hw/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 "hw/sysbus.h"
  26 #include "char/char.h"
  27
  28 #include "trace.h"
  29
  30 #define UART_REG_SIZE 20     /* Size of memory mapped registers */
  31
  32 /* UART status register fields */
  33 #define UART_DATA_READY           (1 <<  0)
  34 #define UART_TRANSMIT_SHIFT_EMPTY (1 <<  1)
  35 #define UART_TRANSMIT_FIFO_EMPTY  (1 <<  2)
  36 #define UART_BREAK_RECEIVED       (1 <<  3)
  37 #define UART_OVERRUN              (1 <<  4)
  38 #define UART_PARITY_ERROR         (1 <<  5)
  39 #define UART_FRAMING_ERROR        (1 <<  6)
  40 #define UART_TRANSMIT_FIFO_HALF   (1 <<  7)
  41 #define UART_RECEIVE_FIFO_HALF    (1 <<  8)
  42 #define UART_TRANSMIT_FIFO_FULL   (1 <<  9)
  43 #define UART_RECEIVE_FIFO_FULL    (1 << 10)
  44
  45 /* UART control register fields */
  46 #define UART_RECEIVE_ENABLE          (1 <<  0)
  47 #define UART_TRANSMIT_ENABLE         (1 <<  1)
  48 #define UART_RECEIVE_INTERRUPT       (1 <<  2)
  49 #define UART_TRANSMIT_INTERRUPT      (1 <<  3)
  50 #define UART_PARITY_SELECT           (1 <<  4)
  51 #define UART_PARITY_ENABLE           (1 <<  5)
  52 #define UART_FLOW_CONTROL            (1 <<  6)
  53 #define UART_LOOPBACK                (1 <<  7)
  54 #define UART_EXTERNAL_CLOCK          (1 <<  8)
  55 #define UART_RECEIVE_FIFO_INTERRUPT  (1 <<  9)
  56 #define UART_TRANSMIT_FIFO_INTERRUPT (1 << 10)
  57 #define UART_FIFO_DEBUG_MODE         (1 << 11)
  58 #define UART_OUTPUT_ENABLE           (1 << 12)
  59 #define UART_FIFO_AVAILABLE          (1 << 31)
  60
  61 /* Memory mapped register offsets */
  62 #define DATA_OFFSET       0x00
  63 #define STATUS_OFFSET     0x04
  64 #define CONTROL_OFFSET    0x08
  65 #define SCALER_OFFSET     0x0C  /* not supported */
  66 #define FIFO_DEBUG_OFFSET 0x10  /* not supported */
  67
  68 #define FIFO_LENGTH 1024
  69
  70 typedef struct UART {
  71     SysBusDevice busdev;
  72     MemoryRegion iomem;
  73     qemu_irq irq;
  74
  75     CharDriverState *chr;
  76
  77     /* registers */
  78     uint32_t status;
  79     uint32_t control;
  80
  81     /* FIFO */
  82     char buffer[FIFO_LENGTH];
  83     int  len;
  84     int  current;
  85 } UART;
  86
  87 static int uart_data_to_read(UART *uart)
  88 {
  89     return uart->current < uart->len;
  90 }
  91
  92 static char uart_pop(UART *uart)
  93 {
  94     char ret;
  95
  96     if (uart->len == 0) {
  97         uart->status &= ~UART_DATA_READY;
  98         return 0;
  99     }
 100
 101     ret = uart->buffer[uart->current++];
 102
 103     if (uart->current >= uart->len) {
 104         /* Flush */
 105         uart->len     = 0;
 106         uart->current = 0;
 107     }
 108
 109     if (!uart_data_to_read(uart)) {
 110         uart->status &= ~UART_DATA_READY;
 111     }
 112
 113     return ret;
 114 }
 115
 116 static void uart_add_to_fifo(UART          *uart,
 117                              const uint8_t *buffer,
 118                              int            length)
 119 {
 120     if (uart->len + length > FIFO_LENGTH) {
 121         abort();
 122     }
 123     memcpy(uart->buffer + uart->len, buffer, length);
 124     uart->len += length;
 125 }
 126
 127 static int grlib_apbuart_can_receive(void *opaque)
 128 {
 129     UART *uart = opaque;
 130
 131     return FIFO_LENGTH - uart->len;
 132 }
 133
 134 static void grlib_apbuart_receive(void *opaque, const uint8_t *buf, int size)
 135 {
 136     UART *uart = opaque;
 137
 138     if (uart->control & UART_RECEIVE_ENABLE) {
 139         uart_add_to_fifo(uart, buf, size);
 140
 141         uart->status |= UART_DATA_READY;
 142
 143         if (uart->control & UART_RECEIVE_INTERRUPT) {
 144             qemu_irq_pulse(uart->irq);
 145         }
 146     }
 147 }
 148
 149 static void grlib_apbuart_event(void *opaque, int event)
 150 {
 151     trace_grlib_apbuart_event(event);
 152 }
 153
 154
 155 static uint64_t grlib_apbuart_read(void *opaque, hwaddr addr,
 156                                    unsigned size)
 157 {
