1 /* 2 * QEMU lowRISC Ibex UART device 3 * 4 * Copyright (c) 2020 Western Digital 5 * 6 * For details check the documentation here: 7 * https://docs.opentitan.org/hw/ip/uart/doc/ 8 * 9 * Permission is hereby granted, free of charge, to any person obtaining a copy 10 * of this software and associated documentation files (the "Software"), to deal 11 * in the Software without restriction, including without limitation the rights 12 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 13 * copies of the Software, and to permit persons to whom the Software is 14 * furnished to do so, subject to the following conditions: 15 * 16 * The above copyright notice and this permission notice shall be included in 17 * all copies or substantial portions of the Software. 18 * 19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 20 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 21 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 22 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 23 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 24 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 25 * THE SOFTWARE. 26 */ 27 28 #include "qemu/osdep.h" 29 #include "hw/char/ibex_uart.h" 30 #include "hw/irq.h" 31 #include "hw/qdev-clock.h" 32 #include "hw/qdev-properties.h" 33 #include "hw/qdev-properties-system.h" 34 #include "migration/vmstate.h" 35 #include "qemu/log.h" 36 #include "qemu/module.h" 37 38 static void ibex_uart_update_irqs(IbexUartState *s) 39 { 40 if (s->uart_intr_state & s->uart_intr_enable & R_INTR_STATE_TX_WATERMARK_MASK) { 41 qemu_set_irq(s->tx_watermark, 1); 42 } else { 43 qemu_set_irq(s->tx_watermark, 0); 44 } 45 46 if (s->uart_intr_state & s->uart_intr_enable & R_INTR_STATE_RX_WATERMARK_MASK) { 47 qemu_set_irq(s->rx_watermark, 1); 48 } else { 49 qemu_set_irq(s->rx_watermark, 0); 50 } 51 52 if (s->uart_intr_state & s->uart_intr_enable & R_INTR_STATE_TX_EMPTY_MASK) { 53 qemu_set_irq(s->tx_empty, 1); 54 } else { 55 qemu_set_irq(s->tx_empty, 0); 56 } 57 58 if (s->uart_intr_state & s->uart_intr_enable & R_INTR_STATE_RX_OVERFLOW_MASK) { 59 qemu_set_irq(s->rx_overflow, 1); 60 } else { 61 qemu_set_irq(s->rx_overflow, 0); 62 } 63 } 64 65 static int ibex_uart_can_receive(void *opaque) 66 { 67 IbexUartState *s = opaque; 68 69 if (s->uart_ctrl & R_CTRL_RX_ENABLE_MASK) { 70 return 1; 71 } 72 73 return 0; 74 } 75 76 static void ibex_uart_receive(void *opaque, const uint8_t *buf, int size) 77 { 78 IbexUartState *s = opaque; 79 uint8_t rx_fifo_level = (s->uart_fifo_ctrl & R_FIFO_CTRL_RXILVL_MASK) 80 >> R_FIFO_CTRL_RXILVL_SHIFT; 81 82 s->uart_rdata = *buf; 83 84 s->uart_status &= ~R_STATUS_RXIDLE_MASK; 85 s->uart_status &= ~R_STATUS_RXEMPTY_MASK; 86 87 if (size > rx_fifo_level) { 88 s->uart_intr_state |= R_INTR_STATE_RX_WATERMARK_MASK; 89 } 90 91 ibex_uart_update_irqs(s); 92 } 93 94 static gboolean