hw/char/riscv_htif.c

   1 /*
   2  * QEMU RISC-V Host Target Interface (HTIF) Emulation
   3  *
   4  * Copyright (c) 2016-2017 Sagar Karandikar, sagark@eecs.berkeley.edu
   5  * Copyright (c) 2017-2018 SiFive, Inc.
   6  *
   7  * This provides HTIF device emulation for QEMU. At the moment this allows
   8  * for identical copies of bbl/linux to run on both spike and QEMU.
   9  *
  10  * This program is free software; you can redistribute it and/or modify it
  11  * under the terms and conditions of the GNU General Public License,
  12  * version 2 or later, as published by the Free Software Foundation.
  13  *
  14  * This program is distributed in the hope it will be useful, but WITHOUT
  15  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  16  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  17  * more details.
  18  *
  19  * You should have received a copy of the GNU General Public License along with
  20  * this program.  If not, see <http://www.gnu.org/licenses/>.
  21  */
  22
  23 #include "qemu/osdep.h"
  24 #include "qapi/error.h"
  25 #include "qemu/log.h"
  26 #include "hw/sysbus.h"
  27 #include "hw/char/riscv_htif.h"
  28 #include "hw/char/serial.h"
  29 #include "chardev/char.h"
  30 #include "chardev/char-fe.h"
  31 #include "qemu/timer.h"
  32 #include "qemu/error-report.h"
  33
  34 #define RISCV_DEBUG_HTIF 0
  35 #define HTIF_DEBUG(fmt, ...)                                                   \
  36     do {                                                                       \
  37         if (RISCV_DEBUG_HTIF) {                                                \
  38             qemu_log_mask(LOG_TRACE, "%s: " fmt "\n", __func__, ##__VA_ARGS__);\
  39         }                                                                      \
  40     } while (0)
  41
  42 static uint64_t fromhost_addr, tohost_addr;
  43 static int address_symbol_set;
  44
  45 void htif_symbol_callback(const char *st_name, int st_info, uint64_t st_value,
  46                           uint64_t st_size)
  47 {
  48     if (strcmp("fromhost", st_name) == 0) {
  49         address_symbol_set |= 1;
  50         fromhost_addr = st_value;
  51         if (st_size != 8) {
  52             error_report("HTIF fromhost must be 8 bytes");
  53             exit(1);
  54         }
  55     } else if (strcmp("tohost", st_name) == 0) {
  56         address_symbol_set |= 2;
  57         tohost_addr = st_value;
  58         if (st_size != 8) {
  59             error_report("HTIF tohost must be 8 bytes");
  60             exit(1);
  61         }
  62     }
  63 }
  64
  65 /*
  66  * Called by the char dev to see if HTIF is ready to accept input.
  67  */
  68 static int htif_can_recv(void *opaque)
  69 {
  70     return 1;
  71 }
  72
  73 /*
  74  * Called by the char dev to supply input to HTIF console.
  75  * We assume that we will receive one character at a time.
  76  */
  77 static void htif_recv(void *opaque, const uint8_t *buf, int size)
  78 {
  79     HTIFState *htifstate = opaque;
  80
  81     if (size != 1) {
  82         return;
  83     }
  84
  85     /* TODO - we need to check whether mfromhost is zero which indicates
  86               the device is ready to receive. The current implementation
  87               will drop characters */
  88
  89     uint64_t val_written = htifstate->pending_read;
  90     uint64_t resp = 0x100 | *buf;
  91
  92     htifstate->env->mfromhost = (val_written >> 48 << 48) | (resp << 16 >> 16);
  93 }
  94
  95 /*
  96  * Called by the char dev to supply special events to the HTIF console.
  97  * Not used for HTIF.
  98  */
  99 static void htif_event(void *opaque, QEMUChrEvent event)
 100 {
 101
 102 }
 103
 104 static int htif_be_change(void *opaque)
 105 {
 106     HTIFState *s = opaque;
 107
 108     qemu_chr_fe_set_handlers(&s->chr, htif_can_recv, htif_recv, htif_event,
 109         htif_be_change, s, NULL, true);
 110
 111     return 0;
 112 }
 113
 114 static void htif_handle_tohost_write(HTIFState *htifstate, uint64_t val_written)
 115 {
 116     uint8_t device = val_written >> 56;
 117     uint8_t cmd = val_written >> 48;
 118     uint64_t payload = val_written & 0xFFFFFFFFFFFFULL;
 119     int resp = 0;
 120
 121     HTIF_DEBUG("mtohost write: device: %d cmd: %d what: %02" PRIx64
 122         " -payload: %016" PRIx64 "\n", device, cmd, payload & 0xFF, payload);
 123
 124     /*
 125      * Currently, there is a fixed mapping of devices:
 126      * 0: riscv-tests Pass/Fail Reporting Only (no syscall proxy)
 127      * 1: Console
 128      */
 129     if (unlikely(device == 0x0)) {
 130         /* frontend syscall handler, shutdown and exit code support */
 131         if (cmd == 0x0) {
 132             if (payload & 0x1) {
 133                 /* exit code */
 134                 int exit_code = payload >> 1;
 135                 exit(exit_code);
 136             } else {
 137                 qemu_log_mask(LOG_UNIMP, "pk syscall proxy not supported\n");
 138             }
 139         } else {
 140             qemu_log("HTIF device %d: unknown command\n", device);
 141         }
