[MIPS] time: SMP-proofing of Sibyte clockevent/clocksource code.

The BCM148 has 4 cores but there are also just 4 generic timers available
so use the ZBbus cycle counter instead of it.  In addition the ZBbus
counter also offers a much higher resolution and 64-bit counting so I'm
considering a later complete conversion to it once I figure out if all
members of the Sibyte SOC family support it - the docs seem to agree but
the headers files seem to disagree ...

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

3 files changed, 93 insertions, 103 deletions

diff --git a/arch/mips/sibyte/bcm1480/irq.c b/arch/mips/sibyte/bcm1480/irq.c
index 7aa79bf63c4..10299bafeab 100644
--- a/arch/mips/sibyte/bcm1480/irq.c
+++ b/arch/mips/sibyte/bcm1480/irq.c
@@ -452,6 +452,43 @@ static void bcm1480_kgdb_interrupt(void)
 
 extern void bcm1480_mailbox_interrupt(void);
 
+static inline void dispatch_ip4(void)
+{
+	int cpu = smp_processor_id();
+	int irq = K_BCM1480_INT_TIMER_0 + cpu;
+
+	/* Reset the timer */
+	__raw_writeq(M_SCD_TIMER_ENABLE|M_SCD_TIMER_MODE_CONTINUOUS,
+	            IOADDR(A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_CFG)));
+
+	do_IRQ(irq);
+}
+
+static inline void dispatch_ip2(void)
+{
+	unsigned long long mask_h, mask_l;
+	unsigned int cpu = smp_processor_id();
+	unsigned long base;
+
+	/*
+	 * Default...we've hit an IP[2] interrupt, which means we've got to
+	 * check the 1480 interrupt registers to figure out what to do.  Need
+	 * to detect which CPU we're on, now that smp_affinity is supported.
+	 */
+	base = A_BCM1480_IMR_MAPPER(cpu);
+	mask_h = __raw_readq(
+		IOADDR(base + R_BCM1480_IMR_INTERRUPT_STATUS_BASE_H));
+	mask_l = __raw_readq(
+		IOADDR(base + R_BCM1480_IMR_INTERRUPT_STATUS_BASE_L));
+
+	if (mask_h) {
+		if (mask_h ^ 1)
+			do_IRQ(fls64(mask_h) - 1);
+		else if (mask_l)
+			do_IRQ(63 + fls64(mask_l));
+	}
+}
+
 asmlinkage void plat_irq_dispatch(void)
 {
 	unsigned int pending;
@@ -469,17 +506,8 @@ asmlinkage void plat_irq_dispatch(void)
 	else
 #endif
 
-	if (pending & CAUSEF_IP4) {
-		int cpu = smp_processor_id();
-		int irq = K_BCM1480_INT_TIMER_0 + cpu;
-
-		/* Reset the timer */
-		__raw_writeq(M_SCD_TIMER_ENABLE|M_SCD_TIMER_MODE_CONTINUOUS,
-		            IOADDR(A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_CFG)));
-
-		do_IRQ(irq);
-	}
-
+	if (pending & CAUSEF_IP4)
+		dispatch_ip4();
 #ifdef CONFIG_SMP
 	else if (pending & CAUSEF_IP3)
 		bcm1480_mailbox_interrupt();
@@ -490,27 +518,6 @@ asmlinkage void plat_irq_dispatch(void)
 		bcm1480_kgdb_interrupt();		/* KGDB (uart 1) */
 #endif
 
-	else if (pending & CAUSEF_IP2) {
-		unsigned long long mask_h, mask_l;
-		unsigned long base;
-
-		/*
-		 * Default...we've hit an IP[2] interrupt, which means we've
-		 * got to check the 1480 interrupt registers to figure out what
-		 * to do.  Need to detect which CPU we're on, now that
-		 * smp_affinity is supported.
-		 */
-		base = A_BCM1480_IMR_MAPPER(smp_processor_id());
-		mask_h = __raw_readq(
-			IOADDR(base + R_BCM1480_IMR_INTERRUPT_STATUS_BASE_H));
-		mask_l = __raw_readq(
-			IOADDR(base + R_BCM1480_IMR_INTERRUPT_STATUS_BASE_L));
-
-		if (mask_h) {
-			if (mask_h ^ 1)
-				do_IRQ(fls64(mask_h) - 1);
-			else
-				do_IRQ(63 + fls64(mask_l));
-		}
-	}
+	else if (pending & CAUSEF_IP2)
+		dispatch_ip2();
 }
diff --git a/arch/mips/sibyte/bcm1480/smp.c b/arch/mips/sibyte/bcm1480/smp.c
index 02b266a31c4..436ba78359a 100644
--- a/arch/mips/sibyte/bcm1480/smp.c
+++ b/arch/mips/sibyte/bcm1480/smp.c
@@ -58,7 +58,7 @@ static void *mailbox_0_regs[] = {
 /*
  * SMP init and finish on secondary CPUs
  */
-void bcm1480_smp_init(void)
+void __cpuinit bcm1480_smp_init(void)
 {
 	unsigned int imask = STATUSF_IP4 | STATUSF_IP3 | STATUSF_IP2 |
 		STATUSF_IP1 | STATUSF_IP0;
@@ -67,7 +67,7 @@ void bcm1480_smp_init(void)
 	change_c0_status(ST0_IM, imask);
 }
 