ibex_uart_xmit(GIOChannel *chan, GIOCondition cond, 95 void *opaque) 96 { 97 IbexUartState *s = opaque; 98 uint8_t tx_fifo_level = (s->uart_fifo_ctrl & R_FIFO_CTRL_TXILVL_MASK) 99 >> R_FIFO_CTRL_TXILVL_SHIFT; 100 int ret; 101 102 /* instant drain the fifo when there's no back-end */ 103 if (!qemu_chr_fe_backend_connected(&s->chr)) { 104 s->tx_level = 0; 105 return FALSE; 106 } 107 108 if (!s->tx_level) { 109 s->uart_status &= ~R_STATUS_TXFULL_MASK; 110 s->uart_status |= R_STATUS_TXEMPTY_MASK; 111 s->uart_intr_state |= R_INTR_STATE_TX_EMPTY_MASK; 112 s->uart_intr_state &= ~R_INTR_STATE_TX_WATERMARK_MASK; 113 ibex_uart_update_irqs(s); 114 return FALSE; 115 } 116 117 ret = qemu_chr_fe_write(&s->chr, s->tx_fifo, s->tx_level); 118 119 if (ret >= 0) { 120 s->tx_level -= ret; 121 memmove(s->tx_fifo, s->tx_fifo + ret, s->tx_level); 122 } 123 124 if (s->tx_level) { 125 guint r = qemu_chr_fe_add_watch(&s->chr, G_IO_OUT | G_IO_HUP, 126 ibex_uart_xmit, s); 127 if (!r) { 128 s->tx_level = 0; 129 return FALSE; 130 } 131 } 132 133 /* Clear the TX Full bit */ 134 if (s->tx_level != IBEX_UART_TX_FIFO_SIZE) { 135 s->uart_status &= ~R_STATUS_TXFULL_MASK; 136 } 137 138 /* Disable the TX_WATERMARK IRQ */ 139 if (s->tx_level < tx_fifo_level) { 140 s->uart_intr_state &= ~R_INTR_STATE_TX_WATERMARK_MASK; 141 } 142 143 /* Set TX empty */ 144 if (s->tx_level == 0) { 145 s->uart_status |= R_STATUS_TXEMPTY_MASK; 146 s->uart_intr_state |= R_INTR_STATE_TX_EMPTY_MASK; 147 } 148 149 ibex_uart_update_irqs(s); 150 return FALSE; 151 } 152 153 static void uart_write_tx_fifo(IbexUartState *s, const uint8_t *buf, 154 int size) 155 { 156 uint64_t current_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); 157 uint8_t tx_fifo_level = (s->uart_fifo_ctrl & R_FIFO_CTRL_TXILVL_MASK) 158 >> R_FIFO_CTRL_TXILVL_SHIFT; 159 160 if (size > IBEX_UART_TX_FIFO_SIZE - s->tx_level) { 161 size = IBEX_UART_TX_FIFO_SIZE - s->tx_level; 162 qemu_log_mask(LOG_GUEST_ERROR, "ibex_uart: TX FIFO overflow"); 163 } 164 165 memcpy(s->tx_fifo + s->tx_level, buf, size); 166 s->tx_level += size; 167 168 if (s->tx_level > 0) { 169 s->uart_status &= ~R_STATUS_TXEMPTY_MASK; 170 } 171 172 if (s->tx_level >= tx_fifo_level) { 173 s->uart_intr_state |= R_INTR_STATE_TX_WATERMARK_MASK; 174 ibex_uart_update_irqs(s); 175 } 176 177 if (s->tx_level == IBEX_UART_TX_FIFO_SIZE) { 178 s->uart_status |= R_STATUS_TXFULL_MASK; 179 } 180 181 timer_mod(s->fifo_trigger_handle, current_time + 182 (s->char_tx_time * 4)); 183 } 184 185 static void ibex_uart_reset(DeviceState *dev) 186 { 187 IbexUartState *s = IBEX_UART(dev); 188 189 s->uart_intr_state = 0x00000000; 190 s->uart_intr_state = 0x00000000; 191 s->uart_intr_enable = 0x00000000; 192 s->uart_ctrl = 0x00000000; 193 s->uart_status = 0x0000003c; 194 s->uart_rdata = 0x00000000; 195 s->uart_fifo_ctrl = 0x00000000; 196 s->uart_fifo_status = 0x00000000; 197 