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 "hw/irq.h" 28 #include "hw/qdev-properties.h" 29 #include "hw/qdev-properties-system.h" 30 #include "qemu/log.h" 31 #include "qemu/module.h" 32 33 #ifndef STM_USART_ERR_DEBUG 34 #define STM_USART_ERR_DEBUG 0 35 #endif 36 37 #define DB_PRINT_L(lvl, fmt, args...) do { \ 38 if (STM_USART_ERR_DEBUG >= lvl) { \ 39 qemu_log("%s: " fmt, __func__, ## args); \ 40 } \ 41 } while (0) 42 43 #define DB_PRINT(fmt, args...) DB_PRINT_L(1, fmt, ## args) 44 45 static int stm32f2xx_usart_can_receive(void *opaque) 46 { 47 STM32F2XXUsartState *s = opaque; 48 49 if (!(s->usart_sr & USART_SR_RXNE)) { 50 return 1; 51 } 52 53 return 0; 54 } 55 56 static void stm32f2xx_update_irq(STM32F2XXUsartState *s) 57 { 58 uint32_t mask = s->usart_sr & s->usart_cr1; 59 60 if (mask & (USART_SR_TXE | USART_SR_TC | USART_SR_RXNE)) { 61 qemu_set_irq(s->irq, 1); 62 } else { 63 qemu_set_irq(s->irq, 0); 64 } 65 } 66 67 static void stm32f2xx_usart_receive(void *opaque, const uint8_t *buf, int size) 68 { 69 STM32F2XXUsartState *s = opaque; 70 71 if (!(s->usart_cr1 & USART_CR1_UE && s->usart_cr1 & USART_CR1_RE)) { 72 /* USART not enabled - drop the chars */ 73 DB_PRINT("Dropping the chars\n"); 74 return; 75 } 76 77 s->usart_dr = *buf; 78 s->usart_sr |= USART_SR_RXNE; 79 80 stm32f2xx_update_irq(s); 81 82 DB_PRINT("Receiving: %c\n", s->usart_dr); 83 } 84 85 static void stm32f2xx_usart_reset(DeviceState *dev) 86 { 87 STM32F2XXUsartState *s = STM32F2XX_USART(dev); 88 89 s->usart_sr = USART_SR_RESET; 90 s->usart_dr = 0x00000000; 91 s->usart_brr = 0x00000000; 92 s->usart_cr1 = 0x00000000; 93 s->usart_cr2 = 0x00000000; 94 s->usart_cr3 = 0x00000000; 95 s->usart_gtpr = 0x00000000; 96 97 stm32f2xx_update_irq(s); 98 } 99 100 static uint64_t stm32f2xx_usart_read(void *opaque, hwaddr addr, 101 unsigned int size) 102 { 103 STM32F2XXUsartState *s = opaque; 104 uint64_t retvalue; 105 106 DB_PRINT("Read 0x%"HWADDR_PRIx"\n", addr); 107 108 switch (addr) { 109 case USART_SR: 110 retvalue = s->usart_sr; 111 qemu_chr_fe_accept_input(&s->chr); 112 return retvalue; 113 case USART_DR: 114 DB_PRINT("Value: 0x%" PRIx32 ", %c\n", s->usart_dr, (char) s->usart_dr); 115 retvalue = s->usart_dr & 0x3FF; 116 s->usart_sr &= ~USART_SR_RXNE; 117 qemu_chr_fe_accept_input(&s->chr); 118 stm32f2xx_update_irq(s); 119 return retvalue; 120 case USART_BRR: 121 return s->usart_brr; 122 case USART_CR1: 123 return s->usart_cr1; 124 case USART_CR2: 125 return s->usart_cr2; 126 case USART_CR3: 127 return s->usart_cr3; 128 case USART_GTPR: 129 return s->usart_gtpr; 130 default: 131 qemu_log_mask(LOG_GUEST_ERROR, 132 "%s: Bad offset 0x%"HWADDR_PRIx"\n", __func__, addr); 133 return 0; 134 } 135 136 return 0; 137 } 138 139 static void stm32f2xx_usart_write(void *opaque, hwaddr addr, 140 uint64_t val64, unsigned int size) 141 { 142 STM32F2XXUsartState *s = opaque; 143 uint32_t value = val64; 144 unsigned char ch; 145 146 DB_PRINT("Write 0x%" PRIx32 ", 0x%"HWADDR_PRIx"\n", value, addr); 147 