1 /*
2 * ARM MPS2 AN505 FPGAIO emulation
3 *
4 * Copyright (c) 2018 Linaro Limited
5 * Written by Peter Maydell
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 or
9 * (at your option) any later version.
10 */
11
12 /* This is a model of the "FPGA system control and I/O" block found
13 * in the AN505 FPGA image for the MPS2 devboard.
14 * It is documented in AN505:
15 * https://developer.arm.com/documentation/dai0505/latest/
16 */
17
18 #include "qemu/osdep.h"
19 #include "qemu/log.h"
20 #include "qemu/module.h"
21 #include "qapi/error.h"
22 #include "trace.h"
23 #include "hw/sysbus.h"
24 #include "migration/vmstate.h"
25 #include "hw/registerfields.h"
26 #include "hw/misc/mps2-fpgaio.h"
27 #include "hw/misc/led.h"
28 #include "hw/qdev-properties.h"
29 #include "qemu/timer.h"
30
31 REG32(LED0, 0)
32 REG32(DBGCTRL, 4)
33 REG32(BUTTON, 8)
34 REG32(CLK1HZ, 0x10)
35 REG32(CLK100HZ, 0x14)
36 REG32(COUNTER, 0x18)
37 REG32(PRESCALE, 0x1c)
38 REG32(PSCNTR, 0x20)
39 REG32(SWITCH, 0x28)
40 REG32(MISC, 0x4c)
41
counter_from_tickoff(int64_t now,int64_t tick_offset,int frq)42 static uint32_t counter_from_tickoff(int64_t now, int64_t tick_offset, int frq)
43 {
44 return muldiv64(now - tick_offset, frq, NANOSECONDS_PER_SECOND);
45 }
46
tickoff_from_counter(int64_t now,uint32_t count,int frq)47 static int64_t tickoff_from_counter(int64_t now, uint32_t count, int frq)
48 {
49 return now - muldiv64(count, NANOSECONDS_PER_SECOND, frq);
50 }
51
resync_counter(MPS2FPGAIO * s)52 static void resync_counter(MPS2FPGAIO *s)
53 {
54 /*
55 * Update s->counter and s->pscntr to their true current values
56 * by calculating how many times PSCNTR has ticked since the
57 * last time we did a resync.
58 */
59 int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
60 int64_t elapsed = now - s->pscntr_sync_ticks;
61
62 /*
63 * Round elapsed down to a whole number of PSCNTR ticks, so we don't
64 * lose time if we do multiple resyncs in a single tick.
65 */
66 uint64_t ticks = muldiv64(elapsed, s->prescale_clk, NANOSECONDS_PER_SECOND);
67
68 /*
69 * Work out what PSCNTR and COUNTER have moved to. We assume that
70 * PSCNTR reloads from PRESCALE one tick-period after it hits zero,
71 * and that COUNTER increments at the same moment.
72 */
73 if (ticks == 0) {
74 /* We haven't ticked since the last time we were asked */
75 return;
76 } else if (ticks < s->pscntr) {
77 /* We haven't yet reached zero, just reduce the PSCNTR */
78 s->pscntr -= ticks;
79 } else {
80 if (s->prescale == 0) {
81 /*
82 * If the reload value is zero then the PSCNTR will stick
83 * at zero once it reaches it, and so we will increment
84 * COUNTER every tick after that.
85 */
86 s->counter += ticks - s->pscntr;
87 s->pscntr = 0;
88 } else {
89 /*
90 * This is the complicated bit. This ASCII art diagram gives an
91 * example with PRESCALE==5 PSCNTR==7:
92 *
93 * ticks 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
94 * PSCNTR 7 6 5 4 3 2 1 0 5 4 3 2 1 0 5
95 * cinc 1 2
96 * y 0 1 2 3 4 5 6 7 8 9 10 11 12
97 * x 0 1 2 3 4 5 0 1 2 3 4 5 0
98 *
99 * where x = y % (s->prescale + 1)
100 * and so PSCNTR = s->prescale - x
101 * and COUNTER is incremented by y / (s->prescale + 1)
102 *
103 * The case where PSCNTR < PRESCALE works out the same,
104 * though we must be careful to calculate y as 64-bit unsigned
105 * for all parts of the expression.
106 * y < 0 is not possible because that implies ticks < s->pscntr.
107 */
108 uint64_t y = ticks - s->pscntr + s->prescale;
109 s->pscntr = s->prescale - (y % (s->prescale + 1));
110 s->counter += y / (s->prescale + 1);
111 }
112 }
113
114 /*
115 * Only advance the sync time to the timestamp of the last PSCNTR tick,
116 * not all the way to 'now', so we don't lose time if we do multiple
117 * resyncs in a single tick.
