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) 241