hw/pl022.c

   1 /*
   2  * Arm PrimeCell PL022 Synchronous Serial Port
   3  *
   4  * Copyright (c) 2007 CodeSourcery.
   5  * Written by Paul Brook
   6  *
   7  * This code is licensed under the GPL.
   8  */
   9
  10 #include "sysbus.h"
  11 #include "ssi.h"
  12
  13 //#define DEBUG_PL022 1
  14
  15 #ifdef DEBUG_PL022
  16 #define DPRINTF(fmt, ...) \
  17 do { printf("pl022: " fmt , ## __VA_ARGS__); } while (0)
  18 #define BADF(fmt, ...) \
  19 do { fprintf(stderr, "pl022: error: " fmt , ## __VA_ARGS__); exit(1);} while (0)
  20 #else
  21 #define DPRINTF(fmt, ...) do {} while(0)
  22 #define BADF(fmt, ...) \
  23 do { fprintf(stderr, "pl022: error: " fmt , ## __VA_ARGS__);} while (0)
  24 #endif
  25
  26 #define PL022_CR1_LBM 0x01
  27 #define PL022_CR1_SSE 0x02
  28 #define PL022_CR1_MS  0x04
  29 #define PL022_CR1_SDO 0x08
  30
  31 #define PL022_SR_TFE  0x01
  32 #define PL022_SR_TNF  0x02
  33 #define PL022_SR_RNE  0x04
  34 #define PL022_SR_RFF  0x08
  35 #define PL022_SR_BSY  0x10
  36
  37 #define PL022_INT_ROR 0x01
  38 #define PL022_INT_RT  0x04
  39 #define PL022_INT_RX  0x04
  40 #define PL022_INT_TX  0x08
  41
  42 typedef struct {
  43     SysBusDevice busdev;
  44     MemoryRegion iomem;
  45     uint32_t cr0;
  46     uint32_t cr1;
  47     uint32_t bitmask;
  48     uint32_t sr;
  49     uint32_t cpsr;
  50     uint32_t is;
  51     uint32_t im;
  52     /* The FIFO head points to the next empty entry.  */
  53     int tx_fifo_head;
  54     int rx_fifo_head;
  55     int tx_fifo_len;
  56     int rx_fifo_len;
  57     uint16_t tx_fifo[8];
  58     uint16_t rx_fifo[8];
  59     qemu_irq irq;
  60     SSIBus *ssi;
  61 } pl022_state;
  62
  63 static const unsigned char pl022_id[8] =
  64   { 0x22, 0x10, 0x04, 0x00, 0x0d, 0xf0, 0x05, 0xb1 };
  65
  66 static void pl022_update(pl022_state *s)
  67 {
  68     s->sr = 0;
  69     if (s->tx_fifo_len == 0)
  70         s->sr |= PL022_SR_TFE;
  71     if (s->tx_fifo_len != 8)
  72         s->sr |= PL022_SR_TNF;
  73     if (s->rx_fifo_len != 0)
  74         s->sr |= PL022_SR_RNE;
  75     if (s->rx_fifo_len == 8)
  76         s->sr |= PL022_SR_RFF;
  77     if (s->tx_fifo_len)
  78         s->sr |= PL022_SR_BSY;
  79     s->is = 0;
  80     if (s->rx_fifo_len >= 4)
  81         s->is |= PL022_INT_RX;
  82     if (s->tx_fifo_len <= 4)
  83         s->is |= PL022_INT_TX;
  84
  85     qemu_set_irq(s->irq, (s->is & s->im) != 0);
  86 }
  87
  88 static void pl022_xfer(pl022_state *s)
  89 {
  90     int i;
  91     int o;
  92     int val;
  93
  94     if ((s->cr1 & PL022_CR1_SSE) == 0) {
  95         pl022_update(s);
  96         DPRINTF("Disabled\n");
  97         return;
  98     }
  99
 100     DPRINTF("Maybe xfer %d/%d\n", s->tx_fifo_len, s->rx_fifo_len);
 101     i = (s->tx_fifo_head - s->tx_fifo_len) & 7;
 102     o = s->rx_fifo_head;
 103     /* ??? We do not emulate the line speed.
 104        This may break some applications.  The are two problematic cases:
 105         (a) A driver feeds data into the TX FIFO until it is full,
 106          and only then drains the RX FIFO.  On real hardware the CPU can
 107          feed data fast enough that the RX fifo never gets chance to overflow.
