1/*
2 * ARM MPS2 SCC emulation
3 *
4 * Copyright (c) 2017 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 SCC (Serial Communication Controller)
13 * found in the FPGA images of MPS2 development boards.
14 *
15 * Documentation of it can be found in the MPS2 TRM:
16 * http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.100112_0100_03_en/index.html
17 * and also in the Application Notes documenting individual FPGA images.
18 */
19
20#include "qemu/osdep.h"
21#include "qemu/log.h"
22#include "qemu/module.h"
23#include "trace.h"
24#include "hw/sysbus.h"
25#include "migration/vmstate.h"
26#include "hw/registerfields.h"
27#include "hw/misc/mps2-scc.h"
28#include "hw/qdev-properties.h"
29
30REG32(CFG0, 0)
31REG32(CFG1, 4)
32REG32(CFG3, 0xc)
33REG32(CFG4, 0x10)
34REG32(CFGDATA_RTN, 0xa0)
35REG32(CFGDATA_OUT, 0xa4)
36REG32(CFGCTRL, 0xa8)
37 FIELD(CFGCTRL, DEVICE, 0, 12)
38 FIELD(CFGCTRL, RES1, 12, 8)
39 FIELD(CFGCTRL, FUNCTION, 20, 6)
40 FIELD(CFGCTRL, RES2, 26, 4)
41 FIELD(CFGCTRL, WRITE, 30, 1)
42 FIELD(CFGCTRL, START, 31, 1)
43REG32(CFGSTAT, 0xac)
44 FIELD(CFGSTAT, DONE, 0, 1)
45 FIELD(CFGSTAT, ERROR, 1, 1)
46REG32(DLL, 0x100)
47REG32(AID, 0xFF8)
48REG32(ID, 0xFFC)
49
50/* Handle a write via the SYS_CFG channel to the specified function/device.
51 * Return false on error (reported to guest via SYS_CFGCTRL ERROR bit).
52 */
53static bool scc_cfg_write(MPS2SCC *s, unsigned function,
54 unsigned device, uint32_t value)
55{
56 trace_mps2_scc_cfg_write(function, device, value);
57
58 if (function != 1 || device >= NUM_OSCCLK) {
59 qemu_log_mask(LOG_GUEST_ERROR,
60 "MPS2 SCC config write: bad function %d device %d\n",
61 function, device);
62 return false;
63 }
64
65 s->oscclk[device] = value;
66 return true;
67}
68
69/* Handle a read via the SYS_CFG channel to the specified function/device.
70 * Return false on error (reported to guest via SYS_CFGCTRL ERROR bit),
71 * or set *value on success.
72 */
73static bool scc_cfg_read(MPS2SCC *s, unsigned function,
74 unsigned device, uint32_t *value)
75{
76 if (function != 1 || device >= NUM_OSCCLK) {
77 qemu_log_mask(LOG_GUEST_ERROR,
78 "MPS2 SCC config read: bad function %d device %d\n",
79 function, device);
80 return false;
81 }
82
83 *value = s->oscclk[device];
84
85 trace_mps2_scc_cfg_read(function, device, *value);
86 return true;
87}
88
89static uint64_t mps2_scc_read(void *opaque, hwaddr offset, unsigned size)
90{
91 MPS2SCC *s = MPS2_SCC(opaque);
92 uint64_t r;
93
94 switch (offset) {
95 case A_CFG0:
96 r = s->cfg0;
97 break;
98 case A_CFG1:
99 r = s->cfg1;
100 break;
101 case A_CFG3:
102 /* These are user-settable DIP switches on the board. We don't
103 * model that, so just return zeroes.
