hw/misc/mps2-scc.c

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