * Table for tracking ASIDs whose lifetime is prolonged.
 */

asiduse smtc_live_asid[MAX_SMTC_TLBS][MAX_SMTC_ASIDS];

/*
 * Clock interrupt "latch" buffers, per "CPU"
 */

unsigned int ipi_timer_latch[NR_CPUS];

/*
 * Number of InterProcessor Interupt (IPI) message buffers to allocate
 */

#define IPIBUF_PER_CPU 4

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static struct smtc_ipi_q IPIQ[NR_CPUS];
static struct smtc_ipi_q freeIPIq;
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/* Forward declarations */

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void ipi_decode(struct smtc_ipi *);
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static void post_direct_ipi(int cpu, struct smtc_ipi *pipi);
static void setup_cross_vpe_interrupts(void);
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void init_smtc_stats(void);

/* Global SMTC Status */

unsigned int smtc_status = 0;

/* Boot command line configuration overrides */

static int vpelimit = 0;
static int tclimit = 0;
static int ipibuffers = 0;
static int nostlb = 0;
static int asidmask = 0;
unsigned long smtc_asid_mask = 0xff;

static int __init maxvpes(char *str)
{
	get_option(&str, &vpelimit);
	return 1;
}

static int __init maxtcs(char *str)
{
	get_option(&str, &tclimit);
	return 1;
}

static int __init ipibufs(char *str)
{
	get_option(&str, &ipibuffers);
	return 1;
}

static int __init stlb_disable(char *s)
{
	nostlb = 1;
	return 1;
}

static int __init asidmask_set(char *str)
{
	get_option(&str, &asidmask);
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	switch (asidmask) {
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	case 0x1:
	case 0x3:
	case 0x7:
	case 0xf:
	case 0x1f:
	case 0x3f:
	case 0x7f:
	case 0xff:
		smtc_asid_mask = (unsigned long)asidmask;
		break;
	default:
		printk("ILLEGAL ASID mask 0x%x from command line\n", asidmask);
	}
	return 1;
}

__setup("maxvpes=", maxvpes);
__setup("maxtcs=", maxtcs);
__setup("ipibufs=", ipibufs);
__setup("nostlb", stlb_disable);
__setup("asidmask=", asidmask_set);

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#ifdef CONFIG_SMTC_IDLE_HOOK_DEBUG
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static int hang_trig = 0;

static int __init hangtrig_enable(char *s)
{
	hang_trig = 1;
	return 1;
}


__setup("hangtrig", hangtrig_enable);

#define DEFAULT_BLOCKED_IPI_LIMIT 32

static int timerq_limit = DEFAULT_BLOCKED_IPI_LIMIT;

static int __init tintq(char *str)
{
	get_option(&str, &timerq_limit);
	return 1;
}

__setup("tintq=", tintq);

int imstuckcount[2][8];
/* vpemask represents IM/IE bits of per-VPE Status registers, low-to-high */
int vpemask[2][8] = {{0,1,1,0,0,0,0,1},{0,1,0,0,0,0,0,1}};
int tcnoprog[NR_CPUS];
static atomic_t idle_hook_initialized = {0};
static int clock_hang_reported[NR_CPUS];

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#endif /* CONFIG_SMTC_IDLE_HOOK_DEBUG */
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/* Initialize shared TLB - the should probably migrate to smtc_setup_cpus() */

void __init sanitize_tlb_entries(void)
{
	printk("Deprecated sanitize_tlb_entries() invoked\n");
}


/*
 * Configure shared TLB - VPC configuration bit must be set by caller
 */

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static void smtc_configure_tlb(void)
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{
	int i,tlbsiz,vpes;
	unsigned long mvpconf0;
	unsigned long config1val;

	/* Set up ASID preservation table */
	for (vpes=0; vpes<MAX_SMTC_TLBS; vpes++) {
	    for(i = 0; i < MAX_SMTC_ASIDS; i++) {
		smtc_live_asid[vpes][i] = 0;
	    }
	}
	mvpconf0 = read_c0_mvpconf0();

	if ((vpes = ((mvpconf0 & MVPCONF0_PVPE)
			>> MVPCONF0_PVPE_SHIFT) + 1) > 1) {
	    /* If we have multiple VPEs, try to share the TLB */
	    if ((mvpconf0 & MVPCONF0_TLBS) && !nostlb) {
		/*
		 * If TLB sizing is programmable, shared TLB
		 * size is the total available complement.
		 * Otherwise, we have to take the sum of all
		 * static VPE TLB entries.
		 */
		if ((tlbsiz = ((mvpconf0 & MVPCONF0_PTLBE)
				>> MVPCONF0_PTLBE_SHIFT)) == 0) {
		    /*
		     * If there's more than one VPE, there had better
		     * be more than one TC, because we need one to bind
		     * to each VPE in turn to be able to read
		     * its configuration state!
		     */
		    settc(1);
		    /* Stop the TC from doing anything foolish */
		    write_tc_c0_tchalt(TCHALT_H);
		    mips_ihb();
		    /* No need to un-Halt - that happens later anyway */
		    for (i=0; i < vpes; i++) {
		    	write_tc_c0_tcbind(i);
			/*
			 * To be 100% sure we're really getting the right
			 * information, we exit the configuration state
			 * and do an IHB after each rebinding.
			 */
			write_c0_mvpcontrol(
				read_c0_mvpcontrol() & ~ MVPCONTROL_VPC );
			mips_ihb();
			/*
			 * Only count if the MMU Type indicated is TLB
			 */
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			if (((read_vpe_c0_config() & MIPS_CONF_MT) >> 7) == 1) {
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				config1val = read_vpe_c0_config1();
				tlbsiz += ((config1val >> 25) & 0x3f) + 1;
			}

