drivers/tty/serial/apbuart.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  Driver for GRLIB serial ports (APBUART)
   4  *
   5  *  Based on linux/drivers/serial/amba.c
   6  *
   7  *  Copyright (C) 2000 Deep Blue Solutions Ltd.
   8  *  Copyright (C) 2003 Konrad Eisele <eiselekd@web.de>
   9  *  Copyright (C) 2006 Daniel Hellstrom <daniel@gaisler.com>, Aeroflex Gaisler AB
  10  *  Copyright (C) 2008 Gilead Kutnick <kutnickg@zin-tech.com>
  11  *  Copyright (C) 2009 Kristoffer Glembo <kristoffer@gaisler.com>, Aeroflex Gaisler AB
  12  */
  13
  14 #include <linux/module.h>
  15 #include <linux/tty.h>
  16 #include <linux/tty_flip.h>
  17 #include <linux/ioport.h>
  18 #include <linux/init.h>
  19 #include <linux/serial.h>
  20 #include <linux/console.h>
  21 #include <linux/sysrq.h>
  22 #include <linux/kthread.h>
  23 #include <linux/device.h>
  24 #include <linux/of.h>
  25 #include <linux/of_device.h>
  26 #include <linux/of_platform.h>
  27 #include <linux/of_irq.h>
  28 #include <linux/platform_device.h>
  29 #include <linux/io.h>
  30 #include <linux/serial_core.h>
  31 #include <asm/irq.h>
  32
  33 #include "apbuart.h"
  34
  35 #define SERIAL_APBUART_MAJOR    TTY_MAJOR
  36 #define SERIAL_APBUART_MINOR    64
  37 #define UART_DUMMY_RSR_RX       0x8000  /* for ignore all read */
  38
  39 static void apbuart_tx_chars(struct uart_port *port);
  40
  41 static void apbuart_stop_tx(struct uart_port *port)
  42 {
  43         unsigned int cr;
  44
  45         cr = UART_GET_CTRL(port);
  46         cr &= ~UART_CTRL_TI;
  47         UART_PUT_CTRL(port, cr);
  48 }
  49
  50 static void apbuart_start_tx(struct uart_port *port)
  51 {
  52         unsigned int cr;
  53
  54         cr = UART_GET_CTRL(port);
  55         cr |= UART_CTRL_TI;
  56         UART_PUT_CTRL(port, cr);
  57
  58         if (UART_GET_STATUS(port) & UART_STATUS_THE)
  59                 apbuart_tx_chars(port);
  60 }
  61
  62 static void apbuart_stop_rx(struct uart_port *port)
  63 {
  64         unsigned int cr;
  65
  66         cr = UART_GET_CTRL(port);
  67         cr &= ~(UART_CTRL_RI);
  68         UART_PUT_CTRL(port, cr);
  69 }
  70
  71 static void apbuart_rx_chars(struct uart_port *port)
  72 {
  73         unsigned int status, ch, rsr, flag;
  74         unsigned int max_chars = port->fifosize;
  75
  76         status = UART_GET_STATUS(port);
  77
  78         while (UART_RX_DATA(status) && (max_chars--)) {
  79
  80                 ch = UART_GET_CHAR(port);
  81                 flag = TTY_NORMAL;
  82
  83                 port->icount.rx++;
  84
  85                 rsr = UART_GET_STATUS(port) | UART_DUMMY_RSR_RX;
  86                 UART_PUT_STATUS(port, 0);
  87                 if (rsr & UART_STATUS_ERR) {
  88
  89                         if (rsr & UART_STATUS_BR) {
  90                                 rsr &= ~(UART_STATUS_FE | UART_STATUS_PE);
  91                                 port->icount.brk++;
  92                                 if (uart_handle_break(port))
  93                                         goto ignore_char;
  94                         } else if (rsr & UART_STATUS_PE) {
  95                                 port->icount.parity++;
  96                         } else if (rsr & UART_STATUS_FE) {
  97                                 port->icount.frame++;
  98                         }
  99                         if (rsr & UART_STATUS_OE)
 100                                 port->icount.overrun++;
 101
 102                         rsr &= port->read_status_mask;
 103
 104                         if (rsr & UART_STATUS_PE)
 105                                 flag = TTY_PARITY;
 106                         else if (rsr & UART_STATUS_FE)
 107                                 flag = TTY_FRAME;
 108                 }
 109
 110                 if (uart_handle_sysrq_char(port, ch))
 111                         goto ignore_char;
 112
 113                 uart_insert_char(port, rsr, UART_STATUS_OE, ch, flag);
 114
 115
 116               ignore_char:
 117                 status = UART_GET_STATUS(port);
 118         }
