[MIPS] Dyntick support for SMTC:
The kernel currently only supports broadcasting of the timer interrupt
from a single timer, not multicasting into two multicast groups of
processors. So the implemented mechanism for SMTC works by broadcasting
the cp0 compare interrupt on VPE 0 and ignoring it on any additional VPEs.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index ecce3aa..d8c9058 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1368,6 +1368,7 @@
depends on CPU_MIPS32_R2
#depends on CPU_MIPS64_R2 # once there is hardware ...
depends on SYS_SUPPORTS_MULTITHREADING
+ select GENERIC_CLOCKEVENTS_BROADCAST
select CPU_MIPSR2_IRQ_VI
select CPU_MIPSR2_IRQ_EI
select CPU_MIPSR2_SRS
@@ -1537,6 +1538,9 @@
depends on !CPU_R3000
default y
+config GENERIC_CLOCKEVENTS_BROADCAST
+ bool
+
#
# Use the generic interrupt handling code in kernel/irq/:
#
diff --git a/arch/mips/kernel/smtc.c b/arch/mips/kernel/smtc.c
index 137183b..4d1ac96 100644
--- a/arch/mips/kernel/smtc.c
+++ b/arch/mips/kernel/smtc.c
@@ -1,5 +1,6 @@
/* Copyright (C) 2004 Mips Technologies, Inc */
+#include <linux/clockchips.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/cpumask.h>
@@ -62,7 +63,7 @@
* Clock interrupt "latch" buffers, per "CPU"
*/
-unsigned int ipi_timer_latch[NR_CPUS];
+static atomic_t ipi_timer_latch[NR_CPUS];
/*
* Number of InterProcessor Interupt (IPI) message buffers to allocate
@@ -296,8 +297,10 @@
__cpu_number_map[i] = i;
__cpu_logical_map[i] = i;
}
+#ifdef CONFIG_MIPS_MT_FPAFF
/* Initialize map of CPUs with FPUs */
cpus_clear(mt_fpu_cpumask);
+#endif
/* One of those TC's is the one booting, and not a secondary... */
printk("%i available secondary CPU TC(s)\n", i - 1);
@@ -359,7 +362,7 @@
IPIQ[i].head = IPIQ[i].tail = NULL;
spin_lock_init(&IPIQ[i].lock);
IPIQ[i].depth = 0;
- ipi_timer_latch[i] = 0;
+ atomic_set(&ipi_timer_latch[i], 0);
}
/* cpu_data index starts at zero */
@@ -482,10 +485,12 @@
/* Set up coprocessor affinity CPU mask(s) */
+#ifdef CONFIG_MIPS_MT_FPAFF
for (tc = 0; tc < ntc; tc++) {
if (cpu_data[tc].options & MIPS_CPU_FPU)
cpu_set(tc, mt_fpu_cpumask);
}
+#endif
/* set up ipi interrupts... */
@@ -702,7 +707,7 @@
* 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)
+static inline int atomic_postincrement(atomic_t *v)
{
unsigned long result;
@@ -714,8 +719,8 @@
" sc %1, %2 \n"
" beqz %1, 1b \n"
__WEAK_LLSC_MB
- : "=&r" (result), "=&r" (temp), "=m" (*pv)
- : "m" (*pv)
+ : "=&r" (result), "=&r" (temp), "=m" (v->counter)
+ : "m" (v->counter)
: "memory");
return result;
@@ -743,6 +748,8 @@
pipi->arg = (void *)action;
pipi->dest = cpu;
if (cpu_data[cpu].vpe_id != cpu_data[smp_processor_id()].vpe_id) {
+ if (type == SMTC_CLOCK_TICK)
+ atomic_inc(&ipi_timer_latch[cpu]);
/* If not on same VPE, enqueue and send cross-VPE interupt */
smtc_ipi_nq(&IPIQ[cpu], pipi);
LOCK_CORE_PRA();
@@ -784,6 +791,8 @@
}
smtc_ipi_nq(&IPIQ[cpu], pipi);
} else {
+ if (type == SMTC_CLOCK_TICK)
+ atomic_inc(&ipi_timer_latch[cpu]);
post_direct_ipi(cpu, pipi);
write_tc_c0_tchalt(0);
UNLOCK_CORE_PRA();
@@ -801,6 +810,7 @@
unsigned long tcrestart;
extern u32 kernelsp[NR_CPUS];
extern void __smtc_ipi_vector(void);