			/* Put core back in configuration state */
			write_c0_mvpcontrol(
				read_c0_mvpcontrol() | MVPCONTROL_VPC );
			mips_ihb();
		    }
		}
		write_c0_mvpcontrol(read_c0_mvpcontrol() | MVPCONTROL_STLB);
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		ehb();
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		/*
		 * Setup kernel data structures to use software total,
		 * rather than read the per-VPE Config1 value. The values
		 * for "CPU 0" gets copied to all the other CPUs as part
		 * of their initialization in smtc_cpu_setup().
		 */

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		/* MIPS32 limits TLB indices to 64 */
		if (tlbsiz > 64)
			tlbsiz = 64;
		cpu_data[0].tlbsize = current_cpu_data.tlbsize = tlbsiz;
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		smtc_status |= SMTC_TLB_SHARED;
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		local_flush_tlb_all();
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		printk("TLB of %d entry pairs shared by %d VPEs\n",
			tlbsiz, vpes);
	    } else {
		printk("WARNING: TLB Not Sharable on SMTC Boot!\n");
	    }
	}
}


/*
 * Incrementally build the CPU map out of constituent MIPS MT cores,
 * using the specified available VPEs and TCs.  Plaform code needs
 * to ensure that each MIPS MT core invokes this routine on reset,
 * one at a time(!).
 *
 * This version of the build_cpu_map and prepare_cpus routines assumes
 * that *all* TCs of a MIPS MT core will be used for Linux, and that
 * they will be spread across *all* available VPEs (to minimise the
 * loss of efficiency due to exception service serialization).
 * An improved version would pick up configuration information and
 * possibly leave some TCs/VPEs as "slave" processors.
 *
 * Use c0_MVPConf0 to find out how many TCs are available, setting up
 * phys_cpu_present_map and the logical/physical mappings.
 */

int __init mipsmt_build_cpu_map(int start_cpu_slot)
{
	int i, ntcs;

	/*
	 * The CPU map isn't actually used for anything at this point,
	 * so it's not clear what else we should do apart from set
	 * everything up so that "logical" = "physical".
	 */
	ntcs = ((read_c0_mvpconf0() & MVPCONF0_PTC) >> MVPCONF0_PTC_SHIFT) + 1;
	for (i=start_cpu_slot; i<NR_CPUS && i<ntcs; i++) {
		cpu_set(i, phys_cpu_present_map);
		__cpu_number_map[i] = i;
		__cpu_logical_map[i] = i;
	}
	/* Initialize map of CPUs with FPUs */
	cpus_clear(mt_fpu_cpumask);

	/* One of those TC's is the one booting, and not a secondary... */
	printk("%i available secondary CPU TC(s)\n", i - 1);

	return i;
}

/*
 * Common setup before any secondaries are started
 * Make sure all CPU's are in a sensible state before we boot any of the
 * secondaries.
 *
 * For MIPS MT "SMTC" operation, we set up all TCs, spread as evenly
 * as possible across the available VPEs.
 */

static void smtc_tc_setup(int vpe, int tc, int cpu)
{
	settc(tc);
	write_tc_c0_tchalt(TCHALT_H);
	mips_ihb();
	write_tc_c0_tcstatus((read_tc_c0_tcstatus()
			& ~(TCSTATUS_TKSU | TCSTATUS_DA | TCSTATUS_IXMT))
			| TCSTATUS_A);
	write_tc_c0_tccontext(0);
	/* Bind tc to vpe */
	write_tc_c0_tcbind(vpe);
	/* In general, all TCs should have the same cpu_data indications */
	memcpy(&cpu_data[cpu], &cpu_data[0], sizeof(struct cpuinfo_mips));
	/* For 34Kf, start with TC/CPU 0 as sole owner of single FPU context */
	if (cpu_data[0].cputype == CPU_34K)
		cpu_data[cpu].options &= ~MIPS_CPU_FPU;
	cpu_data[cpu].vpe_id = vpe;
	cpu_data[cpu].tc_id = tc;
}


void mipsmt_prepare_cpus(void)
{
	int i, vpe, tc, ntc, nvpe, tcpervpe, slop, cpu;
	unsigned long flags;
	unsigned long val;
	int nipi;
	struct smtc_ipi *pipi;

	/* disable interrupts so we can disable MT */
	local_irq_save(flags);
	/* disable MT so we can configure */
	dvpe();
	dmt();

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	spin_lock_init(&freeIPIq.lock);
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	/*
	 * We probably don't have as many VPEs as we do SMP "CPUs",
	 * but it's possible - and in any case we'll never use more!
	 */
	for (i=0; i<NR_CPUS; i++) {
		IPIQ[i].head = IPIQ[i].tail = NULL;
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		spin_lock_init(&IPIQ[i].lock);
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		IPIQ[i].depth = 0;
		ipi_timer_latch[i] = 0;
	}

	/* cpu_data index starts at zero */
	cpu = 0;
	cpu_data[cpu].vpe_id = 0;
	cpu_data[cpu].tc_id = 0;
	cpu++;