 119
 120         spin_unlock(&port->lock);
 121         tty_flip_buffer_push(&port->state->port);
 122         spin_lock(&port->lock);
 123 }
 124
 125 static void apbuart_tx_chars(struct uart_port *port)
 126 {
 127         struct circ_buf *xmit = &port->state->xmit;
 128         int count;
 129
 130         if (port->x_char) {
 131                 UART_PUT_CHAR(port, port->x_char);
 132                 port->icount.tx++;
 133                 port->x_char = 0;
 134                 return;
 135         }
 136
 137         if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
 138                 apbuart_stop_tx(port);
 139                 return;
 140         }
 141
 142         /* amba: fill FIFO */
 143         count = port->fifosize >> 1;
 144         do {
 145                 UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
 146                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 147                 port->icount.tx++;
 148                 if (uart_circ_empty(xmit))
 149                         break;
 150         } while (--count > 0);
 151
 152         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 153                 uart_write_wakeup(port);
 154
 155         if (uart_circ_empty(xmit))
 156                 apbuart_stop_tx(port);
 157 }
 158
 159 static irqreturn_t apbuart_int(int irq, void *dev_id)
 160 {
 161         struct uart_port *port = dev_id;
 162         unsigned int status;
 163
 164         spin_lock(&port->lock);
 165
 166         status = UART_GET_STATUS(port);
 167         if (status & UART_STATUS_DR)
 168                 apbuart_rx_chars(port);
 169         if (status & UART_STATUS_THE)
 170                 apbuart_tx_chars(port);
 171
 172         spin_unlock(&port->lock);
 173
 174         return IRQ_HANDLED;
 175 }
 176
 177 static unsigned int apbuart_tx_empty(struct uart_port *port)
 178 {
 179         unsigned int status = UART_GET_STATUS(port);
 180         return status & UART_STATUS_THE ? TIOCSER_TEMT : 0;
 181 }
 182
 183 static unsigned int apbuart_get_mctrl(struct uart_port *port)
 184 {
 185         /* The GRLIB APBUART handles flow control in hardware */
 186         return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
 187 }
 188
 189 static void apbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 190 {
 191         /* The GRLIB APBUART handles flow control in hardware */
 192 }
 193
 194 static void apbuart_break_ctl(struct uart_port *port, int break_state)
 195 {
 196         /* We don't support sending break */
 197 }
 198
 199 static int apbuart_startup(struct uart_port *port)
 200 {
 201         int retval;
 202         unsigned int cr;
 203
 204         /* Allocate the IRQ */
 205         retval = request_irq(port->irq, apbuart_int, 0, "apbuart", port);
 206         if (retval)
 207                 return retval;
 208
 209         /* Finally, enable interrupts */
 210         cr = UART_GET_CTRL(port);
 211         UART_PUT_CTRL(port,
 212                       cr | UART_CTRL_RE | UART_CTRL_TE |
 213                       UART_CTRL_RI | UART_CTRL_TI);
 214
 215         return 0;
 216 }
 217
 218 static void apbuart_shutdown(struct uart_port *port)
 219 {
 220         unsigned int cr;
 221
 222         /* disable all interrupts, disable the port */
 223         cr = UART_GET_CTRL(port);
 224         UART_PUT_CTRL(port,
 225                       cr & ~(UART_CTRL_RE | UART_CTRL_TE |
 226                              UART_CTRL_RI | UART_CTRL_TI));
 227
 228         /* Free the interrupt */
 229         free_irq(port->irq, port);
 230 }
 231
 232 static void apbuart_set_termios(struct uart_port *port,
 233                                 struct ktermios *termios, struct ktermios *old)
 234 {
 235         unsigned int cr;
 236         unsigned long flags;
 237         unsigned int baud, quot;
 238
 239         /* Ask the core to calculate the divisor for us. */
 240         baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
 241         if (baud == 0)
 242                 panic("invalid baudrate %i\n", port->uartclk / 16);
