hw/arm_timer.c

   1 /*
   2  * ARM PrimeCell Timer modules.
   3  *
   4  * Copyright (c) 2005-2006 CodeSourcery.
   5  * Written by Paul Brook
   6  *
   7  * This code is licensed under the GPL.
   8  */
   9
  10 #include "sysbus.h"
  11 #include "qemu-timer.h"
  12
  13 /* Common timer implementation.  */
  14
  15 #define TIMER_CTRL_ONESHOT      (1 << 0)
  16 #define TIMER_CTRL_32BIT        (1 << 1)
  17 #define TIMER_CTRL_DIV1         (0 << 2)
  18 #define TIMER_CTRL_DIV16        (1 << 2)
  19 #define TIMER_CTRL_DIV256       (2 << 2)
  20 #define TIMER_CTRL_IE           (1 << 5)
  21 #define TIMER_CTRL_PERIODIC     (1 << 6)
  22 #define TIMER_CTRL_ENABLE       (1 << 7)
  23
  24 typedef struct {
  25     ptimer_state *timer;
  26     uint32_t control;
  27     uint32_t limit;
  28     int freq;
  29     int int_level;
  30     qemu_irq irq;
  31 } arm_timer_state;
  32
  33 /* Check all active timers, and schedule the next timer interrupt.  */
  34
  35 static void arm_timer_update(arm_timer_state *s)
  36 {
  37     /* Update interrupts.  */
  38     if (s->int_level && (s->control & TIMER_CTRL_IE)) {
  39         qemu_irq_raise(s->irq);
  40     } else {
  41         qemu_irq_lower(s->irq);
  42     }
  43 }
  44
  45 static uint32_t arm_timer_read(void *opaque, target_phys_addr_t offset)
  46 {
  47     arm_timer_state *s = (arm_timer_state *)opaque;
  48
  49     switch (offset >> 2) {
  50     case 0: /* TimerLoad */
  51     case 6: /* TimerBGLoad */
  52         return s->limit;
  53     case 1: /* TimerValue */
  54         return ptimer_get_count(s->timer);
  55     case 2: /* TimerControl */
  56         return s->control;
  57     case 4: /* TimerRIS */
  58         return s->int_level;
  59     case 5: /* TimerMIS */
  60         if ((s->control & TIMER_CTRL_IE) == 0)
  61             return 0;
  62         return s->int_level;
  63     default:
  64         hw_error("arm_timer_read: Bad offset %x\n", (int)offset);
  65         return 0;
  66     }
  67 }
  68
  69 /* Reset the timer limit after settings have changed.  */
  70 static void arm_timer_recalibrate(arm_timer_state *s, int reload)
  71 {
  72     uint32_t limit;
  73
  74     if ((s->control & (TIMER_CTRL_PERIODIC | TIMER_CTRL_ONESHOT)) == 0) {
  75         /* Free running.  */
  76         if (s->control & TIMER_CTRL_32BIT)
  77             limit = 0xffffffff;
  78         else
  79             limit = 0xffff;
  80     } else {
  81           /* Periodic.  */
  82           limit = s->limit;
  83     }
  84     ptimer_set_limit(s->timer, limit, reload);
  85 }
  86
  87 static void arm_timer_write(void *opaque, target_phys_addr_t offset,
  88                             uint32_t value)
  89 {
  90     arm_timer_state *s = (arm_timer_state *)opaque;
  91     int freq;
  92
  93     switch (offset >> 2) {
  94     case 0: /* TimerLoad */
  95         s->limit = value;
  96         arm_timer_recalibrate(s, 1);
  97         break;
  98     case 1: /* TimerValue */
  99         /* ??? Linux seems to want to write to this readonly register.