	/* Report on boot-time options */
	mips_mt_set_cpuoptions ();
	if (vpelimit > 0)
		printk("Limit of %d VPEs set\n", vpelimit);
	if (tclimit > 0)
		printk("Limit of %d TCs set\n", tclimit);
	if (nostlb) {
		printk("Shared TLB Use Inhibited - UNSAFE for Multi-VPE Operation\n");
	}
	if (asidmask)
		printk("ASID mask value override to 0x%x\n", asidmask);

	/* Temporary */
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#ifdef CONFIG_SMTC_IDLE_HOOK_DEBUG
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	if (hang_trig)
		printk("Logic Analyser Trigger on suspected TC hang\n");
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#endif /* CONFIG_SMTC_IDLE_HOOK_DEBUG */
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	/* Put MVPE's into 'configuration state' */
	write_c0_mvpcontrol( read_c0_mvpcontrol() | MVPCONTROL_VPC );

	val = read_c0_mvpconf0();
	nvpe = ((val & MVPCONF0_PVPE) >> MVPCONF0_PVPE_SHIFT) + 1;
	if (vpelimit > 0 && nvpe > vpelimit)
		nvpe = vpelimit;
	ntc = ((val & MVPCONF0_PTC) >> MVPCONF0_PTC_SHIFT) + 1;
	if (ntc > NR_CPUS)
		ntc = NR_CPUS;
	if (tclimit > 0 && ntc > tclimit)
		ntc = tclimit;
	tcpervpe = ntc / nvpe;
	slop = ntc % nvpe;	/* Residual TCs, < NVPE */

	/* Set up shared TLB */
	smtc_configure_tlb();

	for (tc = 0, vpe = 0 ; (vpe < nvpe) && (tc < ntc) ; vpe++) {
		/*
		 * Set the MVP bits.
		 */
		settc(tc);
		write_vpe_c0_vpeconf0(read_vpe_c0_vpeconf0() | VPECONF0_MVP);
		if (vpe != 0)
			printk(", ");
		printk("VPE %d: TC", vpe);
		for (i = 0; i < tcpervpe; i++) {
			/*
			 * TC 0 is bound to VPE 0 at reset,
			 * and is presumably executing this
			 * code.  Leave it alone!
			 */
			if (tc != 0) {
				smtc_tc_setup(vpe,tc, cpu);
				cpu++;
			}
			printk(" %d", tc);
			tc++;
		}
		if (slop) {
			if (tc != 0) {
				smtc_tc_setup(vpe,tc, cpu);
				cpu++;
			}
			printk(" %d", tc);
			tc++;
			slop--;
		}
		if (vpe != 0) {
			/*
			 * Clear any stale software interrupts from VPE's Cause
			 */
			write_vpe_c0_cause(0);

			/*
			 * Clear ERL/EXL of VPEs other than 0
			 * and set restricted interrupt enable/mask.
			 */
			write_vpe_c0_status((read_vpe_c0_status()
				& ~(ST0_BEV | ST0_ERL | ST0_EXL | ST0_IM))
				| (STATUSF_IP0 | STATUSF_IP1 | STATUSF_IP7
				| ST0_IE));
			/*
			 * set config to be the same as vpe0,
			 *  particularly kseg0 coherency alg
			 */
			write_vpe_c0_config(read_c0_config());
			/* Clear any pending timer interrupt */
			write_vpe_c0_compare(0);
			/* Propagate Config7 */
			write_vpe_c0_config7(read_c0_config7());
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			write_vpe_c0_count(read_c0_count());
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		}
		/* enable multi-threading within VPE */
		write_vpe_c0_vpecontrol(read_vpe_c0_vpecontrol() | VPECONTROL_TE);
		/* enable the VPE */
		write_vpe_c0_vpeconf0(read_vpe_c0_vpeconf0() | VPECONF0_VPA);
	}

	/*
	 * Pull any physically present but unused TCs out of circulation.
	 */
	while (tc < (((val & MVPCONF0_PTC) >> MVPCONF0_PTC_SHIFT) + 1)) {
		cpu_clear(tc, phys_cpu_present_map);
		cpu_clear(tc, cpu_present_map);
		tc++;
	}

	/* release config state */
	write_c0_mvpcontrol( read_c0_mvpcontrol() & ~ MVPCONTROL_VPC );

	printk("\n");

	/* Set up coprocessor affinity CPU mask(s) */

	for (tc = 0; tc < ntc; tc++) {
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		if (cpu_data[tc].options & MIPS_CPU_FPU)
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			cpu_set(tc, mt_fpu_cpumask);
	}

	/* set up ipi interrupts... */

	/* If we have multiple VPEs running, set up the cross-VPE interrupt */

	if (nvpe > 1)
		setup_cross_vpe_interrupts();

	/* Set up queue of free IPI "messages". */
	nipi = NR_CPUS * IPIBUF_PER_CPU;
	if (ipibuffers > 0)
		nipi = ipibuffers;

	pipi = kmalloc(nipi *sizeof(struct smtc_ipi), GFP_KERNEL);
	if (pipi == NULL)
		panic("kmalloc of IPI message buffers failed\n");
	else
		printk("IPI buffer pool of %d buffers\n", nipi);
	for (i = 0; i < nipi; i++) {
		smtc_ipi_nq(&freeIPIq, pipi);
		pipi++;
	}

	/* Arm multithreading and enable other VPEs - but all TCs are Halted */
	emt(EMT_ENABLE);
	evpe(EVPE_ENABLE);
	local_irq_restore(flags);
	/* Initialize SMTC /proc statistics/diagnostics */
	init_smtc_stats();
}


