hw/timer/imx_epit.c

   1 /*
   2  * IMX EPIT Timer
   3  *
   4  * Copyright (c) 2008 OK Labs
   5  * Copyright (c) 2011 NICTA Pty Ltd
   6  * Originally written by Hans Jiang
   7  * Updated by Peter Chubb
   8  * Updated by Jean-Christophe Dubois <jcd@tribudubois.net>
   9  *
  10  * This code is licensed under GPL version 2 or later.  See
  11  * the COPYING file in the top-level directory.
  12  *
  13  */
  14
  15 #include "qemu/osdep.h"
  16 #include "hw/timer/imx_epit.h"
  17 #include "migration/vmstate.h"
  18 #include "hw/irq.h"
  19 #include "hw/misc/imx_ccm.h"
  20 #include "qemu/module.h"
  21 #include "qemu/log.h"
  22
  23 #ifndef DEBUG_IMX_EPIT
  24 #define DEBUG_IMX_EPIT 0
  25 #endif
  26
  27 #define DPRINTF(fmt, args...) \
  28     do { \
  29         if (DEBUG_IMX_EPIT) { \
  30             fprintf(stderr, "[%s]%s: " fmt , TYPE_IMX_EPIT, \
  31                                              __func__, ##args); \
  32         } \
  33     } while (0)
  34
  35 static const char *imx_epit_reg_name(uint32_t reg)
  36 {
  37     switch (reg) {
  38     case 0:
  39         return "CR";
  40     case 1:
  41         return "SR";
  42     case 2:
  43         return "LR";
  44     case 3:
  45         return "CMP";
  46     case 4:
  47         return "CNT";
  48     default:
  49         return "[?]";
  50     }
  51 }
  52
  53 /*
  54  * Exact clock frequencies vary from board to board.
  55  * These are typical.
  56  */
  57 static const IMXClk imx_epit_clocks[] =  {
  58     CLK_NONE,      /* 00 disabled */
  59     CLK_IPG,       /* 01 ipg_clk, ~532MHz */
  60     CLK_IPG_HIGH,  /* 10 ipg_clk_highfreq */
  61     CLK_32k,       /* 11 ipg_clk_32k -- ~32kHz */
  62 };
  63
  64 /*
  65  * Update interrupt status
  66  */
  67 static void imx_epit_update_int(IMXEPITState *s)
  68 {
  69     if (s->sr && (s->cr & CR_OCIEN) && (s->cr & CR_EN)) {
  70         qemu_irq_raise(s->irq);
  71     } else {
  72         qemu_irq_lower(s->irq);
  73     }
  74 }
  75
  76 /*
  77  * Must be called from within a ptimer_transaction_begin/commit block
  78  * for both s->timer_cmp and s->timer_reload.
  79  */
  80 static void imx_epit_set_freq(IMXEPITState *s)
  81 {
  82     uint32_t clksrc;
  83     uint32_t prescaler;
  84
  85     clksrc = extract32(s->cr, CR_CLKSRC_SHIFT, 2);
  86     prescaler = 1 + extract32(s->cr, CR_PRESCALE_SHIFT, 12);
  87
  88     s->freq = imx_ccm_get_clock_frequency(s->ccm,
  89                                 imx_epit_clocks[clksrc]) / prescaler;
  90
  91     DPRINTF("Setting ptimer frequency to %u\n", s->freq);
  92
  93     if (s->freq) {
  94         ptimer_set_freq(s->timer_reload, s->freq);
  95         ptimer_set_freq(s->timer_cmp, s->freq);
  96     }
  97 }
  98
  99 static void imx_epit_reset(DeviceState *dev)
 100 {
 101     IMXEPITState *s = IMX_EPIT(dev);
 102
 103     /*
 104      * Soft reset doesn't touch some bits; hard reset clears them
 105      */
 106     s->cr &= (CR_EN|CR_ENMOD|CR_STOPEN|CR_DOZEN|CR_WAITEN|CR_DBGEN);
 107     s->sr = 0;
 108     s->lr = EPIT_TIMER_MAX;
 109     s->cmp = 0;
 110     s->cnt = 0;
 111     ptimer_transaction_begin(s->timer_cmp);
 112     ptimer_transaction_begin(s->timer_reload);
 113     /* stop both timers */
 114     ptimer_stop(s->timer_cmp);
 115     ptimer_stop(s->timer_reload);
 116     /* compute new frequency */
 117     imx_epit_set_freq(s);
 118     /* init both timers to EPIT_TIMER_MAX */
 119     ptimer_set_limit(s->timer_cmp, EPIT_TIMER_MAX, 1);
 120     ptimer_set_limit(s->timer_reload, EPIT_TIMER_MAX, 1);
 121     if (s->freq && (s->cr & CR_EN)) {
 122         /* if the timer is still enabled, restart it */
 123         ptimer_run(s->timer_reload, 0);
 124     }
 125     ptimer_transaction_commit(s->timer_cmp);
 126     ptimer_transaction_commit(s->timer_reload);
 127 }
 128
 129 static uint32_t imx_epit_update_count(IMXEPITState *s)
 130 {
 131     s->cnt = ptimer_get_count(s->timer_reload);
 132
 133     return s->cnt;
 134 }
 135
 136 static uint64_t imx_epit_read(void *opaque, hwaddr offset, unsigned size)
 137 {
 138     IMXEPITState *s = IMX_EPIT(opaque);
 139     uint32_t reg_value = 0;
 140
 141     switch (offset >> 2) {
 142     case 0: /* Control Register */
 143         reg_value = s->cr;
 144         break;
 145
 146     case 1: /* Status Register */
 147         reg_value = s->sr;
 148         break;
 149
 150     case 2: /* LR - ticks*/
 151         reg_value = s->lr;
 152         break;
 153
 154     case 3: /* CMP */
 155         reg_value = s->cmp;
 156         break;
 157
 158     case 4: /* CNT */
 159         imx_epit_update_count(s);
 160         reg_value = s->cnt;
 161         break;
