hw/char/bcm2835_aux.c

   1 /*
   2  * BCM2835 (Raspberry Pi / Pi 2) Aux block (mini UART and SPI).
   3  * Copyright (c) 2015, Microsoft
   4  * Written by Andrew Baumann
   5  * Based on pl011.c, copyright terms below:
   6  *
   7  * Arm PrimeCell PL011 UART
   8  *
   9  * Copyright (c) 2006 CodeSourcery.
  10  * Written by Paul Brook
  11  *
  12  * This code is licensed under the GPL.
  13  *
  14  * At present only the core UART functions (data path for tx/rx) are
  15  * implemented. The following features/registers are unimplemented:
  16  *  - Line/modem control
  17  *  - Scratch register
  18  *  - Extra control
  19  *  - Baudrate
  20  *  - SPI interfaces
  21  */
  22
  23 #include "qemu/osdep.h"
  24 #include "hw/char/bcm2835_aux.h"
  25 #include "qemu/log.h"
  26 #include "qemu/module.h"
  27
  28 #define AUX_IRQ         0x0
  29 #define AUX_ENABLES     0x4
  30 #define AUX_MU_IO_REG   0x40
  31 #define AUX_MU_IER_REG  0x44
  32 #define AUX_MU_IIR_REG  0x48
  33 #define AUX_MU_LCR_REG  0x4c
  34 #define AUX_MU_MCR_REG  0x50
  35 #define AUX_MU_LSR_REG  0x54
  36 #define AUX_MU_MSR_REG  0x58
  37 #define AUX_MU_SCRATCH  0x5c
  38 #define AUX_MU_CNTL_REG 0x60
  39 #define AUX_MU_STAT_REG 0x64
  40 #define AUX_MU_BAUD_REG 0x68
  41
  42 /* bits in IER/IIR registers */
  43 #define RX_INT  0x1
  44 #define TX_INT  0x2
  45
  46 static void bcm2835_aux_update(BCM2835AuxState *s)
  47 {
  48     /* signal an interrupt if either:
  49      * 1. rx interrupt is enabled and we have a non-empty rx fifo, or
  50      * 2. the tx interrupt is enabled (since we instantly drain the tx fifo)
  51      */
  52     s->iir = 0;
  53     if ((s->ier & RX_INT) && s->read_count != 0) {
  54         s->iir |= RX_INT;
  55     }
  56     if (s->ier & TX_INT) {
  57         s->iir |= TX_INT;
  58     }
  59     qemu_set_irq(s->irq, s->iir != 0);
  60 }
  61
  62 static uint64_t bcm2835_aux_read(void *opaque, hwaddr offset, unsigned size)
  63 {
  64     BCM2835AuxState *s = opaque;
  65     uint32_t c, res;
  66
  67     switch (offset) {
  68     case AUX_IRQ:
  69         return s->iir != 0;
  70
  71     case AUX_ENABLES:
  72         return 1; /* mini UART permanently enabled */
  73
  74     case AUX_MU_IO_REG:
  75         /* "DLAB bit set means access baudrate register" is NYI */
  76         c = s->read_fifo[s->read_pos];
  77         if (s->read_count > 0) {
  78             s->read_count--;
  79             if (++s->read_pos == BCM2835_AUX_RX_FIFO_LEN) {
  80                 s->read_pos = 0;
  81             }
  82         }
  83         qemu_chr_fe_accept_input(&s->chr);
  84         bcm2835_aux_update(s);
  85         return c;
  86
  87     case AUX_MU_IER_REG:
  88         /* "DLAB bit set means access baudrate register" is NYI */
  89         return 0xc0 | s->ier; /* FIFO enables always read 1 */
  90
  91     case AUX_MU_IIR_REG:
  92         res = 0xc0; /* FIFO enables */
  93         /* The spec is unclear on what happens when both tx and rx
  94          * interrupts are active, besides that this cannot occur. At
  95          * present, we choose to prioritise the rx interrupt, since
  96          * the tx fifo is always empty. */
  97         if (s->read_count != 0) {
  98             res |= 0x4;
  99         } else {
 100             res |= 0x2;
 101         }
 102         if (s->iir == 0) {
 103             res |= 0x1;
 104         }
 105         return res;
 106
 107     case AUX_MU_LCR_REG:
