1 /* 2 * ColdFire UART emulation. 3 * 4 * Copyright (c) 2007 CodeSourcery. 5 * 6 * This code is licensed under the GPL 7 */ 8 #include "qemu/osdep.h" 9 #include "hw/hw.h" 10 #include "hw/m68k/mcf.h" 11 #include "sysemu/char.h" 12 #include "exec/address-spaces.h" 13 #include "qapi/error.h" 14 15 typedef struct { 16 MemoryRegion iomem; 17 uint8_t mr[2]; 18 uint8_t sr; 19 uint8_t isr; 20 uint8_t imr; 21 uint8_t bg1; 22 uint8_t bg2; 23 uint8_t fifo[4]; 24 uint8_t tb; 25 int current_mr; 26 int fifo_len; 27 int tx_enabled; 28 int rx_enabled; 29 qemu_irq irq; 30 CharBackend chr; 31 } mcf_uart_state; 32 33 /* UART Status Register bits. */ 34 #define MCF_UART_RxRDY 0x01 35 #define MCF_UART_FFULL 0x02 36 #define MCF_UART_TxRDY 0x04 37 #define MCF_UART_TxEMP 0x08 38 #define MCF_UART_OE 0x10 39 #define MCF_UART_PE 0x20 40 #define MCF_UART_FE 0x40 41 #define MCF_UART_RB 0x80 42 43 /* Interrupt flags. */ 44 #define MCF_UART_TxINT 0x01 45 #define MCF_UART_RxINT 0x02 46 #define MCF_UART_DBINT 0x04 47 #define MCF_UART_COSINT 0x80 48 49 /* UMR1 flags. */ 50 #define MCF_UART_BC0 0x01 51 #define MCF_UART_BC1 0x02 52 #define MCF_UART_PT 0x04 53 #define MCF_UART_PM0 0x08 54 #define MCF_UART_PM1 0x10 55 #define MCF_UART_ERR 0x20 56 #define MCF_UART_RxIRQ 0x40 57 #define MCF_UART_RxRTS 0x80 58 59 static void mcf_uart_update(mcf_uart_state *s) 60 { 61 s->isr &= ~(MCF_UART_TxINT | MCF_UART_RxINT); 62 if (s->sr & MCF_UART_TxRDY) 63 s->isr |= MCF_UART_TxINT; 64 if ((s->sr & ((s->mr[0] & MCF_UART_RxIRQ) 65 ? MCF_UART_FFULL : MCF_UART_RxRDY)) != 0) 66 s->isr |= MCF_UART_RxINT; 67 68 qemu_set_irq(s->irq, (s->isr & s->imr) != 0); 69 } 70 71 uint64_t mcf_uart_read(void *opaque, hwaddr addr, 72 unsigned size) 73 { 74 mcf_uart_state *s = (mcf_uart_state *)opaque; 75 switch (addr & 0x3f) { 76 case 0x00: 77 return s->mr[s->current_mr]; 78 case 0x04: 79 return s->sr; 80 case 0x0c: 81 { 82 uint8_t val; 83 int i; 84 85 if (s->fifo_len == 0) 86 return 0; 87 88 val = s->fifo[0]; 89 s->fifo_len--; 90 for (i = 0; i < s->fifo_len; i++) 91 s->fifo[i] = s->fifo[i + 1]; 92 s->sr &= ~MCF_UART_FFULL; 93 if (s->fifo_len == 0) 94 s->sr &= ~MCF_UART_RxRDY; 95 mcf_uart_update(s); 96 qemu_chr_fe_accept_input(&s->chr); 97 return val; 98 } 99 case 0x10: 100 /* TODO: Implement IPCR. */ 101 return 0; 102 case 0x14: 103 return s->isr; 104 case 0x18: 105 return s->bg1; 106 case 0x1c: 107 return s->bg2; 108 default: 109 return 0; 110 } 111 } 112 113 /* Update TxRDY flag and set data if present and enabled. */ 114 static void mcf_uart_do_tx(mcf_uart_state *s) 115 { 116 if (s->tx_enabled && (s->sr & MCF_UART_TxEMP) == 0) { 117 /* XXX this blocks entire thread. Rewrite to use 118 * qemu_chr_fe_write and background I/O callbacks */ 119 qemu_chr_fe_write_all(&s->chr, (unsigned char *)&s->tb, 1); 120 s->sr |= MCF_UART_TxEMP; 121 } 122 if (s->tx_enabled) { 123 s->sr |= MCF_UART_TxRDY; 124 } else { 125 s->sr &= ~MCF_UART_TxRDY; 126 } 127 } 128 129 static void mcf_do_command(mcf_uart_state *s, uint8_t cmd) 130 { 131 /* Misc command. */ 132 switch ((cmd >> 4) & 7) { 133 case 0: /* No-op. */ 134 break; 135 case 1: /* Reset mode register pointer. */ 136 s->current_mr = 0; 137 break; 138 case 2: /* Reset receiver. */ 139 s->rx_enabled = 0; 140 s->fifo_len = 0; 141 s->sr &= ~(MCF_UART_RxRDY | MCF_UART_FFULL); 142 break; 143 case 3: /* Reset transmitter. */ 144 s->tx_enabled = 0; 145 s->sr |= MCF_UART_TxEMP; 146 s->sr &= ~MCF_UART_TxRDY; 147 break; 148 case 4: /* Reset error status. */ 149 break; 150 case 5: /* Reset break-change interrupt. */ 