1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * altera_jtaguart.c -- Altera JTAG UART driver 4 * 5 * Based on mcf.c -- Freescale ColdFire UART driver 6 * 7 * (C) Copyright 2003-2007, Greg Ungerer <gerg@snapgear.com> 8 * (C) Copyright 2008, Thomas Chou <thomas@wytron.com.tw> 9 * (C) Copyright 2010, Tobias Klauser <tklauser@distanz.ch> 10 */ 11 12 #include <linux/kernel.h> 13 #include <linux/init.h> 14 #include <linux/interrupt.h> 15 #include <linux/module.h> 16 #include <linux/console.h> 17 #include <linux/of.h> 18 #include <linux/tty.h> 19 #include <linux/tty_flip.h> 20 #include <linux/serial.h> 21 #include <linux/serial_core.h> 22 #include <linux/platform_device.h> 23 #include <linux/io.h> 24 #include <linux/altera_jtaguart.h> 25 26 #define DRV_NAME "altera_jtaguart" 27 28 /* 29 * Altera JTAG UART register definitions according to the Altera JTAG UART 30 * datasheet: https://www.altera.com/literature/hb/nios2/n2cpu_nii51009.pdf 31 */ 32 33 #define ALTERA_JTAGUART_SIZE 8 34 35 #define ALTERA_JTAGUART_DATA_REG 0 36 37 #define ALTERA_JTAGUART_DATA_DATA_MSK 0x000000FF 38 #define ALTERA_JTAGUART_DATA_RVALID_MSK 0x00008000 39 #define ALTERA_JTAGUART_DATA_RAVAIL_MSK 0xFFFF0000 40 #define ALTERA_JTAGUART_DATA_RAVAIL_OFF 16 41 42 #define ALTERA_JTAGUART_CONTROL_REG 4 43 44 #define ALTERA_JTAGUART_CONTROL_RE_MSK 0x00000001 45 #define ALTERA_JTAGUART_CONTROL_WE_MSK 0x00000002 46 #define ALTERA_JTAGUART_CONTROL_RI_MSK 0x00000100 47 #define ALTERA_JTAGUART_CONTROL_RI_OFF 8 48 #define ALTERA_JTAGUART_CONTROL_WI_MSK 0x00000200 49 #define ALTERA_JTAGUART_CONTROL_AC_MSK 0x00000400 50 #define ALTERA_JTAGUART_CONTROL_WSPACE_MSK 0xFFFF0000 51 #define ALTERA_JTAGUART_CONTROL_WSPACE_OFF 16 52 53 /* 54 * Local per-uart structure. 55 */ 56 struct altera_jtaguart { 57 struct uart_port port; 58 unsigned int sigs; /* Local copy of line sigs */ 59 unsigned long imr; /* Local IMR mirror */ 60 }; 61 62 static unsigned int altera_jtaguart_tx_empty(struct uart_port *port) 63 { 64 return (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) & 65 ALTERA_JTAGUART_CONTROL_WSPACE_MSK) ? TIOCSER_TEMT : 0; 66 } 67 68 static unsigned int altera_jtaguart_get_mctrl(struct uart_port *port) 69 { 70 return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS; 71 } 72 73 static void altera_jtaguart_set_mctrl(struct uart_port *port, unsigned int sigs) 74 { 75 } 76 77 static void altera_jtaguart_start_tx(struct uart_port *port) 78 { 79 struct altera_jtaguart *pp = 80 container_of(port, struct altera_jtaguart, port); 81 82 pp->imr |= ALTERA_JTAGUART_CONTROL_WE_MSK; 83 writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG); 84 } 85 86 static void altera_jtaguart_stop_tx(struct uart_port *port) 87 { 88 struct altera_jtaguart *pp = 89 container_of(port, struct altera_jtaguart, port); 90 91 pp->imr &= ~ALTERA_JTAGUART_CONTROL_WE_MSK; 92 writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG); 93 } 94 95 static void altera_jtaguart_stop_rx(struct uart_port *port) 96 { 97 struct altera_jtaguart *pp = 98 container_of(port, struct altera_jtaguart, port); 99 100 pp->imr &= ~ALTERA_JTAGUART_CONTROL_RE_MSK; 101 writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG); 102 } 103 104 static void altera_jtaguart_break_ctl(struct uart_port *port, int break_state) 105 { 106 } 107 108 static void altera_jtaguart_set_termios(struct uart_port *port, 109 struct ktermios *termios, 110 struct ktermios *old) 111 { 112 /* Just copy the old termios settings back */ 113 if (old) 114 tty_termios_copy_hw(termios, old); 115 } 116 117 static void altera_jtaguart_rx_chars(struct altera_jtaguart *pp) 118 { 119 struct uart_port *port = &pp->port; 120 unsigned char ch, flag; 121 unsigned long status; 122 123 while ((status = readl(port->membase + ALTERA_JTAGUART_DATA_REG)) & 124 ALTERA_JTAGUART_DATA_RVALID_MSK) { 