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 "hw/registerfields.h"
35 #include "migration/vmstate.h"
36 #include "qemu/log.h"
37 #include "qemu/module.h"
38
39 REG32(INTR_STATE, 0x00)
40 FIELD(INTR_STATE, TX_WATERMARK, 0, 1)
41 FIELD(INTR_STATE, RX_WATERMARK, 1, 1)
42 FIELD(INTR_STATE, TX_EMPTY, 2, 1)
43 FIELD(INTR_STATE, RX_OVERFLOW, 3, 1)
44 REG32(INTR_ENABLE, 0x04)
45 REG32(INTR_TEST, 0x08)
46 REG32(ALERT_TEST, 0x0C)
47 REG32(CTRL, 0x10)
48 FIELD(CTRL, TX_ENABLE, 0, 1)
49 FIELD(CTRL, RX_ENABLE, 1, 1)
50 FIELD(CTRL, NF, 2, 1)
51 FIELD(CTRL, SLPBK, 4, 1)
52 FIELD(CTRL, LLPBK, 5, 1)
53 FIELD(CTRL, PARITY_EN, 6, 1)
54 FIELD(CTRL, PARITY_ODD, 7, 1)
55 FIELD(CTRL, RXBLVL, 8, 2)
56 FIELD(CTRL, NCO, 16, 16)
57 REG32(STATUS, 0x14)
58 FIELD(STATUS, TXFULL, 0, 1)
59 FIELD(STATUS, RXFULL, 1, 1)
60 FIELD(STATUS, TXEMPTY, 2, 1)
61 FIELD(STATUS, RXIDLE, 4, 1)
62 FIELD(STATUS, RXEMPTY, 5, 1)
63 REG32(RDATA, 0x18)
64 REG32(WDATA, 0x1C)
65 REG32(FIFO_CTRL, 0x20)
66 FIELD(FIFO_CTRL, RXRST, 0, 1)
67 FIELD(FIFO_CTRL, TXRST, 1, 1)
68 FIELD(FIFO_CTRL, RXILVL, 2, 3)
69 FIELD(FIFO_CTRL, TXILVL, 5, 2)
70 REG32(FIFO_STATUS, 0x24)
71 FIELD(FIFO_STATUS, TXLVL, 0, 5)
72 FIELD(FIFO_STATUS, RXLVL, 16, 5)
73 REG32(OVRD, 0x28)
74 REG32(VAL, 0x2C)
75 REG32(TIMEOUT_CTRL, 0x30)
76
ibex_uart_update_irqs(IbexUartState * s)77 static void ibex_uart_update_irqs(IbexUartState *s)
78 {
79 if (s->uart_intr_state & s->uart_intr_enable & R_INTR_STATE_TX_WATERMARK_MASK) {
80 qemu_set_irq(s->tx_watermark, 1);
81 } else {
82 qemu_set_irq(s->tx_watermark, 0);
83 }
84
85 if (s->uart_intr_state & s->uart_intr_enable & R_INTR_STATE_RX_WATERMARK_MASK) {
86 qemu_set_irq(s->rx_watermark, 1);
87 } else {
88 qemu_set_irq(s->rx_watermark, 0);
89 }
90
91 if (s->uart_intr_state & s->uart_intr_enable & R_INTR_STATE_TX_EMPTY_MASK) {
92 qemu_set_irq(s->tx_empty, 1);
93 } else {
94 qemu_set_irq(s->tx_empty, 0);
95 }
96
97 if (s->uart_intr_state & s->uart_intr_enable & R_INTR_STATE_RX_OVERFLOW_MASK) {
98 qemu_set_irq(s->rx_overflow, 1);
99 } else {
100 qemu_set_irq(s->rx_overflow, 0);
101 }
102 }
103
ibex_uart_can_receive(void * opaque)104 static int ibex_uart_can_receive(void *opaque)
105 {
106 IbexUartState *s = opaque;
107
108 if ((s->uart_ctrl & R_CTRL_RX_ENABLE_MASK)
109 && !(s->uart_status & R_STATUS_RXFULL_MASK)) {
110 return 1;
111 }
112
113 return 0;
114 }
115
ibex_uart_receive(void * opaque,const uint8_t * buf,int size)116 static void ibex_uart_receive(void *opaque, const uint8_t *buf, int size)
117 {
118 IbexUartState *s = opaque;
119 uint8_t rx_fifo_level = (s->uart_fifo_ctrl & R_FIFO_CTRL_RXILVL_MASK)
120 >> R_FIFO_CTRL_RXILVL_SHIFT;
121
122 s->uart_rdata = *buf;
123
124 s->uart_status &= ~R_STATUS_RXIDLE_MASK;
125 s->uart_status &= ~R_STATUS_RXEMPTY_MASK;
126 /* The RXFULL is set after receiving a single byte
127 * as the FIFO buffers are not yet implemented.
