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 #include "primecell.h"
  13
  14 //#define DEBUG_PL022 1
  15
  16 #ifdef DEBUG_PL022
  17 #define DPRINTF(fmt, ...) \
  18 do { printf("pl022: " fmt , ## __VA_ARGS__); } while (0)
  19 #define BADF(fmt, ...) \
  20 do { fprintf(stderr, "pl022: error: " fmt , ## __VA_ARGS__); exit(1);} while (0)
  21 #else
  22 #define DPRINTF(fmt, ...) do {} while(0)
  23 #define BADF(fmt, ...) \
  24 do { fprintf(stderr, "pl022: error: " fmt , ## __VA_ARGS__);} while (0)
  25 #endif
  26
  27 #define PL022_CR1_LBM 0x01
  28 #define PL022_CR1_SSE 0x02
  29 #define PL022_CR1_MS  0x04
  30 #define PL022_CR1_SDO 0x08
  31
  32 #define PL022_SR_TFE  0x01
  33 #define PL022_SR_TNF  0x02
  34 #define PL022_SR_RNE  0x04
  35 #define PL022_SR_RFF  0x08
  36 #define PL022_SR_BSY  0x10
  37
  38 #define PL022_INT_ROR 0x01
  39 #define PL022_INT_RT  0x04
  40 #define PL022_INT_RX  0x04
  41 #define PL022_INT_TX  0x08
  42
  43 typedef struct {
  44     SysBusDevice busdev;
  45     MemoryRegion iomem;
  46     uint32_t cr0;
  47     uint32_t cr1;
  48     uint32_t bitmask;
  49     uint32_t sr;
  50     uint32_t cpsr;
  51     uint32_t is;
  52     uint32_t im;
  53     /* The FIFO head points to the next empty entry.  */
  54     int tx_fifo_head;
  55     int rx_fifo_head;
  56     int tx_fifo_len;
  57     int rx_fifo_len;
  58     uint16_t tx_fifo[8];
  59     uint16_t rx_fifo[8];
  60     qemu_irq irq;
  61     SSIBus *ssi;
  62 } pl022_state;
  63
  64 static const unsigned char pl022_id[8] =
  65   { 0x22, 0x10, 0x04, 0x00, 0x0d, 0xf0, 0x05, 0xb1 };
  66
  67 static void pl022_update(pl022_state *s)
  68 {
  69     s->sr = 0;
  70     if (s->tx_fifo_len == 0)
  71         s->sr |= PL022_SR_TFE;
  72     if (s->tx_fifo_len != 8)
  73         s->sr |= PL022_SR_TNF;
  74     if (s->rx_fifo_len != 0)
  75         s->sr |= PL022_SR_RNE;
  76     if (s->rx_fifo_len == 8)
  77         s->sr |= PL022_SR_RFF;
  78     if (s->tx_fifo_len)
  79         s->sr |= PL022_SR_BSY;
  80     s->is = 0;
  81     if (s->rx_fifo_len >= 4)
  82         s->is |= PL022_INT_RX;
  83     if (s->tx_fifo_len <= 4)
  84         s->is |= PL022_INT_TX;
  85
  86     qemu_set_irq(s->irq, (s->is & s->im) != 0);
  87 }
  88
  89 static void pl022_xfer(pl022_state *s)
  90 {
  91     int i;
  92     int o;
  93     int val;
  94
  95     if ((s->cr1 & PL022_CR1_SSE) == 0) {
  96         pl022_update(s);
  97         DPRINTF("Disabled\n");
  98         return;
  99     }
 100
 101     DPRINTF("Maybe xfer %d/%d\n", s->tx_fifo_len, s->rx_fifo_len);
 102     i = (s->tx_fifo_head - s->tx_fifo_len) & 7;
 103     o = s->rx_fifo_head;
 104     /* ??? We do not emulate the line speed.
 105        This may break some applications.  The are two problematic cases:
 106         (a) A driver feeds data into the TX FIFO until it is full,
 107          and only then drains the RX FIFO.  On real hardware the CPU can
 108          feed data fast enough that the RX fifo never gets chance to overflow.
 109         (b) A driver transmits data, deliberately allowing the RX FIFO to
 110          overflow because it ignores the RX data anyway.
