arch/arm/mach-tcc8k/time.c

   1 /*
   2  * TCC8000 system timer setup
   3  *
   4  * (C) 2009 Hans J. Koch <hjk@linutronix.de>
   5  *
   6  * Licensed under the terms of the GPL version 2.
   7  *
   8  */
   9
  10 #include <linux/clk.h>
  11 #include <linux/clockchips.h>
  12 #include <linux/init.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/io.h>
  15 #include <linux/irq.h>
  16 #include <linux/kernel.h>
  17 #include <linux/spinlock.h>
  18
  19 #include <asm/mach/time.h>
  20
  21 #include <mach/tcc8k-regs.h>
  22 #include <mach/irqs.h>
  23
  24 #include "common.h"
  25
  26 static void __iomem *timer_base;
  27
  28 static cycle_t tcc_get_cycles(struct clocksource *cs)
  29 {
  30         return __raw_readl(timer_base + TC32MCNT_OFFS);
  31 }
  32
  33 static struct clocksource clocksource_tcc = {
  34         .name           = "tcc_tc32",
  35         .rating         = 200,
  36         .read           = tcc_get_cycles,
  37         .mask           = CLOCKSOURCE_MASK(32),
  38         .shift          = 28,
  39         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  40 };
  41
  42 static int tcc_set_next_event(unsigned long evt,
  43                               struct clock_event_device *unused)
  44 {
  45         unsigned long reg = __raw_readl(timer_base + TC32MCNT_OFFS);
  46
  47         __raw_writel(reg + evt, timer_base + TC32CMP0_OFFS);
  48         return 0;
  49 }
  50
  51 static void tcc_set_mode(enum clock_event_mode mode,
  52                                 struct clock_event_device *evt)
  53 {
  54         unsigned long tc32irq;
  55
  56         switch (mode) {
  57         case CLOCK_EVT_MODE_ONESHOT:
  58                 tc32irq = __raw_readl(timer_base + TC32IRQ_OFFS);
  59                 tc32irq |= TC32IRQ_IRQEN0;
  60                 __raw_writel(tc32irq, timer_base + TC32IRQ_OFFS);
  61                 break;
  62         case CLOCK_EVT_MODE_SHUTDOWN:
  63         case CLOCK_EVT_MODE_UNUSED:
  64                 tc32irq = __raw_readl(timer_base + TC32IRQ_OFFS);
  65                 tc32irq &= ~TC32IRQ_IRQEN0;
  66                 __raw_writel(tc32irq, timer_base + TC32IRQ_OFFS);
  67                 break;
  68         case CLOCK_EVT_MODE_PERIODIC:
  69         case CLOCK_EVT_MODE_RESUME:
  70                 break;
  71         }
  72 }
  73
  74 static irqreturn_t tcc8k_timer_interrupt(int irq, void *dev_id)
  75 {
  76         struct clock_event_device *evt = dev_id;
  77
  78         /* Acknowledge TC32 interrupt by reading TC32IRQ */
  79         __raw_readl(timer_base + TC32IRQ_OFFS);
  80
  81         evt->event_handler(evt);
  82
  83         return IRQ_HANDLED;
  84 }
  85
  86 static struct clock_event_device clockevent_tcc = {
  87         .name           = "tcc_timer1",
  88         .features       = CLOCK_EVT_FEAT_ONESHOT,
  89         .shift          = 32,
  90         .set_mode       = tcc_set_mode,
  91         .set_next_event = tcc_set_next_event,
  92         .rating         = 200,
  93 };
  94
  95 static struct irqaction tcc8k_timer_irq = {
  96         .name           = "TC32_timer",
  97         .flags          = IRQF_DISABLED | IRQF_TIMER,
  98         .handler        = tcc8k_timer_interrupt,
  99         .dev_id         = &clockevent_tcc,
 100 };
 101
 102 static int __init tcc_clockevent_init(struct clk *clock)
 103 {
 104         unsigned int c = clk_get_rate(clock);
 105
 106         clocksource_tcc.mult = clocksource_hz2mult(c,
 107                                         clocksource_tcc.shift);
 108         clocksource_register(&clocksource_tcc);
 109
 110         clockevent_tcc.mult = div_sc(c, NSEC_PER_SEC,
 111                                         clockevent_tcc.shift);
 112         clockevent_tcc.max_delta_ns =
 113                         clockevent_delta2ns(0xfffffffe, &clockevent_tcc);
 114         clockevent_tcc.min_delta_ns =
 115                         clockevent_delta2ns(0xff, &clockevent_tcc);
 116
 117         clockevent_tcc.cpumask = cpumask_of(0);
 118
 119         clockevents_register_device(&clockevent_tcc);
 120
 121         return 0;
 122 }
 123
 124 void __init tcc8k_timer_init(struct clk *clock, void __iomem *base, int irq)
 125 {
 126         u32 reg;
 127
 128         timer_base = base;
 129         tcc8k_timer_irq.irq = irq;
 130
 131         /* Enable clocks */
 132         clk_enable(clock);
 133
 134         /* Initialize 32-bit timer */
 135         reg = __raw_readl(timer_base + TC32EN_OFFS);
 136         reg &= ~TC32EN_ENABLE; /* Disable timer */
 137         __raw_writel(reg, timer_base + TC32EN_OFFS);
 138         /* Free running timer, counting from 0 to 0xffffffff */
 139         __raw_writel(0, timer_base + TC32EN_OFFS);
 140         __raw_writel(0, timer_base + TC32LDV_OFFS);
 141         reg = __raw_readl(timer_base + TC32IRQ_OFFS);
 142         reg |= TC32IRQ_IRQEN0; /* irq at match with CMP0 */
 143         __raw_writel(reg, timer_base + TC32IRQ_OFFS);
 144
 145         __raw_writel(TC32EN_ENABLE, timer_base + TC32EN_OFFS);
 146
 147         tcc_clockevent_init(clock);
 148         setup_irq(irq, &tcc8k_timer_irq);
 149 }