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