 100            Ignore it.  */
 101         break;
 102     case 2: /* TimerControl */
 103         if (s->control & TIMER_CTRL_ENABLE) {
 104             /* Pause the timer if it is running.  This may cause some
 105                inaccuracy dure to rounding, but avoids a whole lot of other
 106                messyness.  */
 107             ptimer_stop(s->timer);
 108         }
 109         s->control = value;
 110         freq = s->freq;
 111         /* ??? Need to recalculate expiry time after changing divisor.  */
 112         switch ((value >> 2) & 3) {
 113         case 1: freq >>= 4; break;
 114         case 2: freq >>= 8; break;
 115         }
 116         arm_timer_recalibrate(s, s->control & TIMER_CTRL_ENABLE);
 117         ptimer_set_freq(s->timer, freq);
 118         if (s->control & TIMER_CTRL_ENABLE) {
 119             /* Restart the timer if still enabled.  */
 120             ptimer_run(s->timer, (s->control & TIMER_CTRL_ONESHOT) != 0);
 121         }
 122         break;
 123     case 3: /* TimerIntClr */
 124         s->int_level = 0;
 125         break;
 126     case 6: /* TimerBGLoad */
 127         s->limit = value;
 128         arm_timer_recalibrate(s, 0);
 129         break;
 130     default:
 131         hw_error("arm_timer_write: Bad offset %x\n", (int)offset);
 132     }
 133     arm_timer_update(s);
 134 }
 135
 136 static void arm_timer_tick(void *opaque)
 137 {
 138     arm_timer_state *s = (arm_timer_state *)opaque;
 139     s->int_level = 1;
 140     arm_timer_update(s);
 141 }
 142
 143 static const VMStateDescription vmstate_arm_timer = {
 144     .name = "arm_timer",
 145     .version_id = 1,
 146     .minimum_version_id = 1,
 147     .minimum_version_id_old = 1,
 148     .fields      = (VMStateField[]) {
 149         VMSTATE_UINT32(control, arm_timer_state),
 150         VMSTATE_UINT32(limit, arm_timer_state),
 151         VMSTATE_INT32(int_level, arm_timer_state),
 152         VMSTATE_PTIMER(timer, arm_timer_state),
 153         VMSTATE_END_OF_LIST()
 154     }
 155 };
 156
 157 static arm_timer_state *arm_timer_init(uint32_t freq)
 158 {
 159     arm_timer_state *s;
 160     QEMUBH *bh;
 161
 162     s = (arm_timer_state *)g_malloc0(sizeof(arm_timer_state));
 163     s->freq = freq;
 164     s->control = TIMER_CTRL_IE;
 165
 166     bh = qemu_bh_new(arm_timer_tick, s);
 167     s->timer = ptimer_init(bh);
 168     vmstate_register(NULL, -1, &vmstate_arm_timer, s);
 169     return s;
 170 }
 171
 172 /* ARM PrimeCell SP804 dual timer module.
 173    Docs for this device don't seem to be publicly available.  This
 174    implementation is based on guesswork, the linux kernel sources and the
 175    Integrator/CP timer modules.  */
 176
 177 typedef struct {
 178     SysBusDevice busdev;
 179     MemoryRegion iomem;
 180     arm_timer_state *timer[2];
 181     int level[2];
 182     qemu_irq irq;
 183 } sp804_state;
 184
 185 /* Merge the IRQs from the two component devices.  */
 186 static void sp804_set_irq(void *opaque, int irq, int level)
 187 {
 188     sp804_state *s = (sp804_state *)opaque;
 189
 190     s->level[irq] = level;
 191     qemu_set_irq(s->irq, s->level[0] || s->level[1]);
 192 }
 193
 194 static uint64_t sp804_read(void *opaque, target_phys_addr_t offset,
 195                            unsigned size)
 196 {
 197     sp804_state *s = (sp804_state *)opaque;
 198
 199     /* ??? Don't know the PrimeCell ID for this device.  */
 200     if (offset < 0x20) {
 201         return arm_timer_read(s->timer[0], offset);
 202     } else {
 203         return arm_timer_read(s->timer[1], offset - 0x20);
 204     }
 205 }
 206
 207 static void sp804_write(void *opaque, target_phys_addr_t offset,
 208                         uint64_t value, unsigned size)
 209 {