 108         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_LCR_REG unsupported\n", __func__);
 109         return 0;
 110
 111     case AUX_MU_MCR_REG:
 112         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_MCR_REG unsupported\n", __func__);
 113         return 0;
 114
 115     case AUX_MU_LSR_REG:
 116         res = 0x60; /* tx idle, empty */
 117         if (s->read_count != 0) {
 118             res |= 0x1;
 119         }
 120         return res;
 121
 122     case AUX_MU_MSR_REG:
 123         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_MSR_REG unsupported\n", __func__);
 124         return 0;
 125
 126     case AUX_MU_SCRATCH:
 127         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_SCRATCH unsupported\n", __func__);
 128         return 0;
 129
 130     case AUX_MU_CNTL_REG:
 131         return 0x3; /* tx, rx enabled */
 132
 133     case AUX_MU_STAT_REG:
 134         res = 0x30e; /* space in the output buffer, empty tx fifo, idle tx/rx */
 135         if (s->read_count > 0) {
 136             res |= 0x1; /* data in input buffer */
 137             assert(s->read_count < BCM2835_AUX_RX_FIFO_LEN);
 138             res |= ((uint32_t)s->read_count) << 16; /* rx fifo fill level */
 139         }
 140         return res;
 141
 142     case AUX_MU_BAUD_REG:
 143         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_BAUD_REG unsupported\n", __func__);
 144         return 0;
 145
 146     default:
 147         qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset %"HWADDR_PRIx"\n",
 148                       __func__, offset);
 149         return 0;
 150     }
 151 }
 152
 153 static void bcm2835_aux_write(void *opaque, hwaddr offset, uint64_t value,
 154                               unsigned size)
 155 {
 156     BCM2835AuxState *s = opaque;
 157     unsigned char ch;
 158
 159     switch (offset) {
 160     case AUX_ENABLES:
 161         if (value != 1) {
 162             qemu_log_mask(LOG_UNIMP, "%s: unsupported attempt to enable SPI "
 163                           "or disable UART\n", __func__);
 164         }
 165         break;
 166
 167     case AUX_MU_IO_REG:
 168         /* "DLAB bit set means access baudrate register" is NYI */
 169         ch = value;
 170         /* XXX this blocks entire thread. Rewrite to use
 171          * qemu_chr_fe_write and background I/O callbacks */
 172         qemu_chr_fe_write_all(&s->chr, &ch, 1);
 173         break;
 174
 175     case AUX_MU_IER_REG:
 176         /* "DLAB bit set means access baudrate register" is NYI */
 177         s->ier = value & (TX_INT | RX_INT);
 178         bcm2835_aux_update(s);
 179         break;
 180
 181     case AUX_MU_IIR_REG:
 182         if (value & 0x2) {
 183             s->read_count = 0;
 184         }
 185         break;
 186
 187     case AUX_MU_LCR_REG:
 188         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_LCR_REG unsupported\n", __func__);
 189         break;
 190
 191     case AUX_MU_MCR_REG:
 192         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_MCR_REG unsupported\n", __func__);
 193         break;
 194
 195     case AUX_MU_SCRATCH:
 196         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_SCRATCH unsupported\n", __func__);
 197         break;
 198
 199     case AUX_MU_CNTL_REG:
 200         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_CNTL_REG unsupported\n", __func__);
 201         break;
 202
 203     case AUX_MU_BAUD_REG:
 204         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_BAUD_REG unsupported\n", __func__);