s->uart_ovrd = 0x00000000; 198 s->uart_val = 0x00000000; 199 s->uart_timeout_ctrl = 0x00000000; 200 201 s->tx_level = 0; 202 203 s->char_tx_time = (NANOSECONDS_PER_SECOND / 230400) * 10; 204 205 ibex_uart_update_irqs(s); 206 } 207 208 static uint64_t ibex_uart_get_baud(IbexUartState *s) 209 { 210 uint64_t baud; 211 212 baud = ((s->uart_ctrl & R_CTRL_NCO_MASK) >> 16); 213 baud *= clock_get_hz(s->f_clk); 214 baud >>= 20; 215 216 return baud; 217 } 218 219 static uint64_t ibex_uart_read(void *opaque, hwaddr addr, 220 unsigned int size) 221 { 222 IbexUartState *s = opaque; 223 uint64_t retvalue = 0; 224 225 switch (addr >> 2) { 226 case R_INTR_STATE: 227 retvalue = s->uart_intr_state; 228 break; 229 case R_INTR_ENABLE: 230 retvalue = s->uart_intr_enable; 231 break; 232 case R_INTR_TEST: 233 qemu_log_mask(LOG_GUEST_ERROR, 234 "%s: wdata is write only\n", __func__); 235 break; 236 237 case R_CTRL: 238 retvalue = s->uart_ctrl; 239 break; 240 case R_STATUS: 241 retvalue = s->uart_status; 242 break; 243 244 case R_RDATA: 245 retvalue = s->uart_rdata; 246 if (s->uart_ctrl & R_CTRL_RX_ENABLE_MASK) { 247 qemu_chr_fe_accept_input(&s->chr); 248 249 s->uart_status |= R_STATUS_RXIDLE_MASK; 250 s->uart_status |= R_STATUS_RXEMPTY_MASK; 251 } 252 break; 253 case R_WDATA: 254 qemu_log_mask(LOG_GUEST_ERROR, 255 "%s: wdata is write only\n", __func__); 256 break; 257 258 case R_FIFO_CTRL: 259 retvalue = s->uart_fifo_ctrl; 260 break; 261 case R_FIFO_STATUS: 262 retvalue = s->uart_fifo_status; 263 264 retvalue |= s->tx_level & 0x1F; 265 266 qemu_log_mask(LOG_UNIMP, 267 "%s: RX fifos are not supported\n", __func__); 268 break; 269 270 case R_OVRD: 271 retvalue = s->uart_ovrd; 272 qemu_log_mask(LOG_UNIMP, 273 "%s: ovrd is not supported\n", __func__); 274 break; 275 case R_VAL: 276 retvalue = s->uart_val; 277 qemu_log_mask(LOG_UNIMP, 278 "%s: val is not supported\n", __func__); 279 break; 280 case R_TIMEOUT_CTRL: 281 retvalue = s->uart_timeout_ctrl; 282 qemu_log_mask(LOG_UNIMP, 283 "%s: timeout_ctrl is not supported\n", __func__); 284 break; 285 default: 286 qemu_log_mask(LOG_GUEST_ERROR, 287 "%s: Bad offset 0x%"HWADDR_PRIx"\n", __func__, addr); 288 return 0; 289 } 290 291 return retvalue; 292 } 293 294 static void ibex_uart_write(void *opaque, hwaddr addr, 295 uint64_t val64, unsigned int size) 296 { 297 IbexUartState *s = opaque; 298 uint32_t value = val64; 299 300 switch (addr >> 2) { 301 case R_INTR_STATE: 302 /* Write 1 clear */ 303 s->uart_intr_state &= ~value; 304 ibex_uart_update_irqs(s); 305 break; 306 case R_INTR_ENABLE: 307 s->uart_intr_enable = value; 308 ibex_uart_update_irqs(s); 309 break; 310 case R_INTR_TEST: 311 s->uart_intr_state |= value; 312 ibex_uart_update_irqs(s); 313 break; 314 315 case R_CTRL: 316 s->uart_ctrl = value; 317 318 if (value & R_CTRL_NF_MASK) { 319 qemu_log_mask(LOG_UNIMP, 320 "%s: UART_CTRL_NF is