/*
 * Setup the PC, SP, and GP of a secondary processor and start it
 * running!
 * smp_bootstrap is the place to resume from
 * __KSTK_TOS(idle) is apparently the stack pointer
 * (unsigned long)idle->thread_info the gp
 *
 */
void smtc_boot_secondary(int cpu, struct task_struct *idle)
{
	extern u32 kernelsp[NR_CPUS];
	long flags;
	int mtflags;

	LOCK_MT_PRA();
	if (cpu_data[cpu].vpe_id != cpu_data[smp_processor_id()].vpe_id) {
		dvpe();
	}
	settc(cpu_data[cpu].tc_id);

	/* pc */
	write_tc_c0_tcrestart((unsigned long)&smp_bootstrap);

	/* stack pointer */
	kernelsp[cpu] = __KSTK_TOS(idle);
	write_tc_gpr_sp(__KSTK_TOS(idle));

	/* global pointer */
	write_tc_gpr_gp((unsigned long)idle->thread_info);

	smtc_status |= SMTC_MTC_ACTIVE;
	write_tc_c0_tchalt(0);
	if (cpu_data[cpu].vpe_id != cpu_data[smp_processor_id()].vpe_id) {
		evpe(EVPE_ENABLE);
	}
	UNLOCK_MT_PRA();
}

void smtc_init_secondary(void)
{
	/*
	 * Start timer on secondary VPEs if necessary.
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	 * plat_timer_setup has already have been invoked by init/main
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	 * on "boot" TC.  Like per_cpu_trap_init() hack, this assumes that
	 * SMTC init code assigns TCs consdecutively and in ascending order
	 * to across available VPEs.
	 */
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	if (((read_c0_tcbind() & TCBIND_CURTC) != 0) &&
	    ((read_c0_tcbind() & TCBIND_CURVPE)
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	    != cpu_data[smp_processor_id() - 1].vpe_id)){
		write_c0_compare (read_c0_count() + mips_hpt_frequency/HZ);
	}

	local_irq_enable();
}

void smtc_smp_finish(void)
{
	printk("TC %d going on-line as CPU %d\n",
		cpu_data[smp_processor_id()].tc_id, smp_processor_id());
}

void smtc_cpus_done(void)
{
}

/*
 * Support for SMTC-optimized driver IRQ registration
 */

/*
 * SMTC Kernel needs to manipulate low-level CPU interrupt mask
 * in do_IRQ. These are passed in setup_irq_smtc() and stored
 * in this table.
 */

int setup_irq_smtc(unsigned int irq, struct irqaction * new,
			unsigned long hwmask)
{
	irq_hwmask[irq] = hwmask;

	return setup_irq(irq, new);
}

/*
 * IPI model for SMTC is tricky, because interrupts aren't TC-specific.
 * Within a VPE one TC can interrupt another by different approaches.
 * The easiest to get right would probably be to make all TCs except
 * the target IXMT and set a software interrupt, but an IXMT-based
 * scheme requires that a handler must run before a new IPI could
 * be sent, which would break the "broadcast" loops in MIPS MT.
 * A more gonzo approach within a VPE is to halt the TC, extract
 * its Restart, Status, and a couple of GPRs, and program the Restart
 * address to emulate an interrupt.
 *
 * Within a VPE, one can be confident that the target TC isn't in
 * a critical EXL state when halted, since the write to the Halt
 * register could not have issued on the writing thread if the
 * halting thread had EXL set. So k0 and k1 of the target TC
 * can be used by the injection code.  Across VPEs, one can't
 * be certain that the target TC isn't in a critical exception
 * state. So we try a two-step process of sending a software
 * interrupt to the target VPE, which either handles the event
 * itself (if it was the target) or injects the event within
 * the VPE.
 */

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static void smtc_ipi_qdump(void)
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{
	int i;

	for (i = 0; i < NR_CPUS ;i++) {
		printk("IPIQ[%d]: head = 0x%x, tail = 0x%x, depth = %d\n",
			i, (unsigned)IPIQ[i].head, (unsigned)IPIQ[i].tail,
			IPIQ[i].depth);
	}
}

/*
 * The standard atomic.h primitives don't quite do what we want
 * here: We need an atomic add-and-return-previous-value (which
 * could be done with atomic_add_return and a decrement) and an
 * atomic set/zero-and-return-previous-value (which can't really
 * be done with the atomic.h primitives). And since this is
 * MIPS MT, we can assume that we have LL/SC.
 */
static __inline__ int atomic_postincrement(unsigned int *pv)
{
	unsigned long result;

	unsigned long temp;

	__asm__ __volatile__(
	"1:	ll	%0, %2					\n"
	"	addu	%1, %0, 1				\n"
	"	sc	%1, %2					\n"
	"	beqz	%1, 1b					\n"
	"	sync						\n"
	: "=&r" (result), "=&r" (temp), "=m" (*pv)
	: "m" (*pv)
	: "memory");

	return result;
}

void smtc_send_ipi(int cpu, int type, unsigned int action)
{
	int tcstatus;
	struct smtc_ipi *pipi;
	long flags;
	int mtflags;