-void bcm1480_smp_finish(void)
+void __cpuinit bcm1480_smp_finish(void)
 {
 	extern void sb1480_clockevent_init(void);
 
diff --git a/arch/mips/sibyte/bcm1480/time.c b/arch/mips/sibyte/bcm1480/time.c
index c730744aa47..610f0253954 100644
--- a/arch/mips/sibyte/bcm1480/time.c
+++ b/arch/mips/sibyte/bcm1480/time.c
@@ -15,22 +15,12 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  */
-
-/*
- * These are routines to set up and handle interrupts from the
- * bcm1480 general purpose timer 0.  We're using the timer as a
- * system clock, so we set it up to run at 100 Hz.  On every
- * interrupt, we update our idea of what the time of day is,
- * then call do_timer() in the architecture-independent kernel
- * code to do general bookkeeping (e.g. update jiffies, run
- * bottom halves, etc.)
- */
 #include <linux/clockchips.h>
 #include <linux/interrupt.h>
+#include <linux/irq.h>
 #include <linux/percpu.h>
 #include <linux/spinlock.h>
 
-#include <asm/irq.h>
 #include <asm/addrspace.h>
 #include <asm/time.h>
 #include <asm/io.h>
@@ -47,33 +37,10 @@
 #define IMR_IP3_VAL	K_BCM1480_INT_MAP_I1
 #define IMR_IP4_VAL	K_BCM1480_INT_MAP_I2
 
-#ifdef CONFIG_SIMULATION
-#define BCM1480_HPT_VALUE	50000
-#else
-#define BCM1480_HPT_VALUE	1000000
-#endif
-
 extern int bcm1480_steal_irq(int irq);
 
-void __init plat_time_init(void)
-{
-	unsigned int cpu = smp_processor_id();
-	unsigned int irq = K_BCM1480_INT_TIMER_0 + cpu;
-
-	BUG_ON(cpu > 3);	/* Only have 4 general purpose timers */
-
-	bcm1480_mask_irq(cpu, irq);
-
-	/* Map the timer interrupt to ip[4] of this cpu */
-	__raw_writeq(IMR_IP4_VAL, IOADDR(A_BCM1480_IMR_REGISTER(cpu, R_BCM1480_IMR_INTERRUPT_MAP_BASE_H)
-	      + (irq<<3)));
-
-	bcm1480_unmask_irq(cpu, irq);
-	bcm1480_steal_irq(irq);
-}
-
 /*
- * The general purpose timer ticks at 1 Mhz independent if
+ * The general purpose timer ticks at 1MHz independent if
  * the rest of the system
  */
 static void sibyte_set_mode(enum clock_event_mode mode,
@@ -88,7 +55,7 @@ static void sibyte_set_mode(enum clock_event_mode mode,
 	switch (mode) {
 	case CLOCK_EVT_MODE_PERIODIC:
 		__raw_writeq(0, timer_cfg);
-		__raw_writeq(BCM1480_HPT_VALUE / HZ - 1, timer_init);
+		__raw_writeq((V_SCD_TIMER_FREQ / HZ) - 1, timer_init);
 		__raw_writeq(M_SCD_TIMER_ENABLE | M_SCD_TIMER_MODE_CONTINUOUS,
 			     timer_cfg);
 		break;
@@ -121,80 +88,96 @@ static int sibyte_next_event(unsigned long delta, struct clock_event_device *cd)
 	return res;
 }
 
-static DEFINE_PER_CPU(struct clock_event_device, sibyte_hpt_clockevent);
-
 static irqreturn_t sibyte_counter_handler(int irq, void *dev_id)
 {
 	unsigned int cpu = smp_processor_id();
-	struct clock_event_device *cd = &per_cpu(sibyte_hpt_clockevent, cpu);
+	struct clock_event_device *cd = dev_id;
+	void __iomem *timer_cfg;
+
+	timer_cfg = IOADDR(A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_CFG));
 