 111
 112        We choose to support (a) by stalling the transmit engine if it would
 113        cause the RX FIFO to overflow.  In practice much transmit-only code
 114        falls into (a) because it flushes the RX FIFO to determine when
 115        the transfer has completed.  */
 116     while (s->tx_fifo_len && s->rx_fifo_len < 8) {
 117         DPRINTF("xfer\n");
 118         val = s->tx_fifo[i];
 119         if (s->cr1 & PL022_CR1_LBM) {
 120             /* Loopback mode.  */
 121         } else {
 122             val = ssi_transfer(s->ssi, val);
 123         }
 124         s->rx_fifo[o] = val & s->bitmask;
 125         i = (i + 1) & 7;
 126         o = (o + 1) & 7;
 127         s->tx_fifo_len--;
 128         s->rx_fifo_len++;
 129     }
 130     s->rx_fifo_head = o;
 131     pl022_update(s);
 132 }
 133
 134 static uint64_t pl022_read(void *opaque, target_phys_addr_t offset,
 135                            unsigned size)
 136 {
 137     pl022_state *s = (pl022_state *)opaque;
 138     int val;
 139
 140     if (offset >= 0xfe0 && offset < 0x1000) {
 141         return pl022_id[(offset - 0xfe0) >> 2];
 142     }
 143     switch (offset) {
 144     case 0x00: /* CR0 */
 145       return s->cr0;
 146     case 0x04: /* CR1 */
 147       return s->cr1;
 148     case 0x08: /* DR */
 149         if (s->rx_fifo_len) {
 150             val = s->rx_fifo[(s->rx_fifo_head - s->rx_fifo_len) & 7];
 151             DPRINTF("RX %02x\n", val);
 152             s->rx_fifo_len--;
 153             pl022_xfer(s);
 154         } else {
 155             val = 0;
 156         }
 157         return val;
 158     case 0x0c: /* SR */
 159         return s->sr;
 160     case 0x10: /* CPSR */
 161         return s->cpsr;
 162     case 0x14: /* IMSC */
 163         return s->im;
 164     case 0x18: /* RIS */
 165         return s->is;
 166     case 0x1c: /* MIS */
 167         return s->im & s->is;
 168     case 0x20: /* DMACR */
 169         /* Not implemented.  */
 170         return 0;
 171     default:
 172         hw_error("pl022_read: Bad offset %x\n", (int)offset);
 173         return 0;
 174     }
 175 }
 176
 177 static void pl022_write(void *opaque, target_phys_addr_t 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             hw_error("pl022: DMA not implemented\n");
 216         }
 217         break;
 218     default:
 219         hw_error("pl022_write: Bad offset %x\n", (int)offset);
 220     }
 221 }
 222
 223 static void pl022_reset(pl022_state *s)
 224 {
 225     s->rx_fifo_len = 0;
 226     s->tx_fifo_len = 0;
 227     s->im = 0;
 228     s->is = PL022_INT_TX;
 229     s->sr = PL022_SR_TFE | PL022_SR_TNF;
 230 }
 231
 232 static const MemoryRegionOps pl022_ops = {
 233     .read = pl022_read,
 234     .write = pl022_write,
 235     .endianness = DEVICE_NATIVE_ENDIAN,
 236 };
 237
 238 static const VMStateDescription vmstate_pl022 = {
 239     .name = "pl022_ssp",
 240     .version_id = 1,
 241     .minimum_version_id = 1,
 242     .minimum_version_id_old = 1,
 243     .fields      = (VMStateField[]) {
 244         VMSTATE_UINT32(cr0, pl022_state),
 245         VMSTATE_UINT32(cr1, pl022_state),
 246         VMSTATE_UINT32(bitmask, pl022_state),
 247         VMSTATE_UINT32(sr, pl022_state),
 248         VMSTATE_UINT32(cpsr, pl022_state),
 249         VMSTATE_UINT32(is, pl022_state),
 250         VMSTATE_UINT32(im, pl022_state),
 251         VMSTATE_INT32(tx_fifo_head, pl022_state),
 252         VMSTATE_INT32(rx_fifo_head, pl022_state),
 253         VMSTATE_INT32(tx_fifo_len, pl022_state),
 254         VMSTATE_INT32(rx_fifo_len, pl022_state),
 255         VMSTATE_UINT16(tx_fifo[0], pl022_state),
 256         VMSTATE_UINT16(rx_fifo[0], pl022_state),
 257         VMSTATE_UINT16(tx_fifo[1], pl022_state),
 258         VMSTATE_UINT16(rx_fifo[1], pl022_state),
 259         VMSTATE_UINT16(tx_fifo[2], pl022_state),
 260         VMSTATE_UINT16(rx_fifo[2], pl022_state),
 261         VMSTATE_UINT16(tx_fifo[3], pl022_state),
 262         VMSTATE_UINT16(rx_fifo[3], pl022_state),
 263         VMSTATE_UINT16(tx_fifo[4], pl022_state),
 264         VMSTATE_UINT16(rx_fifo[4], pl022_state),
 265         VMSTATE_UINT16(tx_fifo[5], pl022_state),
 266         VMSTATE_UINT16(rx_fifo[5], pl022_state),
 267         VMSTATE_UINT16(tx_fifo[6], pl022_state),
 268         VMSTATE_UINT16(rx_fifo[6], pl022_state),
 269         VMSTATE_UINT16(tx_fifo[7], pl022_state),
 270         VMSTATE_UINT16(rx_fifo[7], pl022_state),
 271         VMSTATE_END_OF_LIST()
 272     }
 273 };
 274
 275 static int pl022_init(SysBusDevice *dev)
 276 {
 277     pl022_state *s = FROM_SYSBUS(pl022_state, dev);
 278
 279     memory_region_init_io(&s->iomem, &pl022_ops, s, "pl022", 0x1000);
 280     sysbus_init_mmio(dev, &s->iomem);
 281     sysbus_init_irq(dev, &s->irq);
 282     s->ssi = ssi_create_bus(&dev->qdev, "ssi");
 283     pl022_reset(s);
 284     vmstate_register(&dev->qdev, -1, &vmstate_pl022, s);
 285     return 0;
 286 }
 287
 288 static void pl022_register_devices(void)
 289 {
 290     sysbus_register_dev("pl022", sizeof(pl022_state), pl022_init);
 291 }
 292
 293 device_init(pl022_register_devices)