148 switch (addr) { 149 case USART_SR: 150 if (value <= 0x3FF) { 151 /* I/O being synchronous, TXE is always set. In addition, it may 152 only be set by hardware, so keep it set here. */ 153 s->usart_sr = value | USART_SR_TXE; 154 } else { 155 s->usart_sr &= value; 156 } 157 stm32f2xx_update_irq(s); 158 return; 159 case USART_DR: 160 if (value < 0xF000) { 161 ch = value; 162 /* XXX this blocks entire thread. Rewrite to use 163 * qemu_chr_fe_write and background I/O callbacks */ 164 qemu_chr_fe_write_all(&s->chr, &ch, 1); 165 /* XXX I/O are currently synchronous, making it impossible for 166 software to observe transient states where TXE or TC aren't 167 set. Unlike TXE however, which is read-only, software may 168 clear TC by writing 0 to the SR register, so set it again 169 on each write. */ 170 s->usart_sr |= USART_SR_TC; 171 stm32f2xx_update_irq(s); 172 } 173 return; 174 case USART_BRR: 175 s->usart_brr = value; 176 return; 177 case USART_CR1: 178 s->usart_cr1 = value; 179 stm32f2xx_update_irq(s); 180 return; 181 case USART_CR2: 182 s->usart_cr2 = value; 183 return; 184 case USART_CR3: 185 s->usart_cr3 = value; 186 return; 187 case USART_GTPR: 188 s->usart_gtpr = value; 189 return; 190 default: 191 qemu_log_mask(LOG_GUEST_ERROR, 192 "%s: Bad offset 0x%"HWADDR_PRIx"\n", __func__, addr); 193 } 194 } 195 196 static const MemoryRegionOps stm32f2xx_usart_ops = { 197 .read = stm32f2xx_usart_read, 198 .write = stm32f2xx_usart_write, 199 .endianness = DEVICE_NATIVE_ENDIAN, 200 }; 201 202 static Property stm32f2xx_usart_properties[] = { 203 DEFINE_PROP_CHR("chardev", STM32F2XXUsartState, chr), 204 DEFINE_PROP_END_OF_LIST(), 205 }; 206 207 static void stm32f2xx_usart_init(Object *obj) 208 { 209 STM32F2XXUsartState *s = STM32F2XX_USART(obj); 210 211 sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->irq); 212 213 memory_region_init_io(&s->mmio, obj, &stm32f2xx_usart_ops, s, 214 TYPE_STM32F2XX_USART, 0x400); 215 sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio); 216 } 217 218 static void stm32f2xx_usart_realize(DeviceState *dev, Error **errp) 219 { 220 STM32F2XXUsartState *s = STM32F2XX_USART(dev); 221 222 qemu_chr_fe_set_handlers(&s->chr, stm32f2xx_usart_can_receive, 223 stm32f2xx_usart_receive, NULL, NULL, 224 s, NULL, true); 225 } 226 227 static void stm32f2xx_usart_class_init(ObjectClass *klass, void *data) 228 { 229 DeviceClass *dc = DEVICE_CLASS(klass); 230 231 dc->reset = stm32f2xx_usart_reset; 232 device_class_set_props(dc, stm32f2xx_usart_properties); 233 dc->realize = stm32f2xx_usart_realize; 234 } 235 236 static const TypeInfo stm32f2xx_usart_info = { 237 .name = TYPE_STM32F2XX_USART, 238 .parent = TYPE_SYS_BUS_DEVICE, 239 .instance_size = sizeof(STM32F2XXUsartState), 240 .instance_init = stm32f2xx_usart_init, 241 .class_init = stm32f2xx_usart_class_init, 242 }; 243 244 static void stm32f2xx_usart_register_types(void) 245 { 246 type_register_static(&stm32f2xx_usart_info); 247 } 248 249 type_init(stm32f2xx_usart_register_types) 250