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