hw/char/digic-uart.c

   1 /*
   2  * QEMU model of the Canon DIGIC UART block.
   3  *
   4  * Copyright (C) 2013 Antony Pavlov <antonynpavlov@gmail.com>
   5  *
   6  * This model is based on reverse engineering efforts
   7  * made by CHDK (http://chdk.wikia.com) and
   8  * Magic Lantern (http://www.magiclantern.fm) projects
   9  * contributors.
  10  *
  11  * See "Serial terminal" docs here:
  12  *   http://magiclantern.wikia.com/wiki/Register_Map#Misc_Registers
  13  *
  14  * The QEMU model of the Milkymist UART block by Michael Walle
  15  * is used as a template.
  16  *
  17  * This program is free software; you can redistribute it and/or modify
  18  * it under the terms of the GNU General Public License as published by
  19  * the Free Software Foundation; either version 2 of the License, or
  20  * (at your option) any later version.
  21  *
  22  * This program is distributed in the hope that it will be useful,
  23  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  24  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  25  * GNU General Public License for more details.
  26  *
  27  */
  28
  29 #include "hw/hw.h"
  30 #include "hw/sysbus.h"
  31 #include "sysemu/char.h"
  32
  33 #include "hw/char/digic-uart.h"
  34
  35 enum {
  36     ST_RX_RDY = (1 << 0),
  37     ST_TX_RDY = (1 << 1),
  38 };
  39
  40 static uint64_t digic_uart_read(void *opaque, hwaddr addr,
  41                                 unsigned size)
  42 {
  43     DigicUartState *s = opaque;
  44     uint64_t ret = 0;
  45
  46     addr >>= 2;
  47
  48     switch (addr) {
  49     case R_RX:
  50         s->reg_st &= ~(ST_RX_RDY);
  51         ret = s->reg_rx;
  52         break;
  53
  54     case R_ST:
  55         ret = s->reg_st;
  56         break;
  57
  58     default:
  59         qemu_log_mask(LOG_UNIMP,
  60                       "digic-uart: read access to unknown register 0x"
  61                       TARGET_FMT_plx, addr << 2);
  62     }
  63
  64     return ret;
  65 }
  66
  67 static void digic_uart_write(void *opaque, hwaddr addr, uint64_t value,
  68                              unsigned size)
  69 {
  70     DigicUartState *s = opaque;
  71     unsigned char ch = value;
  72
  73     addr >>= 2;
  74
  75     switch (addr) {
  76     case R_TX:
  77         if (s->chr) {
  78             qemu_chr_fe_write_all(s->chr, &ch, 1);
  79         }
  80         break;
  81
  82     case R_ST:
  83         /*
  84          * Ignore write to R_ST.
  85          *
  86          * The point is that this register is actively used
  87          * during receiving and transmitting symbols,
  88          * but we don't know the function of most of bits.
  89          *
  90          * Ignoring writes to R_ST is only a simplification
  91          * of the model. It has no perceptible side effects
  92          * for existing guests.
  93          */
  94         break;
  95
  96     default:
  97         qemu_log_mask(LOG_UNIMP,
  98                       "digic-uart: write access to unknown register 0x"
  99                       TARGET_FMT_plx, addr << 2);
 100     }
 101 }
 102
 103 static const MemoryRegionOps uart_mmio_ops = {
 104     .read = digic_uart_read,
 105     .write = digic_uart_write,
 106     .valid = {
 107         .min_access_size = 4,
 108         .max_access_size = 4,
 109     },
 110     .endianness = DEVICE_NATIVE_ENDIAN,
 111 };
 112
 113 static int uart_can_rx(void *opaque)
 114 {
 115     DigicUartState *s = opaque;
 116
 117     return !(s->reg_st & ST_RX_RDY);
 118 }
 119
 120 static void uart_rx(void *opaque, const uint8_t *buf, int size)
 121 {
 122     DigicUartState *s = opaque;
 123
 124     assert(uart_can_rx(opaque));
 125
 126     s->reg_st |= ST_RX_RDY;
 127     s->reg_rx = *buf;
 128 }
 129
 130 static void uart_event(void *opaque, int event)
 131 {
 132 }
 133
 134 static void digic_uart_reset(DeviceState *d)
 135 {
 136     DigicUartState *s = DIGIC_UART(d);
 137
 138     s->reg_rx = 0;
 139     s->reg_st = ST_TX_RDY;
 140 }
 141
 142 static void digic_uart_realize(DeviceState *dev, Error **errp)
 143 {
 144     DigicUartState *s = DIGIC_UART(dev);
 145
 146     s->chr = qemu_char_get_next_serial();
 147     if (s->chr) {
 148         qemu_chr_add_handlers(s->chr, uart_can_rx, uart_rx, uart_event, s);
 149     }
 150 }
 151
 152 static void digic_uart_init(Object *obj)
 153 {
 154     DigicUartState *s = DIGIC_UART(obj);
 155
 156     memory_region_init_io(&s->regs_region, OBJECT(s), &uart_mmio_ops, s,
 157                           TYPE_DIGIC_UART, 0x18);
 158     sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->regs_region);
 159 }
 160
 161 static const VMStateDescription vmstate_digic_uart = {
 162     .name = "digic-uart",
 163     .version_id = 1,
 164     .minimum_version_id = 1,
 165     .fields = (VMStateField[]) {
 166         VMSTATE_UINT32(reg_rx, DigicUartState),
 167         VMSTATE_UINT32(reg_st, DigicUartState),
 168         VMSTATE_END_OF_LIST()
 169     }
 170 };
 171
 172 static void digic_uart_class_init(ObjectClass *klass, void *data)
 173 {
 174     DeviceClass *dc = DEVICE_CLASS(klass);
 175
 176     dc->realize = digic_uart_realize;
 177     dc->reset = digic_uart_reset;
 178     dc->vmsd = &vmstate_digic_uart;
 179 }
 180
 181 static const TypeInfo digic_uart_info = {
 182     .name = TYPE_DIGIC_UART,
 183     .parent = TYPE_SYS_BUS_DEVICE,
 184     .instance_size = sizeof(DigicUartState),
 185     .instance_init = digic_uart_init,
 186     .class_init = digic_uart_class_init,
 187 };
 188
 189 static void digic_uart_register_types(void)
 190 {
 191     type_register_static(&digic_uart_info);
 192 }
 193
 194 type_init(digic_uart_register_types)