pl011: fix incorrect logic to set the RXFF flag
[qemu.git] / hw / char / pl011.c
1 /*
2 * Arm PrimeCell PL011 UART
3 *
4 * Copyright (c) 2006 CodeSourcery.
5 * Written by Paul Brook
6 *
7 * This code is licensed under the GPL.
8 */
9
10 #include "hw/sysbus.h"
11 #include "sysemu/char.h"
12
13 #define TYPE_PL011 "pl011"
14 #define PL011(obj) OBJECT_CHECK(PL011State, (obj), TYPE_PL011)
15
16 typedef struct PL011State {
17 SysBusDevice parent_obj;
18
19 MemoryRegion iomem;
20 uint32_t readbuff;
21 uint32_t flags;
22 uint32_t lcr;
23 uint32_t rsr;
24 uint32_t cr;
25 uint32_t dmacr;
26 uint32_t int_enabled;
27 uint32_t int_level;
28 uint32_t read_fifo[16];
29 uint32_t ilpr;
30 uint32_t ibrd;
31 uint32_t fbrd;
32 uint32_t ifl;
33 int read_pos;
34 int read_count;
35 int read_trigger;
36 CharDriverState *chr;
37 qemu_irq irq;
38 const unsigned char *id;
39 } PL011State;
40
41 #define PL011_INT_TX 0x20
42 #define PL011_INT_RX 0x10
43
44 #define PL011_FLAG_TXFE 0x80
45 #define PL011_FLAG_RXFF 0x40
46 #define PL011_FLAG_TXFF 0x20
47 #define PL011_FLAG_RXFE 0x10
48
49 static const unsigned char pl011_id_arm[8] =
50 { 0x11, 0x10, 0x14, 0x00, 0x0d, 0xf0, 0x05, 0xb1 };
51 static const unsigned char pl011_id_luminary[8] =
52 { 0x11, 0x00, 0x18, 0x01, 0x0d, 0xf0, 0x05, 0xb1 };
53
54 static void pl011_update(PL011State *s)
55 {
56 uint32_t flags;
57
58 flags = s->int_level & s->int_enabled;
59 qemu_set_irq(s->irq, flags != 0);
60 }
61
62 static uint64_t pl011_read(void *opaque, hwaddr offset,
63 unsigned size)
64 {
65 PL011State *s = (PL011State *)opaque;
66 uint32_t c;
67
68 if (offset >= 0xfe0 && offset < 0x1000) {
69 return s->id[(offset - 0xfe0) >> 2];
70 }
71 switch (offset >> 2) {
72 case 0: /* UARTDR */
73 s->flags &= ~PL011_FLAG_RXFF;
74 c = s->read_fifo[s->read_pos];
75 if (s->read_count > 0) {
76 s->read_count--;
77 if (++s->read_pos == 16)
78 s->read_pos = 0;
79 }
80 if (s->read_count == 0) {
81 s->flags |= PL011_FLAG_RXFE;
82 }
83 if (s->read_count == s->read_trigger - 1)
84 s->int_level &= ~ PL011_INT_RX;
85 s->rsr = c >> 8;
86 pl011_update(s);
87 if (s->chr) {
88 qemu_chr_accept_input(s->chr);
89 }
90 return c;
91 case 1: /* UARTRSR */
92 return s->rsr;
93 case 6: /* UARTFR */
94 return s->flags;
95 case 8: /* UARTILPR */
96 return s->ilpr;
97 case 9: /* UARTIBRD */
98 return s->ibrd;
99 case 10: /* UARTFBRD */
100 return s->fbrd;
101 case 11: /* UARTLCR_H */
102 return s->lcr;
103 case 12: /* UARTCR */
104 return s->cr;
105 case 13: /* UARTIFLS */
106 return s->ifl;
107 case 14: /* UARTIMSC */
108 return s->int_enabled;
109 case 15: /* UARTRIS */
110 return s->int_level;
111 case 16: /* UARTMIS */
112 return s->int_level & s->int_enabled;
113 case 18: /* UARTDMACR */
114 return s->dmacr;
115 default:
116 qemu_log_mask(LOG_GUEST_ERROR,
117 "pl011_read: Bad offset %x\n", (int)offset);
