m68knommu: MCF5307 PIT GENERIC_CLOCKEVENTS support

The PIT code has been changed in order to suppport GENERIC_CLOCKEVENTS.
The priority of the PIT clocksource has been decreased in favor of the
DMA timer.

pit_cycles_per_jiffy become a constant (PIT_CYCLES_PER_JIFFY) because it
is known at compile time and does not change afterwards.

Signed-off-by: Benedikt Spranger <b.spranger@linutronix.de>
Signed-off-by: Sebastian Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Ungerer <gerg@uclinux.org>

1 files changed, 78 insertions, 13 deletions

diff --git a/arch/m68knommu/platform/coldfire/pit.c b/arch/m68knommu/platform/coldfire/pit.c
index 4290638012e0..c5b916700b22 100644
--- a/arch/m68knommu/platform/coldfire/pit.c
+++ b/arch/m68knommu/platform/coldfire/pit.c
@@ -18,7 +18,7 @@
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
-#include <linux/clocksource.h>
+#include <linux/clockchips.h>
 #include <asm/machdep.h>
 #include <asm/io.h>
 #include <asm/coldfire.h>
@@ -33,22 +33,86 @@
 #define FREQ    ((MCF_CLK / 2) / 64)
 #define TA(a)   (MCF_IPSBAR + MCFPIT_BASE1 + (a))
 #define INTC0   (MCF_IPSBAR + MCFICM_INTC0)
+#define PIT_CYCLES_PER_JIFFY (FREQ / HZ)
 
-static u32 pit_cycles_per_jiffy;
 static u32 pit_cnt;
 
+/*
+ * Initialize the PIT timer.
+ *
+ * This is also called after resume to bring the PIT into operation again.
+ */
+
+static void init_cf_pit_timer(enum clock_event_mode mode,
+                             struct clock_event_device *evt)
+{
+        switch (mode) {
+        case CLOCK_EVT_MODE_PERIODIC:
+
+                __raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
+                __raw_writew(PIT_CYCLES_PER_JIFFY, TA(MCFPIT_PMR));
+                __raw_writew(MCFPIT_PCSR_EN | MCFPIT_PCSR_PIE | \
+                                MCFPIT_PCSR_OVW | MCFPIT_PCSR_RLD | \
+                                MCFPIT_PCSR_CLK64, TA(MCFPIT_PCSR));
+                break;
+
+        case CLOCK_EVT_MODE_SHUTDOWN:
+        case CLOCK_EVT_MODE_UNUSED:
+
+                __raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
+                break;
+
+        case CLOCK_EVT_MODE_ONESHOT:
+
+                __raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
+                __raw_writew(MCFPIT_PCSR_EN | MCFPIT_PCSR_PIE | \
+                                MCFPIT_PCSR_OVW | MCFPIT_PCSR_CLK64, \
+                                TA(MCFPIT_PCSR));
+                break;
+
+        case CLOCK_EVT_MODE_RESUME:
+                /* Nothing to do here */
+                break;
+        }
+}
+
+/*
+ * Program the next event in oneshot mode
+ *
+ * Delta is given in PIT ticks
+ */
+static int cf_pit_next_event(unsigned long delta,
+                struct clock_event_device *evt)
+{
+        __raw_writew(delta, TA(MCFPIT_PMR));
+        return 0;
+}
+
+struct clock_event_device cf_pit_clockevent = {
+        .name           = "pit",
+        .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+        .set_mode       = init_cf_pit_timer,
+        .set_next_event = cf_pit_next_event,
+        .shift          = 32,
+        .irq            = MCFINT_VECBASE + MCFINT_PIT1,
+};
+
+
+
 /***************************************************************************/
 
 static irqreturn_t pit_tick(int irq, void *dummy)
 {
+        struct clock_event_device *evt = &cf_pit_clockevent;
         u16 pcsr;
 
         /* Reset the ColdFire timer */
         pcsr = __raw_readw(TA(MCFPIT_PCSR));
         __raw_writew(pcsr | MCFPIT_PCSR_PIF, TA(MCFPIT_PCSR));
 
-        pit_cnt += pit_cycles_per_jiffy;
-        return arch_timer_interrupt(irq, dummy);
+        pit_cnt += PIT_CYCLES_PER_JIFFY;
+        evt->event_handler(evt);
+        return IRQ_HANDLED;
 }
 
 /***************************************************************************/
@@ -72,14 +136,14 @@ static cycle_t pit_read_clk(void)
         cycles = pit_cnt;
         local_irq_restore(flags);
 
-        return cycles + pit_cycles_per_jiffy - pcntr;
+        return cycles + PIT_CYCLES_PER_JIFFY - pcntr;
 }
 
 /***************************************************************************/
 
 static struct clocksource pit_clk = {
         .name   = "pit",
-        .rating = 250,
+        .rating = 100,
         .read   = pit_read_clk,
         .shift  = 20,
         .mask   = CLOCKSOURCE_MASK(32),
@@ -92,6 +156,14 @@ void hw_timer_init(void)
 {
         u32 imr;
 
+        cf_pit_clockevent.cpumask = cpumask_of_cpu(smp_processor_id());
+        cf_pit_clockevent.mult = div_sc(FREQ, NSEC_PER_SEC, 32);
+        cf_pit_clockevent.max_delta_ns =
+                clockevent_delta2ns(0xFFFF, &cf_pit_clockevent);
+        cf_pit_clockevent.min_delta_ns =
+                clockevent_delta2ns(0x3f, &cf_pit_clockevent);
+        clockevents_register_device(&cf_pit_clockevent);
+
         setup_irq(MCFINT_VECBASE + MCFINT_PIT1, &pit_irq);
 
         __raw_writeb(ICR_INTRCONF, INTC0 + MCFINTC_ICR0 + MCFINT_PIT1);
@@ -99,13 +171,6 @@ void hw_timer_init(void)
         imr &= ~MCFPIT_IMR_IBIT;
         __raw_writel(imr, INTC0 + MCFPIT_IMR);
 
-        /* Set up PIT timer 1 as poll clock */
-        pit_cycles_per_jiffy = FREQ / HZ;
-        __raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
-        __raw_writew(pit_cycles_per_jiffy, TA(MCFPIT_PMR));
-        __raw_writew(MCFPIT_PCSR_EN | MCFPIT_PCSR_PIE | MCFPIT_PCSR_OVW |
-                MCFPIT_PCSR_RLD | MCFPIT_PCSR_CLK64, TA(MCFPIT_PCSR));
-
         pit_clk.mult = clocksource_hz2mult(FREQ, pit_clk.shift);
         clocksource_register(&pit_clk);
 }