1 /* 2 * nRF51 SoC UART emulation 3 * 4 * See nRF51 Series Reference Manual, "29 Universal Asynchronous 5 * Receiver/Transmitter" for hardware specifications: 6 * http://infocenter.nordicsemi.com/pdf/nRF51_RM_v3.0.pdf 7 * 8 * Copyright (c) 2018 Julia Suvorova <jusual@mail.ru> 9 * 10 * This program is free software; you can redistribute it and/or modify 11 * it under the terms of the GNU General Public License version 2 or 12 * (at your option) any later version. 13 */ 14 15 #include "qemu/osdep.h" 16 #include "qemu/log.h" 17 #include "qemu/module.h" 18 #include "hw/char/nrf51_uart.h" 19 #include "hw/irq.h" 20 #include "hw/qdev-properties.h" 21 #include "migration/vmstate.h" 22 #include "trace.h" 23 24 static void nrf51_uart_update_irq(NRF51UARTState *s) 25 { 26 bool irq = false; 27 28 irq |= (s->reg[R_UART_RXDRDY] && 29 (s->reg[R_UART_INTEN] & R_UART_INTEN_RXDRDY_MASK)); 30 irq |= (s->reg[R_UART_TXDRDY] && 31 (s->reg[R_UART_INTEN] & R_UART_INTEN_TXDRDY_MASK)); 32 irq |= (s->reg[R_UART_ERROR] && 33 (s->reg[R_UART_INTEN] & R_UART_INTEN_ERROR_MASK)); 34 irq |= (s->reg[R_UART_RXTO] && 35 (s->reg[R_UART_INTEN] & R_UART_INTEN_RXTO_MASK)); 36 37 qemu_set_irq(s->irq, irq); 38 } 39 40 static uint64_t uart_read(void *opaque, hwaddr addr, unsigned int size) 41 { 42 NRF51UARTState *s = NRF51_UART(opaque); 43 uint64_t r; 44 45 if (!s->enabled) { 46 return 0; 47 } 48 49 switch (addr) { 50 case A_UART_RXD: 51 r = s->rx_fifo[s->rx_fifo_pos]; 52 if (s->rx_started && s->rx_fifo_len) { 53 s->rx_fifo_pos = (s->rx_fifo_pos + 1) % UART_FIFO_LENGTH; 54 s->rx_fifo_len--; 55 if (s->rx_fifo_len) { 56 s->reg[R_UART_RXDRDY] = 1; 57 nrf51_uart_update_irq(s); 58 } 59 qemu_chr_fe_accept_input(&s->chr); 60 } 61 break; 62 case A_UART_INTENSET: 63 case A_UART_INTENCLR: 64 case A_UART_INTEN: 65 r = s->reg[R_UART_INTEN]; 66 break; 67 default: 68 r = s->reg[addr / 4]; 69 break; 70 } 71 72 trace_nrf51_uart_read(addr, r, size); 73 74 return r; 75 } 76 77 static gboolean uart_transmit(GIOChannel *chan, GIOCondition cond, void *opaque) 78 { 79 NRF51UARTState *s = NRF51_UART(opaque); 80 int r; 81 uint8_t c = s->reg[R_UART_TXD]; 82 83 s->watch_tag = 0; 84 85 r = qemu_chr_fe_write(&s->chr, &c, 1); 86 if (r <= 0) { 87 s->watch_tag = qemu_chr_fe_add_watch(&s->chr, G_IO_OUT | G_IO_HUP, 88 uart_transmit, s); 89 if (!s->watch_tag) { 90 /* The hardware has no transmit error reporting, 91 * so silently drop the byte 92 */ 93 goto buffer_drained; 94 } 95 return FALSE; 96 } 97 98 buffer_drained: 99 s->reg[R_UART_TXDRDY] = 1; 100 s->pending_tx_byte = false; 101 return FALSE; 102 } 103 104 static void uart_cancel_transmit(NRF51UARTState *s) 105 { 106 if (s->watch_tag) { 107 g_source_remove(s->watch_tag); 108 s->watch_tag = 0; 109 } 110 } 111 112 static void