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/sysbus.h"
  31 #include "migration/vmstate.h"
  32 #include "chardev/char-fe.h"
  33 #include "qemu/log.h"
  34 #include "qemu/module.h"
  35
  36 #include "hw/char/digic-uart.h"
  37 #include "hw/qdev-properties.h"
  38 #include "hw/qdev-properties-system.h"
  39
  40 enum {
  41     ST_RX_RDY = (1 << 0),
  42     ST_TX_RDY = (1 << 1),
  43 };
  44
  45 static uint64_t digic_uart_read(void *opaque, hwaddr addr,
  46                                 unsigned size)
  47 {
  48     DigicUartState *s = opaque;
  49     uint64_t ret = 0;
  50
  51     addr >>= 2;
  52
  53     switch (addr) {
  54     case R_RX:
  55         s->reg_st &= ~(ST_RX_RDY);
  56         ret = s->reg_rx;
  57         break;
  58
  59     case R_ST:
  60         ret = s->reg_st;
  61         break;
  62
  63     default:
  64         qemu_log_mask(LOG_UNIMP,
  65                       "digic-uart: read access to unknown register 0x"
  66                       HWADDR_FMT_plx "\n", addr << 2);
  67     }
  68
  69     return ret;
  70 }
  71
  72 static void digic_uart_write(void *opaque, hwaddr addr, uint64_t value,
  73                              unsigned size)
  74 {
  75     DigicUartState *s = opaque;
  76     unsigned char ch = value;
  77
  78     addr >>= 2;
  79
  80     switch (addr) {
  81     case R_TX:
  82         /* XXX this blocks entire thread. Rewrite to use
  83          * qemu_chr_fe_write and background I/O callbacks */
  84         qemu_chr_fe_write_all(&s->chr, &ch, 1);
  85         break;
  86
  87     case R_ST:
  88         /*
  89          * Ignore write to R_ST.
  90          *
  91          * The point is that this register is actively used
  92          * during receiving and transmitting symbols,
  93          * but we don't know the function of most of bits.
  94          *
  95          * Ignoring writes to R_ST is only a simplification
  96          * of the model. It has no perceptible side effects
  97          * for existing guests.
  98          */
  99         break;
 100
 101     default:
 102         qemu_log_mask(LOG_UNIMP,
 103                       "digic-uart: write access to unknown register 0x"
 104                       HWADDR_FMT_plx "\n", addr << 2);
 105     }
 106 }
 107
 108 static const MemoryRegionOps uart_mmio_ops = {
 109     .read = digic_uart_read,
 110     .write = digic_uart_write,
 111     .valid = {
 112         .min_access_size = 4,
 113         .max_access_size = 4,
 114     },
 115     .endianness = DEVICE_NATIVE_ENDIAN,
 116 };
 117
 118 static int uart_can_rx(void *opaque)
 119 {
 120     DigicUartState *s = opaque;
 121
 122     return !(s->reg_st & ST_RX_RDY);
 123 }
 124
 125 static void uart_rx(void *opaque, const uint8_t *buf, int size)
 126 {
 127     DigicUartState *s = opaque;
 128
 129     assert(uart_can_rx(opaque));
 130
 131     s->reg_st |= ST_RX_RDY;
 132     s->reg_rx = *buf;
 133 }
 134
 135 static void uart_event(void *opaque, QEMUChrEvent event)
 136 {
 137 }
 138
 139 static void digic_uart_reset(DeviceState *d)
 140 {
 141     DigicUartState *s = DIGIC_UART(d);
 142
 143     s->reg_rx = 0;
 144     s->reg_st = ST_TX_RDY;
 145 }
 146
 147 static void digic_uart_realize(DeviceState *dev, Error **errp)
 148 {
 149     DigicUartState *s = DIGIC_UART(dev);
 150
 151     qemu_chr_fe_set_handlers(&s->chr, uart_can_rx, uart_rx,
 152                              uart_event, NULL, s, NULL, true);
 153 }
 154
 155 static 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
 164 static const VMStateDescription vmstate_digic_uart = {
 165     .name = "digic-uart",
 166     .version_id = 1,
 167     .minimum_version_id = 1,
 168     .fields = (const VMStateField[]) {
 169         VMSTATE_UINT32(reg_rx, DigicUartState),
 170         VMSTATE_UINT32(reg_st, DigicUartState),
 171         VMSTATE_END_OF_LIST()
 172     }
 173 };
 174
 175 static Property digic_uart_properties[] = {
 176     DEFINE_PROP_CHR("chardev", DigicUartState, chr),
 177     DEFINE_PROP_END_OF_LIST(),
 178 };
 179
 180 static void digic_uart_class_init(ObjectClass *klass, void *data)
 181 {
 182     DeviceClass *dc = DEVICE_CLASS(klass);
 183
 184     dc->realize = digic_uart_realize;
 185     dc->reset = digic_uart_reset;
 186     dc->vmsd = &vmstate_digic_uart;
 187     device_class_set_props(dc, digic_uart_properties);
 188 }
 189
 190 static const TypeInfo digic_uart_info = {
 191     .name = TYPE_DIGIC_UART,
 192     .parent = TYPE_SYS_BUS_DEVICE,
 193     .instance_size = sizeof(DigicUartState),
 194     .instance_init = digic_uart_init,
 195     .class_init = digic_uart_class_init,
 196 };
 197
 198 static void digic_uart_register_types(void)
 199 {
 200     type_register_static(&digic_uart_info);
 201 }
 202
 203 type_init(digic_uart_register_types)