kernel/arch/mips/jz4740/time.c

   1 /*
   2  *  Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
   3  *  JZ4740 platform time support
   4  *
   5  *  This program is free software; you can redistribute it and/or modify it
   6  *  under  the terms of the GNU General  Public License as published by the
   7  *  Free Software Foundation;  either version 2 of the License, or (at your
   8  *  option) any later version.
   9  *
  10  *  You should have received a copy of the GNU General Public License along
  11  *  with this program; if not, write to the Free Software Foundation, Inc.,
  12  *  675 Mass Ave, Cambridge, MA 02139, USA.
  13  *
  14  */
  15
  16 #include <linux/interrupt.h>
  17 #include <linux/kernel.h>
  18 #include <linux/time.h>
  19
  20 #include <linux/clockchips.h>
  21 #include <linux/sched_clock.h>
  22
  23 #include <asm/mach-jz4740/irq.h>
  24 #include <asm/mach-jz4740/timer.h>
  25 #include <asm/time.h>
  26
  27 #include "clock.h"
  28
  29 #define TIMER_CLOCKEVENT 0
  30 #define TIMER_CLOCKSOURCE 1
  31
  32 static uint16_t jz4740_jiffies_per_tick;
  33
  34 static cycle_t jz4740_clocksource_read(struct clocksource *cs)
  35 {
  36         return jz4740_timer_get_count(TIMER_CLOCKSOURCE);
  37 }
  38
  39 static struct clocksource jz4740_clocksource = {
  40         .name = "jz4740-timer",
  41         .rating = 200,
  42         .read = jz4740_clocksource_read,
  43         .mask = CLOCKSOURCE_MASK(16),
  44         .flags = CLOCK_SOURCE_IS_CONTINUOUS,
  45 };
  46
  47 static u64 notrace jz4740_read_sched_clock(void)
  48 {
  49         return jz4740_timer_get_count(TIMER_CLOCKSOURCE);
  50 }
  51
  52 static irqreturn_t jz4740_clockevent_irq(int irq, void *devid)
  53 {
  54         struct clock_event_device *cd = devid;
  55
  56         jz4740_timer_ack_full(TIMER_CLOCKEVENT);
  57
  58         if (cd->mode != CLOCK_EVT_MODE_PERIODIC)
  59                 jz4740_timer_disable(TIMER_CLOCKEVENT);
  60
  61         cd->event_handler(cd);
  62
  63         return IRQ_HANDLED;
  64 }
  65
  66 static void jz4740_clockevent_set_mode(enum clock_event_mode mode,
  67         struct clock_event_device *cd)
  68 {
  69         switch (mode) {
  70         case CLOCK_EVT_MODE_PERIODIC:
  71                 jz4740_timer_set_count(TIMER_CLOCKEVENT, 0);
  72                 jz4740_timer_set_period(TIMER_CLOCKEVENT, jz4740_jiffies_per_tick);
  73         case CLOCK_EVT_MODE_RESUME:
  74                 jz4740_timer_irq_full_enable(TIMER_CLOCKEVENT);
  75                 jz4740_timer_enable(TIMER_CLOCKEVENT);
  76                 break;
  77         case CLOCK_EVT_MODE_ONESHOT:
  78         case CLOCK_EVT_MODE_SHUTDOWN:
  79                 jz4740_timer_disable(TIMER_CLOCKEVENT);
  80                 break;
  81         default:
  82                 break;
  83         }
  84 }
  85
  86 static int jz4740_clockevent_set_next(unsigned long evt,
  87         struct clock_event_device *cd)
  88 {
  89         jz4740_timer_set_count(TIMER_CLOCKEVENT, 0);
  90         jz4740_timer_set_period(TIMER_CLOCKEVENT, evt);
  91         jz4740_timer_enable(TIMER_CLOCKEVENT);
  92
  93         return 0;
  94 }
  95
  96 static struct clock_event_device jz4740_clockevent = {
  97         .name = "jz4740-timer",
  98         .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
  99         .set_next_event = jz4740_clockevent_set_next,
 100         .set_mode = jz4740_clockevent_set_mode,
 101         .rating = 200,
 102         .irq = JZ4740_IRQ_TCU0,
 103 };
 104
 105 static struct irqaction timer_irqaction = {
 106         .handler        = jz4740_clockevent_irq,
 107         .flags          = IRQF_PERCPU | IRQF_TIMER,
 108         .name           = "jz4740-timerirq",
 109         .dev_id         = &jz4740_clockevent,
 110 };
 111
 112 void __init plat_time_init(void)
 113 {
 114         int ret;
 115         uint32_t clk_rate;
 116         uint16_t ctrl;
 117
 118         jz4740_timer_init();
 119
 120         clk_rate = jz4740_clock_bdata.ext_rate >> 4;
 121         jz4740_jiffies_per_tick = DIV_ROUND_CLOSEST(clk_rate, HZ);
 122
 123         clockevent_set_clock(&jz4740_clockevent, clk_rate);
 124         jz4740_clockevent.min_delta_ns = clockevent_delta2ns(100, &jz4740_clockevent);
 125         jz4740_clockevent.max_delta_ns = clockevent_delta2ns(0xffff, &jz4740_clockevent);
 126         jz4740_clockevent.cpumask = cpumask_of(0);
 127
 128         clockevents_register_device(&jz4740_clockevent);
 129
 130         ret = clocksource_register_hz(&jz4740_clocksource, clk_rate);
 131
 132         if (ret)
 133                 printk(KERN_ERR "Failed to register clocksource: %d\n", ret);
 134
 135         sched_clock_register(jz4740_read_sched_clock, 16, clk_rate);
 136
 137         setup_irq(JZ4740_IRQ_TCU0, &timer_irqaction);
 138
 139         ctrl = JZ_TIMER_CTRL_PRESCALE_16 | JZ_TIMER_CTRL_SRC_EXT;
 140
 141         jz4740_timer_set_ctrl(TIMER_CLOCKEVENT, ctrl);
 142         jz4740_timer_set_ctrl(TIMER_CLOCKSOURCE, ctrl);
 143
 144         jz4740_timer_set_period(TIMER_CLOCKEVENT, jz4740_jiffies_per_tick);
 145         jz4740_timer_irq_full_enable(TIMER_CLOCKEVENT);
 146
 147         jz4740_timer_set_period(TIMER_CLOCKSOURCE, 0xffff);
 148
 149         jz4740_timer_enable(TIMER_CLOCKEVENT);
 150         jz4740_timer_enable(TIMER_CLOCKSOURCE);
 151 }