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 "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 receive;
  79     uint32_t status;
  80     uint32_t control;
  81
  82     /* FIFO */
  83     char buffer[FIFO_LENGTH];
  84     int  len;
  85     int  current;
  86 } UART;
  87
  88 static int uart_data_to_read(UART *uart)
  89 {
  90     return uart->current < uart->len;
  91 }
  92
  93 static char uart_pop(UART *uart)
  94 {
  95     char ret;
  96
  97     if (uart->len == 0) {
  98         uart->status &= ~UART_DATA_READY;
  99         return 0;
 100     }
 101
 102     ret = uart->buffer[uart->current++];
 103
 104     if (uart->current >= uart->len) {
 105         /* Flush */
 106         uart->len     = 0;
 107         uart->current = 0;
 108     }
 109
 110     if (!uart_data_to_read(uart)) {
 111         uart->status &= ~UART_DATA_READY;
 112     }
 113
 114     return ret;
 115 }
 116
 117 static void uart_add_to_fifo(UART          *uart,
 118                              const uint8_t *buffer,
 119                              int            length)
 120 {
 121     if (uart->len + length > FIFO_LENGTH) {
 122         abort();
 123     }
 124     memcpy(uart->buffer + uart->len, buffer, length);
 125     uart->len += length;
 126 }
 127
 128 static int grlib_apbuart_can_receive(void *opaque)
 129 {
 130     UART *uart = opaque;
 131
 132     return FIFO_LENGTH - uart->len;
 133 }
 134
 135 static void grlib_apbuart_receive(void *opaque, const uint8_t *buf, int size)
 136 {
 137     UART *uart = opaque;
 138
 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 static void grlib_apbuart_event(void *opaque, int event)
 149 {
 150     trace_grlib_apbuart_event(event);
 151 }
 152
 153
 154 static uint64_t grlib_apbuart_read(void *opaque, hwaddr addr,
 155                                    unsigned size)
 156 {
 157     UART     *uart = opaque;
 158
 159     addr &= 0xff;
 160
 161     /* Unit registers */
 162     switch (addr) {
 163     case DATA_OFFSET:
 164     case DATA_OFFSET + 3:       /* when only one byte read */
 165         return uart_pop(uart);
 166
 167     case STATUS_OFFSET:
 168         /* Read Only */
 169         return uart->status;
 170
 171     case CONTROL_OFFSET:
 172         return uart->control;
 173
 174     case SCALER_OFFSET:
 175         /* Not supported */
 176         return 0;
 177
 178     default:
 179         trace_grlib_apbuart_readl_unknown(addr);
 180         return 0;
 181     }
 182 }
 183
 184 static void grlib_apbuart_write(void *opaque, hwaddr addr,
 185                                 uint64_t value, unsigned size)
 186 {
 187     UART          *uart = opaque;
 188     unsigned char  c    = 0;
 189
 190     addr &= 0xff;
 191
 192     /* Unit registers */
 193     switch (addr) {
 194     case DATA_OFFSET:
 195     case DATA_OFFSET + 3:       /* When only one byte write */
 196         c = value & 0xFF;
 197         qemu_chr_fe_write(uart->chr, &c, 1);
 198         return;
 199
 200     case STATUS_OFFSET:
 201         /* Read Only */
 202         return;
 203
 204     case CONTROL_OFFSET:
 205         uart->control = value;
 206         return;
 207
 208     case SCALER_OFFSET:
 209         /* Not supported */
 210         return;
 211
 212     default:
 213         break;
 214     }
 215
 216     trace_grlib_apbuart_writel_unknown(addr, value);
 217 }
 218
 219 static const MemoryRegionOps grlib_apbuart_ops = {
 220     .write      = grlib_apbuart_write,
 221     .read       = grlib_apbuart_read,
 222     .endianness = DEVICE_NATIVE_ENDIAN,
 223 };
 224
 225 static int grlib_apbuart_init(SysBusDevice *dev)
 226 {
 227     UART *uart = FROM_SYSBUS(typeof(*uart), dev);
 228
 229     qemu_chr_add_handlers(uart->chr,
 230                           grlib_apbuart_can_receive,
 231                           grlib_apbuart_receive,
 232                           grlib_apbuart_event,
 233                           uart);
 234
 235     sysbus_init_irq(dev, &uart->irq);
 236
 237     memory_region_init_io(&uart->iomem, &grlib_apbuart_ops, uart,
 238                           "uart", UART_REG_SIZE);
 239
 240     sysbus_init_mmio(dev, &uart->iomem);
 241
 242     return 0;
 243 }
 244
 245 static Property grlib_apbuart_properties[] = {
 246     DEFINE_PROP_CHR("chrdev", UART, chr),
 247     DEFINE_PROP_END_OF_LIST(),
 248 };
 249
 250 static void grlib_apbuart_class_init(ObjectClass *klass, void *data)
 251 {
 252     DeviceClass *dc = DEVICE_CLASS(klass);
 253     SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);
 254
 255     k->init = grlib_apbuart_init;
 256     dc->props = grlib_apbuart_properties;
 257 }
 258
 259 static const TypeInfo grlib_apbuart_info = {
 260     .name          = "grlib,apbuart",
 261     .parent        = TYPE_SYS_BUS_DEVICE,
 262     .instance_size = sizeof(UART),
 263     .class_init    = grlib_apbuart_class_init,
 264 };
 265
 266 static void grlib_apbuart_register_types(void)
 267 {
 268     type_register_static(&grlib_apbuart_info);
 269 }
 270
 271 type_init(grlib_apbuart_register_types)