drivers/tty/serial/altera_jtaguart.c

   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: http://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         spin_unlock(&port->lock);
 135         tty_flip_buffer_push(&port->state->port);
 136         spin_lock(&port->lock);
 137 }
 138
 139 static void altera_jtaguart_tx_chars(struct altera_jtaguart *pp)
 140 {
 141         struct uart_port *port = &pp->port;
 142         struct circ_buf *xmit = &port->state->xmit;
 143         unsigned int pending, count;
 144
 145         if (port->x_char) {
 146                 /* Send special char - probably flow control */
 147                 writel(port->x_char, port->membase + ALTERA_JTAGUART_DATA_REG);
 148                 port->x_char = 0;
 149                 port->icount.tx++;
 150                 return;
 151         }
 152
 153         pending = uart_circ_chars_pending(xmit);
 154         if (pending > 0) {
 155                 count = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
 156                                 ALTERA_JTAGUART_CONTROL_WSPACE_MSK) >>
 157                         ALTERA_JTAGUART_CONTROL_WSPACE_OFF;
 158                 if (count > pending)
 159                         count = pending;
 160                 if (count > 0) {
 161                         pending -= count;
 162                         while (count--) {
 163                                 writel(xmit->buf[xmit->tail],
 164                                        port->membase + ALTERA_JTAGUART_DATA_REG);
 165                                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 166                                 port->icount.tx++;
 167                         }
 168                         if (pending < WAKEUP_CHARS)
 169                                 uart_write_wakeup(port);
 170                 }
 171         }
 172
 173         if (pending == 0) {
 174                 pp->imr &= ~ALTERA_JTAGUART_CONTROL_WE_MSK;
 175                 writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
 176         }
 177 }
 178
 179 static irqreturn_t altera_jtaguart_interrupt(int irq, void *data)
 180 {
 181         struct uart_port *port = data;
 182         struct altera_jtaguart *pp =
 183             container_of(port, struct altera_jtaguart, port);
 184         unsigned int isr;
 185
 186         isr = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) >>
 187                ALTERA_JTAGUART_CONTROL_RI_OFF) & pp->imr;
 188
 189         spin_lock(&port->lock);
 190
 191         if (isr & ALTERA_JTAGUART_CONTROL_RE_MSK)
 192                 altera_jtaguart_rx_chars(pp);
 193         if (isr & ALTERA_JTAGUART_CONTROL_WE_MSK)
 194                 altera_jtaguart_tx_chars(pp);
 195
 196         spin_unlock(&port->lock);
 197
 198         return IRQ_RETVAL(isr);
 199 }
 200
 201 static void altera_jtaguart_config_port(struct uart_port *port, int flags)
 202 {
 203         port->type = PORT_ALTERA_JTAGUART;
 204
 205         /* Clear mask, so no surprise interrupts. */
 206         writel(0, port->membase + ALTERA_JTAGUART_CONTROL_REG);
 207 }
 208
 209 static int altera_jtaguart_startup(struct uart_port *port)
 210 {
 211         struct altera_jtaguart *pp =
 212             container_of(port, struct altera_jtaguart, port);
 213         unsigned long flags;
 214         int ret;
 215
 216         ret = request_irq(port->irq, altera_jtaguart_interrupt, 0,
 217                         DRV_NAME, port);
 218         if (ret) {
 219                 pr_err(DRV_NAME ": unable to attach Altera JTAG UART %d "
 220                        "interrupt vector=%d\n", port->line, port->irq);
 221                 return ret;
 222         }
 223
 224         spin_lock_irqsave(&port->lock, flags);
 225
 226         /* Enable RX interrupts now */
 227         pp->imr = ALTERA_JTAGUART_CONTROL_RE_MSK;
 228         writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
 229
 230         spin_unlock_irqrestore(&port->lock, flags);
 231
 232         return 0;
 233 }
 234
 235 static void altera_jtaguart_shutdown(struct uart_port *port)
 236 {
 237         struct altera_jtaguart *pp =
 238             container_of(port, struct altera_jtaguart, port);
 239         unsigned long flags;
 240
 241         spin_lock_irqsave(&port->lock, flags);
 242
 243         /* Disable all interrupts now */
 244         pp->imr = 0;
 245         writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
 246
 247         spin_unlock_irqrestore(&port->lock, flags);
 248
 249         free_irq(port->irq, port);
 250 }
 251
 252 static const char *altera_jtaguart_type(struct uart_port *port)
 253 {
 254         return (port->type == PORT_ALTERA_JTAGUART) ? "Altera JTAG UART" : NULL;
 255 }
 256
 257 static int altera_jtaguart_request_port(struct uart_port *port)
 258 {
 259         /* UARTs always present */
 260         return 0;
 261 }
 262
 263 static void altera_jtaguart_release_port(struct uart_port *port)
 264 {
 265         /* Nothing to release... */
 266 }
 267
 268 static int altera_jtaguart_verify_port(struct uart_port *port,
 269                                        struct serial_struct *ser)
 270 {
 271         if (ser->type != PORT_UNKNOWN && ser->type != PORT_ALTERA_JTAGUART)
 272                 return -EINVAL;
 273         return 0;
 274 }
 275
 276 /*
 277  *      Define the basic serial functions we support.