 243
 244         /* uart_get_divisor calc a *16 uart freq, apbuart is *8 */
 245         quot = (uart_get_divisor(port, baud)) * 2;
 246         cr = UART_GET_CTRL(port);
 247         cr &= ~(UART_CTRL_PE | UART_CTRL_PS);
 248
 249         if (termios->c_cflag & PARENB) {
 250                 cr |= UART_CTRL_PE;
 251                 if ((termios->c_cflag & PARODD))
 252                         cr |= UART_CTRL_PS;
 253         }
 254
 255         /* Enable flow control. */
 256         if (termios->c_cflag & CRTSCTS)
 257                 cr |= UART_CTRL_FL;
 258
 259         spin_lock_irqsave(&port->lock, flags);
 260
 261         /* Update the per-port timeout. */
 262         uart_update_timeout(port, termios->c_cflag, baud);
 263
 264         port->read_status_mask = UART_STATUS_OE;
 265         if (termios->c_iflag & INPCK)
 266                 port->read_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
 267
 268         /* Characters to ignore */
 269         port->ignore_status_mask = 0;
 270         if (termios->c_iflag & IGNPAR)
 271                 port->ignore_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
 272
 273         /* Ignore all characters if CREAD is not set. */
 274         if ((termios->c_cflag & CREAD) == 0)
 275                 port->ignore_status_mask |= UART_DUMMY_RSR_RX;
 276
 277         /* Set baud rate */
 278         quot -= 1;
 279         UART_PUT_SCAL(port, quot);
 280         UART_PUT_CTRL(port, cr);
 281
 282         spin_unlock_irqrestore(&port->lock, flags);
 283 }
 284
 285 static const char *apbuart_type(struct uart_port *port)
 286 {
 287         return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
 288 }
 289
 290 static void apbuart_release_port(struct uart_port *port)
 291 {
 292         release_mem_region(port->mapbase, 0x100);
 293 }
 294
 295 static int apbuart_request_port(struct uart_port *port)
 296 {
 297         return request_mem_region(port->mapbase, 0x100, "grlib-apbuart")
 298             != NULL ? 0 : -EBUSY;
 299         return 0;
 300 }
 301
 302 /* Configure/autoconfigure the port */
 303 static void apbuart_config_port(struct uart_port *port, int flags)
 304 {
 305         if (flags & UART_CONFIG_TYPE) {
 306                 port->type = PORT_APBUART;
 307                 apbuart_request_port(port);
 308         }
 309 }
 310
 311 /* Verify the new serial_struct (for TIOCSSERIAL) */
 312 static int apbuart_verify_port(struct uart_port *port,
 313                                struct serial_struct *ser)
 314 {
 315         int ret = 0;
 316         if (ser->type != PORT_UNKNOWN && ser->type != PORT_APBUART)
 317                 ret = -EINVAL;
 318         if (ser->irq < 0 || ser->irq >= NR_IRQS)
 319                 ret = -EINVAL;
 320         if (ser->baud_base < 9600)
 321                 ret = -EINVAL;
 322         return ret;
 323 }
 324
 325 static const struct uart_ops grlib_apbuart_ops = {
 326         .tx_empty = apbuart_tx_empty,
 327         .set_mctrl = apbuart_set_mctrl,
 328         .get_mctrl = apbuart_get_mctrl,
 329         .stop_tx = apbuart_stop_tx,
 330         .start_tx = apbuart_start_tx,
 331         .stop_rx = apbuart_stop_rx,
 332         .break_ctl = apbuart_break_ctl,
 333         .startup = apbuart_startup,
 334         .shutdown = apbuart_shutdown,
 335         .set_termios = apbuart_set_termios,
 336         .type = apbuart_type,
 337         .release_port = apbuart_release_port,
 338         .request_port = apbuart_request_port,
 339         .config_port = apbuart_config_port,
 340         .verify_port = apbuart_verify_port,
 341 };
 342
 343 static struct uart_port grlib_apbuart_ports[UART_NR];
 344 static struct device_node *grlib_apbuart_nodes[UART_NR];
 345
 346 static int apbuart_scan_fifo_size(struct uart_port *port, int portnumber)
 347 {
 348         int ctrl, loop = 0;
 349         int status;
 350         int fifosize;
 351         unsigned long flags;
 352
 353         ctrl = UART_GET_CTRL(port);
 354
 355         /*
 356          * Enable the transceiver and wait for it to be ready to send data.