not supported\n", __func__); 321 } 322 if (value & R_CTRL_SLPBK_MASK) { 323 qemu_log_mask(LOG_UNIMP, 324 "%s: UART_CTRL_SLPBK is not supported\n", __func__); 325 } 326 if (value & R_CTRL_LLPBK_MASK) { 327 qemu_log_mask(LOG_UNIMP, 328 "%s: UART_CTRL_LLPBK is not supported\n", __func__); 329 } 330 if (value & R_CTRL_PARITY_EN_MASK) { 331 qemu_log_mask(LOG_UNIMP, 332 "%s: UART_CTRL_PARITY_EN is not supported\n", 333 __func__); 334 } 335 if (value & R_CTRL_PARITY_ODD_MASK) { 336 qemu_log_mask(LOG_UNIMP, 337 "%s: UART_CTRL_PARITY_ODD is not supported\n", 338 __func__); 339 } 340 if (value & R_CTRL_RXBLVL_MASK) { 341 qemu_log_mask(LOG_UNIMP, 342 "%s: UART_CTRL_RXBLVL is not supported\n", __func__); 343 } 344 if (value & R_CTRL_NCO_MASK) { 345 uint64_t baud = ibex_uart_get_baud(s); 346 347 s->char_tx_time = (NANOSECONDS_PER_SECOND / baud) * 10; 348 } 349 break; 350 case R_STATUS: 351 qemu_log_mask(LOG_GUEST_ERROR, 352 "%s: status is read only\n", __func__); 353 break; 354 355 case R_RDATA: 356 qemu_log_mask(LOG_GUEST_ERROR, 357 "%s: rdata is read only\n", __func__); 358 break; 359 case R_WDATA: 360 uart_write_tx_fifo(s, (uint8_t *) &value, 1); 361 break; 362 363 case R_FIFO_CTRL: 364 s->uart_fifo_ctrl = value; 365 366 if (value & R_FIFO_CTRL_RXRST_MASK) { 367 qemu_log_mask(LOG_UNIMP, 368 "%s: RX fifos are not supported\n", __func__); 369 } 370 if (value & R_FIFO_CTRL_TXRST_MASK) { 371 s->tx_level = 0; 372 } 373 break; 374 case R_FIFO_STATUS: 375 qemu_log_mask(LOG_GUEST_ERROR, 376 "%s: fifo_status is read only\n", __func__); 377 break; 378 379 case R_OVRD: 380 s->uart_ovrd = value; 381 qemu_log_mask(LOG_UNIMP, 382 "%s: ovrd is not supported\n", __func__); 383 break; 384 case R_VAL: 385 qemu_log_mask(LOG_GUEST_ERROR, 386 "%s: val is read only\n", __func__); 387 break; 388 case R_TIMEOUT_CTRL: 389 s->uart_timeout_ctrl = value; 390 qemu_log_mask(LOG_UNIMP, 391 "%s: timeout_ctrl is not supported\n", __func__); 392 break; 393 default: 394 qemu_log_mask(LOG_GUEST_ERROR, 395 "%s: Bad offset 0x%"HWADDR_PRIx"\n", __func__, addr); 396 } 397 } 398 399 static void ibex_uart_clk_update(void *opaque) 400 { 401 IbexUartState *s = opaque; 402 403 /* recompute uart's speed on clock change */ 404 uint64_t baud = ibex_uart_get_baud(s); 405 406 s->char_tx_time = (NANOSECONDS_PER_SECOND / baud) * 10; 407 } 408 409 static void fifo_trigger_update(void *opaque) 410 { 411 IbexUartState *s = opaque; 412 413 if (s->uart_ctrl & R_CTRL_TX_ENABLE_MASK) { 414 ibex_uart_xmit(NULL, G_IO_OUT, s); 415 } 416 } 417 418 static const MemoryRegionOps ibex_uart_ops = { 419 .read = ibex_uart_read, 420 .write = ibex_uart_write, 421 .endianness = DEVICE_NATIVE_ENDIAN, 422 .impl.min_access_size = 4, 423 .impl.max_access_size = 4, 424 }; 425 426 static int ibex_uart_post_load(void *opaque, int version_id) 427 { 428 IbexUartState *s = opaque; 429 430 