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 "qemu-error.h"
  29
  30 #define DEFAULT_FREQUENCY (50*1000000)
  31
  32 enum {
  33     R_SR = 0,
  34     R_CR,
  35     R_PERIOD,
  36     R_SNAPSHOT,
  37     R_MAX
  38 };
  39
  40 enum {
  41     SR_TO    = (1 << 0),
  42     SR_RUN   = (1 << 1),
  43 };
  44
  45 enum {
  46     CR_ITO   = (1 << 0),
  47     CR_CONT  = (1 << 1),
  48     CR_START = (1 << 2),
  49     CR_STOP  = (1 << 3),
  50 };
  51
  52 struct LM32TimerState {
  53     SysBusDevice busdev;
  54     MemoryRegion iomem;
  55
  56     QEMUBH *bh;
  57     ptimer_state *ptimer;
  58
  59     qemu_irq irq;
  60     uint32_t freq_hz;
  61
  62     uint32_t regs[R_MAX];
  63 };
  64 typedef struct LM32TimerState LM32TimerState;
  65
  66 static void timer_update_irq(LM32TimerState *s)
  67 {
  68     int state = (s->regs[R_SR] & SR_TO) && (s->regs[R_CR] & CR_ITO);
  69
  70     trace_lm32_timer_irq_state(state);
  71     qemu_set_irq(s->irq, state);
  72 }
  73
  74 static uint64_t timer_read(void *opaque, target_phys_addr_t addr, unsigned size)
  75 {
  76     LM32TimerState *s = opaque;
  77     uint32_t r = 0;
  78
  79     addr >>= 2;
  80     switch (addr) {
  81     case R_SR:
  82     case R_CR:
  83     case R_PERIOD:
  84         r = s->regs[addr];
  85         break;
  86     case R_SNAPSHOT:
  87         r = (uint32_t)ptimer_get_count(s->ptimer);
  88         break;
  89     default:
  90         error_report("lm32_timer: read access to unknown register 0x"
  91                 TARGET_FMT_plx, addr << 2);
  92         break;
  93     }
  94
  95     trace_lm32_timer_memory_read(addr << 2, r);
  96     return r;
  97 }
  98
  99 static void timer_write(void *opaque, target_phys_addr_t addr,
 100                         uint64_t value, unsigned size)
 101 {
 102     LM32TimerState *s = opaque;
 103
 104     trace_lm32_timer_memory_write(addr, value);
 105
 106     addr >>= 2;
 107     switch (addr) {
 108     case R_SR:
 109         s->regs[R_SR] &= ~SR_TO;
 110         break;
 111     case R_CR:
 112         s->regs[R_CR] = value;
 113         if (s->regs[R_CR] & CR_START) {
 114             ptimer_run(s->ptimer, 1);
 115         }
 116         if (s->regs[R_CR] & CR_STOP) {
 117             ptimer_stop(s->ptimer);
 118         }
 119         break;
 120     case R_PERIOD:
 121         s->regs[R_PERIOD] = value;
 122         ptimer_set_count(s->ptimer, value);
 123         break;
 124     case R_SNAPSHOT:
 125         error_report("lm32_timer: write access to read only register 0x"
 126                 TARGET_FMT_plx, addr << 2);
 127         break;
 128     default:
 129         error_report("lm32_timer: write access to unknown register 0x"
 130                 TARGET_FMT_plx, addr << 2);
 131         break;
 132     }
 133     timer_update_irq(s);
 134 }
 135
 136 static const MemoryRegionOps timer_ops = {
 137     .read = timer_read,
 138     .write = timer_write,
 139     .endianness = DEVICE_NATIVE_ENDIAN,
 140     .valid = {
 141         .min_access_size = 4,
 142         .max_access_size = 4,
 143     },
 144 };
 145
 146 static void timer_hit(void *opaque)
 147 {
 148     LM32TimerState *s = opaque;
 149
 150     trace_lm32_timer_hit();
 151
 152     s->regs[R_SR] |= SR_TO;
 153
 154     if (s->regs[R_CR] & CR_CONT) {
 155         ptimer_set_count(s->ptimer, s->regs[R_PERIOD]);
 156         ptimer_run(s->ptimer, 1);
 157     }
 158     timer_update_irq(s);
 159 }
 160
 161 static void timer_reset(DeviceState *d)
 162 {
 163     LM32TimerState *s = container_of(d, LM32TimerState, busdev.qdev);
 164     int i;
 165
 166     for (i = 0; i < R_MAX; i++) {
 167         s->regs[i] = 0;
 168     }
 169     ptimer_stop(s->ptimer);
 170 }
 171
 172 static int lm32_timer_init(SysBusDevice *dev)
 173 {
 174     LM32TimerState *s = FROM_SYSBUS(typeof(*s), dev);
 175
 176     sysbus_init_irq(dev, &s->irq);
 177
 178     s->bh = qemu_bh_new(timer_hit, s);
 179     s->ptimer = ptimer_init(s->bh);
 180     ptimer_set_freq(s->ptimer, s->freq_hz);
 181
 182     memory_region_init_io(&s->iomem, &timer_ops, s, "timer", R_MAX * 4);
 183     sysbus_init_mmio(dev, &s->iomem);
 184
 185     return 0;
 186 }
 187
 188 static const VMStateDescription vmstate_lm32_timer = {
 189     .name = "lm32-timer",
 190     .version_id = 1,
 191     .minimum_version_id = 1,
 192     .minimum_version_id_old = 1,
 193     .fields      = (VMStateField[]) {
 194         VMSTATE_PTIMER(ptimer, LM32TimerState),
 195         VMSTATE_UINT32(freq_hz, LM32TimerState),
 196         VMSTATE_UINT32_ARRAY(regs, LM32TimerState, R_MAX),
 197         VMSTATE_END_OF_LIST()
 198     }
 199 };
 200
 201 static SysBusDeviceInfo lm32_timer_info = {
 202     .init = lm32_timer_init,
 203     .qdev.name  = "lm32-timer",
 204     .qdev.size  = sizeof(LM32TimerState),
 205     .qdev.vmsd  = &vmstate_lm32_timer,
 206     .qdev.reset = timer_reset,
 207     .qdev.props = (Property[]) {
 208         DEFINE_PROP_UINT32(
 209                 "frequency", LM32TimerState, freq_hz, DEFAULT_FREQUENCY
 210         ),
 211         DEFINE_PROP_END_OF_LIST(),
 212     }
 213 };
 214
 215 static void lm32_timer_register(void)
 216 {
 217     sysbus_register_withprop(&lm32_timer_info);
 218 }
 219
 220 device_init(lm32_timer_register)