diff options
Diffstat (limited to 'arch/m68k/coldfire/pit.c')
| -rw-r--r-- | arch/m68k/coldfire/pit.c | 167 |
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); +} + +/***************************************************************************/ |