 357          * Clear interrupts so that this process will not be externally
 358          * interrupted in the middle (which can cause the transceiver to
 359          * drain prematurely).
 360          */
 361
 362         local_irq_save(flags);
 363
 364         UART_PUT_CTRL(port, ctrl | UART_CTRL_TE);
 365
 366         while (!UART_TX_READY(UART_GET_STATUS(port)))
 367                 loop++;
 368
 369         /*
 370          * Disable the transceiver so data isn't actually sent during the
 371          * actual test.
 372          */
 373
 374         UART_PUT_CTRL(port, ctrl & ~(UART_CTRL_TE));
 375
 376         fifosize = 1;
 377         UART_PUT_CHAR(port, 0);
 378
 379         /*
 380          * So long as transmitting a character increments the tranceivier FIFO
 381          * length the FIFO must be at least that big. These bytes will
 382          * automatically drain off of the FIFO.
 383          */
 384
 385         status = UART_GET_STATUS(port);
 386         while (((status >> 20) & 0x3F) == fifosize) {
 387                 fifosize++;
 388                 UART_PUT_CHAR(port, 0);
 389                 status = UART_GET_STATUS(port);
 390         }
 391
 392         fifosize--;
 393
 394         UART_PUT_CTRL(port, ctrl);
 395         local_irq_restore(flags);
 396
 397         if (fifosize == 0)
 398                 fifosize = 1;
 399
 400         return fifosize;
 401 }
 402
 403 static void apbuart_flush_fifo(struct uart_port *port)
 404 {
 405         int i;
 406
 407         for (i = 0; i < port->fifosize; i++)
 408                 UART_GET_CHAR(port);
 409 }
 410
 411
 412 /* ======================================================================== */
 413 /* Console driver, if enabled                                               */
 414 /* ======================================================================== */
 415
 416 #ifdef CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE
 417
 418 static void apbuart_console_putchar(struct uart_port *port, int ch)
 419 {
 420         unsigned int status;
 421         do {
 422                 status = UART_GET_STATUS(port);
 423         } while (!UART_TX_READY(status));
 424         UART_PUT_CHAR(port, ch);
 425 }
 426
 427 static void
 428 apbuart_console_write(struct console *co, const char *s, unsigned int count)
 429 {
 430         struct uart_port *port = &grlib_apbuart_ports[co->index];
 431         unsigned int status, old_cr, new_cr;
 432
 433         /* First save the CR then disable the interrupts */
 434         old_cr = UART_GET_CTRL(port);
 435         new_cr = old_cr & ~(UART_CTRL_RI | UART_CTRL_TI);
 436         UART_PUT_CTRL(port, new_cr);
 437
 438         uart_console_write(port, s, count, apbuart_console_putchar);
 439
 440         /*
 441          *      Finally, wait for transmitter to become empty
 442          *      and restore the TCR
 443          */
 444         do {
 445                 status = UART_GET_STATUS(port);
 446         } while (!UART_TX_READY(status));
 447         UART_PUT_CTRL(port, old_cr);
 448 }
 449
 450 static void __init
 451 apbuart_console_get_options(struct uart_port *port, int *baud,
 452                             int *parity, int *bits)
 453 {
 454         if (UART_GET_CTRL(port) & (UART_CTRL_RE | UART_CTRL_TE)) {
 455
 456                 unsigned int quot, status;
 457                 status = UART_GET_STATUS(port);
 458
 459                 *parity = 'n';
 460                 if (status & UART_CTRL_PE) {
 461                         if ((status & UART_CTRL_PS) == 0)
 462                                 *parity = 'e';
 463                         else
 464                                 *parity = 'o';
 465                 }
 466
 467                 *bits = 8;
 468                 quot = UART_GET_SCAL(port) / 8;
 469                 *baud = port->uartclk / (16 * (quot + 1));
 470         }
 471 }
 472
 473 static int __init apbuart_console_setup(struct console *co, char *options)
 474 {
 475         struct uart_port *port;
 476         int baud = 38400;
 477         int bits = 8;
 478         int parity = 'n';
 479         int flow = 'n';
 480
 481         pr_debug("apbuart_console_setup co=%p, co->index=%i, options=%s\n",
 482                  co, co->index, options);
 483
 484         /*
 485          * Check whether an invalid uart number has been specified, and
 486          * if so, search for the first available port that does have
 487          * console support.
