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 "hw.h"
  11 #include "primecell.h"
  12
  13 //#define DEBUG_PL022 1
  14
  15 #ifdef DEBUG_PL022
  16 #define DPRINTF(fmt, args...) \
  17 do { printf("pl022: " fmt , ##args); } while (0)
  18 #define BADF(fmt, args...) \
  19 do { fprintf(stderr, "pl022: error: " fmt , ##args); exit(1);} while (0)
  20 #else
  21 #define DPRINTF(fmt, args...) do {} while(0)
  22 #define BADF(fmt, args...) \
  23 do { fprintf(stderr, "pl022: error: " fmt , ##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     uint32_t cr0;
  44     uint32_t cr1;
  45     uint32_t bitmask;
  46     uint32_t sr;
  47     uint32_t cpsr;
  48     uint32_t is;
  49     uint32_t im;
  50     /* The FIFO head points to the next empty entry.  */
  51     int tx_fifo_head;
  52     int rx_fifo_head;
  53     int tx_fifo_len;
  54     int rx_fifo_len;
  55     uint16_t tx_fifo[8];
  56     uint16_t rx_fifo[8];
  57     qemu_irq irq;
  58     int (*xfer_cb)(void *, int);
  59     void *opaque;
  60 } pl022_state;
  61
  62 static const unsigned char pl022_id[8] =
  63   { 0x22, 0x10, 0x04, 0x00, 0x0d, 0xf0, 0x05, 0xb1 };
  64
  65 static void pl022_update(pl022_state *s)
  66 {
  67     s->sr = 0;
  68     if (s->tx_fifo_len == 0)
  69         s->sr |= PL022_SR_TFE;
  70     if (s->tx_fifo_len != 8)
  71         s->sr |= PL022_SR_TNF;
  72     if (s->rx_fifo_len != 0)
  73         s->sr |= PL022_SR_RNE;
  74     if (s->rx_fifo_len == 8)
  75         s->sr |= PL022_SR_RFF;
  76     if (s->tx_fifo_len)
  77         s->sr |= PL022_SR_BSY;
  78     s->is = 0;
  79     if (s->rx_fifo_len >= 4)
  80         s->is |= PL022_INT_RX;
  81     if (s->tx_fifo_len <= 4)
  82         s->is |= PL022_INT_TX;
  83
  84     qemu_set_irq(s->irq, (s->is & s->im) != 0);
  85 }
  86
  87 static void pl022_xfer(pl022_state *s)
  88 {
  89     int i;
  90     int o;
  91     int val;
  92
  93     if ((s->cr1 & PL022_CR1_SSE) == 0) {
  94         pl022_update(s);
  95         DPRINTF("Disabled\n");
  96         return;
  97     }
  98
  99     DPRINTF("Maybe xfer %d/%d\n", s->tx_fifo_len, s->rx_fifo_len);
 100     i = (s->tx_fifo_head - s->tx_fifo_len) & 7;
 101     o = s->rx_fifo_head;
 102     /* ??? We do not emulate the line speed.
 103        This may break some applications.  The are two problematic cases:
 104         (a) A driver feeds data into the TX FIFO until it is full,
 105          and only then drains the RX FIFO.  On real hardware the CPU can
 106          feed data fast enough that the RX fifo never gets chance to overflow.
 107         (b) A driver transmits data, deliberately allowing the RX FIFO to
 108          overflow because it ignores the RX data anyway.
