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
   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 "hw/hw.h"
  16 #include "qemu/bitops.h"
  17 #include "qemu/timer.h"
  18 #include "hw/ptimer.h"
  19 #include "hw/sysbus.h"
  20 #include "hw/arm/imx.h"
  21 #include "qemu/main-loop.h"
  22
  23 #define TYPE_IMX_EPIT "imx.epit"
  24
  25 #define DEBUG_TIMER 0
  26 #if DEBUG_TIMER
  27
  28 static char const *imx_epit_reg_name(uint32_t reg)
  29 {
  30     switch (reg) {
  31     case 0:
  32         return "CR";
  33     case 1:
  34         return "SR";
  35     case 2:
  36         return "LR";
  37     case 3:
  38         return "CMP";
  39     case 4:
  40         return "CNT";
  41     default:
  42         return "[?]";
  43     }
  44 }
  45
  46 #  define DPRINTF(fmt, args...) \
  47     do { fprintf(stderr, "%s: " fmt , __func__, ##args); } while (0)
  48 #else
  49 #  define DPRINTF(fmt, args...) do {} while (0)
  50 #endif
  51
  52 /*
  53  * Define to 1 for messages about attempts to
  54  * access unimplemented registers or similar.
  55  */
  56 #define DEBUG_IMPLEMENTATION 1
  57 #if DEBUG_IMPLEMENTATION
  58 #  define IPRINTF(fmt, args...) \
  59           do { fprintf(stderr, "%s: " fmt, __func__, ##args); } while (0)
  60 #else
  61 #  define IPRINTF(fmt, args...) do {} while (0)
  62 #endif
  63
  64 #define IMX_EPIT(obj) \
  65         OBJECT_CHECK(IMXEPITState, (obj), TYPE_IMX_EPIT)
  66
  67 /*
  68  * EPIT: Enhanced periodic interrupt timer
  69  */
  70
  71 #define CR_EN       (1 << 0)
  72 #define CR_ENMOD    (1 << 1)
  73 #define CR_OCIEN    (1 << 2)
  74 #define CR_RLD      (1 << 3)
  75 #define CR_PRESCALE_SHIFT (4)
  76 #define CR_PRESCALE_MASK  (0xfff)
  77 #define CR_SWR      (1 << 16)
  78 #define CR_IOVW     (1 << 17)
  79 #define CR_DBGEN    (1 << 18)
  80 #define CR_WAITEN   (1 << 19)
  81 #define CR_DOZEN    (1 << 20)
  82 #define CR_STOPEN   (1 << 21)
  83 #define CR_CLKSRC_SHIFT (24)
  84 #define CR_CLKSRC_MASK  (0x3 << CR_CLKSRC_SHIFT)
  85
  86 #define TIMER_MAX  0XFFFFFFFFUL
  87
  88 /*
  89  * Exact clock frequencies vary from board to board.
  90  * These are typical.
  91  */
  92 static const IMXClk imx_epit_clocks[] =  {
  93     0,        /* 00 disabled */
  94     IPG,      /* 01 ipg_clk, ~532MHz */
  95     IPG,      /* 10 ipg_clk_highfreq */
  96     CLK_32k,  /* 11 ipg_clk_32k -- ~32kHz */
  97 };
  98
  99 typedef struct {
 100     SysBusDevice busdev;
 101     ptimer_state *timer_reload;
 102     ptimer_state *timer_cmp;
 103     MemoryRegion iomem;
 104     DeviceState *ccm;
 105
 106     uint32_t cr;
 107     uint32_t sr;
 108     uint32_t lr;
 109     uint32_t cmp;
 110     uint32_t cnt;
 111
 112     uint32_t freq;
 113     qemu_irq irq;
 114 } IMXEPITState;
 115
 116 /*
 117  * Update interrupt status
 118  */
 119 static void imx_epit_update_int(IMXEPITState *s)
 120 {
 121     if (s->sr && (s->cr & CR_OCIEN) && (s->cr & CR_EN)) {
 122         qemu_irq_raise(s->irq);
 123     } else {
 124         qemu_irq_lower(s->irq);
 125     }
 126 }
 127
 128 static void imx_epit_set_freq(IMXEPITState *s)
 129 {
 130     uint32_t clksrc;
 131     uint32_t prescaler;
 132     uint32_t freq;
 133
 134     clksrc = extract32(s->cr, CR_CLKSRC_SHIFT, 2);
 135     prescaler = 1 + extract32(s->cr, CR_PRESCALE_SHIFT, 12);
 136
 137     freq = imx_clock_frequency(s->ccm, imx_epit_clocks[clksrc]) / prescaler;
 138
 139     s->freq = freq;
 140
 141     DPRINTF("Setting ptimer frequency to %u\n", freq);
 142
 143     if (freq) {
 144         ptimer_set_freq(s->timer_reload, freq);
 145         ptimer_set_freq(s->timer_cmp, freq);
 146     }
 147 }
 148
 149 static void imx_epit_reset(DeviceState *dev)
 150 {
 151     IMXEPITState *s = IMX_EPIT(dev);
 152
 153     /*
 154      * Soft reset doesn't touch some bits; hard reset clears them
 155      */
 156     s->cr &= (CR_EN|CR_ENMOD|CR_STOPEN|CR_DOZEN|CR_WAITEN|CR_DBGEN);
 157     s->sr = 0;
 158     s->lr = TIMER_MAX;
