arch/m68knommu/platform/coldfire/pit.c

   1 /***************************************************************************/
   2
   3 /*
   4  *      pit.c -- Freescale ColdFire PIT timer. Currently this type of
   5  *               hardware timer only exists in the Freescale ColdFire
   6  *               5270/5271, 5282 and 5208 CPUs. No doubt newer ColdFire
   7  *               family members will probably use it too.
   8  *
   9  *      Copyright (C) 1999-2008, Greg Ungerer (gerg@snapgear.com)
  10  *      Copyright (C) 2001-2004, SnapGear Inc. (www.snapgear.com)
  11  */
  12
  13 /***************************************************************************/
  14
  15 #include <linux/kernel.h>
  16 #include <linux/sched.h>
  17 #include <linux/param.h>
  18 #include <linux/init.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/irq.h>
  21 #include <linux/clockchips.h>
  22 #include <asm/machdep.h>
  23 #include <asm/io.h>
  24 #include <asm/coldfire.h>
  25 #include <asm/mcfpit.h>
  26 #include <asm/mcfsim.h>
  27
  28 /***************************************************************************/
  29
  30 /*
  31  *      By default use timer1 as the system clock timer.
  32  */
  33 #define FREQ    ((MCF_CLK / 2) / 64)
  34 #define TA(a)   (MCF_IPSBAR + MCFPIT_BASE1 + (a))
  35 #define INTC0   (MCF_IPSBAR + MCFICM_INTC0)
  36 #define PIT_CYCLES_PER_JIFFY (FREQ / HZ)
  37
  38 static u32 pit_cnt;
  39
  40 /*
  41  * Initialize the PIT timer.
  42  *
  43  * This is also called after resume to bring the PIT into operation again.
  44  */
  45
  46 static void init_cf_pit_timer(enum clock_event_mode mode,
  47                              struct clock_event_device *evt)
  48 {
  49         switch (mode) {
  50         case CLOCK_EVT_MODE_PERIODIC:
  51
  52                 __raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
  53                 __raw_writew(PIT_CYCLES_PER_JIFFY, TA(MCFPIT_PMR));
  54                 __raw_writew(MCFPIT_PCSR_EN | MCFPIT_PCSR_PIE | \
  55                                 MCFPIT_PCSR_OVW | MCFPIT_PCSR_RLD | \
  56                                 MCFPIT_PCSR_CLK64, TA(MCFPIT_PCSR));
  57                 break;
  58
  59         case CLOCK_EVT_MODE_SHUTDOWN:
  60         case CLOCK_EVT_MODE_UNUSED:
  61
  62                 __raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
  63                 break;
  64
  65         case CLOCK_EVT_MODE_ONESHOT:
  66
  67                 __raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
  68                 __raw_writew(MCFPIT_PCSR_EN | MCFPIT_PCSR_PIE | \
  69                                 MCFPIT_PCSR_OVW | MCFPIT_PCSR_CLK64, \
  70                                 TA(MCFPIT_PCSR));
  71                 break;
  72
  73         case CLOCK_EVT_MODE_RESUME:
  74                 /* Nothing to do here */
  75                 break;
  76         }
  77 }
  78
  79 /*
  80  * Program the next event in oneshot mode
  81  *
  82  * Delta is given in PIT ticks
  83  */
  84 static int cf_pit_next_event(unsigned long delta,
  85                 struct clock_event_device *evt)
  86 {
  87         __raw_writew(delta, TA(MCFPIT_PMR));
  88         return 0;
  89 }
  90
  91 struct clock_event_device cf_pit_clockevent = {
  92         .name           = "pit",
  93         .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
  94         .set_mode       = init_cf_pit_timer,
  95         .set_next_event = cf_pit_next_event,
  96         .shift          = 32,
  97         .irq            = MCFINT_VECBASE + MCFINT_PIT1,
  98 };
  99
 100
 101
 102 /***************************************************************************/
 103
 104 static irqreturn_t pit_tick(int irq, void *dummy)
 105 {
 106         struct clock_event_device *evt = &cf_pit_clockevent;
 107         u16 pcsr;
 108
 109         /* Reset the ColdFire timer */
 110         pcsr = __raw_readw(TA(MCFPIT_PCSR));
 111         __raw_writew(pcsr | MCFPIT_PCSR_PIF, TA(MCFPIT_PCSR));
 112
 113         pit_cnt += PIT_CYCLES_PER_JIFFY;
 114         evt->event_handler(evt);
 115         return IRQ_HANDLED;
 116 }
 117
 118 /***************************************************************************/
 119
 120 static struct irqaction pit_irq = {
 121         .name    = "timer",
 122         .flags   = IRQF_DISABLED | IRQF_TIMER,
 123         .handler = pit_tick,
 124 };
 125
 126 /***************************************************************************/
 127
 128 static cycle_t pit_read_clk(void)
 129 {
 130         unsigned long flags;
 131         u32 cycles;
 132         u16 pcntr;
 133
 134         local_irq_save(flags);
 135         pcntr = __raw_readw(TA(MCFPIT_PCNTR));
 136         cycles = pit_cnt;
 137         local_irq_restore(flags);
 138
 139         return cycles + PIT_CYCLES_PER_JIFFY - pcntr;
 140 }
 141
 142 /***************************************************************************/
 143
 144 static struct clocksource pit_clk = {
 145         .name   = "pit",
 146         .rating = 100,
 147         .read   = pit_read_clk,
 148         .shift  = 20,
 149         .mask   = CLOCKSOURCE_MASK(32),
 150         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
 151 };
 152
 153 /***************************************************************************/
 154
 155 void hw_timer_init(void)
 156 {
 157         u32 imr;
 158
 159         cf_pit_clockevent.cpumask = cpumask_of(smp_processor_id());
 160         cf_pit_clockevent.mult = div_sc(FREQ, NSEC_PER_SEC, 32);
 161         cf_pit_clockevent.max_delta_ns =
 162                 clockevent_delta2ns(0xFFFF, &cf_pit_clockevent);
 163         cf_pit_clockevent.min_delta_ns =
 164                 clockevent_delta2ns(0x3f, &cf_pit_clockevent);
 165         clockevents_register_device(&cf_pit_clockevent);
 166
 167         setup_irq(MCFINT_VECBASE + MCFINT_PIT1, &pit_irq);
 168
 169         __raw_writeb(ICR_INTRCONF, INTC0 + MCFINTC_ICR0 + MCFINT_PIT1);
 170         imr = __raw_readl(INTC0 + MCFPIT_IMR);
 171         imr &= ~MCFPIT_IMR_IBIT;
 172         __raw_writel(imr, INTC0 + MCFPIT_IMR);
 173
 174         pit_clk.mult = clocksource_hz2mult(FREQ, pit_clk.shift);
 175         clocksource_register(&pit_clk);
 176 }
 177
 178 /***************************************************************************/