 162
 163     default:
 164         qemu_log_mask(LOG_GUEST_ERROR, "[%s]%s: Bad register at offset 0x%"
 165                       HWADDR_PRIx "\n", TYPE_IMX_EPIT, __func__, offset);
 166         break;
 167     }
 168
 169     DPRINTF("(%s) = 0x%08x\n", imx_epit_reg_name(offset >> 2), reg_value);
 170
 171     return reg_value;
 172 }
 173
 174 /* Must be called from ptimer_transaction_begin/commit block for s->timer_cmp */
 175 static void imx_epit_reload_compare_timer(IMXEPITState *s)
 176 {
 177     if ((s->cr & (CR_EN | CR_OCIEN)) == (CR_EN | CR_OCIEN))  {
 178         /* if the compare feature is on and timers are running */
 179         uint32_t tmp = imx_epit_update_count(s);
 180         uint64_t next;
 181         if (tmp > s->cmp) {
 182             /* It'll fire in this round of the timer */
 183             next = tmp - s->cmp;
 184         } else { /* catch it next time around */
 185             next = tmp - s->cmp + ((s->cr & CR_RLD) ? EPIT_TIMER_MAX : s->lr);
 186         }
 187         ptimer_set_count(s->timer_cmp, next);
 188     }
 189 }
 190
 191 static void imx_epit_write(void *opaque, hwaddr offset, uint64_t value,
 192                            unsigned size)
 193 {
 194     IMXEPITState *s = IMX_EPIT(opaque);
 195     uint64_t oldcr;
 196
 197     DPRINTF("(%s, value = 0x%08x)\n", imx_epit_reg_name(offset >> 2),
 198             (uint32_t)value);
 199
 200     switch (offset >> 2) {
 201     case 0: /* CR */
 202
 203         oldcr = s->cr;
 204         s->cr = value & 0x03ffffff;
 205         if (s->cr & CR_SWR) {
 206             /* handle the reset */
 207             imx_epit_reset(DEVICE(s));
 208             /*
 209              * TODO: could we 'break' here? following operations appear
 210              * to duplicate the work imx_epit_reset() already did.
 211              */
 212         }
 213
 214         ptimer_transaction_begin(s->timer_cmp);
 215         ptimer_transaction_begin(s->timer_reload);
 216
 217         if (!(s->cr & CR_SWR)) {
 218             imx_epit_set_freq(s);
 219         }
 220
 221         if (s->freq && (s->cr & CR_EN) && !(oldcr & CR_EN)) {
 222             if (s->cr & CR_ENMOD) {
 223                 if (s->cr & CR_RLD) {
 224                     ptimer_set_limit(s->timer_reload, s->lr, 1);
 225                     ptimer_set_limit(s->timer_cmp, s->lr, 1);
 226                 } else {
 227                     ptimer_set_limit(s->timer_reload, EPIT_TIMER_MAX, 1);
 228                     ptimer_set_limit(s->timer_cmp, EPIT_TIMER_MAX, 1);
 229                 }
 230             }
 231
 232             imx_epit_reload_compare_timer(s);
 233             ptimer_run(s->timer_reload, 0);
 234             if (s->cr & CR_OCIEN) {
 235                 ptimer_run(s->timer_cmp, 0);
 236             } else {
 237                 ptimer_stop(s->timer_cmp);
 238             }
 239         } else if (!(s->cr & CR_EN)) {
 240             /* stop both timers */
 241             ptimer_stop(s->timer_reload);
 242             ptimer_stop(s->timer_cmp);
 243         } else  if (s->cr & CR_OCIEN) {
 244             if (!(oldcr & CR_OCIEN)) {
 245                 imx_epit_reload_compare_timer(s);
 246                 ptimer_run(s->timer_cmp, 0);
 247             }
 248         } else {
 249             ptimer_stop(s->timer_cmp);
 250         }
 251
 252         ptimer_transaction_commit(s->timer_cmp);
 253         ptimer_transaction_commit(s->timer_reload);
 254         break;
 255
 256     case 1: /* SR - ACK*/
 257         /* writing 1 to OCIF clear the OCIF bit */
 258         if (value & 0x01) {
 259             s->sr = 0;
 260             imx_epit_update_int(s);
 261         }
 262         break;
 263
 264     case 2: /* LR - set ticks */
 265         s->lr = value;
 266
 267         ptimer_transaction_begin(s->timer_cmp);
 268         ptimer_transaction_begin(s->timer_reload);
 269         if (s->cr & CR_RLD) {
 270             /* Also set the limit if the LRD bit is set */
 271             /* If IOVW bit is set then set the timer value */
 272             ptimer_set_limit(s->timer_reload, s->lr, s->cr & CR_IOVW);
 273             ptimer_set_limit(s->timer_cmp, s->lr, 0);
 274         } else if (s->cr & CR_IOVW) {
 275             /* If IOVW bit is set then set the timer value */
 276             ptimer_set_count(s->timer_reload, s->lr);
 277         }
 278         /*
 279          * Commit the change to s->timer_reload, so it can propagate. Otherwise
 280          * the timer interrupt may not fire properly. The commit must happen
 281          * before calling imx_epit_reload_compare_timer(), which reads
 282          * s->timer_reload internally again.