 159     s->cmp = 0;
 160     s->cnt = 0;
 161     /* stop both timers */
 162     ptimer_stop(s->timer_cmp);
 163     ptimer_stop(s->timer_reload);
 164     /* compute new frequency */
 165     imx_epit_set_freq(s);
 166     /* init both timers to TIMER_MAX */
 167     ptimer_set_limit(s->timer_cmp, TIMER_MAX, 1);
 168     ptimer_set_limit(s->timer_reload, TIMER_MAX, 1);
 169     if (s->freq && (s->cr & CR_EN)) {
 170         /* if the timer is still enabled, restart it */
 171         ptimer_run(s->timer_reload, 0);
 172     }
 173 }
 174
 175 static uint32_t imx_epit_update_count(IMXEPITState *s)
 176 {
 177      s->cnt = ptimer_get_count(s->timer_reload);
 178
 179      return s->cnt;
 180 }
 181
 182 static uint64_t imx_epit_read(void *opaque, hwaddr offset, unsigned size)
 183 {
 184     IMXEPITState *s = IMX_EPIT(opaque);
 185     uint32_t reg_value = 0;
 186     uint32_t reg = offset >> 2;
 187
 188     switch (reg) {
 189     case 0: /* Control Register */
 190         reg_value = s->cr;
 191         break;
 192
 193     case 1: /* Status Register */
 194         reg_value = s->sr;
 195         break;
 196
 197     case 2: /* LR - ticks*/
 198         reg_value = s->lr;
 199         break;
 200
 201     case 3: /* CMP */
 202         reg_value = s->cmp;
 203         break;
 204
 205     case 4: /* CNT */
 206         imx_epit_update_count(s);
 207         reg_value = s->cnt;
 208         break;
 209
 210     default:
 211         IPRINTF("Bad offset %x\n", reg);
 212         break;
 213     }
 214
 215     DPRINTF("(%s) = 0x%08x\n", imx_epit_reg_name(reg), reg_value);
 216
 217     return reg_value;
 218 }
 219
 220 static void imx_epit_reload_compare_timer(IMXEPITState *s)
 221 {
 222     if ((s->cr & (CR_EN | CR_OCIEN)) == (CR_EN | CR_OCIEN))  {
 223         /* if the compare feature is on and timers are running */
 224         uint32_t tmp = imx_epit_update_count(s);
 225         uint64_t next;
 226         if (tmp > s->cmp) {
 227             /* It'll fire in this round of the timer */
 228             next = tmp - s->cmp;
 229         } else { /* catch it next time around */
 230             next = tmp - s->cmp + ((s->cr & CR_RLD) ? TIMER_MAX : s->lr);
 231         }
 232         ptimer_set_count(s->timer_cmp, next);
 233     }
 234 }
 235
 236 static void imx_epit_write(void *opaque, hwaddr offset, uint64_t value,
 237                            unsigned size)
 238 {
 239     IMXEPITState *s = IMX_EPIT(opaque);
 240     uint32_t reg = offset >> 2;
 241     uint64_t oldcr;
 242
 243     DPRINTF("(%s, value = 0x%08x)\n", imx_epit_reg_name(reg), (uint32_t)value);
 244
 245     switch (reg) {
 246     case 0: /* CR */
 247
 248         oldcr = s->cr;
 249         s->cr = value & 0x03ffffff;
 250         if (s->cr & CR_SWR) {
 251             /* handle the reset */
 252             imx_epit_reset(DEVICE(s));
 253         } else {
 254             imx_epit_set_freq(s);
 255         }
 256
 257         if (s->freq && (s->cr & CR_EN) && !(oldcr & CR_EN)) {
 258             if (s->cr & CR_ENMOD) {
 259                 if (s->cr & CR_RLD) {
 260                     ptimer_set_limit(s->timer_reload, s->lr, 1);
 261                     ptimer_set_limit(s->timer_cmp, s->lr, 1);
 262                 } else {
 263                     ptimer_set_limit(s->timer_reload, TIMER_MAX, 1);
 264                     ptimer_set_limit(s->timer_cmp, TIMER_MAX, 1);
 265                 }
 266             }
 267
 268             imx_epit_reload_compare_timer(s);
 269             ptimer_run(s->timer_reload, 0);
 270             if (s->cr & CR_OCIEN) {
 271                 ptimer_run(s->timer_cmp, 0);
 272             } else {
 273                 ptimer_stop(s->timer_cmp);
 274             }
 275         } else if (!(s->cr & CR_EN)) {
 276             /* stop both timers */
 277             ptimer_stop(s->timer_reload);
 278             ptimer_stop(s->timer_cmp);
 279         } else  if (s->cr & CR_OCIEN) {