 108         (b) A driver transmits data, deliberately allowing the RX FIFO to
 109          overflow because it ignores the RX data anyway.
 110
 111        We choose to support (a) by stalling the transmit engine if it would
 112        cause the RX FIFO to overflow.  In practice much transmit-only code
 113        falls into (a) because it flushes the RX FIFO to determine when
 114        the transfer has completed.  */
 115     while (s->tx_fifo_len && s->rx_fifo_len < 8) {
 116         DPRINTF("xfer\n");
 117         val = s->tx_fifo[i];
 118         if (s->cr1 & PL022_CR1_LBM) {
 119             /* Loopback mode.  */
 120         } else {
 121             val = ssi_transfer(s->ssi, val);
 122         }
 123         s->rx_fifo[o] = val & s->bitmask;
 124         i = (i + 1) & 7;
 125         o = (o + 1) & 7;
 126         s->tx_fifo_len--;
 127         s->rx_fifo_len++;
 128     }
 129     s->rx_fifo_head = o;
 130     pl022_update(s);
 131 }
 132
 133 static uint64_t pl022_read(void *opaque, hwaddr offset,
 134                            unsigned size)
 135 {
 136     pl022_state *s = (pl022_state *)opaque;
 137     int val;
 138
 139     if (offset >= 0xfe0 && offset < 0x1000) {
 140         return pl022_id[(offset - 0xfe0) >> 2];
 141     }
 142     switch (offset) {
 143     case 0x00: /* CR0 */
 144       return s->cr0;
 145     case 0x04: /* CR1 */
 146       return s->cr1;
 147     case 0x08: /* DR */
 148         if (s->rx_fifo_len) {
 149             val = s->rx_fifo[(s->rx_fifo_head - s->rx_fifo_len) & 7];
 150             DPRINTF("RX %02x\n", val);
 151             s->rx_fifo_len--;
 152             pl022_xfer(s);
 153         } else {
 154             val = 0;
 155         }
 156         return val;
 157     case 0x0c: /* SR */
 158         return s->sr;
 159     case 0x10: /* CPSR */
 160         return s->cpsr;
 161     case 0x14: /* IMSC */
 162         return s->im;
 163     case 0x18: /* RIS */
 164         return s->is;
 165     case 0x1c: /* MIS */
 166         return s->im & s->is;
 167     case 0x20: /* DMACR */
 168         /* Not implemented.  */
 169         return 0;
 170     default:
 171         qemu_log_mask(LOG_GUEST_ERROR,
 172                       "pl022_read: Bad offset %x\n", (int)offset);
 173         return 0;
 174     }
 175 }
 176
 177 static void pl022_write(void *opaque, hwaddr offset,
 178                         uint64_t value, unsigned size)
 179 {
 180     pl022_state *s = (pl022_state *)opaque;
 181
 182     switch (offset) {
 183     case 0x00: /* CR0 */
 184         s->cr0 = value;
 185         /* Clock rate and format are ignored.  */
 186         s->bitmask = (1 << ((value & 15) + 1)) - 1;
 187         break;
 188     case 0x04: /* CR1 */
 189         s->cr1 = value;
 190         if ((s->cr1 & (PL022_CR1_MS | PL022_CR1_SSE))
 191                    == (PL022_CR1_MS | PL022_CR1_SSE)) {
 192             BADF("SPI slave mode not implemented\n");
 193         }
 194         pl022_xfer(s);
 195         break;
 196     case 0x08: /* DR */
 197         if (s->tx_fifo_len < 8) {
 198             DPRINTF("TX %02x\n", (unsigned)value);
 199             s->tx_fifo[s->tx_fifo_head] = value & s->bitmask;
 200             s->tx_fifo_head = (s->tx_fifo_head + 1) & 7;
 201             s->tx_fifo_len++;
 202             pl022_xfer(s);
 203         }
 204         break;
 205     case 0x10: /* CPSR */
 206         /* Prescaler.  Ignored.  */
 207         s->cpsr = value & 0xff;
 208         break;
