drivers/tty/serial/zs.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * zs.c: Serial port driver for IOASIC DECstations.
   4  *
   5  * Derived from drivers/sbus/char/sunserial.c by Paul Mackerras.
   6  * Derived from drivers/macintosh/macserial.c by Harald Koerfgen.
   7  *
   8  * DECstation changes
   9  * Copyright (C) 1998-2000 Harald Koerfgen
  10  * Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2007  Maciej W. Rozycki
  11  *
  12  * For the rest of the code the original Copyright applies:
  13  * Copyright (C) 1996 Paul Mackerras (Paul.Mackerras@cs.anu.edu.au)
  14  * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
  15  *
  16  *
  17  * Note: for IOASIC systems the wiring is as follows:
  18  *
  19  * mouse/keyboard:
  20  * DIN-7 MJ-4  signal        SCC
  21  * 2     1     TxD       <-  A.TxD
  22  * 3     4     RxD       ->  A.RxD
  23  *
  24  * EIA-232/EIA-423:
  25  * DB-25 MMJ-6 signal        SCC
  26  * 2     2     TxD       <-  B.TxD
  27  * 3     5     RxD       ->  B.RxD
  28  * 4           RTS       <- ~A.RTS
  29  * 5           CTS       -> ~B.CTS
  30  * 6     6     DSR       -> ~A.SYNC
  31  * 8           CD        -> ~B.DCD
  32  * 12          DSRS(DCE) -> ~A.CTS  (*)
  33  * 15          TxC       ->  B.TxC
  34  * 17          RxC       ->  B.RxC
  35  * 20    1     DTR       <- ~A.DTR
  36  * 22          RI        -> ~A.DCD
  37  * 23          DSRS(DTE) <- ~B.RTS
  38  *
  39  * (*) EIA-232 defines the signal at this pin to be SCD, while DSRS(DCE)
  40  *     is shared with DSRS(DTE) at pin 23.
  41  *
  42  * As you can immediately notice the wiring of the RTS, DTR and DSR signals
  43  * is a bit odd.  This makes the handling of port B unnecessarily
  44  * complicated and prevents the use of some automatic modes of operation.
  45  */
  46
  47 #include <linux/bug.h>
  48 #include <linux/console.h>
  49 #include <linux/delay.h>
  50 #include <linux/errno.h>
  51 #include <linux/init.h>
  52 #include <linux/interrupt.h>
  53 #include <linux/io.h>
  54 #include <linux/ioport.h>
  55 #include <linux/irqflags.h>
  56 #include <linux/kernel.h>
  57 #include <linux/module.h>
  58 #include <linux/major.h>
  59 #include <linux/serial.h>
  60 #include <linux/serial_core.h>
  61 #include <linux/spinlock.h>
  62 #include <linux/sysrq.h>
  63 #include <linux/tty.h>
  64 #include <linux/tty_flip.h>
  65 #include <linux/types.h>
  66
  67 #include <linux/atomic.h>
  68
  69 #include <asm/dec/interrupts.h>
  70 #include <asm/dec/ioasic_addrs.h>
  71 #include <asm/dec/system.h>
  72
  73 #include "zs.h"
  74
  75
  76 MODULE_AUTHOR("Maciej W. Rozycki <macro@linux-mips.org>");
  77 MODULE_DESCRIPTION("DECstation Z85C30 serial driver");
  78 MODULE_LICENSE("GPL");
  79
  80
  81 static char zs_name[] __initdata = "DECstation Z85C30 serial driver version ";
  82 static char zs_version[] __initdata = "0.10";
  83
  84 /*
  85  * It would be nice to dynamically allocate everything that
  86  * depends on ZS_NUM_SCCS, so we could support any number of
  87  * Z85C30s, but for now...
