hw/char/stm32f2xx_usart.c

   1 /*
   2  * STM32F2XX USART
   3  *
   4  * Copyright (c) 2014 Alistair Francis <alistair@alistair23.me>
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "qemu/osdep.h"
  26 #include "hw/char/stm32f2xx_usart.h"
  27 #include "qemu/log.h"
  28 #include "qemu/module.h"
  29
  30 #ifndef STM_USART_ERR_DEBUG
  31 #define STM_USART_ERR_DEBUG 0
  32 #endif
  33
  34 #define DB_PRINT_L(lvl, fmt, args...) do { \
  35     if (STM_USART_ERR_DEBUG >= lvl) { \
  36         qemu_log("%s: " fmt, __func__, ## args); \
  37     } \
  38 } while (0)
  39
  40 #define DB_PRINT(fmt, args...) DB_PRINT_L(1, fmt, ## args)
  41
  42 static int stm32f2xx_usart_can_receive(void *opaque)
  43 {
  44     STM32F2XXUsartState *s = opaque;
  45
  46     if (!(s->usart_sr & USART_SR_RXNE)) {
  47         return 1;
  48     }
  49
  50     return 0;
  51 }
  52
  53 static void stm32f2xx_usart_receive(void *opaque, const uint8_t *buf, int size)
  54 {
  55     STM32F2XXUsartState *s = opaque;
  56
  57     if (!(s->usart_cr1 & USART_CR1_UE && s->usart_cr1 & USART_CR1_RE)) {
  58         /* USART not enabled - drop the chars */
  59         DB_PRINT("Dropping the chars\n");
  60         return;
  61     }
  62
  63     s->usart_dr = *buf;
  64     s->usart_sr |= USART_SR_RXNE;
  65
  66     if (s->usart_cr1 & USART_CR1_RXNEIE) {
  67         qemu_set_irq(s->irq, 1);
  68     }
  69
  70     DB_PRINT("Receiving: %c\n", s->usart_dr);
  71 }
  72
  73 static void stm32f2xx_usart_reset(DeviceState *dev)
  74 {
  75     STM32F2XXUsartState *s = STM32F2XX_USART(dev);
  76
  77     s->usart_sr = USART_SR_RESET;
  78     s->usart_dr = 0x00000000;
  79     s->usart_brr = 0x00000000;
  80     s->usart_cr1 = 0x00000000;
  81     s->usart_cr2 = 0x00000000;
  82     s->usart_cr3 = 0x00000000;
  83     s->usart_gtpr = 0x00000000;
  84
  85     qemu_set_irq(s->irq, 0);
  86 }
  87
  88 static uint64_t stm32f2xx_usart_read(void *opaque, hwaddr addr,
  89                                        unsigned int size)
  90 {
  91     STM32F2XXUsartState *s = opaque;
  92     uint64_t retvalue;
  93
  94     DB_PRINT("Read 0x%"HWADDR_PRIx"\n", addr);
  95
  96     switch (addr) {
  97     case USART_SR:
  98         retvalue = s->usart_sr;
  99         qemu_chr_fe_accept_input(&s->chr);
 100         return retvalue;
 101     case USART_DR:
 102         DB_PRINT("Value: 0x%" PRIx32 ", %c\n", s->usart_dr, (char) s->usart_dr);
 103         s->usart_sr &= ~USART_SR_RXNE;
 104         qemu_chr_fe_accept_input(&s->chr);
 105         qemu_set_irq(s->irq, 0);
 106         return s->usart_dr & 0x3FF;
 107     case USART_BRR:
 108         return s->usart_brr;
 109     case USART_CR1:
 110         return s->usart_cr1;
 111     case USART_CR2:
 112         return s->usart_cr2;
 113     case USART_CR3:
 114         return s->usart_cr3;
 115     case USART_GTPR:
 116         return s->usart_gtpr;
 117     default:
 118         qemu_log_mask(LOG_GUEST_ERROR,
 119                       "%s: Bad offset 0x%"HWADDR_PRIx"\n", __func__, addr);
 120         return 0;
 121     }
 122
 123     return 0;
 124 }
 125
 126 static void stm32f2xx_usart_write(void *opaque, hwaddr addr,
 127                                   uint64_t val64, unsigned int size)
 128 {
 129     STM32F2XXUsartState *s = opaque;
 130     uint32_t value = val64;
 131     unsigned char ch;
 132
 133     DB_PRINT("Write 0x%" PRIx32 ", 0x%"HWADDR_PRIx"\n", value, addr);
 134
 135     switch (addr) {
 136     case USART_SR:
 137         if (value <= 0x3FF) {
 138             /* I/O being synchronous, TXE is always set. In addition, it may
