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 base;
  44     uint32_t cr0;
  45     uint32_t cr1;
  46     uint32_t bitmask;
  47     uint32_t sr;
  48     uint32_t cpsr;
  49     uint32_t is;
  50     uint32_t im;
  51     /* The FIFO head points to the next empty entry.  */
  52     int tx_fifo_head;
  53     int rx_fifo_head;
  54     int tx_fifo_len;
  55     int rx_fifo_len;
  56     uint16_t tx_fifo[8];
  57     uint16_t rx_fifo[8];
  58     qemu_irq irq;
  59     int (*xfer_cb)(void *, int);
  60     void *opaque;
  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 if (s->xfer_cb) {
 121             val = s->xfer_cb(s->opaque, val);
 122         } else {
 123             val = 0;
 124         }
 125         s->rx_fifo[o] = val & s->bitmask;
 126         i = (i + 1) & 7;
 127         o = (o + 1) & 7;
 128         s->tx_fifo_len--;
 129         s->rx_fifo_len++;
 130     }
 131     s->rx_fifo_head = o;
 132     pl022_update(s);
 133 }
 134
 135 static uint32_t pl022_read(void *opaque, target_phys_addr_t offset)
 136 {
 137     pl022_state *s = (pl022_state *)opaque;
 138     int val;
 139
 140     offset -= s->base;
 141     if (offset >= 0xfe0 && offset < 0x1000) {
 142         return pl022_id[(offset - 0xfe0) >> 2];
 143     }
 144     switch (offset) {
 145     case 0x00: /* CR0 */
 146       return s->cr0;
 147     case 0x04: /* CR1 */
 148       return s->cr1;
 149     case 0x08: /* DR */
 150         if (s->rx_fifo_len) {
 151             val = s->rx_fifo[(s->rx_fifo_head - s->rx_fifo_len) & 7];
 152             DPRINTF("RX %02x\n", val);
 153             s->rx_fifo_len--;
 154             pl022_xfer(s);
 155         } else {
 156             val = 0;
 157         }
 158         return val;
 159     case 0x0c: /* SR */
 160         return s->sr;
 161     case 0x10: /* CPSR */
 162         return s->cpsr;
 163     case 0x14: /* IMSC */
 164         return s->im;
 165     case 0x18: /* RIS */
 166         return s->is;
 167     case 0x1c: /* MIS */
 168         return s->im & s->is;
 169     case 0x20: /* DMACR */
 170         /* Not implemented.  */
 171         return 0;
 172     default:
 173         cpu_abort (cpu_single_env, "pl022_read: Bad offset %x\n",
 174                    (int)offset);
 175         return 0;
 176     }
 177 }
 178
 179 static void pl022_write(void *opaque, target_phys_addr_t offset,
 180                         uint32_t value)
 181 {
 182     pl022_state *s = (pl022_state *)opaque;
 183
 184     offset -= s->base;
 185     switch (offset) {
 186     case 0x00: /* CR0 */
 187         s->cr0 = value;
 188         /* Clock rate and format are ignored.  */
 189         s->bitmask = (1 << ((value & 15) + 1)) - 1;
 190         break;
 191     case 0x04: /* CR1 */
 192         s->cr1 = value;
 193         if ((s->cr1 & (PL022_CR1_MS | PL022_CR1_SSE))
 194                    == (PL022_CR1_MS | PL022_CR1_SSE)) {
 195             BADF("SPI slave mode not implemented\n");
 196         }
 197         pl022_xfer(s);
 198         break;
 199     case 0x08: /* DR */
 200         if (s->tx_fifo_len < 8) {
 201             DPRINTF("TX %02x\n", value);
 202             s->tx_fifo[s->tx_fifo_head] = value & s->bitmask;
 203             s->tx_fifo_head = (s->tx_fifo_head + 1) & 7;
 204             s->tx_fifo_len++;
 205             pl022_xfer(s);
 206         }
 207         break;
 208     case 0x10: /* CPSR */
 209         /* Prescaler.  Ignored.  */
 210         s->cpsr = value & 0xff;
 211         break;
 212     case 0x14: /* IMSC */
 213         s->im = value;
 214         pl022_update(s);
 215         break;
 216     case 0x20: /* DMACR */
 217         if (value)
 218             cpu_abort (cpu_single_env, "pl022: DMA not implemented\n");
 219         break;
 220     default:
 221         cpu_abort (cpu_single_env, "pl022_write: Bad offset %x\n",
 222                    (int)offset);
 223     }
 224 }
 225
 226 static void pl022_reset(pl022_state *s)
 227 {
 228     s->rx_fifo_len = 0;
 229     s->tx_fifo_len = 0;
 230     s->im = 0;
 231     s->is = PL022_INT_TX;
 232     s->sr = PL022_SR_TFE | PL022_SR_TNF;
 233 }
 234
 235 static CPUReadMemoryFunc *pl022_readfn[] = {
 236    pl022_read,
 237    pl022_read,
 238    pl022_read
 239 };
 240
 241 static CPUWriteMemoryFunc *pl022_writefn[] = {
 242    pl022_write,
 243    pl022_write,
 244    pl022_write
 245 };
 246
 247 void pl022_init(uint32_t base, qemu_irq irq, int (*xfer_cb)(void *, int),
 248                 void * opaque)
 249 {
 250     int iomemtype;
 251     pl022_state *s;
 252
 253     s = (pl022_state *)qemu_mallocz(sizeof(pl022_state));
 254     iomemtype = cpu_register_io_memory(0, pl022_readfn,
 255                                        pl022_writefn, s);
 256     cpu_register_physical_memory(base, 0x00001000, iomemtype);
 257     s->base = base;
 258     s->irq = irq;
 259     s->xfer_cb = xfer_cb;
 260     s->opaque = opaque;
 261     pl022_reset(s);
 262     /* ??? Save/restore.  */
 263 }
 264
 265