  88  */
  89 #define ZS_NUM_SCCS     2               /* Max # of ZS chips supported.  */
  90 #define ZS_NUM_CHAN     2               /* 2 channels per chip.  */
  91 #define ZS_CHAN_A       0               /* Index of the channel A.  */
  92 #define ZS_CHAN_B       1               /* Index of the channel B.  */
  93 #define ZS_CHAN_IO_SIZE 8               /* IOMEM space size.  */
  94 #define ZS_CHAN_IO_STRIDE 4             /* Register alignment.  */
  95 #define ZS_CHAN_IO_OFFSET 1             /* The SCC resides on the high byte
  96                                            of the 16-bit IOBUS.  */
  97 #define ZS_CLOCK        7372800         /* Z85C30 PCLK input clock rate.  */
  98
  99 #define to_zport(uport) container_of(uport, struct zs_port, port)
 100
 101 struct zs_parms {
 102         resource_size_t scc[ZS_NUM_SCCS];
 103         int irq[ZS_NUM_SCCS];
 104 };
 105
 106 static struct zs_scc zs_sccs[ZS_NUM_SCCS];
 107
 108 static u8 zs_init_regs[ZS_NUM_REGS] __initdata = {
 109         0,                              /* write 0 */
 110         PAR_SPEC,                       /* write 1 */
 111         0,                              /* write 2 */
 112         0,                              /* write 3 */
 113         X16CLK | SB1,                   /* write 4 */
 114         0,                              /* write 5 */
 115         0, 0, 0,                        /* write 6, 7, 8 */
 116         MIE | DLC | NV,                 /* write 9 */
 117         NRZ,                            /* write 10 */
 118         TCBR | RCBR,                    /* write 11 */
 119         0, 0,                           /* BRG time constant, write 12 + 13 */
 120         BRSRC | BRENABL,                /* write 14 */
 121         0,                              /* write 15 */
 122 };
 123
 124 /*
 125  * Debugging.
 126  */
 127 #undef ZS_DEBUG_REGS
 128
 129
 130 /*
 131  * Reading and writing Z85C30 registers.
 132  */
 133 static void recovery_delay(void)
 134 {
 135         udelay(2);
 136 }
 137
 138 static u8 read_zsreg(struct zs_port *zport, int reg)
 139 {
 140         void __iomem *control = zport->port.membase + ZS_CHAN_IO_OFFSET;
 141         u8 retval;
 142
 143         if (reg != 0) {
 144                 writeb(reg & 0xf, control);
 145                 fast_iob();
 146                 recovery_delay();
 147         }
 148         retval = readb(control);
 149         recovery_delay();
 150         return retval;
 151 }
 152
 153 static void write_zsreg(struct zs_port *zport, int reg, u8 value)
 154 {
 155         void __iomem *control = zport->port.membase + ZS_CHAN_IO_OFFSET;
 156
 157         if (reg != 0) {
 158                 writeb(reg & 0xf, control);
 159                 fast_iob(); recovery_delay();
 160         }
 161         writeb(value, control);
 162         fast_iob();
 163         recovery_delay();
 164         return;
 165 }
 166
 167 static u8 read_zsdata(struct zs_port *zport)
 168 {
 169         void __iomem *data = zport->port.membase +
 170                              ZS_CHAN_IO_STRIDE + ZS_CHAN_IO_OFFSET;
 171         u8 retval;
 172
 173         retval = readb(data);
 174         recovery_delay();
 175         return retval;
 176 }
 177
 178 static void write_zsdata(struct zs_port *zport, u8 value)
 179 {
 180         void __iomem *data = zport->port.membase +
 181                              ZS_CHAN_IO_STRIDE + ZS_CHAN_IO_OFFSET;
 182
 183         writeb(value, data);
 184         fast_iob();
 185         recovery_delay();
 186         return;
 187 }
 188
 189 #ifdef ZS_DEBUG_REGS
 190 void zs_dump(void)
 191 {
 192         struct zs_port *zport;
 193         int i, j;
 194
 195         for (i = 0; i < ZS_NUM_SCCS * ZS_NUM_CHAN; i++) {