118 return 0;
119 }
120 }
121
122 static void pl011_set_read_trigger(PL011State *s)
123 {
124 #if 0
125 /* The docs say the RX interrupt is triggered when the FIFO exceeds
126 the threshold. However linux only reads the FIFO in response to an
127 interrupt. Triggering the interrupt when the FIFO is non-empty seems
128 to make things work. */
129 if (s->lcr & 0x10)
130 s->read_trigger = (s->ifl >> 1) & 0x1c;
131 else
132 #endif
133 s->read_trigger = 1;
134 }
135
136 static void pl011_write(void *opaque, hwaddr offset,
137 uint64_t value, unsigned size)
138 {
139 PL011State *s = (PL011State *)opaque;
140 unsigned char ch;
141
142 switch (offset >> 2) {
143 case 0: /* UARTDR */
144 /* ??? Check if transmitter is enabled. */
145 ch = value;
146 if (s->chr)
147 qemu_chr_fe_write(s->chr, &ch, 1);
148 s->int_level |= PL011_INT_TX;
149 pl011_update(s);
150 break;
151 case 1: /* UARTRSR/UARTECR */
152 s->rsr = 0;
153 break;
154 case 6: /* UARTFR */
155 /* Writes to Flag register are ignored. */
156 break;
157 case 8: /* UARTUARTILPR */
158 s->ilpr = value;
159 break;
160 case 9: /* UARTIBRD */
161 s->ibrd = value;
162 break;
163 case 10: /* UARTFBRD */
164 s->fbrd = value;
165 break;
166 case 11: /* UARTLCR_H */
167 /* Reset the FIFO state on FIFO enable or disable */
168 if ((s->lcr ^ value) & 0x10) {
169 s->read_count = 0;
170 s->read_pos = 0;
171 }
172 s->lcr = value;
173 pl011_set_read_trigger(s);
174 break;
175 case 12: /* UARTCR */
176 /* ??? Need to implement the enable and loopback bits. */
177 s->cr = value;
178 break;
179 case 13: /* UARTIFS */
180 s->ifl = value;
181 pl011_set_read_trigger(s);
182 break;
183 case 14: /* UARTIMSC */
184 s->int_enabled = value;
185 pl011_update(s);
186 break;
187 case 17: /* UARTICR */
188 s->int_level &= ~value;
189 pl011_update(s);
190 break;
191 case 18: /* UARTDMACR */
192 s->dmacr = value;
193 if (value & 3) {
194 qemu_log_mask(LOG_UNIMP, "pl011: DMA not implemented\n");
195 }
196 break;
197 default:
198 qemu_log_mask(LOG_GUEST_ERROR,
199 "pl011_write: Bad offset %x\n", (int)offset);
200 }
201 }
202
203 static int pl011_can_receive(void *opaque)
204 {
205 PL011State *s = (PL011State *)opaque;
206
207 if (s->lcr & 0x10)
208 return s->read_count < 16;
209 else
210 return s->read_count < 1;
211 }
212
213 static void pl011_put_fifo(void *opaque, uint32_t value)
214 {
215 PL011State *s = (PL011State *)opaque;
216 int slot;
217
218 slot = s->read_pos + s->read_count;
219 if (slot >= 16)
220 slot -= 16;
221 s->read_fifo[slot] = value;
222 s->read_count++;
223 s->flags &= ~PL011_FLAG_RXFE;
224 if (!(s->lcr & 0x10) || s->read_count == 16) {
225 s->flags |= PL011_FLAG_RXFF;
226 }
227 if (s->read_count == s->read_trigger) {
228 s->int_level |= PL011_INT_RX;
229 pl011_update(s);
230 }
231 }
232
233 static void pl011_receive(void *opaque, const uint8_t *buf, int size)
