hw/ssi/sifive_spi.c

   1 /*
   2  * QEMU model of the SiFive SPI Controller
   3  *
   4  * Copyright (c) 2021 Wind River Systems, Inc.
   5  *
   6  * Author:
   7  *   Bin Meng <bin.meng@windriver.com>
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms and conditions of the GNU General Public License,
  11  * version 2 or later, as published by the Free Software Foundation.
  12  *
  13  * This program is distributed in the hope it will be useful, but WITHOUT
  14  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  16  * more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along with
  19  * this program.  If not, see <http://www.gnu.org/licenses/>.
  20  */
  21
  22 #include "qemu/osdep.h"
  23 #include "hw/irq.h"
  24 #include "hw/qdev-properties.h"
  25 #include "hw/sysbus.h"
  26 #include "hw/ssi/ssi.h"
  27 #include "qemu/fifo8.h"
  28 #include "qemu/log.h"
  29 #include "qemu/module.h"
  30 #include "hw/ssi/sifive_spi.h"
  31
  32 #define R_SCKDIV        (0x00 / 4)
  33 #define R_SCKMODE       (0x04 / 4)
  34 #define R_CSID          (0x10 / 4)
  35 #define R_CSDEF         (0x14 / 4)
  36 #define R_CSMODE        (0x18 / 4)
  37 #define R_DELAY0        (0x28 / 4)
  38 #define R_DELAY1        (0x2C / 4)
  39 #define R_FMT           (0x40 / 4)
  40 #define R_TXDATA        (0x48 / 4)
  41 #define R_RXDATA        (0x4C / 4)
  42 #define R_TXMARK        (0x50 / 4)
  43 #define R_RXMARK        (0x54 / 4)
  44 #define R_FCTRL         (0x60 / 4)
  45 #define R_FFMT          (0x64 / 4)
  46 #define R_IE            (0x70 / 4)
  47 #define R_IP            (0x74 / 4)
  48
  49 #define FMT_DIR         (1 << 3)
  50
  51 #define TXDATA_FULL     (1 << 31)
  52 #define RXDATA_EMPTY    (1 << 31)
  53
  54 #define IE_TXWM         (1 << 0)
  55 #define IE_RXWM         (1 << 1)
  56
  57 #define IP_TXWM         (1 << 0)
  58 #define IP_RXWM         (1 << 1)
  59
  60 #define FIFO_CAPACITY   8
  61
  62 static void sifive_spi_txfifo_reset(SiFiveSPIState *s)
  63 {
  64     fifo8_reset(&s->tx_fifo);
  65
  66     s->regs[R_TXDATA] &= ~TXDATA_FULL;
  67     s->regs[R_IP] &= ~IP_TXWM;
  68 }
  69
  70 static void sifive_spi_rxfifo_reset(SiFiveSPIState *s)
  71 {
  72     fifo8_reset(&s->rx_fifo);
  73
  74     s->regs[R_RXDATA] |= RXDATA_EMPTY;
  75     s->regs[R_IP] &= ~IP_RXWM;
  76 }
  77
  78 static void sifive_spi_update_cs(SiFiveSPIState *s)
  79 {
  80     int i;
  81
  82     for (i = 0; i < s->num_cs; i++) {
  83         if (s->regs[R_CSDEF] & (1 << i)) {
  84             qemu_set_irq(s->cs_lines[i], !(s->regs[R_CSMODE]));
  85         }
  86     }
  87 }
  88
  89 static void sifive_spi_update_irq(SiFiveSPIState *s)
  90 {
  91     int level;
  92
  93     if (fifo8_num_used(&s->tx_fifo) < s->regs[R_TXMARK]) {
  94         s->regs[R_IP] |= IP_TXWM;
  95     } else {
  96         s->regs[R_IP] &= ~IP_TXWM;
  97     }
  98
  99     if (fifo8_num_used(&s->rx_fifo) > s->regs[R_RXMARK]) {
 100         s->regs[R_IP] |= IP_RXWM;
 101     } else {
 102         s->regs[R_IP] &= ~IP_RXWM;
 103     }
 104
 105     level = s->regs[R_IP] & s->regs[R_IE] ? 1 : 0;
 106     qemu_set_irq(s->irq, level);
 107 }
 108
 109 static void sifive_spi_reset(DeviceState *d)
 110 {
 111     SiFiveSPIState *s = SIFIVE_SPI(d);
 112
 113     memset(s->regs, 0, sizeof(s->regs));
 114
 115     /* The reset value is high for all implemented CS pins */
 116     s->regs[R_CSDEF] = (1 << s->num_cs) - 1;
 117
 118     /* Populate register with their default value */