 196                 zport = &zs_sccs[i / ZS_NUM_CHAN].zport[i % ZS_NUM_CHAN];
 197
 198                 if (!zport->scc)
 199                         continue;
 200
 201                 for (j = 0; j < 16; j++)
 202                         printk("W%-2d = 0x%02x\t", j, zport->regs[j]);
 203                 printk("\n");
 204                 for (j = 0; j < 16; j++)
 205                         printk("R%-2d = 0x%02x\t", j, read_zsreg(zport, j));
 206                 printk("\n\n");
 207         }
 208 }
 209 #endif
 210
 211
 212 static void zs_spin_lock_cond_irq(spinlock_t *lock, int irq)
 213 {
 214         if (irq)
 215                 spin_lock_irq(lock);
 216         else
 217                 spin_lock(lock);
 218 }
 219
 220 static void zs_spin_unlock_cond_irq(spinlock_t *lock, int irq)
 221 {
 222         if (irq)
 223                 spin_unlock_irq(lock);
 224         else
 225                 spin_unlock(lock);
 226 }
 227
 228 static int zs_receive_drain(struct zs_port *zport)
 229 {
 230         int loops = 10000;
 231
 232         while ((read_zsreg(zport, R0) & Rx_CH_AV) && --loops)
 233                 read_zsdata(zport);
 234         return loops;
 235 }
 236
 237 static int zs_transmit_drain(struct zs_port *zport, int irq)
 238 {
 239         struct zs_scc *scc = zport->scc;
 240         int loops = 10000;
 241
 242         while (!(read_zsreg(zport, R0) & Tx_BUF_EMP) && --loops) {
 243                 zs_spin_unlock_cond_irq(&scc->zlock, irq);
 244                 udelay(2);
 245                 zs_spin_lock_cond_irq(&scc->zlock, irq);
 246         }
 247         return loops;
 248 }
 249
 250 static int zs_line_drain(struct zs_port *zport, int irq)
 251 {
 252         struct zs_scc *scc = zport->scc;
 253         int loops = 10000;
 254
 255         while (!(read_zsreg(zport, R1) & ALL_SNT) && --loops) {
 256                 zs_spin_unlock_cond_irq(&scc->zlock, irq);
 257                 udelay(2);
 258                 zs_spin_lock_cond_irq(&scc->zlock, irq);
 259         }
 260         return loops;
 261 }
 262
 263
 264 static void load_zsregs(struct zs_port *zport, u8 *regs, int irq)
 265 {
 266         /* Let the current transmission finish.  */
 267         zs_line_drain(zport, irq);
 268         /* Load 'em up.  */
 269         write_zsreg(zport, R3, regs[3] & ~RxENABLE);
 270         write_zsreg(zport, R5, regs[5] & ~TxENAB);
 271         write_zsreg(zport, R4, regs[4]);
 272         write_zsreg(zport, R9, regs[9]);
 273         write_zsreg(zport, R1, regs[1]);
 274         write_zsreg(zport, R2, regs[2]);
 275         write_zsreg(zport, R10, regs[10]);
 276         write_zsreg(zport, R14, regs[14] & ~BRENABL);
 277         write_zsreg(zport, R11, regs[11]);
 278         write_zsreg(zport, R12, regs[12]);
 279         write_zsreg(zport, R13, regs[13]);
 280         write_zsreg(zport, R14, regs[14]);
 281         write_zsreg(zport, R15, regs[15]);
 282         if (regs[3] & RxENABLE)
 283                 write_zsreg(zport, R3, regs[3]);
 284         if (regs[5] & TxENAB)
 285                 write_zsreg(zport, R5, regs[5]);
 286         return;
 287 }
 288
 289
 290 /*
 291  * Status handling routines.
 292  */
 293
 294 /*
 295  * zs_tx_empty() -- get the transmitter empty status
 296  *
 297  * Purpose: Let user call ioctl() to get info when the UART physically
 298  *          is emptied.  On bus types like RS485, the transmitter must
 299  *          release the bus after transmitting.  This must be done when
 300  *          the transmit shift register is empty, not be done when the
 301  *          transmit holding register is empty.  This functionality
 302  *          allows an RS485 driver to be written in user space.
