hw/char/lm32_uart.c

   1 /*
   2  *  QEMU model of the LatticeMico32 UART block.
   3  *
   4  *  Copyright (c) 2010 Michael Walle <michael@walle.cc>
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  *
  19  *
  20  * Specification available at:
  21  *   http://www.latticesemi.com/documents/mico32uart.pdf
  22  */
  23
  24
  25 #include "qemu/osdep.h"
  26 #include "hw/hw.h"
  27 #include "hw/sysbus.h"
  28 #include "trace.h"
  29 #include "chardev/char-fe.h"
  30 #include "qemu/error-report.h"
  31
  32 enum {
  33     R_RXTX = 0,
  34     R_IER,
  35     R_IIR,
  36     R_LCR,
  37     R_MCR,
  38     R_LSR,
  39     R_MSR,
  40     R_DIV,
  41     R_MAX
  42 };
  43
  44 enum {
  45     IER_RBRI = (1<<0),
  46     IER_THRI = (1<<1),
  47     IER_RLSI = (1<<2),
  48     IER_MSI  = (1<<3),
  49 };
  50
  51 enum {
  52     IIR_STAT = (1<<0),
  53     IIR_ID0  = (1<<1),
  54     IIR_ID1  = (1<<2),
  55 };
  56
  57 enum {
  58     LCR_WLS0 = (1<<0),
  59     LCR_WLS1 = (1<<1),
  60     LCR_STB  = (1<<2),
  61     LCR_PEN  = (1<<3),
  62     LCR_EPS  = (1<<4),
  63     LCR_SP   = (1<<5),
  64     LCR_SB   = (1<<6),
  65 };
  66
  67 enum {
  68     MCR_DTR  = (1<<0),
  69     MCR_RTS  = (1<<1),
  70 };
  71
  72 enum {
  73     LSR_DR   = (1<<0),
  74     LSR_OE   = (1<<1),
  75     LSR_PE   = (1<<2),
  76     LSR_FE   = (1<<3),
  77     LSR_BI   = (1<<4),
  78     LSR_THRE = (1<<5),
  79     LSR_TEMT = (1<<6),
  80 };
  81
  82 enum {
  83     MSR_DCTS = (1<<0),
  84     MSR_DDSR = (1<<1),
  85     MSR_TERI = (1<<2),
  86     MSR_DDCD = (1<<3),
  87     MSR_CTS  = (1<<4),
  88     MSR_DSR  = (1<<5),
  89     MSR_RI   = (1<<6),
  90     MSR_DCD  = (1<<7),
  91 };
  92
  93 #define TYPE_LM32_UART "lm32-uart"
  94 #define LM32_UART(obj) OBJECT_CHECK(LM32UartState, (obj), TYPE_LM32_UART)
  95
  96 struct LM32UartState {
  97     SysBusDevice parent_obj;
  98
  99     MemoryRegion iomem;
 100     CharBackend chr;
 101     qemu_irq irq;
 102
 103     uint32_t regs[R_MAX];
 104 };
 105 typedef struct LM32UartState LM32UartState;
 106
 107 static void uart_update_irq(LM32UartState *s)
 108 {
 109     unsigned int irq;
 110
 111     if ((s->regs[R_LSR] & (LSR_OE | LSR_PE | LSR_FE | LSR_BI))
 112             && (s->regs[R_IER] & IER_RLSI)) {
 113         irq = 1;
 114         s->regs[R_IIR] = IIR_ID1 | IIR_ID0;
 115     } else if ((s->regs[R_LSR] & LSR_DR) && (s->regs[R_IER] & IER_RBRI)) {
 116         irq = 1;
 117         s->regs[R_IIR] = IIR_ID1;
 118     } else if ((s->regs[R_LSR] & LSR_THRE) && (s->regs[R_IER] & IER_THRI)) {
 119         irq = 1;
 120         s->regs[R_IIR] = IIR_ID0;
 121     } else if ((s->regs[R_MSR] & 0x0f) && (s->regs[R_IER] & IER_MSI)) {
 122         irq = 1;
 123         s->regs[R_IIR] = 0;
 124     } else {
 125         irq = 0;
 126         s->regs[R_IIR] = IIR_STAT;
 127     }
 128
 129     trace_lm32_uart_irq_state(irq);
 130     qemu_set_irq(s->irq, irq);
 131 }
 132
 133 static uint64_t uart_read(void *opaque, hwaddr addr,
 134                           unsigned size)
 135 {
 136     LM32UartState *s = opaque;
 137     uint32_t r = 0;
 138
 139     addr >>= 2;
 140     switch (addr) {
 141     case R_RXTX:
 142         r = s->regs[R_RXTX];
 143         s->regs[R_LSR] &= ~LSR_DR;
 144         uart_update_irq(s);
 145         qemu_chr_fe_accept_input(&s->chr);
 146         break;
 147     case R_IIR:
 148     case R_LSR:
 149     case R_MSR:
 150         r = s->regs[addr];
 151         break;
 152     case R_IER:
 153     case R_LCR:
 154     case R_MCR:
 155     case R_DIV:
 156         error_report("lm32_uart: read access to write only register 0x"
 157                 TARGET_FMT_plx, addr << 2);
 158         break;
 159     default:
 160         error_report("lm32_uart: read access to unknown register 0x"
 161                 TARGET_FMT_plx, addr << 2);
 162         break;
 163     }
 164
 165     trace_lm32_uart_memory_read(addr << 2, r);
 166     return r;
 167 }
 168