+//printk("%s: on %d for %d\n", __func__, smp_processor_id(), cpu);
/* Extract Status, EPC from halted TC */
tcstatus = read_tc_c0_tcstatus();
@@ -851,25 +861,31 @@
smp_call_function_interrupt();
}
+DECLARE_PER_CPU(struct clock_event_device, smtc_dummy_clockevent_device);
+
void ipi_decode(struct smtc_ipi *pipi)
{
+ unsigned int cpu = smp_processor_id();
+ struct clock_event_device *cd;
void *arg_copy = pipi->arg;
int type_copy = pipi->type;
- int dest_copy = pipi->dest;
+ int ticks;
smtc_ipi_nq(&freeIPIq, pipi);
switch (type_copy) {
case SMTC_CLOCK_TICK:
irq_enter();
- kstat_this_cpu.irqs[MIPS_CPU_IRQ_BASE + cp0_compare_irq]++;
- /* Invoke Clock "Interrupt" */
- ipi_timer_latch[dest_copy] = 0;
-#ifdef CONFIG_SMTC_IDLE_HOOK_DEBUG
- clock_hang_reported[dest_copy] = 0;
-#endif /* CONFIG_SMTC_IDLE_HOOK_DEBUG */
- local_timer_interrupt(0, NULL);
+ kstat_this_cpu.irqs[MIPS_CPU_IRQ_BASE + 1]++;
+ cd = &per_cpu(smtc_dummy_clockevent_device, cpu);
+ ticks = atomic_read(&ipi_timer_latch[cpu]);
+ atomic_sub(ticks, &ipi_timer_latch[cpu]);
+ while (ticks) {
+ cd->event_handler(cd);
+ ticks--;
+ }
irq_exit();
break;
+
case LINUX_SMP_IPI:
switch ((int)arg_copy) {
case SMP_RESCHEDULE_YOURSELF:
@@ -921,25 +937,6 @@
}
/*
- * Send clock tick to all TCs except the one executing the funtion
- */
-
-void smtc_timer_broadcast(void)
-{
- 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
@@ -1180,11 +1177,11 @@
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) {
+ atomic_read(&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]);
+ tc, atomic_read(&ipi_timer_latch[tc]));
clock_hang_reported[tc]++;
}
}
@@ -1225,7 +1222,7 @@
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: %d\n", i, atomic_read(&ipi_timer_latch[i]));
}
printk("%d Recoveries of \"stolen\" FPU\n",
atomic_read(&smtc_fpu_recoveries));
diff --git a/arch/mips/kernel/time.c b/arch/mips/kernel/time.c
index 3598884..369a5f9 100644
--- a/arch/mips/kernel/time.c
+++ b/arch/mips/kernel/time.c
@@ -25,6 +25,7 @@
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/module.h>
+#include <linux/kallsyms.h>
#include <asm/bootinfo.h>
#include <asm/cache.h>
@@ -33,6 +34,7 @@
#include <asm/cpu-features.h>
#include <asm/div64.h>
#include <asm/sections.h>
+#include <asm/smtc_ipi.h>
#include <asm/time.h>
#include <irq.h>
@@ -230,12 +232,24 @@
struct clock_event_device *evt)
{
unsigned int cnt;
+ int res;
+#ifdef CONFIG_MIPS_MT_SMTC
+ {
+ unsigned long flags, vpflags;
+ local_irq_save(flags);
+ vpflags = dvpe();
+#endif
cnt = read_c0_count();
cnt += delta;
write_c0_compare(cnt);
-
- return ((long)(read_c0_count() - cnt ) > 0) ? -ETIME : 0;
+ res = ((long)(read_c0_count() - cnt ) > 0) ? -ETIME : 0;
+#ifdef CONFIG_MIPS_MT_SMTC
+ evpe(vpflags);
+ local_irq_restore(flags);
+ }
+#endif
+ return res;
}
static void mips_set_mode(enum clock_event_mode mode,
@@ -244,9 +258,7 @@
/* Nothing to do ... */
}
-struct clock_event_device mips_clockevent;
-
-static struct clock_event_device *global_cd[NR_CPUS];
+static DEFINE_PER_CPU(struct clock_event_device, mips_clockevent_device);
static int cp0_timer_irq_installed;