	if (cpu == smp_processor_id()) {
		printk("Cannot Send IPI to self!\n");
		return;
	}
	/* Set up a descriptor, to be delivered either promptly or queued */
	pipi = smtc_ipi_dq(&freeIPIq);
	if (pipi == NULL) {
		bust_spinlocks(1);
		mips_mt_regdump(dvpe());
		panic("IPI Msg. Buffers Depleted\n");
	}
	pipi->type = type;
	pipi->arg = (void *)action;
	pipi->dest = cpu;
	if (cpu_data[cpu].vpe_id != cpu_data[smp_processor_id()].vpe_id) {
		/* If not on same VPE, enqueue and send cross-VPE interupt */
		smtc_ipi_nq(&IPIQ[cpu], pipi);
		LOCK_CORE_PRA();
		settc(cpu_data[cpu].tc_id);
		write_vpe_c0_cause(read_vpe_c0_cause() | C_SW1);
		UNLOCK_CORE_PRA();
	} else {
		/*
		 * Not sufficient to do a LOCK_MT_PRA (dmt) here,
		 * since ASID shootdown on the other VPE may
		 * collide with this operation.
		 */
		LOCK_CORE_PRA();
		settc(cpu_data[cpu].tc_id);
		/* Halt the targeted TC */
		write_tc_c0_tchalt(TCHALT_H);
		mips_ihb();

		/*
	 	 * Inspect TCStatus - if IXMT is set, we have to queue
		 * a message. Otherwise, we set up the "interrupt"
		 * of the other TC
	 	 */
		tcstatus = read_tc_c0_tcstatus();

		if ((tcstatus & TCSTATUS_IXMT) != 0) {
			/*
			 * Spin-waiting here can deadlock,
			 * so we queue the message for the target TC.
			 */
			write_tc_c0_tchalt(0);
			UNLOCK_CORE_PRA();
			/* Try to reduce redundant timer interrupt messages */
731 732
			if (type == SMTC_CLOCK_TICK) {
			    if (atomic_postincrement(&ipi_timer_latch[cpu])!=0){
733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748
				smtc_ipi_nq(&freeIPIq, pipi);
				return;
			    }
			}
			smtc_ipi_nq(&IPIQ[cpu], pipi);
		} else {
			post_direct_ipi(cpu, pipi);
			write_tc_c0_tchalt(0);
			UNLOCK_CORE_PRA();
		}
	}
}

/*
 * Send IPI message to Halted TC, TargTC/TargVPE already having been set
 */
749
static void post_direct_ipi(int cpu, struct smtc_ipi *pipi)
750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770
{
	struct pt_regs *kstack;
	unsigned long tcstatus;
	unsigned long tcrestart;
	extern u32 kernelsp[NR_CPUS];
	extern void __smtc_ipi_vector(void);

	/* Extract Status, EPC from halted TC */
	tcstatus = read_tc_c0_tcstatus();
	tcrestart = read_tc_c0_tcrestart();
	/* If TCRestart indicates a WAIT instruction, advance the PC */
	if ((tcrestart & 0x80000000)
	    && ((*(unsigned int *)tcrestart & 0xfe00003f) == 0x42000020)) {
		tcrestart += 4;
	}
	/*
	 * Save on TC's future kernel stack
	 *
	 * CU bit of Status is indicator that TC was
	 * already running on a kernel stack...
	 */
771
	if (tcstatus & ST0_CU0)  {
772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793
		/* Note that this "- 1" is pointer arithmetic */
		kstack = ((struct pt_regs *)read_tc_gpr_sp()) - 1;
	} else {
		kstack = ((struct pt_regs *)kernelsp[cpu]) - 1;
	}

	kstack->cp0_epc = (long)tcrestart;
	/* Save TCStatus */
	kstack->cp0_tcstatus = tcstatus;
	/* Pass token of operation to be performed kernel stack pad area */
	kstack->pad0[4] = (unsigned long)pipi;
	/* Pass address of function to be called likewise */
	kstack->pad0[5] = (unsigned long)&ipi_decode;
	/* Set interrupt exempt and kernel mode */
	tcstatus |= TCSTATUS_IXMT;
	tcstatus &= ~TCSTATUS_TKSU;
	write_tc_c0_tcstatus(tcstatus);
	ehb();
	/* Set TC Restart address to be SMTC IPI vector */
	write_tc_c0_tcrestart(__smtc_ipi_vector);
}

794
static void ipi_resched_interrupt(void)
795 796 797 798 799
{
	/* Return from interrupt should be enough to cause scheduler check */
}


800
static void ipi_call_interrupt(void)
801 802 803 804 805
{
	/* Invoke generic function invocation code in smp.c */
	smp_call_function_interrupt();
}

806
void ipi_decode(struct smtc_ipi *pipi)
807 808 809 810 811 812 813
{
	void *arg_copy = pipi->arg;
	int type_copy = pipi->type;
	int dest_copy = pipi->dest;

	smtc_ipi_nq(&freeIPIq, pipi);
	switch (type_copy) {
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	case SMTC_CLOCK_TICK:
		/* Invoke Clock "Interrupt" */
		ipi_timer_latch[dest_copy] = 0;
817
#ifdef CONFIG_SMTC_IDLE_HOOK_DEBUG
818
		clock_hang_reported[dest_copy] = 0;
819
#endif /* CONFIG_SMTC_IDLE_HOOK_DEBUG */
820
		local_timer_interrupt(0, NULL);
821 822 823 824
		break;
	case LINUX_SMP_IPI:
		switch ((int)arg_copy) {
		case SMP_RESCHEDULE_YOURSELF:
825
			ipi_resched_interrupt();
826
			break;
827
		case SMP_CALL_FUNCTION:
828
			ipi_call_interrupt();
829 830
			break;
		default:
831 832
			printk("Impossible SMTC IPI Argument 0x%x\n",
				(int)arg_copy);
833
			break;
834 835 836 837 838
		}
		break;
	default:
		printk("Impossible SMTC IPI Type 0x%x\n", type_copy);
		break;
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	}
}