128 */
129 s->uart_status |= R_STATUS_RXFULL_MASK;
130 s->rx_level += 1;
131
132 if (size > rx_fifo_level) {
133 s->uart_intr_state |= R_INTR_STATE_RX_WATERMARK_MASK;
134 }
135
136 ibex_uart_update_irqs(s);
137 }
138
ibex_uart_xmit(void * do_not_use,GIOCondition cond,void * opaque)139 static gboolean ibex_uart_xmit(void *do_not_use, GIOCondition cond,
140 void *opaque)
141 {
142 IbexUartState *s = opaque;
143 uint8_t tx_fifo_level = (s->uart_fifo_ctrl & R_FIFO_CTRL_TXILVL_MASK)
144 >> R_FIFO_CTRL_TXILVL_SHIFT;
145 int ret;
146
147 /* instant drain the fifo when there's no back-end */
148 if (!qemu_chr_fe_backend_connected(&s->chr)) {
149 s->tx_level = 0;
150 return G_SOURCE_REMOVE;
151 }
152
153 if (!s->tx_level) {
154 s->uart_status &= ~R_STATUS_TXFULL_MASK;
155 s->uart_status |= R_STATUS_TXEMPTY_MASK;
156 s->uart_intr_state |= R_INTR_STATE_TX_EMPTY_MASK;
157 s->uart_intr_state &= ~R_INTR_STATE_TX_WATERMARK_MASK;
158 ibex_uart_update_irqs(s);
159 return G_SOURCE_REMOVE;
160 }
161
162 ret = qemu_chr_fe_write(&s->chr, s->tx_fifo, s->tx_level);
163
164 if (ret >= 0) {
165 s->tx_level -= ret;
166 memmove(s->tx_fifo, s->tx_fifo + ret, s->tx_level);
167 }
168
169 if (s->tx_level) {
170 guint r = qemu_chr_fe_add_watch(&s->chr, G_IO_OUT | G_IO_HUP,
171 ibex_uart_xmit, s);
172 if (!r) {
173 s->tx_level = 0;
174 return G_SOURCE_REMOVE;
175 }
176 }
177
178 /* Clear the TX Full bit */
179 if (s->tx_level != IBEX_UART_TX_FIFO_SIZE) {
180 s->uart_status &= ~R_STATUS_TXFULL_MASK;
181 }
182
183 /* Disable the TX_WATERMARK IRQ */
184 if (s->tx_level < tx_fifo_level) {
185 s->uart_intr_state &= ~R_INTR_STATE_TX_WATERMARK_MASK;
186 }
187
188 /* Set TX empty */
189 if (s->tx_level == 0) {
190 s->uart_status |= R_STATUS_TXEMPTY_MASK;
191 s->uart_intr_state |= R_INTR_STATE_TX_EMPTY_MASK;
192 }
193
194 ibex_uart_update_irqs(s);
195 return G_SOURCE_REMOVE;
196 }
197
uart_write_tx_fifo(IbexUartState * s,const uint8_t * buf,int size)198 static void uart_write_tx_fifo(IbexUartState *s, const uint8_t *buf,
199 int size)
200 {
201 uint64_t current_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
202 uint8_t tx_fifo_level = (s->uart_fifo_ctrl & R_FIFO_CTRL_TXILVL_MASK)
203 >> R_FIFO_CTRL_TXILVL_SHIFT;
204
205 if (size > IBEX_UART_TX_FIFO_SIZE - s->tx_level) {
206 size = IBEX_UART_TX_FIFO_SIZE - s->tx_level;
207 qemu_log_mask(LOG_GUEST_ERROR, "ibex_uart: TX FIFO overflow");
208 }
209
210 memcpy(s->tx_fifo + s->tx_level, buf, size);
211 s->tx_level += size;
212
213 if (s->tx_level > 0) {
214 s->uart_status &= ~R_STATUS_TXEMPTY_MASK;
215 }
216
217 if (s->tx_level >= tx_fifo_level) {
218 s->uart_intr_state |= R_INTR_STATE_TX_WATERMARK_MASK;
219 ibex_uart_update_irqs(s);
220 }
221
222 if (s->tx_level == IBEX_UART_TX_FIFO_SIZE) {
223 s->uart_status |= R_STATUS_TXFULL_MASK;
224 }
225
226 timer_mod(s->fifo_trigger_handle, current_time +
227 (s->char_tx_time * 4));
228 }
229
ibex_uart_reset(DeviceState * dev)230 static void ibex_uart_reset(DeviceState *dev)
231 {
232 IbexUartState *s = IBEX_UART(dev);
233
234 s->uart_intr_state = 0x00000000;
235 s->uart_intr_state = 0x00000000;
236 s->uart_intr_enable = 0x00000000;
237 s->uart_ctrl = 0x00000000;