 169 static void uart_write(void *opaque, hwaddr addr,
 170                        uint64_t value, unsigned size)
 171 {
 172     LM32UartState *s = opaque;
 173     unsigned char ch = value;
 174
 175     trace_lm32_uart_memory_write(addr, value);
 176
 177     addr >>= 2;
 178     switch (addr) {
 179     case R_RXTX:
 180         /* XXX this blocks entire thread. Rewrite to use
 181          * qemu_chr_fe_write and background I/O callbacks */
 182         qemu_chr_fe_write_all(&s->chr, &ch, 1);
 183         break;
 184     case R_IER:
 185     case R_LCR:
 186     case R_MCR:
 187     case R_DIV:
 188         s->regs[addr] = value;
 189         break;
 190     case R_IIR:
 191     case R_LSR:
 192     case R_MSR:
 193         error_report("lm32_uart: write access to read only register 0x"
 194                 TARGET_FMT_plx, addr << 2);
 195         break;
 196     default:
 197         error_report("lm32_uart: write access to unknown register 0x"
 198                 TARGET_FMT_plx, addr << 2);
 199         break;
 200     }
 201     uart_update_irq(s);
 202 }
 203
 204 static const MemoryRegionOps uart_ops = {
 205     .read = uart_read,
 206     .write = uart_write,
 207     .endianness = DEVICE_NATIVE_ENDIAN,
 208     .valid = {
 209         .min_access_size = 4,
 210         .max_access_size = 4,
 211     },
 212 };
 213
 214 static void uart_rx(void *opaque, const uint8_t *buf, int size)
 215 {
 216     LM32UartState *s = opaque;
 217
 218     if (s->regs[R_LSR] & LSR_DR) {
 219         s->regs[R_LSR] |= LSR_OE;
 220     }
 221
 222     s->regs[R_LSR] |= LSR_DR;
 223     s->regs[R_RXTX] = *buf;
 224
 225     uart_update_irq(s);
 226 }
 227
 228 static int uart_can_rx(void *opaque)
 229 {
 230     LM32UartState *s = opaque;
 231
 232     return !(s->regs[R_LSR] & LSR_DR);
 233 }
 234
 235 static void uart_event(void *opaque, int event)
 236 {
 237 }
 238
 239 static void uart_reset(DeviceState *d)
 240 {
 241     LM32UartState *s = LM32_UART(d);
 242     int i;
 243
 244     for (i = 0; i < R_MAX; i++) {
 245         s->regs[i] = 0;
 246     }
 247
 248     /* defaults */
 249     s->regs[R_LSR] = LSR_THRE | LSR_TEMT;
 250 }
 251
 252 static void lm32_uart_init(Object *obj)
 253 {
 254     LM32UartState *s = LM32_UART(obj);
 255     SysBusDevice *dev = SYS_BUS_DEVICE(obj);
 256
 257     sysbus_init_irq(dev, &s->irq);
 258
 259     memory_region_init_io(&s->iomem, obj, &uart_ops, s,
 260                           "uart", R_MAX * 4);
 261     sysbus_init_mmio(dev, &s->iomem);
 262 }
 263
 264 static void lm32_uart_realize(DeviceState *dev, Error **errp)
 265 {
 266     LM32UartState *s = LM32_UART(dev);
 267
 268     qemu_chr_fe_set_handlers(&s->chr, uart_can_rx, uart_rx,
 269                              uart_event, NULL, s, NULL, true);
 270 }
 271
 272 static const VMStateDescription vmstate_lm32_uart = {
 273     .name = "lm32-uart",
 274     .version_id = 1,
 275     .minimum_version_id = 1,
 276     .fields = (VMStateField[]) {
 277         VMSTATE_UINT32_ARRAY(regs, LM32UartState, R_MAX),
 278         VMSTATE_END_OF_LIST()
 279     }
 280 };
 281
 282 static Property lm32_uart_properties[] = {
 283     DEFINE_PROP_CHR("chardev", LM32UartState, chr),
 284     DEFINE_PROP_END_OF_LIST(),
 285 };
 286
 287 static void lm32_uart_class_init(ObjectClass *klass, void *data)
 288 {
 289     DeviceClass *dc = DEVICE_CLASS(klass);
 290
 291     dc->reset = uart_reset;
 292     dc->vmsd = &vmstate_lm32_uart;
 293     dc->props = lm32_uart_properties;
 294     dc->realize = lm32_uart_realize;
 295 }
 296
 297 static const TypeInfo lm32_uart_info = {
 298     .name          = TYPE_LM32_UART,
 299     .parent        = TYPE_SYS_BUS_DEVICE,
 300     .instance_size = sizeof(LM32UartState),
 301     .instance_init = lm32_uart_init,
 302     .class_init    = lm32_uart_class_init,
 303 };
 304
 305 static void lm32_uart_register_types(void)
 306 {
 307     type_register_static(&lm32_uart_info);
 308 }
 309
 310 type_init(lm32_uart_register_types)