 205         break;
 206
 207     default:
 208         qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset %"HWADDR_PRIx"\n",
 209                       __func__, offset);
 210     }
 211
 212     bcm2835_aux_update(s);
 213 }
 214
 215 static int bcm2835_aux_can_receive(void *opaque)
 216 {
 217     BCM2835AuxState *s = opaque;
 218
 219     return s->read_count < BCM2835_AUX_RX_FIFO_LEN;
 220 }
 221
 222 static void bcm2835_aux_put_fifo(void *opaque, uint8_t value)
 223 {
 224     BCM2835AuxState *s = opaque;
 225     int slot;
 226
 227     slot = s->read_pos + s->read_count;
 228     if (slot >= BCM2835_AUX_RX_FIFO_LEN) {
 229         slot -= BCM2835_AUX_RX_FIFO_LEN;
 230     }
 231     s->read_fifo[slot] = value;
 232     s->read_count++;
 233     if (s->read_count == BCM2835_AUX_RX_FIFO_LEN) {
 234         /* buffer full */
 235     }
 236     bcm2835_aux_update(s);
 237 }
 238
 239 static void bcm2835_aux_receive(void *opaque, const uint8_t *buf, int size)
 240 {
 241     bcm2835_aux_put_fifo(opaque, *buf);
 242 }
 243
 244 static const MemoryRegionOps bcm2835_aux_ops = {
 245     .read = bcm2835_aux_read,
 246     .write = bcm2835_aux_write,
 247     .endianness = DEVICE_NATIVE_ENDIAN,
 248     .valid.min_access_size = 4,
 249     .valid.max_access_size = 4,
 250 };
 251
 252 static const VMStateDescription vmstate_bcm2835_aux = {
 253     .name = TYPE_BCM2835_AUX,
 254     .version_id = 1,
 255     .minimum_version_id = 1,
 256     .fields = (VMStateField[]) {
 257         VMSTATE_UINT8_ARRAY(read_fifo, BCM2835AuxState,
 258                             BCM2835_AUX_RX_FIFO_LEN),
 259         VMSTATE_UINT8(read_pos, BCM2835AuxState),
 260         VMSTATE_UINT8(read_count, BCM2835AuxState),
 261         VMSTATE_UINT8(ier, BCM2835AuxState),
 262         VMSTATE_UINT8(iir, BCM2835AuxState),
 263         VMSTATE_END_OF_LIST()
 264     }
 265 };
 266
 267 static void bcm2835_aux_init(Object *obj)
 268 {
 269     SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
 270     BCM2835AuxState *s = BCM2835_AUX(obj);
 271
 272     memory_region_init_io(&s->iomem, OBJECT(s), &bcm2835_aux_ops, s,
 273                           TYPE_BCM2835_AUX, 0x100);
 274     sysbus_init_mmio(sbd, &s->iomem);
 275     sysbus_init_irq(sbd, &s->irq);
 276 }
 277
 278 static void bcm2835_aux_realize(DeviceState *dev, Error **errp)
 279 {
 280     BCM2835AuxState *s = BCM2835_AUX(dev);
 281
 282     qemu_chr_fe_set_handlers(&s->chr, bcm2835_aux_can_receive,
 283                              bcm2835_aux_receive, NULL, NULL, s, NULL, true);
 284 }
 285
 286 static Property bcm2835_aux_props[] = {
 287     DEFINE_PROP_CHR("chardev", BCM2835AuxState, chr),
 288     DEFINE_PROP_END_OF_LIST(),
 289 };
 290
 291 static void bcm2835_aux_class_init(ObjectClass *oc, void *data)
 292 {
 293     DeviceClass *dc = DEVICE_CLASS(oc);
 294
 295     dc->realize = bcm2835_aux_realize;
 296     dc->vmsd = &vmstate_bcm2835_aux;
 297     set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
 298     dc->props = bcm2835_aux_props;
 299 }
 300
 301 static const TypeInfo bcm2835_aux_info = {
 302     .name          = TYPE_BCM2835_AUX,
 303     .parent        = TYPE_SYS_BUS_DEVICE,
 304     .instance_size = sizeof(BCM2835AuxState),
 305     .instance_init = bcm2835_aux_init,
 306     .class_init    = bcm2835_aux_class_init,
 307 };
 308
 309 static void bcm2835_aux_register_types(void)
 310 {
 311     type_register_static(&bcm2835_aux_info);
 312 }
 313
 314 type_init(bcm2835_aux_register_types)