uart_write(void *opaque, hwaddr addr, 113 uint64_t value, unsigned int size) 114 { 115 NRF51UARTState *s = NRF51_UART(opaque); 116 117 trace_nrf51_uart_write(addr, value, size); 118 119 if (!s->enabled && (addr != A_UART_ENABLE)) { 120 return; 121 } 122 123 switch (addr) { 124 case A_UART_TXD: 125 if (!s->pending_tx_byte && s->tx_started) { 126 s->reg[R_UART_TXD] = value; 127 s->pending_tx_byte = true; 128 uart_transmit(NULL, G_IO_OUT, s); 129 } 130 break; 131 case A_UART_INTEN: 132 s->reg[R_UART_INTEN] = value; 133 break; 134 case A_UART_INTENSET: 135 s->reg[R_UART_INTEN] |= value; 136 break; 137 case A_UART_INTENCLR: 138 s->reg[R_UART_INTEN] &= ~value; 139 break; 140 case A_UART_TXDRDY ... A_UART_RXTO: 141 s->reg[addr / 4] = value; 142 break; 143 case A_UART_ERRORSRC: 144 s->reg[addr / 4] &= ~value; 145 break; 146 case A_UART_RXD: 147 break; 148 case A_UART_RXDRDY: 149 if (value == 0) { 150 s->reg[R_UART_RXDRDY] = 0; 151 } 152 break; 153 case A_UART_STARTTX: 154 if (value == 1) { 155 s->tx_started = true; 156 } 157 break; 158 case A_UART_STARTRX: 159 if (value == 1) { 160 s->rx_started = true; 161 } 162 break; 163 case A_UART_ENABLE: 164 if (value) { 165 if (value == 4) { 166 s->enabled = true; 167 } 168 break; 169 } 170 s->enabled = false; 171 value = 1; 172 /* fall through */ 173 case A_UART_SUSPEND: 174 case A_UART_STOPTX: 175 if (value == 1) { 176 s->tx_started = false; 177 } 178 /* fall through */ 179 case A_UART_STOPRX: 180 if (addr != A_UART_STOPTX && value == 1) { 181 s->rx_started = false; 182 s->reg[R_UART_RXTO] = 1; 183 } 184 break; 185 default: 186 s->reg[addr / 4] = value; 187 break; 188 } 189 nrf51_uart_update_irq(s); 190 } 191 192 static const MemoryRegionOps uart_ops = { 193 .read = uart_read, 194 .write = uart_write, 195 .endianness = DEVICE_LITTLE_ENDIAN, 196 }; 197 198 static void nrf51_uart_reset(DeviceState *dev) 199 { 200 NRF51UARTState *s = NRF51_UART(dev); 201 202 s->pending_tx_byte = 0; 203 204 uart_cancel_transmit(s); 205 206 memset(s->reg, 0, sizeof(s->reg)); 207 208 s->reg[R_UART_PSELRTS] = 0xFFFFFFFF; 209 s->reg[R_UART_PSELTXD] = 0xFFFFFFFF; 210 s->reg[R_UART_PSELCTS] = 0xFFFFFFFF; 211 s->reg[R_UART_PSELRXD] = 0xFFFFFFFF; 212 s->reg[R_UART_BAUDRATE] = 0x4000000; 213 214 s->rx_fifo_len = 0; 215 s->rx_fifo_pos = 0; 216 s->rx_started = false; 217 s->tx_started = false; 218 s->enabled = false; 219 } 220 221 static void uart_receive(void *opaque, const uint8_t *buf, int size) 222 { 223 224 NRF51UARTState *s = NRF51_UART(opaque); 225 int i; 226 227 if (size == 0 || s->rx_fifo_len >= UART_FIFO_LENGTH) { 228 return; 229 } 230 231 for (i = 0; i < size; i++) { 232 uint32_t pos = (s->rx_fifo_pos + s->rx_fifo_len) % UART_FIFO_LENGTH; 233 s->rx_fifo[pos] = buf[i]; 234 s->rx_fifo_len++; 235 } 236 237 