summaryrefslogtreecommitdiffstats
path: root/arch/m68k/coldfire/pit.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/m68k/coldfire/pit.c')
-rw-r--r--arch/m68k/coldfire/pit.c167
1 files changed, 167 insertions, 0 deletions
diff --git a/arch/m68k/coldfire/pit.c b/arch/m68k/coldfire/pit.c
new file mode 100644
index 0000000..493b311
--- /dev/null
+++ b/arch/m68k/coldfire/pit.c
@@ -0,0 +1,167 @@
+/***************************************************************************/
+
+/*
+ * pit.c -- Freescale ColdFire PIT timer. Currently this type of
+ * hardware timer only exists in the Freescale ColdFire
+ * 5270/5271, 5282 and 5208 CPUs. No doubt newer ColdFire
+ * family members will probably use it too.
+ *
+ * Copyright (C) 1999-2008, Greg Ungerer (gerg@snapgear.com)
+ * Copyright (C) 2001-2004, SnapGear Inc. (www.snapgear.com)
+ */
+
+/***************************************************************************/
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/param.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/clockchips.h>
+#include <asm/machdep.h>
+#include <asm/io.h>
+#include <asm/coldfire.h>
+#include <asm/mcfpit.h>
+#include <asm/mcfsim.h>
+
+/***************************************************************************/
+
+/*
+ * By default use timer1 as the system clock timer.
+ */
+#define FREQ ((MCF_CLK / 2) / 64)
+#define TA(a) (MCFPIT_BASE1 + (a))
+#define PIT_CYCLES_PER_JIFFY (FREQ / HZ)
+
+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 = MCF_IRQ_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;
+ evt->event_handler(evt);
+ return IRQ_HANDLED;
+}
+
+/***************************************************************************/
+
+static struct irqaction pit_irq = {
+ .name = "timer",
+ .flags = IRQF_TIMER,
+ .handler = pit_tick,
+};
+
+/***************************************************************************/
+
+static cycle_t pit_read_clk(struct clocksource *cs)
+{
+ unsigned long flags;
+ u32 cycles;
+ u16 pcntr;
+
+ local_irq_save(flags);
+ pcntr = __raw_readw(TA(MCFPIT_PCNTR));
+ cycles = pit_cnt;
+ local_irq_restore(flags);
+
+ return cycles + PIT_CYCLES_PER_JIFFY - pcntr;
+}
+
+/***************************************************************************/
+
+static struct clocksource pit_clk = {
+ .name = "pit",
+ .rating = 100,
+ .read = pit_read_clk,
+ .mask = CLOCKSOURCE_MASK(32),
+};
+
+/***************************************************************************/
+
+void hw_timer_init(irq_handler_t handler)
+{
+ cf_pit_clockevent.cpumask = cpumask_of(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(MCF_IRQ_PIT1, &pit_irq);
+
+ clocksource_register_hz(&pit_clk, FREQ);
+}
+
+/***************************************************************************/
OpenPOWER on IntegriCloud