 	/* Reset the timer */
 	__raw_writeq(M_SCD_TIMER_ENABLE | M_SCD_TIMER_MODE_CONTINUOUS,
-	             IOADDR(A_SCD_TIMER_REGISTER(cpu, R_SCD_TIMER_CFG)));
+	             timer_cfg);
 	cd->event_handler(cd);
 
 	return IRQ_HANDLED;
 }
 
-static struct irqaction sibyte_counter_irqaction = {
-	.handler	= sibyte_counter_handler,
-	.flags		= IRQF_DISABLED | IRQF_PERCPU,
-	.name		= "timer",
-};
+static DEFINE_PER_CPU(struct clock_event_device, sibyte_hpt_clockevent);
+static DEFINE_PER_CPU(struct irqaction, sibyte_hpt_irqaction);
+static DEFINE_PER_CPU(char [18], sibyte_hpt_name);
 
-/*
- * This interrupt is "special" in that it doesn't use the request_irq
- * way to hook the irq line.  The timer interrupt is initialized early
- * enough to make this a major pain, and it's also firing enough to
- * warrant a bit of special case code.  bcm1480_timer_interrupt is
- * called directly from irq_handler.S when IP[4] is set during an
- * interrupt
- */
 void __cpuinit sb1480_clockevent_init(void)
 {
 	unsigned int cpu = smp_processor_id();
 	unsigned int irq = K_BCM1480_INT_TIMER_0 + cpu;
+	struct irqaction *action = &per_cpu(sibyte_hpt_irqaction, cpu);
 	struct clock_event_device *cd = &per_cpu(sibyte_hpt_clockevent, cpu);
+	unsigned char *name = per_cpu(sibyte_hpt_name, cpu);
+
+	BUG_ON(cpu > 3);	/* Only have 4 general purpose timers */
 
-	cd->name		= "bcm1480-counter";
+	sprintf(name, "bcm1480-counter %d", cpu);
+	cd->name		= name;
 	cd->features		= CLOCK_EVT_FEAT_PERIODIC |
 				  CLOCK_EVT_MODE_ONESHOT;
+	clockevent_set_clock(cd, V_SCD_TIMER_FREQ);
+	cd->max_delta_ns	= clockevent_delta2ns(0x7fffff, cd);
+	cd->min_delta_ns	= clockevent_delta2ns(1, cd);
+	cd->rating		= 200;
+	cd->irq			= irq;
+	cd->cpumask		= cpumask_of_cpu(cpu);
 	cd->set_next_event	= sibyte_next_event;
 	cd->set_mode		= sibyte_set_mode;
-	cd->irq			= irq;
-	clockevent_set_clock(cd, BCM1480_HPT_VALUE);
+	clockevents_register_device(cd);
+
+	bcm1480_mask_irq(cpu, irq);
+
+	/*
+	 * Map timer interrupt to IP[4] of this cpu
+	 */
+	__raw_writeq(IMR_IP4_VAL,
+		     IOADDR(A_BCM1480_IMR_REGISTER(cpu,
+			R_BCM1480_IMR_INTERRUPT_MAP_BASE_H) + (irq << 3)));
 
-	setup_irq(irq, &sibyte_counter_irqaction);
+	bcm1480_unmask_irq(cpu, irq);
+	bcm1480_steal_irq(irq);
+
+	action->handler	= sibyte_counter_handler;
+	action->flags	= IRQF_DISABLED | IRQF_PERCPU;
+	action->name	= name;
+	action->dev_id	= cd;
+	setup_irq(irq, action);
 }
 
 static cycle_t bcm1480_hpt_read(void)
 {
-	/* We assume this function is called xtime_lock held. */
-	unsigned long count =
-		__raw_readq(IOADDR(A_SCD_TIMER_REGISTER(0, R_SCD_TIMER_CNT)));
-	return (jiffies + 1) * (BCM1480_HPT_VALUE / HZ) - count;
+	return (cycle_t) __raw_readq(IOADDR(A_SCD_ZBBUS_CYCLE_COUNT));
 }
 
 struct clocksource bcm1480_clocksource = {
-	.name	= "MIPS",
+	.name	= "zbbus-cycles",
 	.rating	= 200,
 	.read	= bcm1480_hpt_read,
-	.mask	= CLOCKSOURCE_MASK(32),
-	.shift	= 32,
+	.mask	= CLOCKSOURCE_MASK(64),
 	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
 void __init sb1480_clocksource_init(void)
 {
 	struct clocksource *cs = &bcm1480_clocksource;
+	unsigned int plldiv;
+	unsigned long zbbus;
 
-	clocksource_set_clock(cs, BCM1480_HPT_VALUE);
+	plldiv = G_BCM1480_SYS_PLL_DIV(__raw_readq(IOADDR(A_SCD_SYSTEM_CFG)));
+	zbbus = ((plldiv >> 1) * 50000000) + ((plldiv & 1) * 25000000);
+	clocksource_set_clock(cs, zbbus);
 	clocksource_register(cs);
 }
 
-void __init bcm1480_hpt_setup(void)
+void __init plat_time_init(void)
 {
-	mips_hpt_frequency = BCM1480_HPT_VALUE;
 	sb1480_clocksource_init();
 	sb1480_clockevent_init();
 }