 209     case 0x14: /* IMSC */
 210         s->im = value;
 211         pl022_update(s);
 212         break;
 213     case 0x20: /* DMACR */
 214         if (value) {
 215             qemu_log_mask(LOG_UNIMP, "pl022: DMA not implemented\n");
 216         }
 217         break;
 218     default:
 219         qemu_log_mask(LOG_GUEST_ERROR,
 220                       "pl022_write: Bad offset %x\n", (int)offset);
 221     }
 222 }
 223
 224 static void pl022_reset(pl022_state *s)
 225 {
 226     s->rx_fifo_len = 0;
 227     s->tx_fifo_len = 0;
 228     s->im = 0;
 229     s->is = PL022_INT_TX;
 230     s->sr = PL022_SR_TFE | PL022_SR_TNF;
 231 }
 232
 233 static const MemoryRegionOps pl022_ops = {
 234     .read = pl022_read,
 235     .write = pl022_write,
 236     .endianness = DEVICE_NATIVE_ENDIAN,
 237 };
 238
 239 static const VMStateDescription vmstate_pl022 = {
 240     .name = "pl022_ssp",
 241     .version_id = 1,
 242     .minimum_version_id = 1,
 243     .minimum_version_id_old = 1,
 244     .fields      = (VMStateField[]) {
 245         VMSTATE_UINT32(cr0, pl022_state),
 246         VMSTATE_UINT32(cr1, pl022_state),
 247         VMSTATE_UINT32(bitmask, pl022_state),
 248         VMSTATE_UINT32(sr, pl022_state),
 249         VMSTATE_UINT32(cpsr, pl022_state),
 250         VMSTATE_UINT32(is, pl022_state),
 251         VMSTATE_UINT32(im, pl022_state),
 252         VMSTATE_INT32(tx_fifo_head, pl022_state),
 253         VMSTATE_INT32(rx_fifo_head, pl022_state),
 254         VMSTATE_INT32(tx_fifo_len, pl022_state),
 255         VMSTATE_INT32(rx_fifo_len, pl022_state),
 256         VMSTATE_UINT16(tx_fifo[0], pl022_state),
 257         VMSTATE_UINT16(rx_fifo[0], pl022_state),
 258         VMSTATE_UINT16(tx_fifo[1], pl022_state),
 259         VMSTATE_UINT16(rx_fifo[1], pl022_state),
 260         VMSTATE_UINT16(tx_fifo[2], pl022_state),
 261         VMSTATE_UINT16(rx_fifo[2], pl022_state),
 262         VMSTATE_UINT16(tx_fifo[3], pl022_state),
 263         VMSTATE_UINT16(rx_fifo[3], pl022_state),
 264         VMSTATE_UINT16(tx_fifo[4], pl022_state),
 265         VMSTATE_UINT16(rx_fifo[4], pl022_state),
 266         VMSTATE_UINT16(tx_fifo[5], pl022_state),
 267         VMSTATE_UINT16(rx_fifo[5], pl022_state),
 268         VMSTATE_UINT16(tx_fifo[6], pl022_state),
 269         VMSTATE_UINT16(rx_fifo[6], pl022_state),
 270         VMSTATE_UINT16(tx_fifo[7], pl022_state),
 271         VMSTATE_UINT16(rx_fifo[7], pl022_state),
 272         VMSTATE_END_OF_LIST()
 273     }
 274 };
 275
 276 static int pl022_init(SysBusDevice *dev)
 277 {
 278     pl022_state *s = FROM_SYSBUS(pl022_state, dev);
 279
 280     memory_region_init_io(&s->iomem, &pl022_ops, s, "pl022", 0x1000);
 281     sysbus_init_mmio(dev, &s->iomem);
 282     sysbus_init_irq(dev, &s->irq);
 283     s->ssi = ssi_create_bus(&dev->qdev, "ssi");
 284     pl022_reset(s);
 285     vmstate_register(&dev->qdev, -1, &vmstate_pl022, s);
 286     return 0;
 287 }
 288
 289 static void pl022_class_init(ObjectClass *klass, void *data)
 290 {
 291     SysBusDeviceClass *sdc = SYS_BUS_DEVICE_CLASS(klass);
 292
 293     sdc->init = pl022_init;
 294 }
 295
 296 static const TypeInfo pl022_info = {
 297     .name          = "pl022",
 298     .parent        = TYPE_SYS_BUS_DEVICE,
 299     .instance_size = sizeof(pl022_state),
 300     .class_init    = pl022_class_init,
 301 };
 302
 303 static void pl022_register_types(void)
 304 {
 305     type_register_static(&pl022_info);
 306 }
 307
 308 type_init(pl022_register_types)