125 ch = status & ALTERA_JTAGUART_DATA_DATA_MSK; 126 flag = TTY_NORMAL; 127 port->icount.rx++; 128 129 if (uart_handle_sysrq_char(port, ch)) 130 continue; 131 uart_insert_char(port, 0, 0, ch, flag); 132 } 133 134 tty_flip_buffer_push(&port->state->port); 135 } 136 137 static void altera_jtaguart_tx_chars(struct altera_jtaguart *pp) 138 { 139 struct uart_port *port = &pp->port; 140 struct circ_buf *xmit = &port->state->xmit; 141 unsigned int pending, count; 142 143 if (port->x_char) { 144 /* Send special char - probably flow control */ 145 writel(port->x_char, port->membase + ALTERA_JTAGUART_DATA_REG); 146 port->x_char = 0; 147 port->icount.tx++; 148 return; 149 } 150 151 pending = uart_circ_chars_pending(xmit); 152 if (pending > 0) { 153 count = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) & 154 ALTERA_JTAGUART_CONTROL_WSPACE_MSK) >> 155 ALTERA_JTAGUART_CONTROL_WSPACE_OFF; 156 if (count > pending) 157 count = pending; 158 if (count > 0) { 159 pending -= count; 160 while (count--) { 161 writel(xmit->buf[xmit->tail], 162 port->membase + ALTERA_JTAGUART_DATA_REG); 163 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); 164 port->icount.tx++; 165 } 166 if (pending < WAKEUP_CHARS) 167 uart_write_wakeup(port); 168 } 169 } 170 171 if (pending == 0) { 172 pp->imr &= ~ALTERA_JTAGUART_CONTROL_WE_MSK; 173 writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG); 174 } 175 } 176 177 static irqreturn_t altera_jtaguart_interrupt(int irq, void *data) 178 { 179 struct uart_port *port = data; 180 struct altera_jtaguart *pp = 181 container_of(port, struct altera_jtaguart, port); 182 unsigned int isr; 183 184 isr = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) >> 185 ALTERA_JTAGUART_CONTROL_RI_OFF) & pp->imr; 186 187 spin_lock(&port->lock); 188 189 if (isr & ALTERA_JTAGUART_CONTROL_RE_MSK) 190 altera_jtaguart_rx_chars(pp); 191 if (isr & ALTERA_JTAGUART_CONTROL_WE_MSK) 192 altera_jtaguart_tx_chars(pp); 193 194 spin_unlock(&port->lock); 195 196 return IRQ_RETVAL(isr); 197 } 198 199 static void altera_jtaguart_config_port(struct uart_port *port, int flags) 200 { 201 port->type = PORT_ALTERA_JTAGUART; 202 203 /* Clear mask, so no surprise interrupts. */ 204 writel(0, port->membase + ALTERA_JTAGUART_CONTROL_REG); 205 } 206 207 static int altera_jtaguart_startup(struct uart_port *port) 208 { 209 struct altera_jtaguart *pp = 210 container_of(port, struct altera_jtaguart, port); 211 unsigned long flags; 212 int ret; 213 214 ret = request_irq(port->irq, altera_jtaguart_interrupt, 0, 215 DRV_NAME, port); 216 if (ret) { 217 pr_err(DRV_NAME ": unable to attach Altera JTAG UART %d " 218 "interrupt vector=%d\n", port->line, port->irq); 219 return ret; 220 } 221 222 spin_lock_irqsave(&port->lock, flags); 223 224 /* Enable RX interrupts now */ 225 pp->imr = ALTERA_JTAGUART_CONTROL_RE_MSK; 226 writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG); 227 228 spin_unlock_irqrestore(&port->lock, flags); 229 230 return 0; 231 } 232 233 static void altera_jtaguart_shutdown(struct uart_port *port) 234 { 235 struct altera_jtaguart *pp = 236 container_of(port, struct altera_jtaguart, port); 237 unsigned long flags; 238 239 spin_lock_irqsave(&port->lock, flags); 240 241 /* Disable all interrupts now */ 242 pp->imr = 0; 243 writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG); 244 245 spin_unlock_irqrestore(&port->lock, flags); 246 247 free_irq(port->irq, port); 248 } 249 250 static const char *altera_jtaguart_type(struct uart_port *port) 251 { 252 return (port->type == PORT_ALTERA_JTAGUART) ? "Altera JTAG UART" : NULL; 253 } 254 255 static int altera_jtaguart_request_port(struct uart_port *port) 256 { 257 /* UARTs always present */ 258 return 0; 259 } 260 261 static void altera_jtaguart_release_port(struct uart_port *port) 262 { 263 /* Nothing to release... */ 264 } 265 266 static int altera_jtaguart_verify_port(struct uart_port *port, 267 struct serial_struct *ser) 268 { 269 if (ser->type != PORT_UNKNOWN && ser->type != PORT_ALTERA_JTAGUART) 270 return -EINVAL; 271 return 0; 272 } 273 274 /* 275 * Define the basic serial functions we support. 