hw/char/sifive_uart.c

   1 /*
   2  * QEMU model of the UART on the SiFive E300 and U500 series SOCs.
   3  *
   4  * Copyright (c) 2016 Stefan O'Rear
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms and conditions of the GNU General Public License,
   8  * version 2 or later, as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include "qemu/osdep.h"
  20 #include "qapi/error.h"
  21 #include "qemu/log.h"
  22 #include "migration/vmstate.h"
  23 #include "chardev/char.h"
  24 #include "chardev/char-fe.h"
  25 #include "hw/irq.h"
  26 #include "hw/char/sifive_uart.h"
  27 #include "hw/qdev-properties-system.h"
  28
  29 /*
  30  * Not yet implemented:
  31  *
  32  * Transmit FIFO using "qemu/fifo8.h"
  33  */
  34
  35 /* Returns the state of the IP (interrupt pending) register */
  36 static uint64_t sifive_uart_ip(SiFiveUARTState *s)
  37 {
  38     uint64_t ret = 0;
  39
  40     uint64_t txcnt = SIFIVE_UART_GET_TXCNT(s->txctrl);
  41     uint64_t rxcnt = SIFIVE_UART_GET_RXCNT(s->rxctrl);
  42
  43     if (txcnt != 0) {
  44         ret |= SIFIVE_UART_IP_TXWM;
  45     }
  46     if (s->rx_fifo_len > rxcnt) {
  47         ret |= SIFIVE_UART_IP_RXWM;
  48     }
  49
  50     return ret;
  51 }
  52
  53 static void sifive_uart_update_irq(SiFiveUARTState *s)
  54 {
  55     int cond = 0;
  56     if ((s->ie & SIFIVE_UART_IE_TXWM) ||
  57         ((s->ie & SIFIVE_UART_IE_RXWM) && s->rx_fifo_len)) {
  58         cond = 1;
  59     }
  60     if (cond) {
  61         qemu_irq_raise(s->irq);
  62     } else {
  63         qemu_irq_lower(s->irq);
  64     }
  65 }
  66
  67 static uint64_t
  68 sifive_uart_read(void *opaque, hwaddr addr, unsigned int size)
  69 {
  70     SiFiveUARTState *s = opaque;
  71     unsigned char r;
  72     switch (addr) {
  73     case SIFIVE_UART_RXFIFO:
  74         if (s->rx_fifo_len) {
  75             r = s->rx_fifo[0];
  76             memmove(s->rx_fifo, s->rx_fifo + 1, s->rx_fifo_len - 1);
  77             s->rx_fifo_len--;
  78             qemu_chr_fe_accept_input(&s->chr);
  79             sifive_uart_update_irq(s);
  80             return r;
  81         }
  82         return 0x80000000;
  83
  84     case SIFIVE_UART_TXFIFO:
  85         return 0; /* Should check tx fifo */
  86     case SIFIVE_UART_IE:
  87         return s->ie;
  88     case SIFIVE_UART_IP:
  89         return sifive_uart_ip(s);
  90     case SIFIVE_UART_TXCTRL:
  91         return s->txctrl;
  92     case SIFIVE_UART_RXCTRL:
  93         return s->rxctrl;
  94     case SIFIVE_UART_DIV:
  95         return s->div;
  96     }
  97
  98     qemu_log_mask(LOG_GUEST_ERROR, "%s: bad read: addr=0x%x\n",
  99                   __func__, (int)addr);
 100     return 0;
 101 }
 102
 103 static void
 104 sifive_uart_write(void *opaque, hwaddr addr,
 105                   uint64_t val64, unsigned int size)
 106 {
 107     SiFiveUARTState *s = opaque;
 108     uint32_t value = val64;
 109     unsigned char ch = value;
 110
 111     switch (addr) {
 112     case SIFIVE_UART_TXFIFO:
 113         qemu_chr_fe_write(&s->chr, &ch, 1);
 114         sifive_uart_update_irq(s);
 115         return;
 116     case SIFIVE_UART_IE:
 117         s->ie = val64;
 118         sifive_uart_update_irq(s);
 119         return;
 120     case SIFIVE_UART_TXCTRL:
 121         s->txctrl = val64;
 122         return;
 123     case SIFIVE_UART_RXCTRL:
 124         s->rxctrl = val64;
 125         return;
 126     case SIFIVE_UART_DIV:
 127         s->div = val64;
 128         return;
 129     }
 130     qemu_log_mask(LOG_GUEST_ERROR, "%s: bad write: addr=0x%x v=0x%x\n",
 131                   __func__, (int)addr, (int)value);
 132 }
 133
 134 static const MemoryRegionOps sifive_uart_ops = {
 135     .read = sifive_uart_read,
 136     .write = sifive_uart_write,
 137     .endianness = DEVICE_NATIVE_ENDIAN,
 138     .valid = {
 139         .min_access_size = 4,
 140         .max_access_size = 4
 141     }
 142 };
 143
 144 static void sifive_uart_rx(void *opaque, const uint8_t *buf, int size)
 145 {
 146     SiFiveUARTState *s = opaque;
 147
 148     /* Got a byte.  */
 149     if (s->rx_fifo_len >= sizeof(s->rx_fifo)) {
 150         printf("WARNING: UART dropped char.\n");
 151         return;
 152     }
 153     s->rx_fifo[s->rx_fifo_len++] = *buf;