151 s->isr &= ~MCF_UART_DBINT; 152 break; 153 case 6: /* Start break. */ 154 case 7: /* Stop break. */ 155 break; 156 } 157 158 /* Transmitter command. */ 159 switch ((cmd >> 2) & 3) { 160 case 0: /* No-op. */ 161 break; 162 case 1: /* Enable. */ 163 s->tx_enabled = 1; 164 mcf_uart_do_tx(s); 165 break; 166 case 2: /* Disable. */ 167 s->tx_enabled = 0; 168 mcf_uart_do_tx(s); 169 break; 170 case 3: /* Reserved. */ 171 fprintf(stderr, "mcf_uart: Bad TX command\n"); 172 break; 173 } 174 175 /* Receiver command. */ 176 switch (cmd & 3) { 177 case 0: /* No-op. */ 178 break; 179 case 1: /* Enable. */ 180 s->rx_enabled = 1; 181 break; 182 case 2: 183 s->rx_enabled = 0; 184 break; 185 case 3: /* Reserved. */ 186 fprintf(stderr, "mcf_uart: Bad RX command\n"); 187 break; 188 } 189 } 190 191 void mcf_uart_write(void *opaque, hwaddr addr, 192 uint64_t val, unsigned size) 193 { 194 mcf_uart_state *s = (mcf_uart_state *)opaque; 195 switch (addr & 0x3f) { 196 case 0x00: 197 s->mr[s->current_mr] = val; 198 s->current_mr = 1; 199 break; 200 case 0x04: 201 /* CSR is ignored. */ 202 break; 203 case 0x08: /* Command Register. */ 204 mcf_do_command(s, val); 205 break; 206 case 0x0c: /* Transmit Buffer. */ 207 s->sr &= ~MCF_UART_TxEMP; 208 s->tb = val; 209 mcf_uart_do_tx(s); 210 break; 211 case 0x10: 212 /* ACR is ignored. */ 213 break; 214 case 0x14: 215 s->imr = val; 216 break; 217 default: 218 break; 219 } 220 mcf_uart_update(s); 221 } 222 223 static void mcf_uart_reset(mcf_uart_state *s) 224 { 225 s->fifo_len = 0; 226 s->mr[0] = 0; 227 s->mr[1] = 0; 228 s->sr = MCF_UART_TxEMP; 229 s->tx_enabled = 0; 230 s->rx_enabled = 0; 231 s->isr = 0; 232 s->imr = 0; 233 } 234 235 static void mcf_uart_push_byte(mcf_uart_state *s, uint8_t data) 236 { 237 /* Break events overwrite the last byte if the fifo is full. */ 238 if (s->fifo_len == 4) 239 s->fifo_len--; 240 241 s->fifo[s->fifo_len] = data; 242 s->fifo_len++; 243 s->sr |= MCF_UART_RxRDY; 244 if (s->fifo_len == 4) 245 s->sr |= MCF_UART_FFULL; 246 247 mcf_uart_update(s); 248 } 249 250 static void mcf_uart_event(void *opaque, int event) 251 { 252 mcf_uart_state *s = (mcf_uart_state *)opaque; 253 254 switch (event) { 255 case CHR_EVENT_BREAK: 256 s->isr |= MCF_UART_DBINT; 257 mcf_uart_push_byte(s, 0); 258 break; 259 default: 260 break; 261 } 262 } 263 264 static int mcf_uart_can_receive(void *opaque) 265 { 266 mcf_uart_state *s = (mcf_uart_state *)opaque; 267 268 return s->rx_enabled && (s->sr & MCF_UART_FFULL) == 0; 269 } 270 271 static void mcf_uart_receive(void *opaque, const uint8_t *buf, int size) 272 { 273 mcf_uart_state *s = (mcf_uart_state *)opaque; 274 275 mcf_uart_push_byte(s, buf[0]); 276 } 277 278 void *mcf_uart_init(qemu_irq irq, Chardev *chr) 279 { 280 mcf_uart_state *s; 281 282 s = g_malloc0(sizeof(mcf_uart_state)); 283 s->irq = irq; 284 if (chr) { 285 qemu_chr_fe_init(&s->chr, chr, &error_abort); 286 qemu_chr_fe_set_handlers(&s->chr, mcf_uart_can_receive, 287 mcf_uart_receive, mcf_uart_event, 288 s, NULL, true); 289 } 290 mcf_uart_reset(s); 291 return s; 292 } 293 294 static const MemoryRegionOps mcf_uart_ops = { 295 .read = mcf_uart_read, 296 .write = mcf_uart_write, 297 .endianness = DEVICE_NATIVE_ENDIAN, 298 }; 299 300 void mcf_uart_mm_init(MemoryRegion *sysmem, 301 hwaddr base, 302 qemu_irq irq, 303 Chardev *chr) 304 { 305 mcf_uart_state *s; 306 307 s = mcf_uart_init(irq, chr); 308 memory_region_init_io(&s->iomem, NULL, &mcf_uart_ops, s, "uart", 0x40); 309 memory_region_add_subregion(sysmem, base, &s->iomem); 310 } 311