 210     sp804_state *s = (sp804_state *)opaque;
 211
 212     if (offset < 0x20) {
 213         arm_timer_write(s->timer[0], offset, value);
 214     } else {
 215         arm_timer_write(s->timer[1], offset - 0x20, value);
 216     }
 217 }
 218
 219 static const MemoryRegionOps sp804_ops = {
 220     .read = sp804_read,
 221     .write = sp804_write,
 222     .endianness = DEVICE_NATIVE_ENDIAN,
 223 };
 224
 225 static const VMStateDescription vmstate_sp804 = {
 226     .name = "sp804",
 227     .version_id = 1,
 228     .minimum_version_id = 1,
 229     .minimum_version_id_old = 1,
 230     .fields      = (VMStateField[]) {
 231         VMSTATE_INT32_ARRAY(level, sp804_state, 2),
 232         VMSTATE_END_OF_LIST()
 233     }
 234 };
 235
 236 static int sp804_init(SysBusDevice *dev)
 237 {
 238     sp804_state *s = FROM_SYSBUS(sp804_state, dev);
 239     qemu_irq *qi;
 240
 241     qi = qemu_allocate_irqs(sp804_set_irq, s, 2);
 242     sysbus_init_irq(dev, &s->irq);
 243     /* ??? The timers are actually configurable between 32kHz and 1MHz, but
 244        we don't implement that.  */
 245     s->timer[0] = arm_timer_init(1000000);
 246     s->timer[1] = arm_timer_init(1000000);
 247     s->timer[0]->irq = qi[0];
 248     s->timer[1]->irq = qi[1];
 249     memory_region_init_io(&s->iomem, &sp804_ops, s, "sp804", 0x1000);
 250     sysbus_init_mmio_region(dev, &s->iomem);
 251     vmstate_register(&dev->qdev, -1, &vmstate_sp804, s);
 252     return 0;
 253 }
 254
 255
 256 /* Integrator/CP timer module.  */
 257
 258 typedef struct {
 259     SysBusDevice busdev;
 260     MemoryRegion iomem;
 261     arm_timer_state *timer[3];
 262 } icp_pit_state;
 263
 264 static uint64_t icp_pit_read(void *opaque, target_phys_addr_t offset,
 265                              unsigned size)
 266 {
 267     icp_pit_state *s = (icp_pit_state *)opaque;
 268     int n;
 269
 270     /* ??? Don't know the PrimeCell ID for this device.  */
 271     n = offset >> 8;
 272     if (n > 3) {
 273         hw_error("sp804_read: Bad timer %d\n", n);
 274     }
 275
 276     return arm_timer_read(s->timer[n], offset & 0xff);
 277 }
 278
 279 static void icp_pit_write(void *opaque, target_phys_addr_t offset,
 280                           uint64_t value, unsigned size)
 281 {
 282     icp_pit_state *s = (icp_pit_state *)opaque;
 283     int n;
 284
 285     n = offset >> 8;
 286     if (n > 3) {
 287         hw_error("sp804_write: Bad timer %d\n", n);
 288     }
 289
 290     arm_timer_write(s->timer[n], offset & 0xff, value);
 291 }
 292
 293 static const MemoryRegionOps icp_pit_ops = {
 294     .read = icp_pit_read,
 295     .write = icp_pit_write,
 296     .endianness = DEVICE_NATIVE_ENDIAN,
 297 };
 298
 299 static int icp_pit_init(SysBusDevice *dev)
 300 {
 301     icp_pit_state *s = FROM_SYSBUS(icp_pit_state, dev);
 302
 303     /* Timer 0 runs at the system clock speed (40MHz).  */
 304     s->timer[0] = arm_timer_init(40000000);
 305     /* The other two timers run at 1MHz.  */
 306     s->timer[1] = arm_timer_init(1000000);
 307     s->timer[2] = arm_timer_init(1000000);
 308
 309     sysbus_init_irq(dev, &s->timer[0]->irq);
 310     sysbus_init_irq(dev, &s->timer[1]->irq);
 311     sysbus_init_irq(dev, &s->timer[2]->irq);
 312
 313     memory_region_init_io(&s->iomem, &icp_pit_ops, s, "icp_pit", 0x1000);
 314     sysbus_init_mmio_region(dev, &s->iomem);
 315     /* This device has no state to save/restore.  The component timers will
 316        save themselves.  */
 317     return 0;
 318 }
 319
 320 static void arm_timer_register_devices(void)
 321 {
 322     sysbus_register_dev("integrator_pit", sizeof(icp_pit_state), icp_pit_init);
 323     sysbus_register_dev("sp804", sizeof(sp804_state), sp804_init);
 324 }
 325
 326 device_init(arm_timer_register_devices)