276 */ 277 static const struct uart_ops altera_jtaguart_ops = { 278 .tx_empty = altera_jtaguart_tx_empty, 279 .get_mctrl = altera_jtaguart_get_mctrl, 280 .set_mctrl = altera_jtaguart_set_mctrl, 281 .start_tx = altera_jtaguart_start_tx, 282 .stop_tx = altera_jtaguart_stop_tx, 283 .stop_rx = altera_jtaguart_stop_rx, 284 .break_ctl = altera_jtaguart_break_ctl, 285 .startup = altera_jtaguart_startup, 286 .shutdown = altera_jtaguart_shutdown, 287 .set_termios = altera_jtaguart_set_termios, 288 .type = altera_jtaguart_type, 289 .request_port = altera_jtaguart_request_port, 290 .release_port = altera_jtaguart_release_port, 291 .config_port = altera_jtaguart_config_port, 292 .verify_port = altera_jtaguart_verify_port, 293 }; 294 295 #define ALTERA_JTAGUART_MAXPORTS 1 296 static struct altera_jtaguart altera_jtaguart_ports[ALTERA_JTAGUART_MAXPORTS]; 297 298 #if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE) 299 300 #if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS) 301 static void altera_jtaguart_console_putc(struct uart_port *port, unsigned char c) 302 { 303 unsigned long status; 304 unsigned long flags; 305 306 spin_lock_irqsave(&port->lock, flags); 307 while (((status = readl(port->membase + ALTERA_JTAGUART_CONTROL_REG)) & 308 ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) { 309 if ((status & ALTERA_JTAGUART_CONTROL_AC_MSK) == 0) { 310 spin_unlock_irqrestore(&port->lock, flags); 311 return; /* no connection activity */ 312 } 313 spin_unlock_irqrestore(&port->lock, flags); 314 cpu_relax(); 315 spin_lock_irqsave(&port->lock, flags); 316 } 317 writel(c, port->membase + ALTERA_JTAGUART_DATA_REG); 318 spin_unlock_irqrestore(&port->lock, flags); 319 } 320 #else 321 static void altera_jtaguart_console_putc(struct uart_port *port, unsigned char c) 322 { 323 unsigned long flags; 324 325 spin_lock_irqsave(&port->lock, flags); 326 while ((readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) & 327 ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) { 328 spin_unlock_irqrestore(&port->lock, flags); 329 cpu_relax(); 330 spin_lock_irqsave(&port->lock, flags); 331 } 332 writel(c, port->membase + ALTERA_JTAGUART_DATA_REG); 333 spin_unlock_irqrestore(&port->lock, flags); 334 } 335 #endif 336 337 static void altera_jtaguart_console_write(struct console *co, const char *s, 338 unsigned int count) 339 { 340 struct uart_port *port = &(altera_jtaguart_ports + co->index)->port; 341 342 uart_console_write(port, s, count, altera_jtaguart_console_putc); 343 } 344 345 static int __init altera_jtaguart_console_setup(struct console *co, 346 char *options) 347 { 348 struct uart_port *port; 349 350 if (co->index < 0 || co->index >= ALTERA_JTAGUART_MAXPORTS) 351 return -EINVAL; 352 port = &altera_jtaguart_ports[co->index].port; 353 if (port->membase == NULL) 354 return -ENODEV; 355 return 0; 356 } 357 358 static struct uart_driver altera_jtaguart_driver; 359 360 static struct console altera_jtaguart_console = { 361 .name = "ttyJ", 362 .write = altera_jtaguart_console_write, 363 .device = uart_console_device, 364 .setup = altera_jtaguart_console_setup, 365 .flags = CON_PRINTBUFFER, 366 .index = -1, 367 .data = &altera_jtaguart_driver, 368 }; 369 370 static int __init altera_jtaguart_console_init(void) 371 { 372 register_console(&altera_jtaguart_console); 373 return 0; 374 } 375 376 console_initcall(altera_jtaguart_console_init); 377 378 #define ALTERA_JTAGUART_CONSOLE (&altera_jtaguart_console) 379 380 static void altera_jtaguart_earlycon_write(struct console *co, const char *s, 381 unsigned int count) 382 { 383 struct earlycon_device *dev = co->data; 384 385 uart_console_write(&dev->port, s, count, altera_jtaguart_console_putc); 386 } 387 388 static int __init altera_jtaguart_earlycon_setup(struct earlycon_device *dev, 389 const char *options) 390 { 391 if (!dev->port.membase) 392 return -ENODEV; 393 394 dev->con->write = altera_jtaguart_earlycon_write; 395 return 0; 396 } 397 398 OF_EARLYCON_DECLARE(juart, "altr,juart-1.0", altera_jtaguart_earlycon_setup); 399 400 #else 401 402 #define ALTERA_JTAGUART_CONSOLE NULL 403 404 #endif /* CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE */ 405 406 static struct uart_driver altera_jtaguart_driver = { 407 .owner = THIS_MODULE, 408 .driver_name = "altera_jtaguart", 409 .dev_name = "ttyJ", 410 .major = ALTERA_JTAGUART_MAJOR, 411 .minor = ALTERA_JTAGUART_MINOR, 412 .nr = ALTERA_JTAGUART_MAXPORTS, 413 .cons = ALTERA_JTAGUART_CONSOLE, 414 }; 415 416 static int altera_jtaguart_probe(struct platform_device *pdev) 417 { 418 struct altera_jtaguart_platform_uart *platp = 419 dev_get_platdata(&pdev->dev); 420 struct uart_port *port; 421 struct resource *res_mem; 422 int i = pdev->id; 423 int irq; 424 425 /* -1 emphasizes that the platform must have one port, no .N suffix */ 426 if (i == -1) 427 i = 0; 428 429 if (i >= ALTERA_JTAGUART_MAXPORTS) 430 return -EINVAL; 431 432 port = &altera_jtaguart_ports[i].port; 433 434 res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); 435 if (res_mem) 436 port->mapbase = res_mem->start; 437 else if (platp) 438 port->mapbase = platp->mapbase; 439 else 440 return -ENODEV; 441 442 irq = platform_get_irq_optional(pdev, 0); 443 if (irq < 0 && irq != -ENXIO) 444 return irq; 445 if (irq > 0) 446 port->irq = irq; 447 else if (platp) 448 port->irq = platp->irq; 449 else 450 return -ENODEV; 451 452 port->membase = ioremap(port->mapbase, ALTERA_JTAGUART_SIZE); 453 if (!port->membase) 454 return -ENOMEM; 455 456 port->line = i; 457 port->type = PORT_ALTERA_JTAGUART; 458 port->iotype = SERIAL_IO_MEM; 459 port->ops = &altera_jtaguart_ops; 460 port->flags = UPF_BOOT_AUTOCONF; 461 port->dev = &pdev->dev; 462 463 uart_add_one_port(&altera_jtaguart_driver, port); 464 465 return 0; 466 } 467 468 static int altera_jtaguart_remove(struct platform_device *pdev) 469 { 470 struct uart_port *port; 471 int i = pdev->id; 472 473 if (i == -1) 474 i = 0; 475 476 port = &altera_jtaguart_ports[i].port; 477 uart_remove_one_port(&altera_jtaguart_driver, port); 478 iounmap(port->membase); 479 480 return 0; 481 } 482 483 #ifdef CONFIG_OF 484 static const struct of_device_id altera_jtaguart_match[] = { 485 { .compatible = "ALTR,juart-1.0", }, 486 { .compatible = "altr,juart-1.0", }, 487 {}, 488 }; 489 MODULE_DEVICE_TABLE(of, altera_jtaguart_match); 490 #endif /* CONFIG_OF */ 491 492 static struct platform_driver altera_jtaguart_platform_driver = { 493 .probe = altera_jtaguart_probe, 494 .remove = altera_jtaguart_remove, 495 .driver = { 496 .name = DRV_NAME, 497 .of_match_table = of_match_ptr(altera_jtaguart_match), 498 }, 499 }; 500 501 static int __init altera_jtaguart_init(void) 502 { 503 int rc; 504 505 rc = uart_register_driver(&altera_jtaguart_driver); 506 if (rc) 507 return rc; 508 rc = platform_driver_register(&altera_jtaguart_platform_driver); 509 if (rc) 510 uart_unregister_driver(&altera_jtaguart_driver); 511 return rc; 512 } 513 514 static void __exit altera_jtaguart_exit(void) 515 { 516 platform_driver_unregister(&altera_jtaguart_platform_driver); 517 uart_unregister_driver(&altera_jtaguart_driver); 518 } 519 520 module_init(altera_jtaguart_init); 521 module_exit(altera_jtaguart_exit); 522 523 MODULE_DESCRIPTION("Altera JTAG UART driver"); 524 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>"); 525 MODULE_LICENSE("GPL"); 526 MODULE_ALIAS("platform:" DRV_NAME); 527