[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 7aa79bf63c4a..10299bafeab7 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 02b266a31c46..436ba78359ab 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 c730744aa474..610f0253954d 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();
 }