hw/lm32_timer.c

   1 /*
   2  *  QEMU model of the LatticeMico32 timer block.
   3  *
   4  *  Copyright (c) 2010 Michael Walle <michael@walle.cc>
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  *
  19  *
  20  * Specification available at:
  21  *   http://www.latticesemi.com/documents/mico32timer.pdf
  22  */
  23
  24 #include "hw.h"
  25 #include "sysbus.h"
  26 #include "trace.h"
  27 #include "qemu-timer.h"
  28 #include "ptimer.h"
  29 #include "qemu-error.h"
  30
  31 #define DEFAULT_FREQUENCY (50*1000000)
  32
  33 enum {
  34     R_SR = 0,
  35     R_CR,
  36     R_PERIOD,
  37     R_SNAPSHOT,
  38     R_MAX
  39 };
  40
  41 enum {
  42     SR_TO    = (1 << 0),
  43     SR_RUN   = (1 << 1),
  44 };
  45
  46 enum {
  47     CR_ITO   = (1 << 0),
  48     CR_CONT  = (1 << 1),
  49     CR_START = (1 << 2),
  50     CR_STOP  = (1 << 3),
  51 };
  52
  53 struct LM32TimerState {
  54     SysBusDevice busdev;
  55     MemoryRegion iomem;
  56
  57     QEMUBH *bh;
  58     ptimer_state *ptimer;
  59
  60     qemu_irq irq;
  61     uint32_t freq_hz;
  62
  63     uint32_t regs[R_MAX];
  64 };
  65 typedef struct LM32TimerState LM32TimerState;
  66
  67 static void timer_update_irq(LM32TimerState *s)
  68 {
  69     int state = (s->regs[R_SR] & SR_TO) && (s->regs[R_CR] & CR_ITO);
  70
  71     trace_lm32_timer_irq_state(state);
  72     qemu_set_irq(s->irq, state);
  73 }
  74
  75 static uint64_t timer_read(void *opaque, target_phys_addr_t addr, unsigned size)
  76 {
  77     LM32TimerState *s = opaque;
  78     uint32_t r = 0;
  79
  80     addr >>= 2;
  81     switch (addr) {
  82     case R_SR:
  83     case R_CR:
  84     case R_PERIOD:
  85         r = s->regs[addr];
  86         break;
  87     case R_SNAPSHOT:
  88         r = (uint32_t)ptimer_get_count(s->ptimer);
  89         break;
  90     default:
  91         error_report("lm32_timer: read access to unknown register 0x"
  92                 TARGET_FMT_plx, addr << 2);
  93         break;
  94     }
  95
  96     trace_lm32_timer_memory_read(addr << 2, r);
  97     return r;
  98 }
  99
 100 static void timer_write(void *opaque, target_phys_addr_t addr,
 101                         uint64_t value, unsigned size)
 102 {
 103     LM32TimerState *s = opaque;
 104
 105     trace_lm32_timer_memory_write(addr, value);
 106
 107     addr >>= 2;
 108     switch (addr) {
 109     case R_SR:
 110         s->regs[R_SR] &= ~SR_TO;
 111         break;
 112     case R_CR:
 113         s->regs[R_CR] = value;
 114         if (s->regs[R_CR] & CR_START) {
 115             ptimer_run(s->ptimer, 1);
 116         }
 117         if (s->regs[R_CR] & CR_STOP) {
 118             ptimer_stop(s->ptimer);
 119         }
 120         break;
 121     case R_PERIOD:
 122         s->regs[R_PERIOD] = value;
 123         ptimer_set_count(s->ptimer, value);
 124         break;
 125     case R_SNAPSHOT:
 126         error_report("lm32_timer: write access to read only register 0x"
 127                 TARGET_FMT_plx, addr << 2);
 128         break;
 129     default:
 130         error_report("lm32_timer: write access to unknown register 0x"
 131                 TARGET_FMT_plx, addr << 2);
 132         break;
 133     }
 134     timer_update_irq(s);
 135 }
 136
 137 static const MemoryRegionOps timer_ops = {
 138     .read = timer_read,
 139     .write = timer_write,
 140     .endianness = DEVICE_NATIVE_ENDIAN,
 141     .valid = {
 142         .min_access_size = 4,
 143         .max_access_size = 4,
 144     },
 145 };
 146
 147 static void timer_hit(void *opaque)
 148 {
 149     LM32TimerState *s = opaque;
 150
 151     trace_lm32_timer_hit();
 152
 153     s->regs[R_SR] |= SR_TO;
 154
 155     if (s->regs[R_CR] & CR_CONT) {
 156         ptimer_set_count(s->ptimer, s->regs[R_PERIOD]);
 157         ptimer_run(s->ptimer, 1);
 158     }
 159     timer_update_irq(s);
 160 }
 161
 162 static void timer_reset(DeviceState *d)
 163 {
 164     LM32TimerState *s = container_of(d, LM32TimerState, busdev.qdev);
 165     int i;
 166
 167     for (i = 0; i < R_MAX; i++) {
 168         s->regs[i] = 0;
 169     }
 170     ptimer_stop(s->ptimer);
 171 }
 172
 173 static int lm32_timer_init(SysBusDevice *dev)
 174 {
 175     LM32TimerState *s = FROM_SYSBUS(typeof(*s), dev);
 176
 177     sysbus_init_irq(dev, &s->irq);
 178
 179     s->bh = qemu_bh_new(timer_hit, s);
 180     s->ptimer = ptimer_init(s->bh);
 181     ptimer_set_freq(s->ptimer, s->freq_hz);
 182
 183     memory_region_init_io(&s->iomem, &timer_ops, s, "timer", R_MAX * 4);
 184     sysbus_init_mmio(dev, &s->iomem);
 185
 186     return 0;
 187 }
 188
 189 static const VMStateDescription vmstate_lm32_timer = {
 190     .name = "lm32-timer",
 191     .version_id = 1,
 192     .minimum_version_id = 1,
 193     .minimum_version_id_old = 1,
 194     .fields      = (VMStateField[]) {
 195         VMSTATE_PTIMER(ptimer, LM32TimerState),
 196         VMSTATE_UINT32(freq_hz, LM32TimerState),
 197         VMSTATE_UINT32_ARRAY(regs, LM32TimerState, R_MAX),
 198         VMSTATE_END_OF_LIST()
 199     }
 200 };
 201
 202 static SysBusDeviceInfo lm32_timer_info = {
 203     .init = lm32_timer_init,
 204     .qdev.name  = "lm32-timer",
 205     .qdev.size  = sizeof(LM32TimerState),
 206     .qdev.vmsd  = &vmstate_lm32_timer,
 207     .qdev.reset = timer_reset,
 208     .qdev.props = (Property[]) {
 209         DEFINE_PROP_UINT32(
 210                 "frequency", LM32TimerState, freq_hz, DEFAULT_FREQUENCY
 211         ),
 212         DEFINE_PROP_END_OF_LIST(),
 213     }
 214 };
 215
 216 static void lm32_timer_register(void)
 217 {
 218     sysbus_register_withprop(&lm32_timer_info);
 219 }
 220
 221 device_init(lm32_timer_register)