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 /* The time when TTCR changes */ 29 static uint64_t last_clk; 30 static int is_counting; 31 32 void cpu_openrisc_count_update(OpenRISCCPU *cpu) 33 { 34 uint64_t now; 35 36 if (!is_counting) { 37 return; 38 } 39 now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); 40 cpu->env.ttcr += (uint32_t)((now - last_clk) / TIMER_PERIOD); 41 last_clk = now; 42 } 43 44 void cpu_openrisc_timer_update(OpenRISCCPU *cpu) 45 { 46 uint32_t wait; 47 uint64_t now, next; 48 49 if (!is_counting) { 50 return; 51 } 52 53 cpu_openrisc_count_update(cpu); 54 now = last_clk; 55 56 if ((cpu->env.ttmr & TTMR_TP) <= (cpu->env.ttcr & TTMR_TP)) { 57 wait = TTMR_TP - (cpu->env.ttcr & TTMR_TP) + 1; 58 wait += cpu->env.ttmr & TTMR_TP; 59 } else { 60 wait = (cpu->env.ttmr & TTMR_TP) - (cpu->env.ttcr & TTMR_TP); 61 } 62 next = now + (uint64_t)wait * TIMER_PERIOD; 63 timer_mod(cpu->env.timer, next); 64 } 65 66 void cpu_openrisc_count_start(OpenRISCCPU *cpu) 67 { 68 is_counting = 1; 69 cpu_openrisc_count_update(cpu); 70 } 71 72 void cpu_openrisc_count_stop(OpenRISCCPU *cpu) 73 { 74 timer_del(cpu->env.timer); 75 cpu_openrisc_count_update(cpu); 76 is_counting = 0; 77 } 78 79 static void openrisc_timer_cb(void *opaque) 80 { 81 OpenRISCCPU *cpu = opaque; 82 83 if ((cpu->env.ttmr & TTMR_IE) && 84 timer_expired(cpu->env.timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL))) { 85 CPUState *cs = CPU(cpu); 86 87 cpu->env.ttmr |= TTMR_IP; 88 cs->interrupt_request |= CPU_INTERRUPT_TIMER; 89 } 90 91 switch (cpu->env.ttmr & TTMR_M) { 92 case TIMER_NONE: 93 break; 94 case TIMER_INTR: 95 cpu->env.ttcr = 0; 96 break; 97 case TIMER_SHOT: 98 cpu_openrisc_count_stop(cpu); 99 break; 100 case TIMER_CONT: 101 break; 102 } 103 104 cpu_openrisc_timer_update(cpu); 105 } 106 107 void cpu_openrisc_clock_init(OpenRISCCPU *cpu) 108 { 109 cpu->env.timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, &openrisc_timer_cb, cpu); 110 cpu->env.ttmr = 0x00000000; 111 cpu->env.ttcr = 0x00000000; 112 } 113