 303  */
 304 static unsigned int zs_tx_empty(struct uart_port *uport)
 305 {
 306         struct zs_port *zport = to_zport(uport);
 307         struct zs_scc *scc = zport->scc;
 308         unsigned long flags;
 309         u8 status;
 310
 311         spin_lock_irqsave(&scc->zlock, flags);
 312         status = read_zsreg(zport, R1);
 313         spin_unlock_irqrestore(&scc->zlock, flags);
 314
 315         return status & ALL_SNT ? TIOCSER_TEMT : 0;
 316 }
 317
 318 static unsigned int zs_raw_get_ab_mctrl(struct zs_port *zport_a,
 319                                         struct zs_port *zport_b)
 320 {
 321         u8 status_a, status_b;
 322         unsigned int mctrl;
 323
 324         status_a = read_zsreg(zport_a, R0);
 325         status_b = read_zsreg(zport_b, R0);
 326
 327         mctrl = ((status_b & CTS) ? TIOCM_CTS : 0) |
 328                 ((status_b & DCD) ? TIOCM_CAR : 0) |
 329                 ((status_a & DCD) ? TIOCM_RNG : 0) |
 330                 ((status_a & SYNC_HUNT) ? TIOCM_DSR : 0);
 331
 332         return mctrl;
 333 }
 334
 335 static unsigned int zs_raw_get_mctrl(struct zs_port *zport)
 336 {
 337         struct zs_port *zport_a = &zport->scc->zport[ZS_CHAN_A];
 338
 339         return zport != zport_a ? zs_raw_get_ab_mctrl(zport_a, zport) : 0;
 340 }
 341
 342 static unsigned int zs_raw_xor_mctrl(struct zs_port *zport)
 343 {
 344         struct zs_port *zport_a = &zport->scc->zport[ZS_CHAN_A];
 345         unsigned int mmask, mctrl, delta;
 346         u8 mask_a, mask_b;
 347
 348         if (zport == zport_a)
 349                 return 0;
 350
 351         mask_a = zport_a->regs[15];
 352         mask_b = zport->regs[15];
 353
 354         mmask = ((mask_b & CTSIE) ? TIOCM_CTS : 0) |
 355                 ((mask_b & DCDIE) ? TIOCM_CAR : 0) |
 356                 ((mask_a & DCDIE) ? TIOCM_RNG : 0) |
 357                 ((mask_a & SYNCIE) ? TIOCM_DSR : 0);
 358
 359         mctrl = zport->mctrl;
 360         if (mmask) {
 361                 mctrl &= ~mmask;
 362                 mctrl |= zs_raw_get_ab_mctrl(zport_a, zport) & mmask;
 363         }
 364
 365         delta = mctrl ^ zport->mctrl;
 366         if (delta)
 367                 zport->mctrl = mctrl;
 368
 369         return delta;
 370 }
 371
 372 static unsigned int zs_get_mctrl(struct uart_port *uport)
 373 {
 374         struct zs_port *zport = to_zport(uport);
 375         struct zs_scc *scc = zport->scc;
 376         unsigned int mctrl;
 377
 378         spin_lock(&scc->zlock);
 379         mctrl = zs_raw_get_mctrl(zport);
 380         spin_unlock(&scc->zlock);
 381
 382         return mctrl;
 383 }
 384
 385 static void zs_set_mctrl(struct uart_port *uport, unsigned int mctrl)
 386 {
 387         struct zs_port *zport = to_zport(uport);
 388         struct zs_scc *scc = zport->scc;
 389         struct zs_port *zport_a = &scc->zport[ZS_CHAN_A];
 390         u8 oldloop, newloop;
 391
 392         spin_lock(&scc->zlock);
 393         if (zport != zport_a) {
 394                 if (mctrl & TIOCM_DTR)
 395                         zport_a->regs[5] |= DTR;
 396                 else
 397                         zport_a->regs[5] &= ~DTR;
 398                 if (mctrl & TIOCM_RTS)
 399                         zport_a->regs[5] |= RTS;
 400                 else
 401                         zport_a->regs[5] &= ~RTS;
 402                 write_zsreg(zport_a, R5, zport_a->regs[5]);
 403         }
 404
 405         /* Rarely modified, so don't poke at hardware unless necessary. */
 406         oldloop = zport->regs[14];
 407         newloop = oldloop;
 408         if (mctrl & TIOCM_LOOP)
 409                 newloop |= LOOPBAK;
 410         else
 411                 newloop &= ~LOOPBAK;
 412         if (newloop != oldloop) {
 413                 zport->regs[14] = newloop;
 414                 write_zsreg(zport, R14, zport->regs[14]);
 415         }
 416         spin_unlock(&scc->zlock);
 417 }
 418
 419 static void zs_raw_stop_tx(struct zs_port *zport)
 420 {