 119     s->regs[R_SCKDIV] = 0x03;
 120     s->regs[R_DELAY0] = 0x1001;
 121     s->regs[R_DELAY1] = 0x01;
 122
 123     sifive_spi_txfifo_reset(s);
 124     sifive_spi_rxfifo_reset(s);
 125
 126     sifive_spi_update_cs(s);
 127     sifive_spi_update_irq(s);
 128 }
 129
 130 static void sifive_spi_flush_txfifo(SiFiveSPIState *s)
 131 {
 132     uint8_t tx;
 133     uint8_t rx;
 134
 135     while (!fifo8_is_empty(&s->tx_fifo)) {
 136         tx = fifo8_pop(&s->tx_fifo);
 137         rx = ssi_transfer(s->spi, tx);
 138
 139         if (!fifo8_is_full(&s->rx_fifo)) {
 140             if (!(s->regs[R_FMT] & FMT_DIR)) {
 141                 fifo8_push(&s->rx_fifo, rx);
 142             }
 143         }
 144     }
 145 }
 146
 147 static bool sifive_spi_is_bad_reg(hwaddr addr, bool allow_reserved)
 148 {
 149     bool bad;
 150
 151     switch (addr) {
 152     /* reserved offsets */
 153     case 0x08:
 154     case 0x0C:
 155     case 0x1C:
 156     case 0x20:
 157     case 0x24:
 158     case 0x30:
 159     case 0x34:
 160     case 0x38:
 161     case 0x3C:
 162     case 0x44:
 163     case 0x58:
 164     case 0x5C:
 165     case 0x68:
 166     case 0x6C:
 167         bad = allow_reserved ? false : true;
 168         break;
 169     default:
 170         bad = false;
 171     }
 172
 173     if (addr >= (SIFIVE_SPI_REG_NUM << 2)) {
 174         bad = true;
 175     }
 176
 177     return bad;
 178 }
 179
 180 static uint64_t sifive_spi_read(void *opaque, hwaddr addr, unsigned int size)
 181 {
 182     SiFiveSPIState *s = opaque;
 183     uint32_t r;
 184
 185     if (sifive_spi_is_bad_reg(addr, true)) {
 186         qemu_log_mask(LOG_GUEST_ERROR, "%s: bad read at address 0x%"
 187                       HWADDR_PRIx "\n", __func__, addr);
 188         return 0;
 189     }
 190
 191     addr >>= 2;
 192     switch (addr) {
 193     case R_TXDATA:
 194         if (fifo8_is_full(&s->tx_fifo)) {
 195             return TXDATA_FULL;
 196         }
 197         r = 0;
 198         break;
 199
 200     case R_RXDATA:
 201         if (fifo8_is_empty(&s->rx_fifo)) {
 202             return RXDATA_EMPTY;
 203         }
 204         r = fifo8_pop(&s->rx_fifo);
 205         break;
 206
 207     default:
 208         r = s->regs[addr];
 209         break;
 210     }
 211
 212     sifive_spi_update_irq(s);
 213
 214     return r;
 215 }
 216
 217 static void sifive_spi_write(void *opaque, hwaddr addr,
 218                              uint64_t val64, unsigned int size)
 219 {
 220     SiFiveSPIState *s = opaque;
 221     uint32_t value = val64;
 222
 223     if (sifive_spi_is_bad_reg(addr, false)) {
 224         qemu_log_mask(LOG_GUEST_ERROR, "%s: bad write at addr=0x%"
 225                       HWADDR_PRIx " value=0x%x\n", __func__, addr, value);
 226         return;
 227     }
 228
 229     addr >>= 2;
 230     switch (addr) {
 231     case R_CSID:
 232         if (value >= s->num_cs) {
 233             qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid csid %d\n",
 234                           __func__, value);
 235         } else {
 236             s->regs[R_CSID] = value;
 237             sifive_spi_update_cs(s);
 238         }
 239         break;
 240
 241     case R_CSDEF:
 242         if (value >= (1 << s->num_cs)) {
 243             qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid csdef %x\n",
 244                           __func__, value);
 245         } else {