238 s->uart_status = 0x0000003c;
239 s->uart_rdata = 0x00000000;
240 s->uart_fifo_ctrl = 0x00000000;
241 s->uart_fifo_status = 0x00000000;
242 s->uart_ovrd = 0x00000000;
243 s->uart_val = 0x00000000;
244 s->uart_timeout_ctrl = 0x00000000;
245
246 s->tx_level = 0;
247 s->rx_level = 0;
248
249 s->char_tx_time = (NANOSECONDS_PER_SECOND / 230400) * 10;
250
251 ibex_uart_update_irqs(s);
252 }
253
ibex_uart_get_baud(IbexUartState * s)254 static uint64_t ibex_uart_get_baud(IbexUartState *s)
255 {
256 uint64_t baud;
257
258 baud = ((s->uart_ctrl & R_CTRL_NCO_MASK) >> 16);
259 baud *= clock_get_hz(s->f_clk);
260 baud >>= 20;
261
262 return baud;
263 }
264
ibex_uart_read(void * opaque,hwaddr addr,unsigned int size)265 static uint64_t ibex_uart_read(void *opaque, hwaddr addr,
266 unsigned int size)
267 {
268 IbexUartState *s = opaque;
269 uint64_t retvalue = 0;
270
271 switch (addr >> 2) {
272 case R_INTR_STATE:
273 retvalue = s->uart_intr_state;
274 break;
275 case R_INTR_ENABLE:
276 retvalue = s->uart_intr_enable;
277 break;
278 case R_INTR_TEST:
279 qemu_log_mask(LOG_GUEST_ERROR,
280 "%s: wdata is write only\n", __func__);
281 break;
282
283 case R_CTRL:
284 retvalue = s->uart_ctrl;
285 break;
286 case R_STATUS:
287 retvalue = s->uart_status;
288 break;
289
290 case R_RDATA:
291 retvalue = s->uart_rdata;
292 if ((s->uart_ctrl & R_CTRL_RX_ENABLE_MASK) && (s->rx_level > 0)) {
293 qemu_chr_fe_accept_input(&s->chr);
294
295 s->rx_level -= 1;
296 s->uart_status &= ~R_STATUS_RXFULL_MASK;
297 if (s->rx_level == 0) {
298 s->uart_status |= R_STATUS_RXIDLE_MASK;
299 s->uart_status |= R_STATUS_RXEMPTY_MASK;
300 }
301 }
302 break;
303 case R_WDATA:
304 qemu_log_mask(LOG_GUEST_ERROR,
305 "%s: wdata is write only\n", __func__);
306 break;
307
308 case R_FIFO_CTRL:
309 retvalue = s->uart_fifo_ctrl;
310 break;
311 case R_FIFO_STATUS:
312 retvalue = s->uart_fifo_status;
313
314 retvalue |= (s->rx_level & 0x1F) << R_FIFO_STATUS_RXLVL_SHIFT;
315 retvalue |= (s->tx_level & 0x1F) << R_FIFO_STATUS_TXLVL_SHIFT;
316
317 qemu_log_mask(LOG_UNIMP,
318 "%s: RX fifos are not supported\n", __func__);
319 break;
320
321 case R_OVRD:
322 retvalue = s->uart_ovrd;
323 qemu_log_mask(LOG_UNIMP,
324 "%s: ovrd is not supported\n", __func__);
325 break;
326 case R_VAL:
327 retvalue = s->uart_val;
328 qemu_log_mask(LOG_UNIMP,
329 "%s: val is not supported\n", __func__);
330 break;
331 case R_TIMEOUT_CTRL:
332 retvalue = s->uart_timeout_ctrl;
333 qemu_log_mask(LOG_UNIMP,
334 "%s: timeout_ctrl is not supported\n", __func__);
335 break;
336 default:
337 qemu_log_mask(LOG_GUEST_ERROR,
338 "%s: Bad offset 0x%"HWADDR_PRIx"\n", __func__, addr);
339 return 0;
340 }
341
342 return retvalue;
343 }
344
ibex_uart_write(void * opaque,hwaddr addr,uint64_t val64,unsigned int size)345 static void ibex_uart_write(void *opaque, hwaddr addr,
346 uint64_t val64, unsigned int size)
347 {
348 IbexUartState *s = opaque;
349 uint32_t value = val64;
350
351 switch (addr >> 2) {
352 case R_INTR_STATE:
353 /* Write 1 clear */
354 s->uart_intr_state &= ~value;
355 ibex_uart_update_irqs(s);
356 break;
357 case R_INTR_ENABLE:
358 s->uart_intr_enable = value;
359 ibex_uart_update_irqs(s);
360 break;