 488          */
 489         if (co->index >= grlib_apbuart_port_nr)
 490                 co->index = 0;
 491
 492         port = &grlib_apbuart_ports[co->index];
 493
 494         spin_lock_init(&port->lock);
 495
 496         if (options)
 497                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 498         else
 499                 apbuart_console_get_options(port, &baud, &parity, &bits);
 500
 501         return uart_set_options(port, co, baud, parity, bits, flow);
 502 }
 503
 504 static struct uart_driver grlib_apbuart_driver;
 505
 506 static struct console grlib_apbuart_console = {
 507         .name = "ttyS",
 508         .write = apbuart_console_write,
 509         .device = uart_console_device,
 510         .setup = apbuart_console_setup,
 511         .flags = CON_PRINTBUFFER,
 512         .index = -1,
 513         .data = &grlib_apbuart_driver,
 514 };
 515
 516
 517 static int grlib_apbuart_configure(void);
 518
 519 static int __init apbuart_console_init(void)
 520 {
 521         if (grlib_apbuart_configure())
 522                 return -ENODEV;
 523         register_console(&grlib_apbuart_console);
 524         return 0;
 525 }
 526
 527 console_initcall(apbuart_console_init);
 528
 529 #define APBUART_CONSOLE (&grlib_apbuart_console)
 530 #else
 531 #define APBUART_CONSOLE NULL
 532 #endif
 533
 534 static struct uart_driver grlib_apbuart_driver = {
 535         .owner = THIS_MODULE,
 536         .driver_name = "serial",
 537         .dev_name = "ttyS",
 538         .major = SERIAL_APBUART_MAJOR,
 539         .minor = SERIAL_APBUART_MINOR,
 540         .nr = UART_NR,
 541         .cons = APBUART_CONSOLE,
 542 };
 543
 544
 545 /* ======================================================================== */
 546 /* OF Platform Driver                                                       */
 547 /* ======================================================================== */
 548
 549 static int apbuart_probe(struct platform_device *op)
 550 {
 551         int i;
 552         struct uart_port *port = NULL;
 553
 554         for (i = 0; i < grlib_apbuart_port_nr; i++) {
 555                 if (op->dev.of_node == grlib_apbuart_nodes[i])
 556                         break;
 557         }
 558
 559         port = &grlib_apbuart_ports[i];
 560         port->dev = &op->dev;
 561         port->irq = op->archdata.irqs[0];
 562
 563         uart_add_one_port(&grlib_apbuart_driver, (struct uart_port *) port);
 564
 565         apbuart_flush_fifo((struct uart_port *) port);
 566
 567         printk(KERN_INFO "grlib-apbuart at 0x%llx, irq %d\n",
 568                (unsigned long long) port->mapbase, port->irq);
 569         return 0;
 570 }
 571
 572 static const struct of_device_id apbuart_match[] = {
 573         {
 574          .name = "GAISLER_APBUART",
 575          },
 576         {
 577          .name = "01_00c",
 578          },
 579         {},
 580 };
 581 MODULE_DEVICE_TABLE(of, apbuart_match);
 582
 583 static struct platform_driver grlib_apbuart_of_driver = {
 584         .probe = apbuart_probe,
 585         .driver = {
 586                 .name = "grlib-apbuart",
 587                 .of_match_table = apbuart_match,
 588         },
 589 };
 590
 591
 592 static int __init grlib_apbuart_configure(void)
 593 {
 594         struct device_node *np;
 595         int line = 0;
 596
 597         for_each_matching_node(np, apbuart_match) {
 598                 const int *ampopts;