 154
 155     sifive_uart_update_irq(s);
 156 }
 157
 158 static int sifive_uart_can_rx(void *opaque)
 159 {
 160     SiFiveUARTState *s = opaque;
 161
 162     return s->rx_fifo_len < sizeof(s->rx_fifo);
 163 }
 164
 165 static void sifive_uart_event(void *opaque, QEMUChrEvent event)
 166 {
 167 }
 168
 169 static int sifive_uart_be_change(void *opaque)
 170 {
 171     SiFiveUARTState *s = opaque;
 172
 173     qemu_chr_fe_set_handlers(&s->chr, sifive_uart_can_rx, sifive_uart_rx,
 174                              sifive_uart_event, sifive_uart_be_change, s,
 175                              NULL, true);
 176
 177     return 0;
 178 }
 179
 180 static Property sifive_uart_properties[] = {
 181     DEFINE_PROP_CHR("chardev", SiFiveUARTState, chr),
 182     DEFINE_PROP_END_OF_LIST(),
 183 };
 184
 185 static void sifive_uart_init(Object *obj)
 186 {
 187     SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
 188     SiFiveUARTState *s = SIFIVE_UART(obj);
 189
 190     memory_region_init_io(&s->mmio, OBJECT(s), &sifive_uart_ops, s,
 191                           TYPE_SIFIVE_UART, SIFIVE_UART_MAX);
 192     sysbus_init_mmio(sbd, &s->mmio);
 193     sysbus_init_irq(sbd, &s->irq);
 194 }
 195
 196 static void sifive_uart_realize(DeviceState *dev, Error **errp)
 197 {
 198     SiFiveUARTState *s = SIFIVE_UART(dev);
 199
 200     qemu_chr_fe_set_handlers(&s->chr, sifive_uart_can_rx, sifive_uart_rx,
 201                              sifive_uart_event, sifive_uart_be_change, s,
 202                              NULL, true);
 203
 204 }
 205
 206 static void sifive_uart_reset_enter(Object *obj, ResetType type)
 207 {
 208     SiFiveUARTState *s = SIFIVE_UART(obj);
 209     s->ie = 0;
 210     s->ip = 0;
 211     s->txctrl = 0;
 212     s->rxctrl = 0;
 213     s->div = 0;
 214     s->rx_fifo_len = 0;
 215 }
 216
 217 static void sifive_uart_reset_hold(Object *obj)
 218 {
 219     SiFiveUARTState *s = SIFIVE_UART(obj);
 220     qemu_irq_lower(s->irq);
 221 }
 222
 223 static const VMStateDescription vmstate_sifive_uart = {
 224     .name = TYPE_SIFIVE_UART,
 225     .version_id = 1,
 226     .minimum_version_id = 1,
 227     .fields = (const VMStateField[]) {
 228         VMSTATE_UINT8_ARRAY(rx_fifo, SiFiveUARTState,
 229                             SIFIVE_UART_RX_FIFO_SIZE),
 230         VMSTATE_UINT8(rx_fifo_len, SiFiveUARTState),
 231         VMSTATE_UINT32(ie, SiFiveUARTState),
 232         VMSTATE_UINT32(ip, SiFiveUARTState),
 233         VMSTATE_UINT32(txctrl, SiFiveUARTState),
 234         VMSTATE_UINT32(rxctrl, SiFiveUARTState),
 235         VMSTATE_UINT32(div, SiFiveUARTState),
 236         VMSTATE_END_OF_LIST()
 237     },
 238 };
 239
 240
 241 static void sifive_uart_class_init(ObjectClass *oc, void *data)
 242 {
 243     DeviceClass *dc = DEVICE_CLASS(oc);
 244     ResettableClass *rc = RESETTABLE_CLASS(oc);
 245
 246     dc->realize = sifive_uart_realize;
 247     dc->vmsd = &vmstate_sifive_uart;
 248     rc->phases.enter = sifive_uart_reset_enter;
 249     rc->phases.hold  = sifive_uart_reset_hold;
 250     device_class_set_props(dc, sifive_uart_properties);
 251     set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
 252 }
 253
 254 static const TypeInfo sifive_uart_info = {
 255     .name          = TYPE_SIFIVE_UART,
 256     .parent        = TYPE_SYS_BUS_DEVICE,
 257     .instance_size = sizeof(SiFiveUARTState),
 258     .instance_init = sifive_uart_init,
 259     .class_init    = sifive_uart_class_init,
 260 };
 261
 262 static void sifive_uart_register_types(void)
 263 {
 264     type_register_static(&sifive_uart_info);
 265 }
 266
 267 type_init(sifive_uart_register_types)
 268
 269 /*
 270  * Create UART device.
 271  */
 272 SiFiveUARTState *sifive_uart_create(MemoryRegion *address_space, hwaddr base,
 273     Chardev *chr, qemu_irq irq)
 274 {
 275     DeviceState *dev;
 276     SysBusDevice *s;
 277
 278     dev = qdev_new("riscv.sifive.uart");
 279     s = SYS_BUS_DEVICE(dev);
 280     qdev_prop_set_chr(dev, "chardev", chr);
 281     sysbus_realize_and_unref(s, &error_fatal);
 282     memory_region_add_subregion(address_space, base,
 283                                 sysbus_mmio_get_region(s, 0));
 284     sysbus_connect_irq(s, 0, irq);
 285
 286     return SIFIVE_UART(dev);
 287 }