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 "chardev/char-fe.h"
  33 #include "qemu/log.h"
  34
  35 #include "hw/char/digic-uart.h"
  36
  37 enum {
  38     ST_RX_RDY = (1 << 0),
  39     ST_TX_RDY = (1 << 1),
  40 };
  41
  42 static 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
  69 static 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         /* XXX this blocks entire thread. Rewrite to use
  80          * qemu_chr_fe_write and background I/O callbacks */
  81         qemu_chr_fe_write_all(&s->chr, &ch, 1);
  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
 105 static 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
 115 static int uart_can_rx(void *opaque)
 116 {
 117     DigicUartState *s = opaque;
 118
 119     return !(s->reg_st & ST_RX_RDY);
 120 }
 121
 122 static 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
 132 static void uart_event(void *opaque, int event)
 133 {
 134 }
 135
 136 static 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
 144 static void digic_uart_realize(DeviceState *dev, Error **errp)
 145 {
 146     DigicUartState *s = DIGIC_UART(dev);
 147
 148     qemu_chr_fe_set_handlers(&s->chr, uart_can_rx, uart_rx,
 149                              uart_event, NULL, s, NULL, true);
 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 Property digic_uart_properties[] = {
 173     DEFINE_PROP_CHR("chardev", DigicUartState, chr),
 174     DEFINE_PROP_END_OF_LIST(),
 175 };
 176
 177 static void digic_uart_class_init(ObjectClass *klass, void *data)
 178 {
 179     DeviceClass *dc = DEVICE_CLASS(klass);
 180
 181     dc->realize = digic_uart_realize;
 182     dc->reset = digic_uart_reset;
 183     dc->vmsd = &vmstate_digic_uart;
 184     dc->props = digic_uart_properties;
 185 }
 186
 187 static const TypeInfo digic_uart_info = {
 188     .name = TYPE_DIGIC_UART,
 189     .parent = TYPE_SYS_BUS_DEVICE,
 190     .instance_size = sizeof(DigicUartState),
 191     .instance_init = digic_uart_init,
 192     .class_init = digic_uart_class_init,
 193 };
 194
 195 static void digic_uart_register_types(void)
 196 {
 197     type_register_static(&digic_uart_info);
 198 }
 199
 200 type_init(digic_uart_register_types)