 283          */
 284         ptimer_transaction_commit(s->timer_reload);
 285         imx_epit_reload_compare_timer(s);
 286         ptimer_transaction_commit(s->timer_cmp);
 287         break;
 288
 289     case 3: /* CMP */
 290         s->cmp = value;
 291
 292         ptimer_transaction_begin(s->timer_cmp);
 293         imx_epit_reload_compare_timer(s);
 294         ptimer_transaction_commit(s->timer_cmp);
 295
 296         break;
 297
 298     default:
 299         qemu_log_mask(LOG_GUEST_ERROR, "[%s]%s: Bad register at offset 0x%"
 300                       HWADDR_PRIx "\n", TYPE_IMX_EPIT, __func__, offset);
 301
 302         break;
 303     }
 304 }
 305 static void imx_epit_cmp(void *opaque)
 306 {
 307     IMXEPITState *s = IMX_EPIT(opaque);
 308
 309     DPRINTF("sr was %d\n", s->sr);
 310
 311     s->sr = 1;
 312     imx_epit_update_int(s);
 313 }
 314
 315 static void imx_epit_reload(void *opaque)
 316 {
 317     /* No action required on rollover of timer_reload */
 318 }
 319
 320 static const MemoryRegionOps imx_epit_ops = {
 321     .read = imx_epit_read,
 322     .write = imx_epit_write,
 323     .endianness = DEVICE_NATIVE_ENDIAN,
 324 };
 325
 326 static const VMStateDescription vmstate_imx_timer_epit = {
 327     .name = TYPE_IMX_EPIT,
 328     .version_id = 2,
 329     .minimum_version_id = 2,
 330     .fields = (VMStateField[]) {
 331         VMSTATE_UINT32(cr, IMXEPITState),
 332         VMSTATE_UINT32(sr, IMXEPITState),
 333         VMSTATE_UINT32(lr, IMXEPITState),
 334         VMSTATE_UINT32(cmp, IMXEPITState),
 335         VMSTATE_UINT32(cnt, IMXEPITState),
 336         VMSTATE_UINT32(freq, IMXEPITState),
 337         VMSTATE_PTIMER(timer_reload, IMXEPITState),
 338         VMSTATE_PTIMER(timer_cmp, IMXEPITState),
 339         VMSTATE_END_OF_LIST()
 340     }
 341 };
 342
 343 static void imx_epit_realize(DeviceState *dev, Error **errp)
 344 {
 345     IMXEPITState *s = IMX_EPIT(dev);
 346     SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
 347
 348     DPRINTF("\n");
 349
 350     sysbus_init_irq(sbd, &s->irq);
 351     memory_region_init_io(&s->iomem, OBJECT(s), &imx_epit_ops, s, TYPE_IMX_EPIT,
 352                           0x00001000);
 353     sysbus_init_mmio(sbd, &s->iomem);
 354
 355     s->timer_reload = ptimer_init(imx_epit_reload, s, PTIMER_POLICY_LEGACY);
 356
 357     s->timer_cmp = ptimer_init(imx_epit_cmp, s, PTIMER_POLICY_LEGACY);
 358 }
 359
 360 static void imx_epit_class_init(ObjectClass *klass, void *data)
 361 {
 362     DeviceClass *dc  = DEVICE_CLASS(klass);
 363
 364     dc->realize = imx_epit_realize;
 365     dc->reset = imx_epit_reset;
 366     dc->vmsd = &vmstate_imx_timer_epit;
 367     dc->desc = "i.MX periodic timer";
 368 }
 369
 370 static const TypeInfo imx_epit_info = {
 371     .name = TYPE_IMX_EPIT,
 372     .parent = TYPE_SYS_BUS_DEVICE,
 373     .instance_size = sizeof(IMXEPITState),
 374     .class_init = imx_epit_class_init,
 375 };
 376
 377 static void imx_epit_register_types(void)
 378 {
 379     type_register_static(&imx_epit_info);
 380 }
 381
 382 type_init(imx_epit_register_types)