hw/etraxfs_ser.c

   1 /*
   2  * QEMU ETRAX System Emulator
   3  *
   4  * Copyright (c) 2007 Edgar E. Iglesias, Axis Communications AB.
   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 "qemu-char.h"
  27
  28 #define D(x)
  29
  30 #define RW_TR_CTRL     (0x00 / 4)
  31 #define RW_TR_DMA_EN   (0x04 / 4)
  32 #define RW_REC_CTRL    (0x08 / 4)
  33 #define RW_DOUT        (0x1c / 4)
  34 #define RS_STAT_DIN    (0x20 / 4)
  35 #define R_STAT_DIN     (0x24 / 4)
  36 #define RW_INTR_MASK   (0x2c / 4)
  37 #define RW_ACK_INTR    (0x30 / 4)
  38 #define R_INTR         (0x34 / 4)
  39 #define R_MASKED_INTR  (0x38 / 4)
  40 #define R_MAX          (0x3c / 4)
  41
  42 #define STAT_DAV     16
  43 #define STAT_TR_IDLE 22
  44 #define STAT_TR_RDY  24
  45
  46 struct etrax_serial
  47 {
  48     SysBusDevice busdev;
  49     CharDriverState *chr;
  50     qemu_irq irq;
  51
  52     int pending_tx;
  53
  54     uint8_t rx_fifo[16];
  55     unsigned int rx_fifo_pos;
  56     unsigned int rx_fifo_len;
  57
  58     /* Control registers.  */
  59     uint32_t regs[R_MAX];
  60 };
  61
  62 static void ser_update_irq(struct etrax_serial *s)
  63 {
  64
  65     if (s->rx_fifo_len) {
  66         s->regs[R_INTR] |= 8;
  67     } else {
  68         s->regs[R_INTR] &= ~8;
  69     }
  70
  71     s->regs[R_MASKED_INTR] = s->regs[R_INTR] & s->regs[RW_INTR_MASK];
  72     qemu_set_irq(s->irq, !!s->regs[R_MASKED_INTR]);
  73 }
  74
  75 static uint32_t ser_readl (void *opaque, target_phys_addr_t addr)
  76 {
  77     struct etrax_serial *s = opaque;
  78     D(CPUState *env = s->env);
  79     uint32_t r = 0;
  80
  81     addr >>= 2;
  82     switch (addr)
  83     {
  84         case R_STAT_DIN:
  85             r = s->rx_fifo[(s->rx_fifo_pos - s->rx_fifo_len) & 15];
  86             if (s->rx_fifo_len) {
  87                 r |= 1 << STAT_DAV;
  88             }
  89             r |= 1 << STAT_TR_RDY;
  90             r |= 1 << STAT_TR_IDLE;
  91             break;
  92         case RS_STAT_DIN:
  93             r = s->rx_fifo[(s->rx_fifo_pos - s->rx_fifo_len) & 15];
  94             if (s->rx_fifo_len) {
  95                 r |= 1 << STAT_DAV;
  96                 s->rx_fifo_len--;
  97             }
  98             r |= 1 << STAT_TR_RDY;
  99             r |= 1 << STAT_TR_IDLE;
 100             break;
 101         default:
 102             r = s->regs[addr];
 103             D(printf ("%s " TARGET_FMT_plx "=%x\n", __func__, addr, r));
 104             break;
 105     }
 106     return r;
 107 }
 108
 109 static void
 110 ser_writel (void *opaque, target_phys_addr_t addr, uint32_t value)
 111 {
 112     struct etrax_serial *s = opaque;
 113     unsigned char ch = value;
 114     D(CPUState *env = s->env);
 115
 116     D(printf ("%s " TARGET_FMT_plx "=%x\n",  __func__, addr, value));
 117     addr >>= 2;
 118     switch (addr)
 119     {
 120         case RW_DOUT:
 121             qemu_chr_write(s->chr, &ch, 1);
 122             s->regs[R_INTR] |= 3;
 123             s->pending_tx = 1;
 124             s->regs[addr] = value;
 125             break;
 126         case RW_ACK_INTR:
 127             if (s->pending_tx) {
 128                 value &= ~1;
 129                 s->pending_tx = 0;
 130                 D(printf("fixedup value=%x r_intr=%x\n", value, s->regs[R_INTR]));
 131             }
 132             s->regs[addr] = value;
 133             s->regs[R_INTR] &= ~value;
 134             D(printf("r_intr=%x\n", s->regs[R_INTR]));
 135             break;
 136         default:
 137             s->regs[addr] = value;
 138             break;
 139     }
 140     ser_update_irq(s);
 141 }
 142
 143 static CPUReadMemoryFunc * const ser_read[] = {
 144     NULL, NULL,
 145     &ser_readl,
 146 };
 147
 148 static CPUWriteMemoryFunc * const ser_write[] = {
 149     NULL, NULL,
 150     &ser_writel,
 151 };
 152
 153 static void serial_receive(void *opaque, const uint8_t *buf, int size)
 154 {
 155     struct etrax_serial *s = opaque;
 156     int i;
 157
 158     /* Got a byte.  */
 159     if (s->rx_fifo_len >= 16) {
 160         printf("WARNING: UART dropped char.\n");
 161         return;
 162     }
 163
 164     for (i = 0; i < size; i++) {
 165         s->rx_fifo[s->rx_fifo_pos] = buf[i];
 166         s->rx_fifo_pos++;
 167         s->rx_fifo_pos &= 15;
 168         s->rx_fifo_len++;
 169     }
 170
 171     ser_update_irq(s);
 172 }
 173
 174 static int serial_can_receive(void *opaque)
 175 {
 176     struct etrax_serial *s = opaque;
 177     int r;
 178
 179     /* Is the receiver enabled?  */
 180     if (!(s->regs[RW_REC_CTRL] & (1 << 3))) {
 181         return 0;
 182     }
 183
 184     r = sizeof(s->rx_fifo) - s->rx_fifo_len;
 185     return r;
 186 }
 187
 188 static void serial_event(void *opaque, int event)
 189 {
 190
 191 }
 192
 193 static int etraxfs_ser_init(SysBusDevice *dev)
 194 {
 195     struct etrax_serial *s = FROM_SYSBUS(typeof (*s), dev);
 196     int ser_regs;
 197
 198     /* transmitter begins ready and idle.  */
 199     s->regs[RS_STAT_DIN] |= (1 << STAT_TR_RDY);
 200     s->regs[RS_STAT_DIN] |= (1 << STAT_TR_IDLE);
 201
 202     sysbus_init_irq(dev, &s->irq);
 203     ser_regs = cpu_register_io_memory(ser_read, ser_write, s);
 204     sysbus_init_mmio(dev, R_MAX * 4, ser_regs);
 205     s->chr = qdev_init_chardev(&dev->qdev);
 206     if (s->chr)
 207         qemu_chr_add_handlers(s->chr,
 208                       serial_can_receive, serial_receive,
 209                       serial_event, s);
 210     return 0;
 211 }
 212
 213 static void etraxfs_serial_register(void)
 214 {
 215     sysbus_register_dev("etraxfs,serial", sizeof (struct etrax_serial),
 216                 etraxfs_ser_init);
 217 }
 218
 219 device_init(etraxfs_serial_register)