 278  */
 279 static const struct uart_ops altera_jtaguart_ops = {
 280         .tx_empty       = altera_jtaguart_tx_empty,
 281         .get_mctrl      = altera_jtaguart_get_mctrl,
 282         .set_mctrl      = altera_jtaguart_set_mctrl,
 283         .start_tx       = altera_jtaguart_start_tx,
 284         .stop_tx        = altera_jtaguart_stop_tx,
 285         .stop_rx        = altera_jtaguart_stop_rx,
 286         .break_ctl      = altera_jtaguart_break_ctl,
 287         .startup        = altera_jtaguart_startup,
 288         .shutdown       = altera_jtaguart_shutdown,
 289         .set_termios    = altera_jtaguart_set_termios,
 290         .type           = altera_jtaguart_type,
 291         .request_port   = altera_jtaguart_request_port,
 292         .release_port   = altera_jtaguart_release_port,
 293         .config_port    = altera_jtaguart_config_port,
 294         .verify_port    = altera_jtaguart_verify_port,
 295 };
 296
 297 #define ALTERA_JTAGUART_MAXPORTS 1
 298 static struct altera_jtaguart altera_jtaguart_ports[ALTERA_JTAGUART_MAXPORTS];
 299
 300 #if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE)
 301
 302 #if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS)
 303 static void altera_jtaguart_console_putc(struct uart_port *port, int c)
 304 {
 305         unsigned long status;
 306         unsigned long flags;
 307
 308         spin_lock_irqsave(&port->lock, flags);
 309         while (((status = readl(port->membase + ALTERA_JTAGUART_CONTROL_REG)) &
 310                 ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) {
 311                 if ((status & ALTERA_JTAGUART_CONTROL_AC_MSK) == 0) {
 312                         spin_unlock_irqrestore(&port->lock, flags);
 313                         return; /* no connection activity */
 314                 }
 315                 spin_unlock_irqrestore(&port->lock, flags);
 316                 cpu_relax();
 317                 spin_lock_irqsave(&port->lock, flags);
 318         }
 319         writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
 320         spin_unlock_irqrestore(&port->lock, flags);
 321 }
 322 #else
 323 static void altera_jtaguart_console_putc(struct uart_port *port, int c)
 324 {
 325         unsigned long flags;
 326
 327         spin_lock_irqsave(&port->lock, flags);
 328         while ((readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
 329                 ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) {
 330                 spin_unlock_irqrestore(&port->lock, flags);
 331                 cpu_relax();
 332                 spin_lock_irqsave(&port->lock, flags);
 333         }
 334         writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
 335         spin_unlock_irqrestore(&port->lock, flags);
 336 }
 337 #endif
 338
 339 static void altera_jtaguart_console_write(struct console *co, const char *s,
 340                                           unsigned int count)
 341 {
 342         struct uart_port *port = &(altera_jtaguart_ports + co->index)->port;
 343
 344         uart_console_write(port, s, count, altera_jtaguart_console_putc);
 345 }
 346
 347 static int __init altera_jtaguart_console_setup(struct console *co,
 348                                                 char *options)
 349 {
 350         struct uart_port *port;
 351
 352         if (co->index < 0 || co->index >= ALTERA_JTAGUART_MAXPORTS)
 353                 return -EINVAL;
 354         port = &altera_jtaguart_ports[co->index].port;
 355         if (port->membase == NULL)
 356                 return -ENODEV;
 357         return 0;
 358 }
 359
 360 static struct uart_driver altera_jtaguart_driver;
 361
 362 static struct console altera_jtaguart_console = {
 363         .name   = "ttyJ",
 364         .write  = altera_jtaguart_console_write,
 365         .device = uart_console_device,
 366         .setup  = altera_jtaguart_console_setup,
 367         .flags  = CON_PRINTBUFFER,
 368         .index  = -1,
 369         .data   = &altera_jtaguart_driver,
 370 };
 371
 372 static int __init altera_jtaguart_console_init(void)
 373 {
 374         register_console(&altera_jtaguart_console);
 375         return 0;
 376 }
 377
 378 console_initcall(altera_jtaguart_console_init);
 379
 380 #define ALTERA_JTAGUART_CONSOLE (&altera_jtaguart_console)
 381
 382 static void altera_jtaguart_earlycon_write(struct console *co, const char *s,
 383                                            unsigned int count)
 384 {
 385         struct earlycon_device *dev = co->data;
 386
 387         uart_console_write(&dev->port, s, count, altera_jtaguart_console_putc);
