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 licenced 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     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 uint32_t pl022_read(void *opaque, target_phys_addr_t offset)
 134 {
 135     pl022_state *s = (pl022_state *)opaque;
 136     int val;
 137
 138     if (offset >= 0xfe0 && offset < 0x1000) {
 139         return pl022_id[(offset - 0xfe0) >> 2];
 140     }
 141     switch (offset) {
 142     case 0x00: /* CR0 */
 143       return s->cr0;
 144     case 0x04: /* CR1 */
 145       return s->cr1;
 146     case 0x08: /* DR */
 147         if (s->rx_fifo_len) {
 148             val = s->rx_fifo[(s->rx_fifo_head - s->rx_fifo_len) & 7];
 149             DPRINTF("RX %02x\n", val);
 150             s->rx_fifo_len--;
 151             pl022_xfer(s);
 152         } else {
 153             val = 0;
 154         }
 155         return val;
 156     case 0x0c: /* SR */
 157         return s->sr;
 158     case 0x10: /* CPSR */
 159         return s->cpsr;
 160     case 0x14: /* IMSC */
 161         return s->im;
 162     case 0x18: /* RIS */
 163         return s->is;
 164     case 0x1c: /* MIS */
 165         return s->im & s->is;
 166     case 0x20: /* DMACR */
 167         /* Not implemented.  */
 168         return 0;
 169     default:
 170         hw_error("pl022_read: Bad offset %x\n", (int)offset);
 171         return 0;
 172     }
 173 }
 174
 175 static void pl022_write(void *opaque, target_phys_addr_t offset,
 176                         uint32_t value)
 177 {
 178     pl022_state *s = (pl022_state *)opaque;
 179
 180     switch (offset) {
 181     case 0x00: /* CR0 */
 182         s->cr0 = value;
 183         /* Clock rate and format are ignored.  */
 184         s->bitmask = (1 << ((value & 15) + 1)) - 1;
 185         break;
 186     case 0x04: /* CR1 */
 187         s->cr1 = value;
 188         if ((s->cr1 & (PL022_CR1_MS | PL022_CR1_SSE))
 189                    == (PL022_CR1_MS | PL022_CR1_SSE)) {
 190             BADF("SPI slave mode not implemented\n");
 191         }
 192         pl022_xfer(s);
 193         break;
 194     case 0x08: /* DR */
 195         if (s->tx_fifo_len < 8) {
 196             DPRINTF("TX %02x\n", value);
 197             s->tx_fifo[s->tx_fifo_head] = value & s->bitmask;
 198             s->tx_fifo_head = (s->tx_fifo_head + 1) & 7;
 199             s->tx_fifo_len++;
 200             pl022_xfer(s);
 201         }
 202         break;
 203     case 0x10: /* CPSR */
 204         /* Prescaler.  Ignored.  */
 205         s->cpsr = value & 0xff;
 206         break;
 207     case 0x14: /* IMSC */
 208         s->im = value;
 209         pl022_update(s);
 210         break;
 211     case 0x20: /* DMACR */
 212         if (value) {
 213             hw_error("pl022: DMA not implemented\n");
 214         }
 215         break;
 216     default:
 217         hw_error("pl022_write: Bad offset %x\n", (int)offset);
 218     }
 219 }
 220
 221 static void pl022_reset(pl022_state *s)
 222 {
 223     s->rx_fifo_len = 0;
 224     s->tx_fifo_len = 0;
 225     s->im = 0;
 226     s->is = PL022_INT_TX;
 227     s->sr = PL022_SR_TFE | PL022_SR_TNF;
 228 }
 229
 230 static CPUReadMemoryFunc *pl022_readfn[] = {
 231    pl022_read,
 232    pl022_read,
 233    pl022_read
 234 };
 235
 236 static CPUWriteMemoryFunc *pl022_writefn[] = {
 237    pl022_write,
 238    pl022_write,
 239    pl022_write
 240 };
 241
 242 static void pl022_save(QEMUFile *f, void *opaque)
 243 {
 244     pl022_state *s = (pl022_state *)opaque;
 245     int i;
 246
 247     qemu_put_be32(f, s->cr0);
 248     qemu_put_be32(f, s->cr1);
 249     qemu_put_be32(f, s->bitmask);
 250     qemu_put_be32(f, s->sr);
 251     qemu_put_be32(f, s->cpsr);
 252     qemu_put_be32(f, s->is);
 253     qemu_put_be32(f, s->im);
 254     qemu_put_be32(f, s->tx_fifo_head);
 255     qemu_put_be32(f, s->rx_fifo_head);
 256     qemu_put_be32(f, s->tx_fifo_len);
 257     qemu_put_be32(f, s->rx_fifo_len);
 258     for (i = 0; i < 8; i++) {
 259         qemu_put_be16(f, s->tx_fifo[i]);
 260         qemu_put_be16(f, s->rx_fifo[i]);
 261     }
 262 }
 263
 264 static int pl022_load(QEMUFile *f, void *opaque, int version_id)
 265 {
 266     pl022_state *s = (pl022_state *)opaque;
 267     int i;
 268
 269     if (version_id != 1)
 270         return -EINVAL;
 271
 272     s->cr0 = qemu_get_be32(f);
 273     s->cr1 = qemu_get_be32(f);
 274     s->bitmask = qemu_get_be32(f);
 275     s->sr = qemu_get_be32(f);
 276     s->cpsr = qemu_get_be32(f);
 277     s->is = qemu_get_be32(f);
 278     s->im = qemu_get_be32(f);
 279     s->tx_fifo_head = qemu_get_be32(f);
 280     s->rx_fifo_head = qemu_get_be32(f);
 281     s->tx_fifo_len = qemu_get_be32(f);
 282     s->rx_fifo_len = qemu_get_be32(f);
 283     for (i = 0; i < 8; i++) {
 284         s->tx_fifo[i] = qemu_get_be16(f);
 285         s->rx_fifo[i] = qemu_get_be16(f);
 286     }
 287
 288     return 0;
 289 }
 290
 291 static void pl022_init(SysBusDevice *dev)
 292 {
 293     pl022_state *s = FROM_SYSBUS(pl022_state, dev);
 294     int iomemtype;
 295
 296     iomemtype = cpu_register_io_memory(0, pl022_readfn,
 297                                        pl022_writefn, s);
 298     sysbus_init_mmio(dev, 0x1000, iomemtype);
 299     sysbus_init_irq(dev, &s->irq);
 300     s->ssi = ssi_create_bus();
 301     qdev_attach_child_bus(&dev->qdev, "ssi", s->ssi);
 302     pl022_reset(s);
 303     register_savevm("pl022_ssp", -1, 1, pl022_save, pl022_load, s);
 304 }
 305
 306 static void pl022_register_devices(void)
 307 {
 308     sysbus_register_dev("pl022", sizeof(pl022_state), pl022_init);
 309 }
 310
 311 device_init(pl022_register_devices)