234 {
235 pl011_put_fifo(opaque, *buf);
236 }
237
238 static void pl011_event(void *opaque, int event)
239 {
240 if (event == CHR_EVENT_BREAK)
241 pl011_put_fifo(opaque, 0x400);
242 }
243
244 static const MemoryRegionOps pl011_ops = {
245 .read = pl011_read,
246 .write = pl011_write,
247 .endianness = DEVICE_NATIVE_ENDIAN,
248 };
249
250 static const VMStateDescription vmstate_pl011 = {
251 .name = "pl011",
252 .version_id = 2,
253 .minimum_version_id = 2,
254 .minimum_version_id_old = 2,
255 .fields = (VMStateField[]) {
256 VMSTATE_UINT32(readbuff, PL011State),
257 VMSTATE_UINT32(flags, PL011State),
258 VMSTATE_UINT32(lcr, PL011State),
259 VMSTATE_UINT32(rsr, PL011State),
260 VMSTATE_UINT32(cr, PL011State),
261 VMSTATE_UINT32(dmacr, PL011State),
262 VMSTATE_UINT32(int_enabled, PL011State),
263 VMSTATE_UINT32(int_level, PL011State),
264 VMSTATE_UINT32_ARRAY(read_fifo, PL011State, 16),
265 VMSTATE_UINT32(ilpr, PL011State),
266 VMSTATE_UINT32(ibrd, PL011State),
267 VMSTATE_UINT32(fbrd, PL011State),
268 VMSTATE_UINT32(ifl, PL011State),
269 VMSTATE_INT32(read_pos, PL011State),
270 VMSTATE_INT32(read_count, PL011State),
271 VMSTATE_INT32(read_trigger, PL011State),
272 VMSTATE_END_OF_LIST()
273 }
274 };
275
276 static void pl011_init(Object *obj)
277 {
278 SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
279 PL011State *s = PL011(obj);
280
281 memory_region_init_io(&s->iomem, OBJECT(s), &pl011_ops, s, "pl011", 0x1000);
282 sysbus_init_mmio(sbd, &s->iomem);
283 sysbus_init_irq(sbd, &s->irq);
284
285 s->read_trigger = 1;
286 s->ifl = 0x12;
287 s->cr = 0x300;
288 s->flags = 0x90;
289
290 s->id = pl011_id_arm;
291 }
292
293 static void pl011_realize(DeviceState *dev, Error **errp)
294 {
295 PL011State *s = PL011(dev);
296
297 s->chr = qemu_char_get_next_serial();
298
299 if (s->chr) {
300 qemu_chr_add_handlers(s->chr, pl011_can_receive, pl011_receive,
301 pl011_event, s);
302 }
303 }
304
305 static void pl011_class_init(ObjectClass *oc, void *data)
306 {
307 DeviceClass *dc = DEVICE_CLASS(oc);
308
309 dc->realize = pl011_realize;
310 dc->vmsd = &vmstate_pl011;
311 }
312
313 static const TypeInfo pl011_arm_info = {
314 .name = TYPE_PL011,
315 .parent = TYPE_SYS_BUS_DEVICE,
316 .instance_size = sizeof(PL011State),
317 .instance_init = pl011_init,
318 .class_init = pl011_class_init,
319 };
320
321 static void pl011_luminary_init(Object *obj)
322 {
323 PL011State *s = PL011(obj);
324
325 s->id = pl011_id_luminary;
326 }
327
328 static const TypeInfo pl011_luminary_info = {
329 .name = "pl011_luminary",
330 .parent = TYPE_PL011,
331 .instance_init = pl011_luminary_init,
332 };
333
334 static void pl011_register_types(void)
335 {
336 type_register_static(&pl011_arm_info);
337 type_register_static(&pl011_luminary_info);
338 }
339
340 type_init(pl011_register_types)