 139                only be set by hardware, so keep it set here. */
 140             s->usart_sr = value | USART_SR_TXE;
 141         } else {
 142             s->usart_sr &= value;
 143         }
 144         if (!(s->usart_sr & USART_SR_RXNE)) {
 145             qemu_set_irq(s->irq, 0);
 146         }
 147         return;
 148     case USART_DR:
 149         if (value < 0xF000) {
 150             ch = value;
 151             /* XXX this blocks entire thread. Rewrite to use
 152              * qemu_chr_fe_write and background I/O callbacks */
 153             qemu_chr_fe_write_all(&s->chr, &ch, 1);
 154             /* XXX I/O are currently synchronous, making it impossible for
 155                software to observe transient states where TXE or TC aren't
 156                set. Unlike TXE however, which is read-only, software may
 157                clear TC by writing 0 to the SR register, so set it again
 158                on each write. */
 159             s->usart_sr |= USART_SR_TC;
 160         }
 161         return;
 162     case USART_BRR:
 163         s->usart_brr = value;
 164         return;
 165     case USART_CR1:
 166         s->usart_cr1 = value;
 167             if (s->usart_cr1 & USART_CR1_RXNEIE &&
 168                 s->usart_sr & USART_SR_RXNE) {
 169                 qemu_set_irq(s->irq, 1);
 170             }
 171         return;
 172     case USART_CR2:
 173         s->usart_cr2 = value;
 174         return;
 175     case USART_CR3:
 176         s->usart_cr3 = value;
 177         return;
 178     case USART_GTPR:
 179         s->usart_gtpr = value;
 180         return;
 181     default:
 182         qemu_log_mask(LOG_GUEST_ERROR,
 183                       "%s: Bad offset 0x%"HWADDR_PRIx"\n", __func__, addr);
 184     }
 185 }
 186
 187 static const MemoryRegionOps stm32f2xx_usart_ops = {
 188     .read = stm32f2xx_usart_read,
 189     .write = stm32f2xx_usart_write,
 190     .endianness = DEVICE_NATIVE_ENDIAN,
 191 };
 192
 193 static Property stm32f2xx_usart_properties[] = {
 194     DEFINE_PROP_CHR("chardev", STM32F2XXUsartState, chr),
 195     DEFINE_PROP_END_OF_LIST(),
 196 };
 197
 198 static void stm32f2xx_usart_init(Object *obj)
 199 {
 200     STM32F2XXUsartState *s = STM32F2XX_USART(obj);
 201
 202     sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->irq);
 203
 204     memory_region_init_io(&s->mmio, obj, &stm32f2xx_usart_ops, s,
 205                           TYPE_STM32F2XX_USART, 0x400);
 206     sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio);
 207 }
 208
 209 static void stm32f2xx_usart_realize(DeviceState *dev, Error **errp)
 210 {
 211     STM32F2XXUsartState *s = STM32F2XX_USART(dev);
 212
 213     qemu_chr_fe_set_handlers(&s->chr, stm32f2xx_usart_can_receive,
 214                              stm32f2xx_usart_receive, NULL, NULL,
 215                              s, NULL, true);
 216 }
 217
 218 static void stm32f2xx_usart_class_init(ObjectClass *klass, void *data)
 219 {
 220     DeviceClass *dc = DEVICE_CLASS(klass);
 221
 222     dc->reset = stm32f2xx_usart_reset;
 223     dc->props = stm32f2xx_usart_properties;
 224     dc->realize = stm32f2xx_usart_realize;
 225 }
 226
 227 static const TypeInfo stm32f2xx_usart_info = {
 228     .name          = TYPE_STM32F2XX_USART,
 229     .parent        = TYPE_SYS_BUS_DEVICE,
 230     .instance_size = sizeof(STM32F2XXUsartState),
 231     .instance_init = stm32f2xx_usart_init,
 232     .class_init    = stm32f2xx_usart_class_init,
 233 };
 234
 235 static void stm32f2xx_usart_register_types(void)
 236 {
 237     type_register_static(&stm32f2xx_usart_info);
 238 }
 239
 240 type_init(stm32f2xx_usart_register_types)