openrisc: initial SMP support

This patch introduces the SMP support for the OpenRISC architecture.
The SMP architecture requires cores which have multi-core features which
have been introduced a few years back including:

 - New SPRS SPR_COREID SPR_NUMCORES
 - Shadow SPRs
 - Atomic Instructions
 - Cache Coherency
 - A wired in IPI controller

This patch adds all of the SMP specific changes to core infrastructure,
it looks big but it needs to go all together as its hard to split this
one up.

Boot loader spinning of second cpu is not supported yet, it's assumed
that Linux is booted straight after cpu reset.

The bulk of these changes are trivial changes to refactor to use per cpu
data structures throughout.  The addition of the smp.c and changes in
time.c are the changes.  Some specific notes:

MM changes
----------
The reason why this is created as an array, and not with DEFINE_PER_CPU
is that doing it this way, we'll save a load in the tlb-miss handler
(the load from __per_cpu_offset).

TLB Flush
---------
The SMP implementation of flush_tlb_* works by sending out a
function-call IPI to all the non-local cpus by using the generic
on_each_cpu() function.

Currently, all flush_tlb_* functions will result in a flush_tlb_all(),
which has always been the behaviour in the UP case.

CPU INFO
--------
This creates a per cpu cpuinfo struct and fills it out accordingly for
each activated cpu.  show_cpuinfo is also updated to reflect new version
information in later versions of the spec.

SMP API
-------
This imitates the arm64 implementation by having a smp_cross_call
callback that can be set by set_smp_cross_call to initiate an IPI and a
handle_IPI function that is expected to be called from an IPI irqchip
driver.

Signed-off-by: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
[shorne@gmail.com: added cpu stop, checkpatch fixes, wrote commit message]
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 31 insertions, 20 deletions

diff --git a/arch/openrisc/kernel/time.c b/arch/openrisc/kernel/time.c
index 687c11d048d7..ab04eaedbf8d 100644
--- a/arch/openrisc/kernel/time.c
+++ b/arch/openrisc/kernel/time.c
@@ -53,13 +53,32 @@ static int openrisc_timer_set_next_event(unsigned long delta,
  * timers) we cannot enable the PERIODIC feature.  The tick timer can run using
  * one-shot events, so no problem.
  */
+DEFINE_PER_CPU(struct clock_event_device, clockevent_openrisc_timer);
 
-static struct clock_event_device clockevent_openrisc_timer = {
-	.name = "openrisc_timer_clockevent",
-	.features = CLOCK_EVT_FEAT_ONESHOT,
-	.rating = 300,
-	.set_next_event = openrisc_timer_set_next_event,
-};
+void openrisc_clockevent_init(void)
+{
+	unsigned int cpu = smp_processor_id();
+	struct clock_event_device *evt =
+		&per_cpu(clockevent_openrisc_timer, cpu);
+	struct cpuinfo_or1k *cpuinfo = &cpuinfo_or1k[cpu];
+
+	mtspr(SPR_TTMR, SPR_TTMR_CR);
+
+#ifdef CONFIG_SMP
+	evt->broadcast = tick_broadcast;
+#endif
+	evt->name = "openrisc_timer_clockevent",
+	evt->features = CLOCK_EVT_FEAT_ONESHOT,
+	evt->rating = 300,
+	evt->set_next_event = openrisc_timer_set_next_event,
+
+	evt->cpumask = cpumask_of(cpu);
+
+	/* We only have 28 bits */
+	clockevents_config_and_register(evt, cpuinfo->clock_frequency,
+					100, 0x0fffffff);
+
+}
 
 static inline void timer_ack(void)
 {
@@ -83,7 +102,9 @@ static inline void timer_ack(void)
 irqreturn_t __irq_entry timer_interrupt(struct pt_regs *regs)
 {
 	struct pt_regs *old_regs = set_irq_regs(regs);
-	struct clock_event_device *evt = &clockevent_openrisc_timer;
+	unsigned int cpu = smp_processor_id();
+	struct clock_event_device *evt =
+		&per_cpu(clockevent_openrisc_timer, cpu);
 
 	timer_ack();
 
@@ -99,24 +120,12 @@ irqreturn_t __irq_entry timer_interrupt(struct pt_regs *regs)
 	return IRQ_HANDLED;
 }
 
-static __init void openrisc_clockevent_init(void)
-{
-	clockevent_openrisc_timer.cpumask = cpumask_of(0);
-
-	/* We only have 28 bits */
-	clockevents_config_and_register(&clockevent_openrisc_timer,
-					cpuinfo.clock_frequency,
-					100, 0x0fffffff);
-
-}
-
 /**
  * Clocksource: Based on OpenRISC timer/counter
  *
  * This sets up the OpenRISC Tick Timer as a clock source.  The tick timer
  * is 32 bits wide and runs at the CPU clock frequency.
  */
-
 static u64 openrisc_timer_read(struct clocksource *cs)
 {
 	return (u64) mfspr(SPR_TTCR);
@@ -132,7 +141,9 @@ static struct clocksource openrisc_timer = {
 
 static int __init openrisc_timer_init(void)
 {
-	if (clocksource_register_hz(&openrisc_timer, cpuinfo.clock_frequency))
+	struct cpuinfo_or1k *cpuinfo = &cpuinfo_or1k[smp_processor_id()];
+
+	if (clocksource_register_hz(&openrisc_timer, cpuinfo->clock_frequency))
 		panic("failed to register clocksource");
 
 	/* Enable the incrementer: 'continuous' mode with interrupt disabled */