 246             s->regs[R_CSDEF] = value;
 247         }
 248         break;
 249
 250     case R_CSMODE:
 251         if (value > 3) {
 252             qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid csmode %x\n",
 253                           __func__, value);
 254         } else {
 255             s->regs[R_CSMODE] = value;
 256             sifive_spi_update_cs(s);
 257         }
 258         break;
 259
 260     case R_TXDATA:
 261         if (!fifo8_is_full(&s->tx_fifo)) {
 262             fifo8_push(&s->tx_fifo, (uint8_t)value);
 263             sifive_spi_flush_txfifo(s);
 264         }
 265         break;
 266
 267     case R_RXDATA:
 268     case R_IP:
 269         qemu_log_mask(LOG_GUEST_ERROR,
 270                       "%s: invalid write to read-only register 0x%"
 271                       HWADDR_PRIx " with 0x%x\n", __func__, addr << 2, value);
 272         break;
 273
 274     case R_TXMARK:
 275     case R_RXMARK:
 276         if (value >= FIFO_CAPACITY) {
 277             qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid watermark %d\n",
 278                           __func__, value);
 279         } else {
 280             s->regs[addr] = value;
 281         }
 282         break;
 283
 284     case R_FCTRL:
 285     case R_FFMT:
 286         qemu_log_mask(LOG_UNIMP,
 287                       "%s: direct-map flash interface unimplemented\n",
 288                       __func__);
 289         break;
 290
 291     default:
 292         s->regs[addr] = value;
 293         break;
 294     }
 295
 296     sifive_spi_update_irq(s);
 297 }
 298
 299 static const MemoryRegionOps sifive_spi_ops = {
 300     .read = sifive_spi_read,
 301     .write = sifive_spi_write,
 302     .endianness = DEVICE_LITTLE_ENDIAN,
 303     .valid = {
 304         .min_access_size = 4,
 305         .max_access_size = 4
 306     }
 307 };
 308
 309 static void sifive_spi_realize(DeviceState *dev, Error **errp)
 310 {
 311     SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
 312     SiFiveSPIState *s = SIFIVE_SPI(dev);
 313     int i;
 314
 315     s->spi = ssi_create_bus(dev, "spi");
 316     sysbus_init_irq(sbd, &s->irq);
 317
 318     s->cs_lines = g_new0(qemu_irq, s->num_cs);
 319     for (i = 0; i < s->num_cs; i++) {
 320         sysbus_init_irq(sbd, &s->cs_lines[i]);
 321     }
 322
 323     memory_region_init_io(&s->mmio, OBJECT(s), &sifive_spi_ops, s,
 324                           TYPE_SIFIVE_SPI, 0x1000);
 325     sysbus_init_mmio(sbd, &s->mmio);
 326
 327     fifo8_create(&s->tx_fifo, FIFO_CAPACITY);
 328     fifo8_create(&s->rx_fifo, FIFO_CAPACITY);
 329 }
 330
 331 static Property sifive_spi_properties[] = {
 332     DEFINE_PROP_UINT32("num-cs", SiFiveSPIState, num_cs, 1),
 333     DEFINE_PROP_END_OF_LIST(),
 334 };
 335
 336 static void sifive_spi_class_init(ObjectClass *klass, void *data)
 337 {
 338     DeviceClass *dc = DEVICE_CLASS(klass);
 339
 340     device_class_set_props(dc, sifive_spi_properties);
 341     dc->reset = sifive_spi_reset;
 342     dc->realize = sifive_spi_realize;
 343 }
 344
 345 static const TypeInfo sifive_spi_info = {
 346     .name           = TYPE_SIFIVE_SPI,
 347     .parent         = TYPE_SYS_BUS_DEVICE,
 348     .instance_size  = sizeof(SiFiveSPIState),
 349     .class_init     = sifive_spi_class_init,
 350 };
 351
 352 static void sifive_spi_register_types(void)
 353 {
 354     type_register_static(&sifive_spi_info);
 355 }
 356
 357 type_init(sifive_spi_register_types)