hw/openrisc/cputimer.c

   1 /*
   2  * QEMU OpenRISC timer support
   3  *
   4  * Copyright (c) 2011-2012 Jia Liu <proljc@gmail.com>
   5  *                         Zhizhou Zhang <etouzh@gmail.com>
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #include "qemu/osdep.h"
  22 #include "cpu.h"
  23 #include "migration/vmstate.h"
  24 #include "qemu/timer.h"
  25 #include "sysemu/reset.h"
  26
  27 #define TIMER_PERIOD 50 /* 50 ns period for 20 MHz timer */
  28
  29 /* Tick Timer global state to allow all cores to be in sync */
  30 typedef struct OR1KTimerState {
  31     uint32_t ttcr;
  32     uint64_t last_clk;
  33 } OR1KTimerState;
  34
  35 static OR1KTimerState *or1k_timer;
  36
  37 void cpu_openrisc_count_set(OpenRISCCPU *cpu, uint32_t val)
  38 {
  39     or1k_timer->ttcr = val;
  40 }
  41
  42 uint32_t cpu_openrisc_count_get(OpenRISCCPU *cpu)
  43 {
  44     return or1k_timer->ttcr;
  45 }
  46
  47 /* Add elapsed ticks to ttcr */
  48 void cpu_openrisc_count_update(OpenRISCCPU *cpu)
  49 {
  50     uint64_t now;
  51
  52     if (!cpu->env.is_counting) {
  53         return;
  54     }
  55     now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
  56     or1k_timer->ttcr += (uint32_t)((now - or1k_timer->last_clk)
  57                                     / TIMER_PERIOD);
  58     or1k_timer->last_clk = now;
  59 }
  60
  61 /* Update the next timeout time as difference between ttmr and ttcr */
  62 void cpu_openrisc_timer_update(OpenRISCCPU *cpu)
  63 {
  64     uint32_t wait;
  65     uint64_t now, next;
  66
  67     if (!cpu->env.is_counting) {
  68         return;
  69     }
  70
  71     cpu_openrisc_count_update(cpu);
  72     now = or1k_timer->last_clk;
  73
  74     if ((cpu->env.ttmr & TTMR_TP) <= (or1k_timer->ttcr & TTMR_TP)) {
  75         wait = TTMR_TP - (or1k_timer->ttcr & TTMR_TP) + 1;
  76         wait += cpu->env.ttmr & TTMR_TP;
  77     } else {
  78         wait = (cpu->env.ttmr & TTMR_TP) - (or1k_timer->ttcr & TTMR_TP);
  79     }
  80     next = now + (uint64_t)wait * TIMER_PERIOD;
  81     timer_mod(cpu->env.timer, next);
  82 }
  83
  84 void cpu_openrisc_count_start(OpenRISCCPU *cpu)
  85 {
  86     cpu->env.is_counting = 1;
  87     cpu_openrisc_count_update(cpu);
  88 }
  89
  90 void cpu_openrisc_count_stop(OpenRISCCPU *cpu)
  91 {
  92     timer_del(cpu->env.timer);
  93     cpu_openrisc_count_update(cpu);
  94     cpu->env.is_counting = 0;
  95 }
  96
  97 static void openrisc_timer_cb(void *opaque)
  98 {
  99     OpenRISCCPU *cpu = opaque;
 100
 101     if ((cpu->env.ttmr & TTMR_IE) &&
 102          timer_expired(cpu->env.timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL))) {
 103         CPUState *cs = CPU(cpu);
 104
 105         cpu->env.ttmr |= TTMR_IP;
 106         cs->interrupt_request |= CPU_INTERRUPT_TIMER;
 107     }
 108
 109     switch (cpu->env.ttmr & TTMR_M) {
 110     case TIMER_NONE:
 111         break;
 112     case TIMER_INTR:
 113         or1k_timer->ttcr = 0;
 114         break;
 115     case TIMER_SHOT:
 116         cpu_openrisc_count_stop(cpu);
 117         break;
 118     case TIMER_CONT:
 119         break;
 120     }
 121
 122     cpu_openrisc_timer_update(cpu);
 123     qemu_cpu_kick(CPU(cpu));
 124 }
 125
 126 /* Reset the per CPU counter state. */
 127 static void openrisc_count_reset(void *opaque)
 128 {
 129     OpenRISCCPU *cpu = opaque;
 130
 131     if (cpu->env.is_counting) {
 132         cpu_openrisc_count_stop(cpu);
 133     }
 134     cpu->env.ttmr = 0x00000000;
 135 }
 136
 137 /* Reset the global timer state. */
 138 static void openrisc_timer_reset(void *opaque)
 139 {
 140     or1k_timer->ttcr = 0x00000000;
 141     or1k_timer->last_clk = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
 142 }
 143
 144 static const VMStateDescription vmstate_or1k_timer = {
 145     .name = "or1k_timer",
 146     .version_id = 1,
 147     .minimum_version_id = 1,
 148     .fields = (VMStateField[]) {
 149         VMSTATE_UINT32(ttcr, OR1KTimerState),
 150         VMSTATE_UINT64(last_clk, OR1KTimerState),
 151         VMSTATE_END_OF_LIST()
 152     }
 153 };
 154
 155 void cpu_openrisc_clock_init(OpenRISCCPU *cpu)
 156 {
 157     cpu->env.timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, &openrisc_timer_cb, cpu);
 158
 159     qemu_register_reset(openrisc_count_reset, cpu);
 160     if (or1k_timer == NULL) {
 161         or1k_timer = g_new0(OR1KTimerState, 1);
 162         qemu_register_reset(openrisc_timer_reset, cpu);
 163         vmstate_register(NULL, 0, &vmstate_or1k_timer, or1k_timer);
 164     }
 165 }