118 */
119 s->pscntr_sync_ticks += muldiv64(ticks, NANOSECONDS_PER_SECOND,
120 s->prescale_clk);
121 }
122
mps2_fpgaio_read(void * opaque,hwaddr offset,unsigned size)123 static uint64_t mps2_fpgaio_read(void *opaque, hwaddr offset, unsigned size)
124 {
125 MPS2FPGAIO *s = MPS2_FPGAIO(opaque);
126 uint64_t r;
127 int64_t now;
128
129 switch (offset) {
130 case A_LED0:
131 r = s->led0;
132 break;
133 case A_DBGCTRL:
134 if (!s->has_dbgctrl) {
135 goto bad_offset;
136 }
137 r = s->dbgctrl;
138 break;
139 case A_BUTTON:
140 /* User-pressable board buttons. We don't model that, so just return
141 * zeroes.
142 */
143 r = 0;
144 break;
145 case A_PRESCALE:
146 r = s->prescale;
147 break;
148 case A_MISC:
149 r = s->misc;
150 break;
151 case A_CLK1HZ:
152 now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
153 r = counter_from_tickoff(now, s->clk1hz_tick_offset, 1);
154 break;
155 case A_CLK100HZ:
156 now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
157 r = counter_from_tickoff(now, s->clk100hz_tick_offset, 100);
158 break;
159 case A_COUNTER:
160 resync_counter(s);
161 r = s->counter;
162 break;
163 case A_PSCNTR:
164 resync_counter(s);
165 r = s->pscntr;
166 break;
167 case A_SWITCH:
168 if (!s->has_switches) {
169 goto bad_offset;
170 }
171 /* User-togglable board switches. We don't model that, so report 0. */
172 r = 0;
173 break;
174 default:
175 bad_offset:
176 qemu_log_mask(LOG_GUEST_ERROR,
177 "MPS2 FPGAIO read: bad offset %x\n", (int) offset);
178 r = 0;
179 break;
180 }
181
182 trace_mps2_fpgaio_read(offset, r, size);
183 return r;
184 }
185
mps2_fpgaio_write(void * opaque,hwaddr offset,uint64_t value,unsigned size)186 static void mps2_fpgaio_write(void *opaque, hwaddr offset, uint64_t value,
187 unsigned size)
188 {
189 MPS2FPGAIO *s = MPS2_FPGAIO(opaque);
190 int64_t now;
191
192 trace_mps2_fpgaio_write(offset, value, size);
193
194 switch (offset) {
195 case A_LED0:
196 if (s->num_leds != 0) {
197 uint32_t i;
198
199 s->led0 = value & MAKE_64BIT_MASK(0, s->num_leds);
200 for (i = 0; i < s->num_leds; i++) {
201 led_set_state(s->led[i], value & (1 << i));
202 }
203 }
204 break;
205 case A_DBGCTRL:
206 if (!s->has_dbgctrl) {
207 goto bad_offset;
208 }
209 qemu_log_mask(LOG_UNIMP,
210 "MPS2 FPGAIO: DBGCTRL unimplemented\n");
211 s->dbgctrl = value;
212 break;
213 case A_PRESCALE:
214 resync_counter(s);
215 s->prescale = value;
216 break;
217 case A_MISC:
218 /* These are control bits for some of the other devices on the
219 * board (SPI, CLCD, etc). We don't implement that yet, so just
220 * make the bits read as written.
