[MIPS] MT: Improved multithreading support.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/smtc.c b/arch/mips/kernel/smtc.c
new file mode 100644
index 0000000..2e8e52c
--- /dev/null
+++ b/arch/mips/kernel/smtc.c
@@ -0,0 +1,1322 @@
+/* Copyright (C) 2004 Mips Technologies, Inc */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/cpumask.h>
+#include <linux/interrupt.h>
+
+#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.
+ */
+
+/*
+ * MIPSCPU_INT_BASE is identically defined in both
+ * asm-mips/mips-boards/maltaint.h and asm-mips/mips-boards/simint.h,
+ * but as yet there's no properly organized include structure that
+ * will ensure that the right *int.h file will be included for a
+ * given platform build.
+ */
+
+#define MIPSCPU_INT_BASE 16
+
+#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
+
+struct smtc_ipi_q IPIQ[NR_CPUS];
+struct smtc_ipi_q freeIPIq;
+
+
+/* Forward declarations */
+
+void ipi_decode(struct pt_regs *, struct smtc_ipi *);
+void post_direct_ipi(int cpu, struct smtc_ipi *pipi);
+void setup_cross_vpe_interrupts(void);
+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);
+ switch(asidmask) {
+ 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);
+
+/* Enable additional debug checks before going into CPU idle loop */
+#define SMTC_IDLE_HOOK_DEBUG
+
+#ifdef SMTC_IDLE_HOOK_DEBUG
+
+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];
+
+#endif /* SMTC_IDLE_HOOK_DEBUG */
+
+/* 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
+ */
+
+void smtc_configure_tlb(void)
+{
+ 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
+ */
+ if(((read_vpe_c0_config() & MIPS_CONF_MT) >> 7) == 1) {
+ 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);
+
+ /*
+ * 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().
+ */
+
+ tlbsiz = tlbsiz & 0x3f; /* MIPS32 limits TLB indices to 64 */
+ cpu_data[0].tlbsize = tlbsiz;
+ smtc_status |= SMTC_TLB_SHARED;
+
+ 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();
+
+ freeIPIq.lock = SPIN_LOCK_UNLOCKED;
+
+ /*
+ * 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;
+ IPIQ[i].lock = SPIN_LOCK_UNLOCKED;
+ 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 */
+#ifdef SMTC_IDLE_HOOK_DEBUG
+ if (hang_trig)
+ printk("Logic Analyser Trigger on suspected TC hang\n");
+#endif /* SMTC_IDLE_HOOK_DEBUG */
+
+ /* 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());
+ }
+ /* 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++) {
+ if(cpu_data[tc].options & MIPS_CPU_FPU)
+ 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.
+ * mips_timer_setup should already have been invoked by init/main
+ * 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.
+ */
+ if(((read_c0_tcbind() & TCBIND_CURTC) != 0)
+ && ((read_c0_tcbind() & TCBIND_CURVPE)
+ != 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.
+ */
+
+void smtc_ipi_qdump(void)
+{
+ 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;
+}
+
+/* No longer used in IPI dispatch, but retained for future recycling */
+
+static __inline__ int atomic_postclear(unsigned int *pv)
+{
+ unsigned long result;
+
+ unsigned long temp;
+
+ __asm__ __volatile__(
+ "1: ll %0, %2 \n"
+ " or %1, $0, $0 \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 */
+ if(type == SMTC_CLOCK_TICK) {
+ if(atomic_postincrement(&ipi_timer_latch[cpu])!=0) {
+ 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
+ */
+void post_direct_ipi(int cpu, struct smtc_ipi *pipi)
+{
+ 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...
+ */
+ if(tcstatus & ST0_CU0) {
+ /* 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);
+}
+
+void ipi_resched_interrupt(struct pt_regs *regs)
+{
+ /* Return from interrupt should be enough to cause scheduler check */
+}
+
+
+void ipi_call_interrupt(struct pt_regs *regs)
+{
+ /* Invoke generic function invocation code in smp.c */
+ smp_call_function_interrupt();
+}
+
+void ipi_decode(struct pt_regs *regs, struct smtc_ipi *pipi)
+{
+ void *arg_copy = pipi->arg;
+ int type_copy = pipi->type;
+ int dest_copy = pipi->dest;
+
+ smtc_ipi_nq(&freeIPIq, pipi);
+ switch (type_copy) {
+ case SMTC_CLOCK_TICK:
+ /* Invoke Clock "Interrupt" */
+ ipi_timer_latch[dest_copy] = 0;
+#ifdef SMTC_IDLE_HOOK_DEBUG
+ clock_hang_reported[dest_copy] = 0;
+#endif /* SMTC_IDLE_HOOK_DEBUG */
+ local_timer_interrupt(0, NULL, regs);
+ break;
+ case LINUX_SMP_IPI:
+ switch ((int)arg_copy) {
+ case SMP_RESCHEDULE_YOURSELF:
+ ipi_resched_interrupt(regs);
+ break;
+ case SMP_CALL_FUNCTION:
+ ipi_call_interrupt(regs);
+ break;
+ default:
+ printk("Impossible SMTC IPI Argument 0x%x\n",
+ (int)arg_copy);
+ break;
+ }
+ break;
+ default:
+ printk("Impossible SMTC IPI Type 0x%x\n", type_copy);
+ break;
+ }
+}
+
+void deferred_smtc_ipi(struct pt_regs *regs)
+{
+ 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.
+ */
+ if(IPIQ[q].head != NULL) {
+ while((pipi = smtc_ipi_dq(&IPIQ[q])) != NULL) {
+ /* ipi_decode() should be called with interrupts off */
+ local_irq_save(flags);
+ ipi_decode(regs, pipi);
+ 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.
+ */
+
+static int cpu_ipi_irq = MIPSCPU_INT_BASE + MIPS_CPU_IPI_IRQ;
+
+static irqreturn_t ipi_interrupt(int irq, void *dev_idm, struct pt_regs *regs)
+{
+ 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);
+ ipi_decode(regs, pipi);
+ local_irq_restore(flags);
+ }
+ }
+ }
+
+ return IRQ_HANDLED;
+}
+
+static void ipi_irq_dispatch(struct pt_regs *regs)
+{
+ do_IRQ(cpu_ipi_irq, regs);
+}
+
+static struct irqaction irq_ipi;
+
+void setup_cross_vpe_interrupts(void)
+{
+ 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;
+ irq_ipi.flags = SA_INTERRUPT;
+ 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;
+}
+
+/*
+ * SMTC-specific hacks invoked from elsewhere in the kernel.
+ */
+
+void smtc_idle_loop_hook(void)
+{
+#ifdef SMTC_IDLE_HOOK_DEBUG
+ 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);
+#endif /* SMTC_IDLE_HOOK_DEBUG */
+ /*
+ * 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 *);
+
+ if ((pipi = smtc_ipi_dq(&IPIQ[smp_processor_id()])) != NULL) {
+ self_ipi(pipi);
+ smtc_cpu_stats[smp_processor_id()].selfipis++;
+ }
+ }
+}
+
+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
+ * held by another TC, it'll never be freed.
+ *
+ * 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();
+ if((ehi & ASID_MASK) == asid) {
+ /*
+ * 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.
+ */
+
+int halt_state_save[NR_CPUS];
+
+/*
+ * 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();
+}