 109
 110        We choose to support (a) by stalling the transmit engine if it would
 111        cause the RX FIFO to overflow.  In practice much transmit-only code
 112        falls into (a) because it flushes the RX FIFO to determine when
 113        the transfer has completed.  */
 114     while (s->tx_fifo_len && s->rx_fifo_len < 8) {
 115         DPRINTF("xfer\n");
 116         val = s->tx_fifo[i];
 117         if (s->cr1 & PL022_CR1_LBM) {
 118             /* Loopback mode.  */
 119         } else if (s->xfer_cb) {
 120             val = s->xfer_cb(s->opaque, val);
 121         } else {
 122             val = 0;
 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 uint32_t pl022_read(void *opaque, target_phys_addr_t offset)
 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         cpu_abort (cpu_single_env, "pl022_read: Bad offset %x\n",
 172                    (int)offset);
 173         return 0;
 174     }
 175 }
 176
 177 static void pl022_write(void *opaque, target_phys_addr_t offset,
 178                         uint32_t value)
 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", 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             cpu_abort (cpu_single_env, "pl022: DMA not implemented\n");
 216         break;
 217     default:
 218         cpu_abort (cpu_single_env, "pl022_write: Bad offset %x\n",
 219                    (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 CPUReadMemoryFunc *pl022_readfn[] = {
 233    pl022_read,
 234    pl022_read,
 235    pl022_read
 236 };
 237
 238 static CPUWriteMemoryFunc *pl022_writefn[] = {
 239    pl022_write,
 240    pl022_write,
 241    pl022_write
 242 };
 243
 244 static void pl022_save(QEMUFile *f, void *opaque)
 245 {
 246     pl022_state *s = (pl022_state *)opaque;
 247     int i;
 248
 249     qemu_put_be32(f, s->cr0);
 250     qemu_put_be32(f, s->cr1);
 251     qemu_put_be32(f, s->bitmask);
 252     qemu_put_be32(f, s->sr);
 253     qemu_put_be32(f, s->cpsr);
 254     qemu_put_be32(f, s->is);
 255     qemu_put_be32(f, s->im);
 256     qemu_put_be32(f, s->tx_fifo_head);
 257     qemu_put_be32(f, s->rx_fifo_head);
 258     qemu_put_be32(f, s->tx_fifo_len);
 259     qemu_put_be32(f, s->rx_fifo_len);
 260     for (i = 0; i < 8; i++) {
 261         qemu_put_be16(f, s->tx_fifo[i]);
 262         qemu_put_be16(f, s->rx_fifo[i]);
 263     }
 264 }
 265
 266 static int pl022_load(QEMUFile *f, void *opaque, int version_id)
 267 {
 268     pl022_state *s = (pl022_state *)opaque;
 269     int i;
 270
 271     if (version_id != 1)
 272         return -EINVAL;
 273
 274     s->cr0 = qemu_get_be32(f);
 275     s->cr1 = qemu_get_be32(f);
 276     s->bitmask = qemu_get_be32(f);
 277     s->sr = qemu_get_be32(f);
 278     s->cpsr = qemu_get_be32(f);
 279     s->is = qemu_get_be32(f);
 280     s->im = qemu_get_be32(f);
 281     s->tx_fifo_head = qemu_get_be32(f);
 282     s->rx_fifo_head = qemu_get_be32(f);
 283     s->tx_fifo_len = qemu_get_be32(f);
 284     s->rx_fifo_len = qemu_get_be32(f);
 285     for (i = 0; i < 8; i++) {
 286         s->tx_fifo[i] = qemu_get_be16(f);
 287         s->rx_fifo[i] = qemu_get_be16(f);
 288     }
 289
 290     return 0;
 291 }
 292
 293 void pl022_init(uint32_t base, qemu_irq irq, int (*xfer_cb)(void *, int),
 294                 void * opaque)
 295 {
 296     int iomemtype;
 297     pl022_state *s;
 298
 299     s = (pl022_state *)qemu_mallocz(sizeof(pl022_state));
 300     iomemtype = cpu_register_io_memory(0, pl022_readfn,
 301                                        pl022_writefn, s);
 302     cpu_register_physical_memory(base, 0x00001000, iomemtype);
 303     s->irq = irq;
 304     s->xfer_cb = xfer_cb;
 305     s->opaque = opaque;
 306     pl022_reset(s);
 307     register_savevm("pl022_ssp", -1, 1, pl022_save, pl022_load, s);
 308 }