 388 }
 389
 390 static int __init altera_jtaguart_earlycon_setup(struct earlycon_device *dev,
 391                                                  const char *options)
 392 {
 393         if (!dev->port.membase)
 394                 return -ENODEV;
 395
 396         dev->con->write = altera_jtaguart_earlycon_write;
 397         return 0;
 398 }
 399
 400 OF_EARLYCON_DECLARE(juart, "altr,juart-1.0", altera_jtaguart_earlycon_setup);
 401
 402 #else
 403
 404 #define ALTERA_JTAGUART_CONSOLE NULL
 405
 406 #endif /* CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE */
 407
 408 static struct uart_driver altera_jtaguart_driver = {
 409         .owner          = THIS_MODULE,
 410         .driver_name    = "altera_jtaguart",
 411         .dev_name       = "ttyJ",
 412         .major          = ALTERA_JTAGUART_MAJOR,
 413         .minor          = ALTERA_JTAGUART_MINOR,
 414         .nr             = ALTERA_JTAGUART_MAXPORTS,
 415         .cons           = ALTERA_JTAGUART_CONSOLE,
 416 };
 417
 418 static int altera_jtaguart_probe(struct platform_device *pdev)
 419 {
 420         struct altera_jtaguart_platform_uart *platp =
 421                         dev_get_platdata(&pdev->dev);
 422         struct uart_port *port;
 423         struct resource *res_irq, *res_mem;
 424         int i = pdev->id;
 425
 426         /* -1 emphasizes that the platform must have one port, no .N suffix */
 427         if (i == -1)
 428                 i = 0;
 429
 430         if (i >= ALTERA_JTAGUART_MAXPORTS)
 431                 return -EINVAL;
 432
 433         port = &altera_jtaguart_ports[i].port;
 434
 435         res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 436         if (res_mem)
 437                 port->mapbase = res_mem->start;
 438         else if (platp)
 439                 port->mapbase = platp->mapbase;
 440         else
 441                 return -ENODEV;
 442
 443         res_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 444         if (res_irq)
 445                 port->irq = res_irq->start;
 446         else if (platp)
 447                 port->irq = platp->irq;
 448         else
 449                 return -ENODEV;
 450
 451         port->membase = ioremap(port->mapbase, ALTERA_JTAGUART_SIZE);
 452         if (!port->membase)
 453                 return -ENOMEM;
 454
 455         port->line = i;
 456         port->type = PORT_ALTERA_JTAGUART;
 457         port->iotype = SERIAL_IO_MEM;
 458         port->ops = &altera_jtaguart_ops;
 459         port->flags = UPF_BOOT_AUTOCONF;
 460         port->dev = &pdev->dev;
 461
 462         uart_add_one_port(&altera_jtaguart_driver, port);
 463
 464         return 0;
 465 }
 466
 467 static int altera_jtaguart_remove(struct platform_device *pdev)
 468 {
 469         struct uart_port *port;
 470         int i = pdev->id;
 471
 472         if (i == -1)
 473                 i = 0;
 474
 475         port = &altera_jtaguart_ports[i].port;
 476         uart_remove_one_port(&altera_jtaguart_driver, port);
 477         iounmap(port->membase);
 478
 479         return 0;
 480 }
 481
 482 #ifdef CONFIG_OF
 483 static const struct of_device_id altera_jtaguart_match[] = {
 484         { .compatible = "ALTR,juart-1.0", },
 485         { .compatible = "altr,juart-1.0", },
 486         {},
 487 };
 488 MODULE_DEVICE_TABLE(of, altera_jtaguart_match);
 489 #endif /* CONFIG_OF */
 490
 491 static struct platform_driver altera_jtaguart_platform_driver = {
 492         .probe  = altera_jtaguart_probe,
 493         .remove = altera_jtaguart_remove,
 494         .driver = {
 495                 .name           = DRV_NAME,
 496                 .of_match_table = of_match_ptr(altera_jtaguart_match),
 497         },
 498 };
 499
 500 static int __init altera_jtaguart_init(void)
 501 {
 502         int rc;
 503
 504         rc = uart_register_driver(&altera_jtaguart_driver);
 505         if (rc)
 506                 return rc;
 507         rc = platform_driver_register(&altera_jtaguart_platform_driver);
 508         if (rc)
 509                 uart_unregister_driver(&altera_jtaguart_driver);
 510         return rc;
 511 }
 512
 513 static void __exit altera_jtaguart_exit(void)
 514 {
 515         platform_driver_unregister(&altera_jtaguart_platform_driver);
 516         uart_unregister_driver(&altera_jtaguart_driver);
 517 }
 518
 519 module_init(altera_jtaguart_init);
 520 module_exit(altera_jtaguart_exit);
 521
 522 MODULE_DESCRIPTION("Altera JTAG UART driver");
 523 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
 524 MODULE_LICENSE("GPL");
 525 MODULE_ALIAS("platform:" DRV_NAME);