361 case R_INTR_TEST:
362 s->uart_intr_state |= value;
363 ibex_uart_update_irqs(s);
364 break;
365
366 case R_CTRL:
367 s->uart_ctrl = value;
368
369 if (value & R_CTRL_NF_MASK) {
370 qemu_log_mask(LOG_UNIMP,
371 "%s: UART_CTRL_NF is not supported\n", __func__);
372 }
373 if (value & R_CTRL_SLPBK_MASK) {
374 qemu_log_mask(LOG_UNIMP,
375 "%s: UART_CTRL_SLPBK is not supported\n", __func__);
376 }
377 if (value & R_CTRL_LLPBK_MASK) {
378 qemu_log_mask(LOG_UNIMP,
379 "%s: UART_CTRL_LLPBK is not supported\n", __func__);
380 }
381 if (value & R_CTRL_PARITY_EN_MASK) {
382 qemu_log_mask(LOG_UNIMP,
383 "%s: UART_CTRL_PARITY_EN is not supported\n",
384 __func__);
385 }
386 if (value & R_CTRL_PARITY_ODD_MASK) {
387 qemu_log_mask(LOG_UNIMP,
388 "%s: UART_CTRL_PARITY_ODD is not supported\n",
389 __func__);
390 }
391 if (value & R_CTRL_RXBLVL_MASK) {
392 qemu_log_mask(LOG_UNIMP,
393 "%s: UART_CTRL_RXBLVL is not supported\n", __func__);
394 }
395 if (value & R_CTRL_NCO_MASK) {
396 uint64_t baud = ibex_uart_get_baud(s);
397
398 s->char_tx_time = (NANOSECONDS_PER_SECOND / baud) * 10;
399 }
400 break;
401 case R_STATUS:
402 qemu_log_mask(LOG_GUEST_ERROR,
403 "%s: status is read only\n", __func__);
404 break;
405
406 case R_RDATA:
407 qemu_log_mask(LOG_GUEST_ERROR,
408 "%s: rdata is read only\n", __func__);
409 break;
410 case R_WDATA:
411 uart_write_tx_fifo(s, (uint8_t *) &value, 1);
412 break;
413
414 case R_FIFO_CTRL:
415 s->uart_fifo_ctrl = value;
416
417 if (value & R_FIFO_CTRL_RXRST_MASK) {
418 s->rx_level = 0;
419 qemu_log_mask(LOG_UNIMP,
420 "%s: RX fifos are not supported\n", __func__);
421 }
422 if (value & R_FIFO_CTRL_TXRST_MASK) {
423 s->tx_level = 0;
424 }
425 break;
426 case R_FIFO_STATUS:
427 qemu_log_mask(LOG_GUEST_ERROR,
428 "%s: fifo_status is read only\n", __func__);
429 break;
430
431 case R_OVRD:
432 s->uart_ovrd = value;
433 qemu_log_mask(LOG_UNIMP,
434 "%s: ovrd is not supported\n", __func__);
435 break;
436 case R_VAL:
437 qemu_log_mask(LOG_GUEST_ERROR,
438 "%s: val is read only\n", __func__);
439 break;
440 case R_TIMEOUT_CTRL:
441 s->uart_timeout_ctrl = value;
442 qemu_log_mask(LOG_UNIMP,
443 "%s: timeout_ctrl is not supported\n", __func__);
444 break;
445 default:
446 qemu_log_mask(LOG_GUEST_ERROR,
447 "%s: Bad offset 0x%"HWADDR_PRIx"\n", __func__, addr);
448 }
449 }
450
ibex_uart_clk_update(void * opaque,ClockEvent event)451 static void ibex_uart_clk_update(void *opaque, ClockEvent event)
452 {
453 IbexUartState *s = opaque;
454
455 /* recompute uart's speed on clock change */
456 uint64_t baud = ibex_uart_get_baud(s);
457
458 s->char_tx_time = (NANOSECONDS_PER_SECOND / baud) * 10;
459 }
460
fifo_trigger_update(void * opaque)461 static void fifo_trigger_update(void *opaque)
462 {
463 IbexUartState *s = opaque;
464
465 if (s->uart_ctrl & R_CTRL_TX_ENABLE_MASK) {
466 ibex_uart_xmit(NULL, G_IO_OUT, s);
467 }
468 }
469
470 static const MemoryRegionOps ibex_uart_ops = {
471 .read = ibex_uart_read,
472 .write = ibex_uart_write,
473 .endianness = DEVICE_NATIVE_ENDIAN,
474 .impl.min_access_size = 4,
475 .impl.max_access_size = 4,
476 };
477
ibex_uart_post_load(void * opaque,int version_id)478 static int ibex_uart_post_load(void *opaque, int version_id)
