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     /* This pending thing is a hack.  */
  53     int pending_tx;
  54
  55     /* Control registers.  */
  56     uint32_t regs[R_MAX];
  57 };
  58
  59 static void ser_update_irq(struct etrax_serial *s)
  60 {
  61     s->regs[R_INTR] &= ~(s->regs[RW_ACK_INTR]);
  62     s->regs[R_MASKED_INTR] = s->regs[R_INTR] & s->regs[RW_INTR_MASK];
  63
  64     qemu_set_irq(s->irq, !!s->regs[R_MASKED_INTR]);
  65     s->regs[RW_ACK_INTR] = 0;
  66 }
  67
  68 static uint32_t ser_readl (void *opaque, target_phys_addr_t addr)
  69 {
  70     struct etrax_serial *s = opaque;
  71     D(CPUState *env = s->env);
  72     uint32_t r = 0;
  73
  74     addr >>= 2;
  75     switch (addr)
  76     {
  77         case R_STAT_DIN:
  78             r = s->regs[RS_STAT_DIN];
  79             break;
  80         case RS_STAT_DIN:
  81             r = s->regs[addr];
  82             /* Read side-effect: clear dav.  */
  83             s->regs[addr] &= ~(1 << STAT_DAV);
  84             break;
  85         default:
  86             r = s->regs[addr];
  87             D(printf ("%s %x=%x\n", __func__, addr, r));
  88             break;
  89     }
  90     return r;
  91 }
  92
  93 static void
  94 ser_writel (void *opaque, target_phys_addr_t addr, uint32_t value)
  95 {
  96     struct etrax_serial *s = opaque;
  97     unsigned char ch = value;
  98     D(CPUState *env = s->env);
  99
 100     D(printf ("%s %x %x\n",  __func__, addr, value));
 101     addr >>= 2;
 102     switch (addr)
 103     {
 104         case RW_DOUT:
 105             qemu_chr_write(s->chr, &ch, 1);
 106             s->regs[R_INTR] |= 1;
 107             s->pending_tx = 1;
 108             s->regs[addr] = value;
 109             break;
 110         case RW_ACK_INTR:
 111             s->regs[addr] = value;
 112             if (s->pending_tx && (s->regs[addr] & 1)) {
 113                 s->regs[R_INTR] |= 1;
 114                 s->pending_tx = 0;
 115                 s->regs[addr] &= ~1;
 116             }
 117             break;
 118         default:
 119             s->regs[addr] = value;
 120             break;
 121     }
 122     ser_update_irq(s);
 123 }
 124
 125 static CPUReadMemoryFunc *ser_read[] = {
 126     NULL, NULL,
 127     &ser_readl,
 128 };
 129
 130 static CPUWriteMemoryFunc *ser_write[] = {
 131     NULL, NULL,
 132     &ser_writel,
 133 };
 134
 135 static void serial_receive(void *opaque, const uint8_t *buf, int size)
 136 {
 137     struct etrax_serial *s = opaque;
 138
 139     s->regs[R_INTR] |= 8;
 140     s->regs[RS_STAT_DIN] &= ~0xff;
 141     s->regs[RS_STAT_DIN] |= (buf[0] & 0xff);
 142     s->regs[RS_STAT_DIN] |= (1 << STAT_DAV); /* dav.  */
 143     ser_update_irq(s);
 144 }
 145
 146 static int serial_can_receive(void *opaque)
 147 {
 148     struct etrax_serial *s = opaque;
 149     int r;
 150
 151     /* Is the receiver enabled?  */
 152     r = s->regs[RW_REC_CTRL] & 1;
 153
 154     /* Pending rx data?  */
 155     r |= !(s->regs[R_INTR] & 8);
 156     return r;
 157 }
 158
 159 static void serial_event(void *opaque, int event)
 160 {
 161
 162 }
 163
 164 static void etraxfs_ser_init(SysBusDevice *dev)
 165 {
 166     struct etrax_serial *s = FROM_SYSBUS(typeof (*s), dev);
 167     int ser_regs;
 168
 169     /* transmitter begins ready and idle.  */
 170     s->regs[RS_STAT_DIN] |= (1 << STAT_TR_RDY);
 171     s->regs[RS_STAT_DIN] |= (1 << STAT_TR_IDLE);
 172
 173     sysbus_init_irq(dev, &s->irq);
 174     ser_regs = cpu_register_io_memory(ser_read, ser_write, s);
 175     sysbus_init_mmio(dev, R_MAX * 4, ser_regs);
 176     s->chr = qdev_init_chardev(&dev->qdev);
 177     if (s->chr)
 178         qemu_chr_add_handlers(s->chr,
 179                       serial_can_receive, serial_receive,
 180                       serial_event, s);
 181 }
 182
 183 static void etraxfs_serial_register(void)
 184 {
 185     sysbus_register_dev("etraxfs,serial", sizeof (struct etrax_serial),
 186                 etraxfs_ser_init);
 187 }
 188
 189 device_init(etraxfs_serial_register)