842
void deferred_smtc_ipi(void)
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{
	struct smtc_ipi *pipi;
	unsigned long flags;
/* DEBUG */
	int q = smp_processor_id();

	/*
	 * Test is not atomic, but much faster than a dequeue,
	 * and the vast majority of invocations will have a null queue.
	 */
853
	if (IPIQ[q].head != NULL) {
854 855 856
		while((pipi = smtc_ipi_dq(&IPIQ[q])) != NULL) {
			/* ipi_decode() should be called with interrupts off */
			local_irq_save(flags);
857
			ipi_decode(pipi);
858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888
			local_irq_restore(flags);
		}
	}
}

/*
 * Send clock tick to all TCs except the one executing the funtion
 */

void smtc_timer_broadcast(int vpe)
{
	int cpu;
	int myTC = cpu_data[smp_processor_id()].tc_id;
	int myVPE = cpu_data[smp_processor_id()].vpe_id;

	smtc_cpu_stats[smp_processor_id()].timerints++;

	for_each_online_cpu(cpu) {
		if (cpu_data[cpu].vpe_id == myVPE &&
		    cpu_data[cpu].tc_id != myTC)
			smtc_send_ipi(cpu, SMTC_CLOCK_TICK, 0);
	}
}

/*
 * Cross-VPE interrupts in the SMTC prototype use "software interrupts"
 * set via cross-VPE MTTR manipulation of the Cause register. It would be
 * in some regards preferable to have external logic for "doorbell" hardware
 * interrupts.
 */

889
static int cpu_ipi_irq = MIPS_CPU_IRQ_BASE + MIPS_CPU_IPI_IRQ;
890

891
static irqreturn_t ipi_interrupt(int irq, void *dev_idm)
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{
	int my_vpe = cpu_data[smp_processor_id()].vpe_id;
	int my_tc = cpu_data[smp_processor_id()].tc_id;
	int cpu;
	struct smtc_ipi *pipi;
	unsigned long tcstatus;
	int sent;
	long flags;
	unsigned int mtflags;
	unsigned int vpflags;

	/*
	 * So long as cross-VPE interrupts are done via
	 * MFTR/MTTR read-modify-writes of Cause, we need
	 * to stop other VPEs whenever the local VPE does
	 * anything similar.
	 */
	local_irq_save(flags);
	vpflags = dvpe();
	clear_c0_cause(0x100 << MIPS_CPU_IPI_IRQ);
	set_c0_status(0x100 << MIPS_CPU_IPI_IRQ);
	irq_enable_hazard();
	evpe(vpflags);
	local_irq_restore(flags);

	/*
	 * Cross-VPE Interrupt handler: Try to directly deliver IPIs
	 * queued for TCs on this VPE other than the current one.
	 * Return-from-interrupt should cause us to drain the queue
	 * for the current TC, so we ought not to have to do it explicitly here.
	 */

	for_each_online_cpu(cpu) {
		if (cpu_data[cpu].vpe_id != my_vpe)
			continue;

		pipi = smtc_ipi_dq(&IPIQ[cpu]);
		if (pipi != NULL) {
			if (cpu_data[cpu].tc_id != my_tc) {
				sent = 0;
				LOCK_MT_PRA();
				settc(cpu_data[cpu].tc_id);
				write_tc_c0_tchalt(TCHALT_H);
				mips_ihb();
				tcstatus = read_tc_c0_tcstatus();
				if ((tcstatus & TCSTATUS_IXMT) == 0) {
					post_direct_ipi(cpu, pipi);
					sent = 1;
				}
				write_tc_c0_tchalt(0);
				UNLOCK_MT_PRA();
				if (!sent) {
					smtc_ipi_req(&IPIQ[cpu], pipi);
				}
			} else {
				/*
				 * ipi_decode() should be called
				 * with interrupts off
				 */
				local_irq_save(flags);
952
				ipi_decode(pipi);
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				local_irq_restore(flags);
			}
		}
	}

	return IRQ_HANDLED;
}

961
static void ipi_irq_dispatch(void)
962
{
963
	do_IRQ(cpu_ipi_irq);
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}

static struct irqaction irq_ipi;

968
static void setup_cross_vpe_interrupts(void)
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{
	if (!cpu_has_vint)
		panic("SMTC Kernel requires Vectored Interupt support");

	set_vi_handler(MIPS_CPU_IPI_IRQ, ipi_irq_dispatch);

	irq_ipi.handler = ipi_interrupt;
976
	irq_ipi.flags = IRQF_DISABLED;
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	irq_ipi.name = "SMTC_IPI";

	setup_irq_smtc(cpu_ipi_irq, &irq_ipi, (0x100 << MIPS_CPU_IPI_IRQ));

	irq_desc[cpu_ipi_irq].status |= IRQ_PER_CPU;
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	set_irq_handler(cpu_ipi_irq, handle_percpu_irq);
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}