 142     } else if (likely(device == 0x1)) {
 143         /* HTIF Console */
 144         if (cmd == 0x0) {
 145             /* this should be a queue, but not yet implemented as such */
 146             htifstate->pending_read = val_written;
 147             htifstate->env->mtohost = 0; /* clear to indicate we read */
 148             return;
 149         } else if (cmd == 0x1) {
 150             qemu_chr_fe_write(&htifstate->chr, (uint8_t *)&payload, 1);
 151             resp = 0x100 | (uint8_t)payload;
 152         } else {
 153             qemu_log("HTIF device %d: unknown command\n", device);
 154         }
 155     } else {
 156         qemu_log("HTIF unknown device or command\n");
 157         HTIF_DEBUG("device: %d cmd: %d what: %02" PRIx64
 158             " payload: %016" PRIx64, device, cmd, payload & 0xFF, payload);
 159     }
 160     /*
 161      * - latest bbl does not set fromhost to 0 if there is a value in tohost
 162      * - with this code enabled, qemu hangs waiting for fromhost to go to 0
 163      * - with this code disabled, qemu works with bbl priv v1.9.1 and v1.10
 164      * - HTIF needs protocol documentation and a more complete state machine
 165
 166         while (!htifstate->fromhost_inprogress &&
 167             htifstate->env->mfromhost != 0x0) {
 168         }
 169     */
 170     htifstate->env->mfromhost = (val_written >> 48 << 48) | (resp << 16 >> 16);
 171     htifstate->env->mtohost = 0; /* clear to indicate we read */
 172 }
 173
 174 #define TOHOST_OFFSET1 (htifstate->tohost_offset)
 175 #define TOHOST_OFFSET2 (htifstate->tohost_offset + 4)
 176 #define FROMHOST_OFFSET1 (htifstate->fromhost_offset)
 177 #define FROMHOST_OFFSET2 (htifstate->fromhost_offset + 4)
 178
 179 /* CPU wants to read an HTIF register */
 180 static uint64_t htif_mm_read(void *opaque, hwaddr addr, unsigned size)
 181 {
 182     HTIFState *htifstate = opaque;
 183     if (addr == TOHOST_OFFSET1) {
 184         return htifstate->env->mtohost & 0xFFFFFFFF;
 185     } else if (addr == TOHOST_OFFSET2) {
 186         return (htifstate->env->mtohost >> 32) & 0xFFFFFFFF;
 187     } else if (addr == FROMHOST_OFFSET1) {
 188         return htifstate->env->mfromhost & 0xFFFFFFFF;
 189     } else if (addr == FROMHOST_OFFSET2) {
 190         return (htifstate->env->mfromhost >> 32) & 0xFFFFFFFF;
 191     } else {
 192         qemu_log("Invalid htif read: address %016" PRIx64 "\n",
 193             (uint64_t)addr);
 194         return 0;
 195     }
 196 }
 197
 198 /* CPU wrote to an HTIF register */
 199 static void htif_mm_write(void *opaque, hwaddr addr,
 200                             uint64_t value, unsigned size)
 201 {
 202     HTIFState *htifstate = opaque;
 203     if (addr == TOHOST_OFFSET1) {
 204         if (htifstate->env->mtohost == 0x0) {
 205             htifstate->allow_tohost = 1;
 206             htifstate->env->mtohost = value & 0xFFFFFFFF;
 207         } else {
 208             htifstate->allow_tohost = 0;
 209         }
 210     } else if (addr == TOHOST_OFFSET2) {
 211         if (htifstate->allow_tohost) {
 212             htifstate->env->mtohost |= value << 32;
 213             htif_handle_tohost_write(htifstate, htifstate->env->mtohost);
 214         }
 215     } else if (addr == FROMHOST_OFFSET1) {
 216         htifstate->fromhost_inprogress = 1;
 217         htifstate->env->mfromhost = value & 0xFFFFFFFF;
 218     } else if (addr == FROMHOST_OFFSET2) {
 219         htifstate->env->mfromhost |= value << 32;
 220         htifstate->fromhost_inprogress = 0;
 221     } else {
 222         qemu_log("Invalid htif write: address %016" PRIx64 "\n",
 223             (uint64_t)addr);
 224     }
 225 }
 226
 227 static const MemoryRegionOps htif_mm_ops = {
 228     .read = htif_mm_read,
 229     .write = htif_mm_write,
 230 };
 231
 232 HTIFState *htif_mm_init(MemoryRegion *address_space, MemoryRegion *main_mem,
 233     CPURISCVState *env, Chardev *chr)
 234 {
 235     uint64_t base = MIN(tohost_addr, fromhost_addr);
 236     uint64_t size = MAX(tohost_addr + 8, fromhost_addr + 8) - base;
 237     uint64_t tohost_offset = tohost_addr - base;
 238     uint64_t fromhost_offset = fromhost_addr - base;
 239
 240     HTIFState *s = g_malloc0(sizeof(HTIFState));
 241     s->address_space = address_space;
 242     s->main_mem = main_mem;
 243     s->main_mem_ram_ptr = memory_region_get_ram_ptr(main_mem);
 244     s->env = env;
 245     s->tohost_offset = tohost_offset;
 246     s->fromhost_offset = fromhost_offset;
 247     s->pending_read = 0;
 248     s->allow_tohost = 0;
 249     s->fromhost_inprogress = 0;
 250     qemu_chr_fe_init(&s->chr, chr, &error_abort);
 251     qemu_chr_fe_set_handlers(&s->chr, htif_can_recv, htif_recv, htif_event,
 252         htif_be_change, s, NULL, true);
 253     if (address_symbol_set == 3) {
 254         memory_region_init_io(&s->mmio, NULL, &htif_mm_ops, s,
 255                               TYPE_HTIF_UART, size);
 256         memory_region_add_subregion_overlap(address_space, base,
 257                                             &s->mmio, 1);
 258     }
 259
 260     return s;
 261 }