static irqreturn_t timer_interrupt(int irq, void *dev_id)
@@ -271,7 +283,12 @@
*/
if (!r2 || (read_c0_cause() & (1 << 30))) {
c0_timer_ack();
- cd = global_cd[cpu];
+#ifdef CONFIG_MIPS_MT_SMTC
+ if (cpu_data[cpu].vpe_id)
+ goto out;
+ cpu = 0;
+#endif
+ cd = &per_cpu(mips_clockevent_device, cpu);
cd->event_handler(cd);
}
@@ -281,7 +298,11 @@
static struct irqaction timer_irqaction = {
.handler = timer_interrupt,
+#ifdef CONFIG_MIPS_MT_SMTC
+ .flags = IRQF_DISABLED,
+#else
.flags = IRQF_DISABLED | IRQF_PERCPU,
+#endif
.name = "timer",
};
@@ -316,6 +337,60 @@
{
}
+#ifdef CONFIG_MIPS_MT_SMTC
+DEFINE_PER_CPU(struct clock_event_device, smtc_dummy_clockevent_device);
+
+static void smtc_set_mode(enum clock_event_mode mode,
+ struct clock_event_device *evt)
+{
+}
+
+int dummycnt[NR_CPUS];
+
+static void mips_broadcast(cpumask_t mask)
+{
+ unsigned int cpu;
+
+ for_each_cpu_mask(cpu, mask)
+ smtc_send_ipi(cpu, SMTC_CLOCK_TICK, 0);
+}
+
+static void setup_smtc_dummy_clockevent_device(void)
+{
+ //uint64_t mips_freq = mips_hpt_^frequency;
+ unsigned int cpu = smp_processor_id();
+ struct clock_event_device *cd;
+
+ cd = &per_cpu(smtc_dummy_clockevent_device, cpu);
+
+ cd->name = "SMTC";
+ cd->features = CLOCK_EVT_FEAT_DUMMY;
+
+ /* Calculate the min / max delta */
+ cd->mult = 0; //div_sc((unsigned long) mips_freq, NSEC_PER_SEC, 32);
+ cd->shift = 0; //32;
+ cd->max_delta_ns = 0; //clockevent_delta2ns(0x7fffffff, cd);
+ cd->min_delta_ns = 0; //clockevent_delta2ns(0x30, cd);
+
+ cd->rating = 200;
+ cd->irq = 17; //-1;
+// if (cpu)
+// cd->cpumask = CPU_MASK_ALL; // cpumask_of_cpu(cpu);
+// else
+ cd->cpumask = cpumask_of_cpu(cpu);
+
+ cd->set_mode = smtc_set_mode;
+
+ cd->broadcast = mips_broadcast;
+
+ clockevents_register_device(cd);
+}
+#endif
+
+static void mips_event_handler(struct clock_event_device *dev)
+{
+}
+
void __cpuinit mips_clockevent_init(void)
{
uint64_t mips_freq = mips_hpt_frequency;
@@ -326,12 +401,18 @@
if (!cpu_has_counter)
return;
- if (cpu == 0)
- cd = &mips_clockevent;
- else
- cd = kzalloc(sizeof(*cd), GFP_ATOMIC);
- if (!cd)
- return; /* We're probably roadkill ... */
+#ifdef CONFIG_MIPS_MT_SMTC
+ setup_smtc_dummy_clockevent_device();
+
+ /*
+ * On SMTC we only register VPE0's compare interrupt as clockevent
+ * device.
+ */
+ if (cpu)
+ return;
+#endif
+
+ cd = &per_cpu(mips_clockevent_device, cpu);
cd->name = "MIPS";
cd->features = CLOCK_EVT_FEAT_ONESHOT;
@@ -344,11 +425,15 @@
cd->rating = 300;
cd->irq = irq;
+#ifdef CONFIG_MIPS_MT_SMTC
+ cd->cpumask = CPU_MASK_ALL;
+#else
cd->cpumask = cpumask_of_cpu(cpu);
+#endif
cd->set_next_event = mips_next_event;
cd->set_mode = mips_set_mode;
+ cd->event_handler = mips_event_handler;
- global_cd[cpu] = cd;
clockevents_register_device(cd);
if (!cp0_timer_irq_installed) {
diff --git a/arch/mips/mips-boards/generic/time.c b/arch/mips/mips-boards/generic/time.c
index 2c8db3e..cf55ecd 100644
--- a/arch/mips/mips-boards/generic/time.c
+++ b/arch/mips/mips-boards/generic/time.c
@@ -55,7 +55,6 @@
static int mips_cpu_timer_irq;
extern int cp0_perfcount_irq;
-extern void smtc_timer_broadcast(void);
static void mips_timer_dispatch(void)
{