 280             if (!(oldcr & CR_OCIEN)) {
 281                 imx_epit_reload_compare_timer(s);
 282                 ptimer_run(s->timer_cmp, 0);
 283             }
 284         } else {
 285             ptimer_stop(s->timer_cmp);
 286         }
 287         break;
 288
 289     case 1: /* SR - ACK*/
 290         /* writing 1 to OCIF clear the OCIF bit */
 291         if (value & 0x01) {
 292             s->sr = 0;
 293             imx_epit_update_int(s);
 294         }
 295         break;
 296
 297     case 2: /* LR - set ticks */
 298         s->lr = value;
 299
 300         if (s->cr & CR_RLD) {
 301             /* Also set the limit if the LRD bit is set */
 302             /* If IOVW bit is set then set the timer value */
 303             ptimer_set_limit(s->timer_reload, s->lr, s->cr & CR_IOVW);
 304             ptimer_set_limit(s->timer_cmp, s->lr, 0);
 305         } else if (s->cr & CR_IOVW) {
 306             /* If IOVW bit is set then set the timer value */
 307             ptimer_set_count(s->timer_reload, s->lr);
 308         }
 309
 310         imx_epit_reload_compare_timer(s);
 311         break;
 312
 313     case 3: /* CMP */
 314         s->cmp = value;
 315
 316         imx_epit_reload_compare_timer(s);
 317
 318         break;
 319
 320     default:
 321         IPRINTF("Bad offset %x\n", reg);
 322
 323         break;
 324     }
 325 }
 326 static void imx_epit_cmp(void *opaque)
 327 {
 328     IMXEPITState *s = IMX_EPIT(opaque);
 329
 330     DPRINTF("sr was %d\n", s->sr);
 331
 332     s->sr = 1;
 333     imx_epit_update_int(s);
 334 }
 335
 336 void imx_timerp_create(const hwaddr addr, qemu_irq irq, DeviceState *ccm)
 337 {
 338     IMXEPITState *pp;
 339     DeviceState *dev;
 340
 341     dev = sysbus_create_simple(TYPE_IMX_EPIT, addr, irq);
 342     pp = IMX_EPIT(dev);
 343     pp->ccm = ccm;
 344 }
 345
 346 static const MemoryRegionOps imx_epit_ops = {
 347   .read = imx_epit_read,
 348   .write = imx_epit_write,
 349   .endianness = DEVICE_NATIVE_ENDIAN,
 350 };
 351
 352 static const VMStateDescription vmstate_imx_timer_epit = {
 353     .name = "imx.epit",
 354     .version_id = 2,
 355     .minimum_version_id = 2,
 356     .minimum_version_id_old = 2,
 357     .fields      = (VMStateField[]) {
 358         VMSTATE_UINT32(cr, IMXEPITState),
 359         VMSTATE_UINT32(sr, IMXEPITState),
 360         VMSTATE_UINT32(lr, IMXEPITState),
 361         VMSTATE_UINT32(cmp, IMXEPITState),
 362         VMSTATE_UINT32(cnt, IMXEPITState),
 363         VMSTATE_UINT32(freq, IMXEPITState),
 364         VMSTATE_PTIMER(timer_reload, IMXEPITState),
 365         VMSTATE_PTIMER(timer_cmp, IMXEPITState),
 366         VMSTATE_END_OF_LIST()
 367     }
 368 };
 369
 370 static void imx_epit_realize(DeviceState *dev, Error **errp)
 371 {
 372     IMXEPITState *s = IMX_EPIT(dev);
 373     SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
 374     QEMUBH *bh;
 375
 376     DPRINTF("\n");
 377
 378     sysbus_init_irq(sbd, &s->irq);
 379     memory_region_init_io(&s->iomem, OBJECT(s), &imx_epit_ops, s, TYPE_IMX_EPIT,
 380                           0x00001000);
 381     sysbus_init_mmio(sbd, &s->iomem);
 382
 383     s->timer_reload = ptimer_init(NULL);
 384
 385     bh = qemu_bh_new(imx_epit_cmp, s);
 386     s->timer_cmp = ptimer_init(bh);
 387 }
 388
 389 static void imx_epit_class_init(ObjectClass *klass, void *data)
 390 {
 391     DeviceClass *dc  = DEVICE_CLASS(klass);
 392
 393     dc->realize = imx_epit_realize;
 394     dc->reset = imx_epit_reset;
 395     dc->vmsd = &vmstate_imx_timer_epit;
 396     dc->desc = "i.MX periodic timer";
 397 }
 398
 399 static const TypeInfo imx_epit_info = {
 400     .name = TYPE_IMX_EPIT,
 401     .parent = TYPE_SYS_BUS_DEVICE,
 402     .instance_size = sizeof(IMXEPITState),
 403     .class_init = imx_epit_class_init,
 404 };
 405
 406 static void imx_epit_register_types(void)
 407 {
 408     type_register_static(&imx_epit_info);
 409 }
 410
 411 type_init(imx_epit_register_types)