/*
 * SMTC-specific hacks invoked from elsewhere in the kernel.
 */

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void smtc_ipi_replay(void)
{
	/*
	 * To the extent that we've ever turned interrupts off,
	 * we may have accumulated deferred IPIs.  This is subtle.
	 * If we use the smtc_ipi_qdepth() macro, we'll get an
	 * exact number - but we'll also disable interrupts
	 * and create a window of failure where a new IPI gets
	 * queued after we test the depth but before we re-enable
	 * interrupts. So long as IXMT never gets set, however,
	 * we should be OK:  If we pick up something and dispatch
	 * it here, that's great. If we see nothing, but concurrent
	 * with this operation, another TC sends us an IPI, IXMT
	 * is clear, and we'll handle it as a real pseudo-interrupt
	 * and not a pseudo-pseudo interrupt.
	 */
	if (IPIQ[smp_processor_id()].depth > 0) {
		struct smtc_ipi *pipi;
		extern void self_ipi(struct smtc_ipi *);

		while ((pipi = smtc_ipi_dq(&IPIQ[smp_processor_id()]))) {
			self_ipi(pipi);
			smtc_cpu_stats[smp_processor_id()].selfipis++;
		}
	}
}

1016 1017
EXPORT_SYMBOL(smtc_ipi_replay);

1018 1019
void smtc_idle_loop_hook(void)
{
1020
#ifdef CONFIG_SMTC_IDLE_HOOK_DEBUG
1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112
	int im;
	int flags;
	int mtflags;
	int bit;
	int vpe;
	int tc;
	int hook_ntcs;
	/*
	 * printk within DMT-protected regions can deadlock,
	 * so buffer diagnostic messages for later output.
	 */
	char *pdb_msg;
	char id_ho_db_msg[768]; /* worst-case use should be less than 700 */

	if (atomic_read(&idle_hook_initialized) == 0) { /* fast test */
		if (atomic_add_return(1, &idle_hook_initialized) == 1) {
			int mvpconf0;
			/* Tedious stuff to just do once */
			mvpconf0 = read_c0_mvpconf0();
			hook_ntcs = ((mvpconf0 & MVPCONF0_PTC) >> MVPCONF0_PTC_SHIFT) + 1;
			if (hook_ntcs > NR_CPUS)
				hook_ntcs = NR_CPUS;
			for (tc = 0; tc < hook_ntcs; tc++) {
				tcnoprog[tc] = 0;
				clock_hang_reported[tc] = 0;
	    		}
			for (vpe = 0; vpe < 2; vpe++)
				for (im = 0; im < 8; im++)
					imstuckcount[vpe][im] = 0;
			printk("Idle loop test hook initialized for %d TCs\n", hook_ntcs);
			atomic_set(&idle_hook_initialized, 1000);
		} else {
			/* Someone else is initializing in parallel - let 'em finish */
			while (atomic_read(&idle_hook_initialized) < 1000)
				;
		}
	}

	/* Have we stupidly left IXMT set somewhere? */
	if (read_c0_tcstatus() & 0x400) {
		write_c0_tcstatus(read_c0_tcstatus() & ~0x400);
		ehb();
		printk("Dangling IXMT in cpu_idle()\n");
	}

	/* Have we stupidly left an IM bit turned off? */
#define IM_LIMIT 2000
	local_irq_save(flags);
	mtflags = dmt();
	pdb_msg = &id_ho_db_msg[0];
	im = read_c0_status();
	vpe = cpu_data[smp_processor_id()].vpe_id;
	for (bit = 0; bit < 8; bit++) {
		/*
		 * In current prototype, I/O interrupts
		 * are masked for VPE > 0
		 */
		if (vpemask[vpe][bit]) {
			if (!(im & (0x100 << bit)))
				imstuckcount[vpe][bit]++;
			else
				imstuckcount[vpe][bit] = 0;
			if (imstuckcount[vpe][bit] > IM_LIMIT) {
				set_c0_status(0x100 << bit);
				ehb();
				imstuckcount[vpe][bit] = 0;
				pdb_msg += sprintf(pdb_msg,
					"Dangling IM %d fixed for VPE %d\n", bit,
					vpe);
			}
		}
	}

	/*
	 * Now that we limit outstanding timer IPIs, check for hung TC
	 */
	for (tc = 0; tc < NR_CPUS; tc++) {
		/* Don't check ourself - we'll dequeue IPIs just below */
		if ((tc != smp_processor_id()) &&
		    ipi_timer_latch[tc] > timerq_limit) {
		    if (clock_hang_reported[tc] == 0) {
			pdb_msg += sprintf(pdb_msg,
				"TC %d looks hung with timer latch at %d\n",
				tc, ipi_timer_latch[tc]);
			clock_hang_reported[tc]++;
			}
		}
	}
	emt(mtflags);
	local_irq_restore(flags);
	if (pdb_msg != &id_ho_db_msg[0])
		printk("CPU%d: %s", smp_processor_id(), id_ho_db_msg);
1113
#endif /* CONFIG_SMTC_IDLE_HOOK_DEBUG */
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1115
	/*
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	 * Replay any accumulated deferred IPIs. If "Instant Replay"
	 * is in use, there should never be any.
1118
	 */
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#ifndef CONFIG_MIPS_MT_SMTC_INSTANT_REPLAY
	smtc_ipi_replay();
#endif /* CONFIG_MIPS_MT_SMTC_INSTANT_REPLAY */
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}

void smtc_soft_dump(void)
{
	int i;

	printk("Counter Interrupts taken per CPU (TC)\n");
	for (i=0; i < NR_CPUS; i++) {
		printk("%d: %ld\n", i, smtc_cpu_stats[i].timerints);
	}
	printk("Self-IPI invocations:\n");
	for (i=0; i < NR_CPUS; i++) {
		printk("%d: %ld\n", i, smtc_cpu_stats[i].selfipis);
	}
	smtc_ipi_qdump();
	printk("Timer IPI Backlogs:\n");
	for (i=0; i < NR_CPUS; i++) {
		printk("%d: %d\n", i, ipi_timer_latch[i]);
	}
	printk("%d Recoveries of \"stolen\" FPU\n",
	       atomic_read(&smtc_fpu_recoveries));
}