221 */
222 qemu_log_mask(LOG_UNIMP,
223 "MPS2 FPGAIO: MISC control bits unimplemented\n");
224 s->misc = value;
225 break;
226 case A_CLK1HZ:
227 now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
228 s->clk1hz_tick_offset = tickoff_from_counter(now, value, 1);
229 break;
230 case A_CLK100HZ:
231 now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
232 s->clk100hz_tick_offset = tickoff_from_counter(now, value, 100);
233 break;
234 case A_COUNTER:
235 resync_counter(s);
236 s->counter = value;
237 break;
238 case A_PSCNTR:
239 resync_counter(s);
240 s->pscntr = value;
241 break;
242 default:
243 bad_offset:
244 qemu_log_mask(LOG_GUEST_ERROR,
245 "MPS2 FPGAIO write: bad offset 0x%x\n", (int) offset);
246 break;
247 }
248 }
249
250 static const MemoryRegionOps mps2_fpgaio_ops = {
251 .read = mps2_fpgaio_read,
252 .write = mps2_fpgaio_write,
253 .endianness = DEVICE_LITTLE_ENDIAN,
254 };
255
mps2_fpgaio_reset(DeviceState * dev)256 static void mps2_fpgaio_reset(DeviceState *dev)
257 {
258 MPS2FPGAIO *s = MPS2_FPGAIO(dev);
259 int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
260
261 trace_mps2_fpgaio_reset();
262 s->led0 = 0;
263 s->prescale = 0;
264 s->misc = 0;
265 s->clk1hz_tick_offset = tickoff_from_counter(now, 0, 1);
266 s->clk100hz_tick_offset = tickoff_from_counter(now, 0, 100);
267 s->counter = 0;
268 s->pscntr = 0;
269 s->pscntr_sync_ticks = now;
270
271 for (size_t i = 0; i < s->num_leds; i++) {
272 device_cold_reset(DEVICE(s->led[i]));
273 }
274 }
275
mps2_fpgaio_init(Object * obj)276 static void mps2_fpgaio_init(Object *obj)
277 {
278 SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
279 MPS2FPGAIO *s = MPS2_FPGAIO(obj);
280
281 memory_region_init_io(&s->iomem, obj, &mps2_fpgaio_ops, s,
282 "mps2-fpgaio", 0x1000);
283 sysbus_init_mmio(sbd, &s->iomem);
284 }
285
mps2_fpgaio_realize(DeviceState * dev,Error ** errp)286 static void mps2_fpgaio_realize(DeviceState *dev, Error **errp)
287 {
288 MPS2FPGAIO *s = MPS2_FPGAIO(dev);
289 uint32_t i;
290
291 if (s->num_leds > MPS2FPGAIO_MAX_LEDS) {
292 error_setg(errp, "num-leds cannot be greater than %d",
293 MPS2FPGAIO_MAX_LEDS);
294 return;
295 }
296
297 for (i = 0; i < s->num_leds; i++) {
298 g_autofree char *ledname = g_strdup_printf("USERLED%d", i);
299 s->led[i] = led_create_simple(OBJECT(dev), GPIO_POLARITY_ACTIVE_HIGH,
300 LED_COLOR_GREEN, ledname);
301 }
302 }
303
304 static const VMStateDescription mps2_fpgaio_vmstate = {
305 .name = "mps2-fpgaio",
306 .version_id = 3,
307 .minimum_version_id = 3,
308 .fields = (const VMStateField[]) {
309 VMSTATE_UINT32(led0, MPS2FPGAIO),
310 VMSTATE_UINT32(prescale, MPS2FPGAIO),
311 VMSTATE_UINT32(misc, MPS2FPGAIO),
312 VMSTATE_UINT32(dbgctrl, MPS2FPGAIO),
313 VMSTATE_INT64(clk1hz_tick_offset, MPS2FPGAIO),
314 VMSTATE_INT64(clk100hz_tick_offset, MPS2FPGAIO),
315 VMSTATE_UINT32(counter, MPS2FPGAIO),
316 VMSTATE_UINT32(pscntr, MPS2FPGAIO),
317 VMSTATE_INT64(pscntr_sync_ticks, MPS2FPGAIO),
318 VMSTATE_END_OF_LIST()
319 },
320 };
321
322 static Property mps2_fpgaio_properties[] = {
323 /* Frequency of the prescale counter */
324 DEFINE_PROP_UINT32("prescale-clk", MPS2FPGAIO, prescale_clk, 20000000),
325 /* Number of LEDs controlled by LED0 register */
326 DEFINE_PROP_UINT32("num-leds", MPS2FPGAIO, num_leds, 2),
327 DEFINE_PROP_BOOL("has-switches", MPS2FPGAIO, has_switches, false),
328 DEFINE_PROP_BOOL("has-dbgctrl", MPS2FPGAIO, has_dbgctrl, false),
329 DEFINE_PROP_END_OF_LIST(),
330 };
331
mps2_fpgaio_class_init(ObjectClass * klass,void * data)332 static void mps2_fpgaio_class_init(ObjectClass *klass, void *data)
333 {
334 DeviceClass *dc = DEVICE_CLASS(klass);
335
336 dc->vmsd = &mps2_fpgaio_vmstate;
337 dc->realize = mps2_fpgaio_realize;
338 dc->reset = mps2_fpgaio_reset;
339 device_class_set_props(dc, mps2_fpgaio_properties);
340 }
341
342 static const TypeInfo mps2_fpgaio_info = {
343 .name = TYPE_MPS2_FPGAIO,
344 .parent = TYPE_SYS_BUS_DEVICE,
345 .instance_size = sizeof(MPS2FPGAIO),
346 .instance_init = mps2_fpgaio_init,
347 .class_init = mps2_fpgaio_class_init,
348 };
349
mps2_fpgaio_register_types(void)350 static void mps2_fpgaio_register_types(void)
351 {
352 type_register_static(&mps2_fpgaio_info);
353 }
354
355 type_init(mps2_fpgaio_register_types);
356