LXR qemu/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 "qemu/osdep.h"
  30#include "hw/hw.h"
  31#include "hw/sysbus.h"
  32#include "sysemu/char.h"
  33#include "qemu/log.h"
  34
  35#include "hw/char/digic-uart.h"
  36
  37enum {
  38    ST_RX_RDY = (1 << 0),
  39    ST_TX_RDY = (1 << 1),
  40};
  41
  42static uint64_t digic_uart_read(void *opaque, hwaddr addr,
  43                                unsigned size)
  44{
  45    DigicUartState *s = opaque;
  46    uint64_t ret = 0;
  47
  48    addr >>= 2;
  49
  50    switch (addr) {
  51    case R_RX:
  52        s->reg_st &= ~(ST_RX_RDY);
  53        ret = s->reg_rx;
  54        break;
  55
  56    case R_ST:
  57        ret = s->reg_st;
  58        break;
  59
  60    default:
  61        qemu_log_mask(LOG_UNIMP,
  62                      "digic-uart: read access to unknown register 0x"
  63                      TARGET_FMT_plx, addr << 2);
  64    }
  65
  66    return ret;
  67}
  68
  69static void digic_uart_write(void *opaque, hwaddr addr, uint64_t value,
  70                             unsigned size)
  71{
  72    DigicUartState *s = opaque;
  73    unsigned char ch = value;
  74
  75    addr >>= 2;
  76
  77    switch (addr) {
  78    case R_TX:
  79        if (s->chr) {
  80            qemu_chr_fe_write_all(s->chr, &ch, 1);
  81        }
  82        break;
  83
  84    case R_ST:
  85        /*
  86         * Ignore write to R_ST.
  87         *
  88         * The point is that this register is actively used
  89         * during receiving and transmitting symbols,
  90         * but we don't know the function of most of bits.
  91         *
  92         * Ignoring writes to R_ST is only a simplification
  93         * of the model. It has no perceptible side effects
  94         * for existing guests.
  95         */
  96        break;
  97
  98    default:
  99        qemu_log_mask(LOG_UNIMP,
 100                      "digic-uart: write access to unknown register 0x"
 101                      TARGET_FMT_plx, addr << 2);
 102    }
 103}
 104
 105static const MemoryRegionOps uart_mmio_ops = {
 106    .read = digic_uart_read,
 107    .write = digic_uart_write,
 108    .valid = {
 109        .min_access_size = 4,
 110        .max_access_size = 4,
 111    },
 112    .endianness = DEVICE_NATIVE_ENDIAN,
 113};
 114
 115static int uart_can_rx(void *opaque)
 116{
 117    DigicUartState *s = opaque;
 118
 119    return !(s->reg_st & ST_RX_RDY);
 120}
 121
 122static void uart_rx(void *opaque, const uint8_t *buf, int size)
 123{
 124    DigicUartState *s = opaque;
 125
 126    assert(uart_can_rx(opaque));
 127
 128    s->reg_st |= ST_RX_RDY;
 129    s->reg_rx = *buf;
 130}
 131
 132static void uart_event(void *opaque, int event)
 133{
 134}
 135
 136static void digic_uart_reset(DeviceState *d)
 137{
 138    DigicUartState *s = DIGIC_UART(d);
 139
 140    s->reg_rx = 0;
 141    s->reg_st = ST_TX_RDY;
 142}
 143
 144static void digic_uart_realize(DeviceState *dev, Error **errp)
 145{
 146    DigicUartState *s = DIGIC_UART(dev);
 147
 148    /* FIXME use a qdev chardev prop instead of qemu_char_get_next_serial() */
 149    s->chr = qemu_char_get_next_serial();
 150    if (s->chr) {
 151        qemu_chr_add_handlers(s->chr, uart_can_rx, uart_rx, uart_event, s);
 152    }
 153}
 154
 155static void digic_uart_init(Object *obj)
 156{
 157    DigicUartState *s = DIGIC_UART(obj);
 158
 159    memory_region_init_io(&s->regs_region, OBJECT(s), &uart_mmio_ops, s,
 160                          TYPE_DIGIC_UART, 0x18);
 161    sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->regs_region);
 162}
 163
 164static const VMStateDescription vmstate_digic_uart = {
 165    .name = "digic-uart",
 166    .version_id = 1,
 167    .minimum_version_id = 1,
 168    .fields = (VMStateField[]) {
 169        VMSTATE_UINT32(reg_rx, DigicUartState),
 170        VMSTATE_UINT32(reg_st, DigicUartState),
 171        VMSTATE_END_OF_LIST()
 172    }
 173};
 174
 175static void digic_uart_class_init(ObjectClass *klass, void *data)
 176{
 177    DeviceClass *dc = DEVICE_CLASS(klass);
 178
 179    dc->realize = digic_uart_realize;
 180    dc->reset = digic_uart_reset;
 181    dc->vmsd = &vmstate_digic_uart;
 182    /* Reason: realize() method uses qemu_char_get_next_serial() */
 183    dc->cannot_instantiate_with_device_add_yet = true;
 184}
 185
 186static const TypeInfo digic_uart_info = {
 187    .name = TYPE_DIGIC_UART,
 188    .parent = TYPE_SYS_BUS_DEVICE,
 189    .instance_size = sizeof(DigicUartState),
 190    .instance_init = digic_uart_init,
 191    .class_init = digic_uart_class_init,
 192};
 193
 194static void digic_uart_register_types(void)
 195{
 196    type_register_static(&digic_uart_info);
 197}
 198
 199type_init(digic_uart_register_types)
 200