 421         write_zsreg(zport, R0, RES_Tx_P);
 422         zport->tx_stopped = 1;
 423 }
 424
 425 static void zs_stop_tx(struct uart_port *uport)
 426 {
 427         struct zs_port *zport = to_zport(uport);
 428         struct zs_scc *scc = zport->scc;
 429
 430         spin_lock(&scc->zlock);
 431         zs_raw_stop_tx(zport);
 432         spin_unlock(&scc->zlock);
 433 }
 434
 435 static void zs_raw_transmit_chars(struct zs_port *);
 436
 437 static void zs_start_tx(struct uart_port *uport)
 438 {
 439         struct zs_port *zport = to_zport(uport);
 440         struct zs_scc *scc = zport->scc;
 441
 442         spin_lock(&scc->zlock);
 443         if (zport->tx_stopped) {
 444                 zs_transmit_drain(zport, 0);
 445                 zport->tx_stopped = 0;
 446                 zs_raw_transmit_chars(zport);
 447         }
 448         spin_unlock(&scc->zlock);
 449 }
 450
 451 static void zs_stop_rx(struct uart_port *uport)
 452 {
 453         struct zs_port *zport = to_zport(uport);
 454         struct zs_scc *scc = zport->scc;
 455         struct zs_port *zport_a = &scc->zport[ZS_CHAN_A];
 456
 457         spin_lock(&scc->zlock);
 458         zport->regs[15] &= ~BRKIE;
 459         zport->regs[1] &= ~(RxINT_MASK | TxINT_ENAB);
 460         zport->regs[1] |= RxINT_DISAB;
 461
 462         if (zport != zport_a) {
 463                 /* A-side DCD tracks RI and SYNC tracks DSR.  */
 464                 zport_a->regs[15] &= ~(DCDIE | SYNCIE);
 465                 write_zsreg(zport_a, R15, zport_a->regs[15]);
 466                 if (!(zport_a->regs[15] & BRKIE)) {
 467                         zport_a->regs[1] &= ~EXT_INT_ENAB;
 468                         write_zsreg(zport_a, R1, zport_a->regs[1]);
 469                 }
 470
 471                 /* This-side DCD tracks DCD and CTS tracks CTS.  */
 472                 zport->regs[15] &= ~(DCDIE | CTSIE);
 473                 zport->regs[1] &= ~EXT_INT_ENAB;
 474         } else {
 475                 /* DCD tracks RI and SYNC tracks DSR for the B side.  */
 476                 if (!(zport->regs[15] & (DCDIE | SYNCIE)))
 477                         zport->regs[1] &= ~EXT_INT_ENAB;
 478         }
 479
 480         write_zsreg(zport, R15, zport->regs[15]);
 481         write_zsreg(zport, R1, zport->regs[1]);
 482         spin_unlock(&scc->zlock);
 483 }
 484
 485 static void zs_enable_ms(struct uart_port *uport)
 486 {
 487         struct zs_port *zport = to_zport(uport);
 488         struct zs_scc *scc = zport->scc;
 489         struct zs_port *zport_a = &scc->zport[ZS_CHAN_A];
 490
 491         if (zport == zport_a)
 492                 return;
 493
 494         spin_lock(&scc->zlock);
 495
 496         /* Clear Ext interrupts if not being handled already.  */
 497         if (!(zport_a->regs[1] & EXT_INT_ENAB))
 498                 write_zsreg(zport_a, R0, RES_EXT_INT);
 499
 500         /* A-side DCD tracks RI and SYNC tracks DSR.  */
 501         zport_a->regs[1] |= EXT_INT_ENAB;
 502         zport_a->regs[15] |= DCDIE | SYNCIE;
 503
 504         /* This-side DCD tracks DCD and CTS tracks CTS.  */
 505         zport->regs[15] |= DCDIE | CTSIE;
 506
 507         zs_raw_xor_mctrl(zport);
 508
 509         write_zsreg(zport_a, R1, zport_a->regs[1]);
 510         write_zsreg(zport_a, R15, zport_a->regs[15]);
 511         write_zsreg(zport, R15, zport->regs[15]);
 512         spin_unlock(&scc->zlock);
 513 }
 514
 515 static void zs_break_ctl(struct uart_port *uport, int break_state)
 516 {
 517         struct zs_port *zport = to_zport(uport);
 518         struct zs_scc *scc = zport->scc;
 519         unsigned long flags;
 520
 521         spin_lock_irqsave(&scc->zlock, flags);
 522         if (break_state == -1)
 523                 zport->regs[5] |= SND_BRK;
 524         else
 525                 zport->regs[5] &= ~SND_BRK;
 526         write_zsreg(zport, R5, zport->regs[5]);
 527         spin_unlock_irqrestore(&scc->zlock, flags);
 528 }
 529
 530
 531 /*
 532  * Interrupt handling routines.
