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 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 "hw/hw.h"
  24 #include "qemu/timer.h"
  25
  26 #define TIMER_PERIOD 50 /* 50 ns period for 20 MHz timer */
  27
  28 /* Tick Timer global state to allow all cores to be in sync */
  29 typedef struct OR1KTimerState {
  30     uint32_t ttcr;
  31     uint64_t last_clk;
  32 } OR1KTimerState;
  33
  34 static OR1KTimerState *or1k_timer;
  35
  36 void cpu_openrisc_count_set(OpenRISCCPU *cpu, uint32_t val)
  37 {
  38     or1k_timer->ttcr = val;
  39 }
  40
  41 uint32_t cpu_openrisc_count_get(OpenRISCCPU *cpu)
  42 {
  43     return or1k_timer->ttcr;
  44 }
  45
  46 /* Add elapsed ticks to ttcr */
  47 void cpu_openrisc_count_update(OpenRISCCPU *cpu)
  48 {
  49     uint64_t now;
  50
  51     if (!cpu->env.is_counting) {
  52         return;
  53     }
  54     now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
  55     or1k_timer->ttcr += (uint32_t)((now - or1k_timer->last_clk)
  56                                     / TIMER_PERIOD);
  57     or1k_timer->last_clk = now;
  58 }
  59
  60 /* Update the next timeout time as difference between ttmr and ttcr */
  61 void cpu_openrisc_timer_update(OpenRISCCPU *cpu)
  62 {
  63     uint32_t wait;
  64     uint64_t now, next;
  65
  66     if (!cpu->env.is_counting) {
  67         return;
  68     }
  69
  70     cpu_openrisc_count_update(cpu);
  71     now = or1k_timer->last_clk;
  72
  73     if ((cpu->env.ttmr & TTMR_TP) <= (or1k_timer->ttcr & TTMR_TP)) {
  74         wait = TTMR_TP - (or1k_timer->ttcr & TTMR_TP) + 1;
  75         wait += cpu->env.ttmr & TTMR_TP;
  76     } else {
  77         wait = (cpu->env.ttmr & TTMR_TP) - (or1k_timer->ttcr & TTMR_TP);
  78     }
  79     next = now + (uint64_t)wait * TIMER_PERIOD;
  80     timer_mod(cpu->env.timer, next);
  81 }
  82
  83 void cpu_openrisc_count_start(OpenRISCCPU *cpu)
  84 {
  85     cpu->env.is_counting = 1;
  86     cpu_openrisc_count_update(cpu);
  87 }
  88
  89 void cpu_openrisc_count_stop(OpenRISCCPU *cpu)
  90 {
  91     timer_del(cpu->env.timer);
  92     cpu_openrisc_count_update(cpu);
  93     cpu->env.is_counting = 0;
  94 }
  95
  96 static void openrisc_timer_cb(void *opaque)
  97 {
  98     OpenRISCCPU *cpu = opaque;
  99
 100     if ((cpu->env.ttmr & TTMR_IE) &&
 101          timer_expired(cpu->env.timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL))) {
 102         CPUState *cs = CPU(cpu);
 103
 104         cpu->env.ttmr |= TTMR_IP;
 105         cs->interrupt_request |= CPU_INTERRUPT_TIMER;
 106     }
 107
 108     switch (cpu->env.ttmr & TTMR_M) {
 109     case TIMER_NONE:
 110         break;
 111     case TIMER_INTR:
 112         or1k_timer->ttcr = 0;
 113         break;
 114     case TIMER_SHOT:
 115         cpu_openrisc_count_stop(cpu);
 116         break;
 117     case TIMER_CONT:
 118         break;
 119     }
 120
 121     cpu_openrisc_timer_update(cpu);
 122     qemu_cpu_kick(CPU(cpu));
 123 }
 124
 125 static const VMStateDescription vmstate_or1k_timer = {
 126     .name = "or1k_timer",
 127     .version_id = 1,
 128     .minimum_version_id = 1,
 129     .fields = (VMStateField[]) {
 130         VMSTATE_UINT32(ttcr, OR1KTimerState),
 131         VMSTATE_UINT64(last_clk, OR1KTimerState),
 132         VMSTATE_END_OF_LIST()
 133     }
 134 };
 135
 136 void cpu_openrisc_clock_init(OpenRISCCPU *cpu)
 137 {
 138     cpu->env.timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, &openrisc_timer_cb, cpu);
 139     cpu->env.ttmr = 0x00000000;
 140
 141     if (or1k_timer == NULL) {
 142         or1k_timer = g_new0(OR1KTimerState, 1);
 143         vmstate_register(NULL, 0, &vmstate_or1k_timer, or1k_timer);
 144     }
 145 }