104 */
105 r = 0;
106 break;
107 case A_CFG4:
108 r = s->cfg4;
109 break;
110 case A_CFGDATA_RTN:
111 r = s->cfgdata_rtn;
112 break;
113 case A_CFGDATA_OUT:
114 r = s->cfgdata_out;
115 break;
116 case A_CFGCTRL:
117 r = s->cfgctrl;
118 break;
119 case A_CFGSTAT:
120 r = s->cfgstat;
121 break;
122 case A_DLL:
123 r = s->dll;
124 break;
125 case A_AID:
126 r = s->aid;
127 break;
128 case A_ID:
129 r = s->id;
130 break;
131 default:
132 qemu_log_mask(LOG_GUEST_ERROR,
133 "MPS2 SCC read: bad offset %x\n", (int) offset);
134 r = 0;
135 break;
136 }
137
138 trace_mps2_scc_read(offset, r, size);
139 return r;
140}
141
142static void mps2_scc_write(void *opaque, hwaddr offset, uint64_t value,
143 unsigned size)
144{
145 MPS2SCC *s = MPS2_SCC(opaque);
146
147 trace_mps2_scc_write(offset, value, size);
148
149 switch (offset) {
150 case A_CFG0:
151 /* TODO on some boards bit 0 controls RAM remapping */
152 s->cfg0 = value;
153 break;
154 case A_CFG1:
155 /* CFG1 bits [7:0] control the board LEDs. We don't currently have
156 * a mechanism for displaying this graphically, so use a trace event.
157 */
158 trace_mps2_scc_leds(value & 0x80 ? '*' : '.',
159 value & 0x40 ? '*' : '.',
160 value & 0x20 ? '*' : '.',
161 value & 0x10 ? '*' : '.',
162 value & 0x08 ? '*' : '.',
163 value & 0x04 ? '*' : '.',
164 value & 0x02 ? '*' : '.',
165 value & 0x01 ? '*' : '.');
166 s->cfg1 = value;
167 break;
168 case A_CFGDATA_OUT:
169 s->cfgdata_out = value;
170 break;
171 case A_CFGCTRL:
172 /* Writing to CFGCTRL clears SYS_CFGSTAT */
173 s->cfgstat = 0;
174 s->cfgctrl = value & ~(R_CFGCTRL_RES1_MASK |
175 R_CFGCTRL_RES2_MASK |
176 R_CFGCTRL_START_MASK);
177
178 if (value & R_CFGCTRL_START_MASK) {
179 /* Start bit set -- do a read or write (instantaneously) */
180 int device = extract32(s->cfgctrl, R_CFGCTRL_DEVICE_SHIFT,
181 R_CFGCTRL_DEVICE_LENGTH);
182 int function = extract32(s->cfgctrl, R_CFGCTRL_FUNCTION_SHIFT,
183 R_CFGCTRL_FUNCTION_LENGTH);
184
185 s->cfgstat = R_CFGSTAT_DONE_MASK;
186 if (s->cfgctrl & R_CFGCTRL_WRITE_MASK) {
187 if (!scc_cfg_write(s, function, device, s->cfgdata_out)) {
188 s->cfgstat |= R_CFGSTAT_ERROR_MASK;
189 }
190 } else {
191 uint32_t result;
192 if (!scc_cfg_read(s, function, device, &result)) {
193 s->cfgstat |= R_CFGSTAT_ERROR_MASK;
194 } else {
195 s->cfgdata_rtn = result;
196 }
197 }
198 }
199 break;
200 case A_DLL:
201 /* DLL stands for Digital Locked Loop.
202 * Bits [31:24] (DLL_LOCK_MASK) are writable, and indicate a
203 * mask of which of the DLL_LOCKED bits [16:23] should be ORed
204 * together to determine the ALL_UNMASKED_DLLS_LOCKED bit [0].
205 * For QEMU, our DLLs are always locked, so we can leave bit 0
206 * as 1 always and don't need to recalculate it.
