hw/char/grlib_apbuart.c

   1 /*
   2  * QEMU GRLIB APB UART Emulator
   3  *
   4  * Copyright (c) 2010-2011 AdaCore
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "qemu/osdep.h"
  26 #include "hw/sysbus.h"
  27 #include "chardev/char-fe.h"
  28
  29 #include "trace.h"
  30
  31 #define UART_REG_SIZE 20     /* Size of memory mapped registers */
  32
  33 /* UART status register fields */
  34 #define UART_DATA_READY           (1 <<  0)
  35 #define UART_TRANSMIT_SHIFT_EMPTY (1 <<  1)
  36 #define UART_TRANSMIT_FIFO_EMPTY  (1 <<  2)
  37 #define UART_BREAK_RECEIVED       (1 <<  3)
  38 #define UART_OVERRUN              (1 <<  4)
  39 #define UART_PARITY_ERROR         (1 <<  5)
  40 #define UART_FRAMING_ERROR        (1 <<  6)
  41 #define UART_TRANSMIT_FIFO_HALF   (1 <<  7)
  42 #define UART_RECEIVE_FIFO_HALF    (1 <<  8)
  43 #define UART_TRANSMIT_FIFO_FULL   (1 <<  9)
  44 #define UART_RECEIVE_FIFO_FULL    (1 << 10)
  45
  46 /* UART control register fields */
  47 #define UART_RECEIVE_ENABLE          (1 <<  0)
  48 #define UART_TRANSMIT_ENABLE         (1 <<  1)
  49 #define UART_RECEIVE_INTERRUPT       (1 <<  2)
  50 #define UART_TRANSMIT_INTERRUPT      (1 <<  3)
  51 #define UART_PARITY_SELECT           (1 <<  4)
  52 #define UART_PARITY_ENABLE           (1 <<  5)
  53 #define UART_FLOW_CONTROL            (1 <<  6)
  54 #define UART_LOOPBACK                (1 <<  7)
  55 #define UART_EXTERNAL_CLOCK          (1 <<  8)
  56 #define UART_RECEIVE_FIFO_INTERRUPT  (1 <<  9)
  57 #define UART_TRANSMIT_FIFO_INTERRUPT (1 << 10)
  58 #define UART_FIFO_DEBUG_MODE         (1 << 11)
  59 #define UART_OUTPUT_ENABLE           (1 << 12)
  60 #define UART_FIFO_AVAILABLE          (1 << 31)
  61
  62 /* Memory mapped register offsets */
  63 #define DATA_OFFSET       0x00
  64 #define STATUS_OFFSET     0x04
  65 #define CONTROL_OFFSET    0x08
  66 #define SCALER_OFFSET     0x0C  /* not supported */
  67 #define FIFO_DEBUG_OFFSET 0x10  /* not supported */
  68
  69 #define FIFO_LENGTH 1024
  70
  71 #define TYPE_GRLIB_APB_UART "grlib,apbuart"
  72 #define GRLIB_APB_UART(obj) \
  73     OBJECT_CHECK(UART, (obj), TYPE_GRLIB_APB_UART)
  74
  75 typedef struct UART {
  76     SysBusDevice parent_obj;
  77
  78     MemoryRegion iomem;
  79     qemu_irq irq;
  80
  81     CharBackend chr;
  82
  83     /* registers */
  84     uint32_t status;
  85     uint32_t control;
  86
  87     /* FIFO */
  88     char buffer[FIFO_LENGTH];
  89     int  len;
  90     int  current;
  91 } UART;
  92
  93 static int uart_data_to_read(UART *uart)
  94 {
  95     return uart->current < uart->len;
  96 }
  97
  98 static char uart_pop(UART *uart)
  99 {
 100     char ret;
 101
 102     if (uart->len == 0) {
 103         uart->status &= ~UART_DATA_READY;
 104         return 0;
 105     }
 106
 107     ret = uart->buffer[uart->current++];
 108
 109     if (uart->current >= uart->len) {
 110         /* Flush */
 111         uart->len     = 0;
 112         uart->current = 0;
 113     }
 114
 115     if (!uart_data_to_read(uart)) {
 116         uart->status &= ~UART_DATA_READY;
 117     }
 118
 119     return ret;
 120 }
 121
 122 static void uart_add_to_fifo(UART          *uart,
 123                              const uint8_t *buffer,
 124                              int            length)
 125 {
 126     if (uart->len + length > FIFO_LENGTH) {
 127         abort();
 128     }
 129     memcpy(uart->buffer + uart->len, buffer, length);
 130     uart->len += length;
 131 }
 132
 133 static int grlib_apbuart_can_receive(void *opaque)
 134 {
 135     UART *uart = opaque;
 136
 137     return FIFO_LENGTH - uart->len;
 138 }
 139
 140 static void grlib_apbuart_receive(void *opaque, const uint8_t *buf, int size)
 141 {
 142     UART *uart = opaque;
 143
 144     if (uart->control & UART_RECEIVE_ENABLE) {
 145         uart_add_to_fifo(uart, buf, size);
 146
 147         uart->status |= UART_DATA_READY;
 148
 149         if (uart->control & UART_RECEIVE_INTERRUPT) {
 150             qemu_irq_pulse(uart->irq);
 151         }
 152     }
 153 }
 154
 155 static void grlib_apbuart_event(void *opaque, int event)
 156 {
 157     trace_grlib_apbuart_event(event);
 158 }
 159
 160
 161 static uint64_t grlib_apbuart_read(void *opaque, hwaddr addr,