 158     UART     *uart = opaque;
 159
 160     addr &= 0xff;
 161
 162     /* Unit registers */
 163     switch (addr) {
 164     case DATA_OFFSET:
 165     case DATA_OFFSET + 3:       /* when only one byte read */
 166         return uart_pop(uart);
 167
 168     case STATUS_OFFSET:
 169         /* Read Only */
 170         return uart->status;
 171
 172     case CONTROL_OFFSET:
 173         return uart->control;
 174
 175     case SCALER_OFFSET:
 176         /* Not supported */
 177         return 0;
 178
 179     default:
 180         trace_grlib_apbuart_readl_unknown(addr);
 181         return 0;
 182     }
 183 }
 184
 185 static void grlib_apbuart_write(void *opaque, hwaddr addr,
 186                                 uint64_t value, unsigned size)
 187 {
 188     UART          *uart = opaque;
 189     unsigned char  c    = 0;
 190
 191     addr &= 0xff;
 192
 193     /* Unit registers */
 194     switch (addr) {
 195     case DATA_OFFSET:
 196     case DATA_OFFSET + 3:       /* When only one byte write */
 197         /* Transmit when character device available and transmitter enabled */
 198         if ((uart->chr) && (uart->control & UART_TRANSMIT_ENABLE)) {
 199             c = value & 0xFF;
 200             qemu_chr_fe_write(uart->chr, &c, 1);
 201             /* Generate interrupt */
 202             if (uart->control & UART_TRANSMIT_INTERRUPT) {
 203                 qemu_irq_pulse(uart->irq);
 204             }
 205         }
 206         return;
 207
 208     case STATUS_OFFSET:
 209         /* Read Only */
 210         return;
 211
 212     case CONTROL_OFFSET:
 213         uart->control = value;
 214         return;
 215
 216     case SCALER_OFFSET:
 217         /* Not supported */
 218         return;
 219
 220     default:
 221         break;
 222     }
 223
 224     trace_grlib_apbuart_writel_unknown(addr, value);
 225 }
 226
 227 static const MemoryRegionOps grlib_apbuart_ops = {
 228     .write      = grlib_apbuart_write,
 229     .read       = grlib_apbuart_read,
 230     .endianness = DEVICE_NATIVE_ENDIAN,
 231 };
 232
 233 static int grlib_apbuart_init(SysBusDevice *dev)
 234 {
 235     UART *uart = FROM_SYSBUS(typeof(*uart), dev);
 236
 237     qemu_chr_add_handlers(uart->chr,
 238                           grlib_apbuart_can_receive,
 239                           grlib_apbuart_receive,
 240                           grlib_apbuart_event,
 241                           uart);
 242
 243     sysbus_init_irq(dev, &uart->irq);
 244
 245     memory_region_init_io(&uart->iomem, &grlib_apbuart_ops, uart,
 246                           "uart", UART_REG_SIZE);
 247
 248     sysbus_init_mmio(dev, &uart->iomem);
 249
 250     return 0;
 251 }
 252
 253 static void grlib_apbuart_reset(DeviceState *d)
 254 {
 255     UART *uart = container_of(d, UART, busdev.qdev);
 256
 257     /* Transmitter FIFO and shift registers are always empty in QEMU */
 258     uart->status =  UART_TRANSMIT_FIFO_EMPTY | UART_TRANSMIT_SHIFT_EMPTY;
 259     /* Everything is off */
 260     uart->control = 0;
 261     /* Flush receive FIFO */
 262     uart->len = 0;
 263     uart->current = 0;
 264 }
 265
 266 static Property grlib_apbuart_properties[] = {
 267     DEFINE_PROP_CHR("chrdev", UART, chr),
 268     DEFINE_PROP_END_OF_LIST(),
 269 };
 270
 271 static void grlib_apbuart_class_init(ObjectClass *klass, void *data)
 272 {
 273     DeviceClass *dc = DEVICE_CLASS(klass);
 274     SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);
 275
 276     k->init = grlib_apbuart_init;
 277     dc->reset = grlib_apbuart_reset;
 278     dc->props = grlib_apbuart_properties;
 279 }
 280
 281 static const TypeInfo grlib_apbuart_info = {
 282     .name          = "grlib,apbuart",
 283     .parent        = TYPE_SYS_BUS_DEVICE,
 284     .instance_size = sizeof(UART),
 285     .class_init    = grlib_apbuart_class_init,
 286 };
 287
 288 static void grlib_apbuart_register_types(void)
 289 {
 290     type_register_static(&grlib_apbuart_info);
 291 }
 292
 293 type_init(grlib_apbuart_register_types)