207 */
208 s->dll = deposit32(s->dll, 24, 8, extract32(value, 24, 8));
209 break;
210 default:
211 qemu_log_mask(LOG_GUEST_ERROR,
212 "MPS2 SCC write: bad offset 0x%x\n", (int) offset);
213 break;
214 }
215}
216
217static const MemoryRegionOps mps2_scc_ops = {
218 .read = mps2_scc_read,
219 .write = mps2_scc_write,
220 .endianness = DEVICE_LITTLE_ENDIAN,
221};
222
223static void mps2_scc_reset(DeviceState *dev)
224{
225 MPS2SCC *s = MPS2_SCC(dev);
226 int i;
227
228 trace_mps2_scc_reset();
229 s->cfg0 = 0;
230 s->cfg1 = 0;
231 s->cfgdata_rtn = 0;
232 s->cfgdata_out = 0;
233 s->cfgctrl = 0x100000;
234 s->cfgstat = 0;
235 s->dll = 0xffff0001;
236 for (i = 0; i < NUM_OSCCLK; i++) {
237 s->oscclk[i] = s->oscclk_reset[i];
238 }
239}
240
241static void mps2_scc_init(Object *obj)
242{
243 SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
244 MPS2SCC *s = MPS2_SCC(obj);
245
246 memory_region_init_io(&s->iomem, obj, &mps2_scc_ops, s, "mps2-scc", 0x1000);
247 sysbus_init_mmio(sbd, &s->iomem);
248}
249
250static void mps2_scc_realize(DeviceState *dev, Error **errp)
251{
252}
253
254static const VMStateDescription mps2_scc_vmstate = {
255 .name = "mps2-scc",
256 .version_id = 1,
257 .minimum_version_id = 1,
258 .fields = (VMStateField[]) {
259 VMSTATE_UINT32(cfg0, MPS2SCC),
260 VMSTATE_UINT32(cfg1, MPS2SCC),
261 VMSTATE_UINT32(cfgdata_rtn, MPS2SCC),
262 VMSTATE_UINT32(cfgdata_out, MPS2SCC),
263 VMSTATE_UINT32(cfgctrl, MPS2SCC),
264 VMSTATE_UINT32(cfgstat, MPS2SCC),
265 VMSTATE_UINT32(dll, MPS2SCC),
266 VMSTATE_UINT32_ARRAY(oscclk, MPS2SCC, NUM_OSCCLK),
267 VMSTATE_END_OF_LIST()
268 }
269};
270
271static Property mps2_scc_properties[] = {
272 /* Values for various read-only ID registers (which are specific
273 * to the board model or FPGA image)
274 */
275 DEFINE_PROP_UINT32("scc-cfg4", MPS2SCC, cfg4, 0),
276 DEFINE_PROP_UINT32("scc-aid", MPS2SCC, aid, 0),
277 DEFINE_PROP_UINT32("scc-id", MPS2SCC, id, 0),
278 /* These are the initial settings for the source clocks on the board.
279 * In hardware they can be configured via a config file read by the
280 * motherboard configuration controller to suit the FPGA image.
281 * These default values are used by most of the standard FPGA images.
282 */
283 DEFINE_PROP_UINT32("oscclk0", MPS2SCC, oscclk_reset[0], 50000000),
284 DEFINE_PROP_UINT32("oscclk1", MPS2SCC, oscclk_reset[1], 24576000),
285 DEFINE_PROP_UINT32("oscclk2", MPS2SCC, oscclk_reset[2], 25000000),
286 DEFINE_PROP_END_OF_LIST(),
287};
288
289static void mps2_scc_class_init(ObjectClass *klass, void *data)
290{
291 DeviceClass *dc = DEVICE_CLASS(klass);
292
293 dc->realize = mps2_scc_realize;
294 dc->vmsd = &mps2_scc_vmstate;
295 dc->reset = mps2_scc_reset;
296 dc->props = mps2_scc_properties;
297}
298
299static const TypeInfo mps2_scc_info = {
300 .name = TYPE_MPS2_SCC,
301 .parent = TYPE_SYS_BUS_DEVICE,
302 .instance_size = sizeof(MPS2SCC),
303 .instance_init = mps2_scc_init,
304 .class_init = mps2_scc_class_init,
305};
306
307static void mps2_scc_register_types(void)
308{
309 type_register_static(&mps2_scc_info);
310}
311
312type_init(mps2_scc_register_types);
313