479 {
480 IbexUartState *s = opaque;
481
482 ibex_uart_update_irqs(s);
483 return 0;
484 }
485
486 static const VMStateDescription vmstate_ibex_uart = {
487 .name = TYPE_IBEX_UART,
488 .version_id = 1,
489 .minimum_version_id = 1,
490 .post_load = ibex_uart_post_load,
491 .fields = (const VMStateField[]) {
492 VMSTATE_UINT8_ARRAY(tx_fifo, IbexUartState,
493 IBEX_UART_TX_FIFO_SIZE),
494 VMSTATE_UINT32(tx_level, IbexUartState),
495 VMSTATE_UINT64(char_tx_time, IbexUartState),
496 VMSTATE_TIMER_PTR(fifo_trigger_handle, IbexUartState),
497 VMSTATE_UINT32(uart_intr_state, IbexUartState),
498 VMSTATE_UINT32(uart_intr_enable, IbexUartState),
499 VMSTATE_UINT32(uart_ctrl, IbexUartState),
500 VMSTATE_UINT32(uart_status, IbexUartState),
501 VMSTATE_UINT32(uart_rdata, IbexUartState),
502 VMSTATE_UINT32(uart_fifo_ctrl, IbexUartState),
503 VMSTATE_UINT32(uart_fifo_status, IbexUartState),
504 VMSTATE_UINT32(uart_ovrd, IbexUartState),
505 VMSTATE_UINT32(uart_val, IbexUartState),
506 VMSTATE_UINT32(uart_timeout_ctrl, IbexUartState),
507 VMSTATE_END_OF_LIST()
508 }
509 };
510
511 static Property ibex_uart_properties[] = {
512 DEFINE_PROP_CHR("chardev", IbexUartState, chr),
513 DEFINE_PROP_END_OF_LIST(),
514 };
515
ibex_uart_init(Object * obj)516 static void ibex_uart_init(Object *obj)
517 {
518 IbexUartState *s = IBEX_UART(obj);
519
520 s->f_clk = qdev_init_clock_in(DEVICE(obj), "f_clock",
521 ibex_uart_clk_update, s, ClockUpdate);
522 clock_set_hz(s->f_clk, IBEX_UART_CLOCK);
523
524 sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->tx_watermark);
525 sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->rx_watermark);
526 sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->tx_empty);
527 sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->rx_overflow);
528
529 memory_region_init_io(&s->mmio, obj, &ibex_uart_ops, s,
530 TYPE_IBEX_UART, 0x400);
531 sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio);
532 }
533
ibex_uart_realize(DeviceState * dev,Error ** errp)534 static void ibex_uart_realize(DeviceState *dev, Error **errp)
535 {
536 IbexUartState *s = IBEX_UART(dev);
537
538 s->fifo_trigger_handle = timer_new_ns(QEMU_CLOCK_VIRTUAL,
539 fifo_trigger_update, s);
540
541 qemu_chr_fe_set_handlers(&s->chr, ibex_uart_can_receive,
542 ibex_uart_receive, NULL, NULL,
543 s, NULL, true);
544 }
545
ibex_uart_class_init(ObjectClass * klass,void * data)546 static void ibex_uart_class_init(ObjectClass *klass, void *data)
547 {
548 DeviceClass *dc = DEVICE_CLASS(klass);
549
550 dc->reset = ibex_uart_reset;
551 dc->realize = ibex_uart_realize;
552 dc->vmsd = &vmstate_ibex_uart;
553 device_class_set_props(dc, ibex_uart_properties);
554 set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
555 }
556
557 static const TypeInfo ibex_uart_info = {
558 .name = TYPE_IBEX_UART,
559 .parent = TYPE_SYS_BUS_DEVICE,
560 .instance_size = sizeof(IbexUartState),
561 .instance_init = ibex_uart_init,
562 .class_init = ibex_uart_class_init,
563 };
564
ibex_uart_register_types(void)565 static void ibex_uart_register_types(void)
566 {
567 type_register_static(&ibex_uart_info);
568 }
569
570 type_init(ibex_uart_register_types)
571