 599                 const u32 *freq_hz;
 600                 const struct amba_prom_registers *regs;
 601                 struct uart_port *port;
 602                 unsigned long addr;
 603
 604                 ampopts = of_get_property(np, "ampopts", NULL);
 605                 if (ampopts && (*ampopts == 0))
 606                         continue; /* Ignore if used by another OS instance */
 607                 regs = of_get_property(np, "reg", NULL);
 608                 /* Frequency of APB Bus is frequency of UART */
 609                 freq_hz = of_get_property(np, "freq", NULL);
 610
 611                 if (!regs || !freq_hz || (*freq_hz == 0))
 612                         continue;
 613
 614                 grlib_apbuart_nodes[line] = np;
 615
 616                 addr = regs->phys_addr;
 617
 618                 port = &grlib_apbuart_ports[line];
 619
 620                 port->mapbase = addr;
 621                 port->membase = ioremap(addr, sizeof(struct grlib_apbuart_regs_map));
 622                 port->irq = 0;
 623                 port->iotype = UPIO_MEM;
 624                 port->ops = &grlib_apbuart_ops;
 625                 port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE);
 626                 port->flags = UPF_BOOT_AUTOCONF;
 627                 port->line = line;
 628                 port->uartclk = *freq_hz;
 629                 port->fifosize = apbuart_scan_fifo_size((struct uart_port *) port, line);
 630                 line++;
 631
 632                 /* We support maximum UART_NR uarts ... */
 633                 if (line == UART_NR)
 634                         break;
 635         }
 636
 637         grlib_apbuart_driver.nr = grlib_apbuart_port_nr = line;
 638         return line ? 0 : -ENODEV;
 639 }
 640
 641 static int __init grlib_apbuart_init(void)
 642 {
 643         int ret;
 644
 645         /* Find all APBUARTS in device the tree and initialize their ports */
 646         ret = grlib_apbuart_configure();
 647         if (ret)
 648                 return ret;
 649
 650         printk(KERN_INFO "Serial: GRLIB APBUART driver\n");
 651
 652         ret = uart_register_driver(&grlib_apbuart_driver);
 653
 654         if (ret) {
 655                 printk(KERN_ERR "%s: uart_register_driver failed (%i)\n",
 656                        __FILE__, ret);
 657                 return ret;
 658         }
 659
 660         ret = platform_driver_register(&grlib_apbuart_of_driver);
 661         if (ret) {
 662                 printk(KERN_ERR
 663                        "%s: platform_driver_register failed (%i)\n",
 664                        __FILE__, ret);
 665                 uart_unregister_driver(&grlib_apbuart_driver);
 666                 return ret;
 667         }
 668
 669         return ret;
 670 }
 671
 672 static void __exit grlib_apbuart_exit(void)
 673 {
 674         int i;
 675
 676         for (i = 0; i < grlib_apbuart_port_nr; i++)
 677                 uart_remove_one_port(&grlib_apbuart_driver,
 678                                      &grlib_apbuart_ports[i]);
 679
 680         uart_unregister_driver(&grlib_apbuart_driver);
 681         platform_driver_unregister(&grlib_apbuart_of_driver);
 682 }
 683
 684 module_init(grlib_apbuart_init);
 685 module_exit(grlib_apbuart_exit);
 686
 687 MODULE_AUTHOR("Aeroflex Gaisler AB");
 688 MODULE_DESCRIPTION("GRLIB APBUART serial driver");
 689 MODULE_VERSION("2.1");
 690 MODULE_LICENSE("GPL");