 162                                    unsigned size)
 163 {
 164     UART     *uart = opaque;
 165
 166     addr &= 0xff;
 167
 168     /* Unit registers */
 169     switch (addr) {
 170     case DATA_OFFSET:
 171     case DATA_OFFSET + 3:       /* when only one byte read */
 172         return uart_pop(uart);
 173
 174     case STATUS_OFFSET:
 175         /* Read Only */
 176         return uart->status;
 177
 178     case CONTROL_OFFSET:
 179         return uart->control;
 180
 181     case SCALER_OFFSET:
 182         /* Not supported */
 183         return 0;
 184
 185     default:
 186         trace_grlib_apbuart_readl_unknown(addr);
 187         return 0;
 188     }
 189 }
 190
 191 static void grlib_apbuart_write(void *opaque, hwaddr addr,
 192                                 uint64_t value, unsigned size)
 193 {
 194     UART          *uart = opaque;
 195     unsigned char  c    = 0;
 196
 197     addr &= 0xff;
 198
 199     /* Unit registers */
 200     switch (addr) {
 201     case DATA_OFFSET:
 202     case DATA_OFFSET + 3:       /* When only one byte write */
 203         /* Transmit when character device available and transmitter enabled */
 204         if (qemu_chr_fe_backend_connected(&uart->chr) &&
 205             (uart->control & UART_TRANSMIT_ENABLE)) {
 206             c = value & 0xFF;
 207             /* XXX this blocks entire thread. Rewrite to use
 208              * qemu_chr_fe_write and background I/O callbacks */
 209             qemu_chr_fe_write_all(&uart->chr, &c, 1);
 210             /* Generate interrupt */
 211             if (uart->control & UART_TRANSMIT_INTERRUPT) {
 212                 qemu_irq_pulse(uart->irq);
 213             }
 214         }
 215         return;
 216
 217     case STATUS_OFFSET:
 218         /* Read Only */
 219         return;
 220
 221     case CONTROL_OFFSET:
 222         uart->control = value;
 223         return;
 224
 225     case SCALER_OFFSET:
 226         /* Not supported */
 227         return;
 228
 229     default:
 230         break;
 231     }
 232
 233     trace_grlib_apbuart_writel_unknown(addr, value);
 234 }
 235
 236 static const MemoryRegionOps grlib_apbuart_ops = {
 237     .write      = grlib_apbuart_write,
 238     .read       = grlib_apbuart_read,
 239     .endianness = DEVICE_NATIVE_ENDIAN,
 240 };
 241
 242 static int grlib_apbuart_init(SysBusDevice *dev)
 243 {
 244     UART *uart = GRLIB_APB_UART(dev);
 245
 246     qemu_chr_fe_set_handlers(&uart->chr,
 247                              grlib_apbuart_can_receive,
 248                              grlib_apbuart_receive,
 249                              grlib_apbuart_event,
 250                              NULL, uart, NULL, true);
 251
 252     sysbus_init_irq(dev, &uart->irq);
 253
 254     memory_region_init_io(&uart->iomem, OBJECT(uart), &grlib_apbuart_ops, uart,
 255                           "uart", UART_REG_SIZE);
 256
 257     sysbus_init_mmio(dev, &uart->iomem);
 258
 259     return 0;
 260 }
 261
 262 static void grlib_apbuart_reset(DeviceState *d)
 263 {
 264     UART *uart = GRLIB_APB_UART(d);
 265
 266     /* Transmitter FIFO and shift registers are always empty in QEMU */
 267     uart->status =  UART_TRANSMIT_FIFO_EMPTY | UART_TRANSMIT_SHIFT_EMPTY;
 268     /* Everything is off */
 269     uart->control = 0;
 270     /* Flush receive FIFO */
 271     uart->len = 0;
 272     uart->current = 0;
 273 }
 274
 275 static Property grlib_apbuart_properties[] = {
 276     DEFINE_PROP_CHR("chrdev", UART, chr),
 277     DEFINE_PROP_END_OF_LIST(),
 278 };
 279
 280 static void grlib_apbuart_class_init(ObjectClass *klass, void *data)
 281 {
 282     DeviceClass *dc = DEVICE_CLASS(klass);
 283     SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);
 284
 285     k->init = grlib_apbuart_init;
 286     dc->reset = grlib_apbuart_reset;
 287     dc->props = grlib_apbuart_properties;
 288 }
 289
 290 static const TypeInfo grlib_apbuart_info = {
 291     .name          = TYPE_GRLIB_APB_UART,
 292     .parent        = TYPE_SYS_BUS_DEVICE,
 293     .instance_size = sizeof(UART),
 294     .class_init    = grlib_apbuart_class_init,
 295 };
 296
 297 static void grlib_apbuart_register_types(void)
 298 {
 299     type_register_static(&grlib_apbuart_info);
 300 }
 301
 302 type_init(grlib_apbuart_register_types)