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: 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, int 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, int 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_irq, *res_mem;
 422         int i = pdev->id;
 423
 424         /* -1 emphasizes that the platform must have one port, no .N suffix */
 425         if (i == -1)
 426                 i = 0;
 427
 428         if (i >= ALTERA_JTAGUART_MAXPORTS)
 429                 return -EINVAL;
 430
 431         port = &altera_jtaguart_ports[i].port;
 432
 433         res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 434         if (res_mem)
 435                 port->mapbase = res_mem->start;
 436         else if (platp)
 437                 port->mapbase = platp->mapbase;
 438         else
 439                 return -ENODEV;
 440
 441         res_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 442         if (res_irq)
 443                 port->irq = res_irq->start;
 444         else if (platp)
 445                 port->irq = platp->irq;
 446         else
 447                 return -ENODEV;
 448
 449         port->membase = ioremap(port->mapbase, ALTERA_JTAGUART_SIZE);
 450         if (!port->membase)
 451                 return -ENOMEM;
 452
 453         port->line = i;
 454         port->type = PORT_ALTERA_JTAGUART;
 455         port->iotype = SERIAL_IO_MEM;
 456         port->ops = &altera_jtaguart_ops;
 457         port->flags = UPF_BOOT_AUTOCONF;
 458         port->dev = &pdev->dev;
 459
 460         uart_add_one_port(&altera_jtaguart_driver, port);
 461
 462         return 0;
 463 }
 464
 465 static int altera_jtaguart_remove(struct platform_device *pdev)
 466 {
 467         struct uart_port *port;
 468         int i = pdev->id;
 469
 470         if (i == -1)
 471                 i = 0;
 472
 473         port = &altera_jtaguart_ports[i].port;
 474         uart_remove_one_port(&altera_jtaguart_driver, port);
 475         iounmap(port->membase);
 476
 477         return 0;
 478 }
 479
 480 #ifdef CONFIG_OF
 481 static const struct of_device_id altera_jtaguart_match[] = {
 482         { .compatible = "ALTR,juart-1.0", },
 483         { .compatible = "altr,juart-1.0", },
 484         {},
 485 };
 486 MODULE_DEVICE_TABLE(of, altera_jtaguart_match);
 487 #endif /* CONFIG_OF */
 488
 489 static struct platform_driver altera_jtaguart_platform_driver = {
 490         .probe  = altera_jtaguart_probe,
 491         .remove = altera_jtaguart_remove,
 492         .driver = {
 493                 .name           = DRV_NAME,
 494                 .of_match_table = of_match_ptr(altera_jtaguart_match),
 495         },
 496 };
 497
 498 static int __init altera_jtaguart_init(void)
 499 {
 500         int rc;
 501
 502         rc = uart_register_driver(&altera_jtaguart_driver);
 503         if (rc)
 504                 return rc;
 505         rc = platform_driver_register(&altera_jtaguart_platform_driver);
 506         if (rc)
 507                 uart_unregister_driver(&altera_jtaguart_driver);
 508         return rc;
 509 }
 510
 511 static void __exit altera_jtaguart_exit(void)
 512 {
 513         platform_driver_unregister(&altera_jtaguart_platform_driver);
 514         uart_unregister_driver(&altera_jtaguart_driver);
 515 }
 516
 517 module_init(altera_jtaguart_init);
 518 module_exit(altera_jtaguart_exit);
 519
 520 MODULE_DESCRIPTION("Altera JTAG UART driver");
 521 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
 522 MODULE_LICENSE("GPL");
 523 MODULE_ALIAS("platform:" DRV_NAME);