/*
 * TLB management routines special to SMTC
 */

void smtc_get_new_mmu_context(struct mm_struct *mm, unsigned long cpu)
{
	unsigned long flags, mtflags, tcstat, prevhalt, asid;
	int tlb, i;

	/*
	 * It would be nice to be able to use a spinlock here,
	 * but this is invoked from within TLB flush routines
	 * that protect themselves with DVPE, so if a lock is
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	 * held by another TC, it'll never be freed.
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	 *
	 * DVPE/DMT must not be done with interrupts enabled,
	 * so even so most callers will already have disabled
	 * them, let's be really careful...
	 */

	local_irq_save(flags);
	if (smtc_status & SMTC_TLB_SHARED) {
		mtflags = dvpe();
		tlb = 0;
	} else {
		mtflags = dmt();
		tlb = cpu_data[cpu].vpe_id;
	}
	asid = asid_cache(cpu);

	do {
		if (!((asid += ASID_INC) & ASID_MASK) ) {
			if (cpu_has_vtag_icache)
				flush_icache_all();
			/* Traverse all online CPUs (hack requires contigous range) */
			for (i = 0; i < num_online_cpus(); i++) {
				/*
				 * We don't need to worry about our own CPU, nor those of
				 * CPUs who don't share our TLB.
				 */
				if ((i != smp_processor_id()) &&
				    ((smtc_status & SMTC_TLB_SHARED) ||
				     (cpu_data[i].vpe_id == cpu_data[cpu].vpe_id))) {
					settc(cpu_data[i].tc_id);
					prevhalt = read_tc_c0_tchalt() & TCHALT_H;
					if (!prevhalt) {
						write_tc_c0_tchalt(TCHALT_H);
						mips_ihb();
					}
					tcstat = read_tc_c0_tcstatus();
					smtc_live_asid[tlb][(tcstat & ASID_MASK)] |= (asiduse)(0x1 << i);
					if (!prevhalt)
						write_tc_c0_tchalt(0);
				}
			}
			if (!asid)		/* fix version if needed */
				asid = ASID_FIRST_VERSION;
			local_flush_tlb_all();	/* start new asid cycle */
		}
	} while (smtc_live_asid[tlb][(asid & ASID_MASK)]);

	/*
	 * SMTC shares the TLB within VPEs and possibly across all VPEs.
	 */
	for (i = 0; i < num_online_cpus(); i++) {
		if ((smtc_status & SMTC_TLB_SHARED) ||
		    (cpu_data[i].vpe_id == cpu_data[cpu].vpe_id))
			cpu_context(i, mm) = asid_cache(i) = asid;
	}

	if (smtc_status & SMTC_TLB_SHARED)
		evpe(mtflags);
	else
		emt(mtflags);
	local_irq_restore(flags);
}

/*
 * Invoked from macros defined in mmu_context.h
 * which must already have disabled interrupts
 * and done a DVPE or DMT as appropriate.
 */

void smtc_flush_tlb_asid(unsigned long asid)
{
	int entry;
	unsigned long ehi;

	entry = read_c0_wired();

	/* Traverse all non-wired entries */
	while (entry < current_cpu_data.tlbsize) {
		write_c0_index(entry);
		ehb();
		tlb_read();
		ehb();
		ehi = read_c0_entryhi();
1243
		if ((ehi & ASID_MASK) == asid) {
1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263
		    /*
		     * Invalidate only entries with specified ASID,
		     * makiing sure all entries differ.
		     */
		    write_c0_entryhi(CKSEG0 + (entry << (PAGE_SHIFT + 1)));
		    write_c0_entrylo0(0);
		    write_c0_entrylo1(0);
		    mtc0_tlbw_hazard();
		    tlb_write_indexed();
		}
		entry++;
	}
	write_c0_index(PARKED_INDEX);
	tlbw_use_hazard();
}

/*
 * Support for single-threading cache flush operations.
 */

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static int halt_state_save[NR_CPUS];
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/*
 * To really, really be sure that nothing is being done
 * by other TCs, halt them all.  This code assumes that
 * a DVPE has already been done, so while their Halted
 * state is theoretically architecturally unstable, in
 * practice, it's not going to change while we're looking
 * at it.
 */

void smtc_cflush_lockdown(void)
{
	int cpu;

	for_each_online_cpu(cpu) {
		if (cpu != smp_processor_id()) {
			settc(cpu_data[cpu].tc_id);
			halt_state_save[cpu] = read_tc_c0_tchalt();
			write_tc_c0_tchalt(TCHALT_H);
		}
	}
	mips_ihb();
}

/* It would be cheating to change the cpu_online states during a flush! */

void smtc_cflush_release(void)
{
	int cpu;

	/*
	 * Start with a hazard barrier to ensure
	 * that all CACHE ops have played through.
	 */
	mips_ihb();

	for_each_online_cpu(cpu) {
		if (cpu != smp_processor_id()) {
			settc(cpu_data[cpu].tc_id);
			write_tc_c0_tchalt(halt_state_save[cpu]);
		}
	}
	mips_ihb();
}