s->reg[R_UART_RXDRDY] = 1; 238 nrf51_uart_update_irq(s); 239 } 240 241 static int uart_can_receive(void *opaque) 242 { 243 NRF51UARTState *s = NRF51_UART(opaque); 244 245 return s->rx_started ? (UART_FIFO_LENGTH - s->rx_fifo_len) : 0; 246 } 247 248 static void uart_event(void *opaque, QEMUChrEvent event) 249 { 250 NRF51UARTState *s = NRF51_UART(opaque); 251 252 if (event == CHR_EVENT_BREAK) { 253 s->reg[R_UART_ERRORSRC] |= 3; 254 s->reg[R_UART_ERROR] = 1; 255 nrf51_uart_update_irq(s); 256 } 257 } 258 259 static void nrf51_uart_realize(DeviceState *dev, Error **errp) 260 { 261 NRF51UARTState *s = NRF51_UART(dev); 262 263 qemu_chr_fe_set_handlers(&s->chr, uart_can_receive, uart_receive, 264 uart_event, NULL, s, NULL, true); 265 } 266 267 static void nrf51_uart_init(Object *obj) 268 { 269 NRF51UARTState *s = NRF51_UART(obj); 270 SysBusDevice *sbd = SYS_BUS_DEVICE(obj); 271 272 memory_region_init_io(&s->iomem, obj, &uart_ops, s, 273 "nrf51_soc.uart", UART_SIZE); 274 sysbus_init_mmio(sbd, &s->iomem); 275 sysbus_init_irq(sbd, &s->irq); 276 } 277 278 static int nrf51_uart_post_load(void *opaque, int version_id) 279 { 280 NRF51UARTState *s = NRF51_UART(opaque); 281 282 if (s->pending_tx_byte) { 283 s->watch_tag = qemu_chr_fe_add_watch(&s->chr, G_IO_OUT | G_IO_HUP, 284 uart_transmit, s); 285 } 286 287 return 0; 288 } 289 290 static const VMStateDescription nrf51_uart_vmstate = { 291 .name = "nrf51_soc.uart", 292 .post_load = nrf51_uart_post_load, 293 .fields = (VMStateField[]) { 294 VMSTATE_UINT32_ARRAY(reg, NRF51UARTState, 0x56C), 295 VMSTATE_UINT8_ARRAY(rx_fifo, NRF51UARTState, UART_FIFO_LENGTH), 296 VMSTATE_UINT32(rx_fifo_pos, NRF51UARTState), 297 VMSTATE_UINT32(rx_fifo_len, NRF51UARTState), 298 VMSTATE_BOOL(rx_started, NRF51UARTState), 299 VMSTATE_BOOL(tx_started, NRF51UARTState), 300 VMSTATE_BOOL(pending_tx_byte, NRF51UARTState), 301 VMSTATE_BOOL(enabled, NRF51UARTState), 302 VMSTATE_END_OF_LIST() 303 } 304 }; 305 306 static Property nrf51_uart_properties[] = { 307 DEFINE_PROP_CHR("chardev", NRF51UARTState, chr), 308 DEFINE_PROP_END_OF_LIST(), 309 }; 310 311 static void nrf51_uart_class_init(ObjectClass *klass, void *data) 312 { 313 DeviceClass *dc = DEVICE_CLASS(klass); 314 315 dc->reset = nrf51_uart_reset; 316 dc->realize = nrf51_uart_realize; 317 dc->props = nrf51_uart_properties; 318 dc->vmsd = &nrf51_uart_vmstate; 319 } 320 321 static const TypeInfo nrf51_uart_info = { 322 .name = TYPE_NRF51_UART, 323 .parent = TYPE_SYS_BUS_DEVICE, 324 .instance_size = sizeof(NRF51UARTState), 325 .instance_init = nrf51_uart_init, 326 .class_init = nrf51_uart_class_init 327 }; 328 329 static void nrf51_uart_register_types(void) 330 { 331 type_register_static(&nrf51_uart_info); 332 } 333 334 type_init(nrf51_uart_register_types) 335