ibex_uart_update_irqs(s); 431 return 0; 432 } 433 434 static const VMStateDescription vmstate_ibex_uart = { 435 .name = TYPE_IBEX_UART, 436 .version_id = 1, 437 .minimum_version_id = 1, 438 .post_load = ibex_uart_post_load, 439 .fields = (VMStateField[]) { 440 VMSTATE_UINT8_ARRAY(tx_fifo, IbexUartState, 441 IBEX_UART_TX_FIFO_SIZE), 442 VMSTATE_UINT32(tx_level, IbexUartState), 443 VMSTATE_UINT64(char_tx_time, IbexUartState), 444 VMSTATE_TIMER_PTR(fifo_trigger_handle, IbexUartState), 445 VMSTATE_UINT32(uart_intr_state, IbexUartState), 446 VMSTATE_UINT32(uart_intr_enable, IbexUartState), 447 VMSTATE_UINT32(uart_ctrl, IbexUartState), 448 VMSTATE_UINT32(uart_status, IbexUartState), 449 VMSTATE_UINT32(uart_rdata, IbexUartState), 450 VMSTATE_UINT32(uart_fifo_ctrl, IbexUartState), 451 VMSTATE_UINT32(uart_fifo_status, IbexUartState), 452 VMSTATE_UINT32(uart_ovrd, IbexUartState), 453 VMSTATE_UINT32(uart_val, IbexUartState), 454 VMSTATE_UINT32(uart_timeout_ctrl, IbexUartState), 455 VMSTATE_END_OF_LIST() 456 } 457 }; 458 459 static Property ibex_uart_properties[] = { 460 DEFINE_PROP_CHR("chardev", IbexUartState, chr), 461 DEFINE_PROP_END_OF_LIST(), 462 }; 463 464 static void ibex_uart_init(Object *obj) 465 { 466 IbexUartState *s = IBEX_UART(obj); 467 468 s->f_clk = qdev_init_clock_in(DEVICE(obj), "f_clock", 469 ibex_uart_clk_update, s); 470 clock_set_hz(s->f_clk, IBEX_UART_CLOCK); 471 472 sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->tx_watermark); 473 sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->rx_watermark); 474 sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->tx_empty); 475 sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->rx_overflow); 476 477 memory_region_init_io(&s->mmio, obj, &ibex_uart_ops, s, 478 TYPE_IBEX_UART, 0x400); 479 sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio); 480 } 481 482 static void ibex_uart_realize(DeviceState *dev, Error **errp) 483 { 484 IbexUartState *s = IBEX_UART(dev); 485 486 s->fifo_trigger_handle = timer_new_ns(QEMU_CLOCK_VIRTUAL, 487 fifo_trigger_update, s); 488 489 qemu_chr_fe_set_handlers(&s->chr, ibex_uart_can_receive, 490 ibex_uart_receive, NULL, NULL, 491 s, NULL, true); 492 } 493 494 static void ibex_uart_class_init(ObjectClass *klass, void *data) 495 { 496 DeviceClass *dc = DEVICE_CLASS(klass); 497 498 dc->reset = ibex_uart_reset; 499 dc->realize = ibex_uart_realize; 500 dc->vmsd = &vmstate_ibex_uart; 501 device_class_set_props(dc, ibex_uart_properties); 502 } 503 504 static const TypeInfo ibex_uart_info = { 505 .name = TYPE_IBEX_UART, 506 .parent = TYPE_SYS_BUS_DEVICE, 507 .instance_size = sizeof(IbexUartState), 508 .instance_init = ibex_uart_init, 509 .class_init = ibex_uart_class_init, 510 }; 511 512 static void ibex_uart_register_types(void) 513 { 514 type_register_static(&ibex_uart_info); 515 } 516 517 type_init(ibex_uart_register_types) 518