release/src-rt-6.x.4708/linux/linux-2.6.36/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
  22 #include <asm/mach-jz4740/irq.h>
  23 #include <asm/time.h>
  24
  25 #include "clock.h"
  26 #include "timer.h"
  27
  28 #define TIMER_CLOCKEVENT 0
  29 #define TIMER_CLOCKSOURCE 1
  30
  31 static uint16_t jz4740_jiffies_per_tick;
  32
  33 static cycle_t jz4740_clocksource_read(struct clocksource *cs)
  34 {
  35         return jz4740_timer_get_count(TIMER_CLOCKSOURCE);
  36 }
  37
  38 static struct clocksource jz4740_clocksource = {
  39         .name = "jz4740-timer",
  40         .rating = 200,
  41         .read = jz4740_clocksource_read,
  42         .mask = CLOCKSOURCE_MASK(16),
  43         .flags = CLOCK_SOURCE_IS_CONTINUOUS,
  44 };
  45
  46 static irqreturn_t jz4740_clockevent_irq(int irq, void *devid)
  47 {
  48         struct clock_event_device *cd = devid;
  49
  50         jz4740_timer_ack_full(TIMER_CLOCKEVENT);
  51
  52         if (cd->mode != CLOCK_EVT_MODE_PERIODIC)
  53                 jz4740_timer_disable(TIMER_CLOCKEVENT);
  54
  55         cd->event_handler(cd);
  56
  57         return IRQ_HANDLED;
  58 }
  59
  60 static void jz4740_clockevent_set_mode(enum clock_event_mode mode,
  61         struct clock_event_device *cd)
  62 {
  63         switch (mode) {
  64         case CLOCK_EVT_MODE_PERIODIC:
  65                 jz4740_timer_set_count(TIMER_CLOCKEVENT, 0);
  66                 jz4740_timer_set_period(TIMER_CLOCKEVENT, jz4740_jiffies_per_tick);
  67         case CLOCK_EVT_MODE_RESUME:
  68                 jz4740_timer_irq_full_enable(TIMER_CLOCKEVENT);
  69                 jz4740_timer_enable(TIMER_CLOCKEVENT);
  70                 break;
  71         case CLOCK_EVT_MODE_ONESHOT:
  72         case CLOCK_EVT_MODE_SHUTDOWN:
  73                 jz4740_timer_disable(TIMER_CLOCKEVENT);
  74                 break;
  75         default:
  76                 break;
  77         }
  78 }
  79
  80 static int jz4740_clockevent_set_next(unsigned long evt,
  81         struct clock_event_device *cd)
  82 {
  83         jz4740_timer_set_count(TIMER_CLOCKEVENT, 0);
  84         jz4740_timer_set_period(TIMER_CLOCKEVENT, evt);
  85         jz4740_timer_enable(TIMER_CLOCKEVENT);
  86
  87         return 0;
  88 }
  89
  90 static struct clock_event_device jz4740_clockevent = {
  91         .name = "jz4740-timer",
  92         .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
  93         .set_next_event = jz4740_clockevent_set_next,
  94         .set_mode = jz4740_clockevent_set_mode,
  95         .rating = 200,
  96         .irq = JZ4740_IRQ_TCU0,
  97 };
  98
  99 static struct irqaction timer_irqaction = {
 100         .handler        = jz4740_clockevent_irq,
 101         .flags          = IRQF_PERCPU | IRQF_TIMER,
 102         .name           = "jz4740-timerirq",
 103         .dev_id         = &jz4740_clockevent,
 104 };
 105
 106 void __init plat_time_init(void)
 107 {
 108         int ret;
 109         uint32_t clk_rate;
 110         uint16_t ctrl;
 111
 112         jz4740_timer_init();
 113
 114         clk_rate = jz4740_clock_bdata.ext_rate >> 4;
 115         jz4740_jiffies_per_tick = DIV_ROUND_CLOSEST(clk_rate, HZ);
 116
 117         clockevent_set_clock(&jz4740_clockevent, clk_rate);
 118         jz4740_clockevent.min_delta_ns = clockevent_delta2ns(100, &jz4740_clockevent);
 119         jz4740_clockevent.max_delta_ns = clockevent_delta2ns(0xffff, &jz4740_clockevent);
 120         jz4740_clockevent.cpumask = cpumask_of(0);
 121
 122         clockevents_register_device(&jz4740_clockevent);
 123
 124         clocksource_set_clock(&jz4740_clocksource, clk_rate);
 125         ret = clocksource_register(&jz4740_clocksource);
 126
 127         if (ret)
 128                 printk(KERN_ERR "Failed to register clocksource: %d\n", ret);
 129
 130         setup_irq(JZ4740_IRQ_TCU0, &timer_irqaction);
 131
 132         ctrl = JZ_TIMER_CTRL_PRESCALE_16 | JZ_TIMER_CTRL_SRC_EXT;
 133
 134         jz4740_timer_set_ctrl(TIMER_CLOCKEVENT, ctrl);
 135         jz4740_timer_set_ctrl(TIMER_CLOCKSOURCE, ctrl);
 136
 137         jz4740_timer_set_period(TIMER_CLOCKEVENT, jz4740_jiffies_per_tick);
 138         jz4740_timer_irq_full_enable(TIMER_CLOCKEVENT);
 139
 140         jz4740_timer_set_period(TIMER_CLOCKSOURCE, 0xffff);
 141
 142         jz4740_timer_enable(TIMER_CLOCKEVENT);
 143         jz4740_timer_enable(TIMER_CLOCKSOURCE);
 144 }