 533  */
 534 #define Rx_BRK 0x0100                   /* BREAK event software flag.  */
 535 #define Rx_SYS 0x0200                   /* SysRq event software flag.  */
 536
 537 static void zs_receive_chars(struct zs_port *zport)
 538 {
 539         struct uart_port *uport = &zport->port;
 540         struct zs_scc *scc = zport->scc;
 541         struct uart_icount *icount;
 542         unsigned int avail, status, ch, flag;
 543         int count;
 544
 545         for (count = 16; count; count--) {
 546                 spin_lock(&scc->zlock);
 547                 avail = read_zsreg(zport, R0) & Rx_CH_AV;
 548                 spin_unlock(&scc->zlock);
 549                 if (!avail)
 550                         break;
 551
 552                 spin_lock(&scc->zlock);
 553                 status = read_zsreg(zport, R1) & (Rx_OVR | FRM_ERR | PAR_ERR);
 554                 ch = read_zsdata(zport);
 555                 spin_unlock(&scc->zlock);
 556
 557                 flag = TTY_NORMAL;
 558
 559                 icount = &uport->icount;
 560                 icount->rx++;
 561
 562                 /* Handle the null char got when BREAK is removed.  */
 563                 if (!ch)
 564                         status |= zport->tty_break;
 565                 if (unlikely(status &
 566                              (Rx_OVR | FRM_ERR | PAR_ERR | Rx_SYS | Rx_BRK))) {
 567                         zport->tty_break = 0;
 568
 569                         /* Reset the error indication.  */
 570                         if (status & (Rx_OVR | FRM_ERR | PAR_ERR)) {
 571                                 spin_lock(&scc->zlock);
 572                                 write_zsreg(zport, R0, ERR_RES);
 573                                 spin_unlock(&scc->zlock);
 574                         }
 575
 576                         if (status & (Rx_SYS | Rx_BRK)) {
 577                                 icount->brk++;
 578                                 /* SysRq discards the null char.  */
 579                                 if (status & Rx_SYS)
 580                                         continue;
 581                         } else if (status & FRM_ERR)
 582                                 icount->frame++;
 583                         else if (status & PAR_ERR)
 584                                 icount->parity++;
 585                         if (status & Rx_OVR)
 586                                 icount->overrun++;
 587
 588                         status &= uport->read_status_mask;
 589                         if (status & Rx_BRK)
 590                                 flag = TTY_BREAK;
 591                         else if (status & FRM_ERR)
 592                                 flag = TTY_FRAME;
 593                         else if (status & PAR_ERR)
 594                                 flag = TTY_PARITY;
 595                 }
 596
 597                 if (uart_handle_sysrq_char(uport, ch))
 598                         continue;
 599
 600                 uart_insert_char(uport, status, Rx_OVR, ch, flag);
 601         }
 602
 603         tty_flip_buffer_push(&uport->state->port);
 604 }
 605
 606 static void zs_raw_transmit_chars(struct zs_port *zport)
 607 {
 608         struct circ_buf *xmit = &zport->port.state->xmit;
 609
 610         /* XON/XOFF chars.  */
 611         if (zport->port.x_char) {
 612                 write_zsdata(zport, zport->port.x_char);
 613                 zport->port.icount.tx++;
 614                 zport->port.x_char = 0;
 615                 return;
 616         }
 617
 618         /* If nothing to do or stopped or hardware stopped.  */
 619         if (uart_circ_empty(xmit) || uart_tx_stopped(&zport->port)) {
 620                 zs_raw_stop_tx(zport);
 621                 return;
 622         }
 623
 624         /* Send char.  */
 625         write_zsdata(zport, xmit->buf[xmit->tail]);
 626         xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 627         zport->port.icount.tx++;
 628
 629         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 630                 uart_write_wakeup(&zport->port);
 631
 632         /* Are we are done?  */
 633         if (uart_circ_empty(xmit))
 634                 zs_raw_stop_tx(zport);
 635 }
 636
 637 static void zs_transmit_chars(struct zs_port *zport)
 638 {
 639         struct zs_scc *scc = zport->scc;
 640
 641         spin_lock(&scc->zlock);
 642         zs_raw_transmit_chars(zport);
 643         spin_unlock(&scc->zlock);
 644 }
 645
 646 static void zs_status_handle(struct zs_port *zport, struct zs_port *zport_a)
 647 {
 648         struct uart_port *uport = &zport->port;
 649         struct zs_scc *scc = zport->scc;
 650         unsigned int delta;
 651         u8 status, brk;
 652
 653         spin_lock(&scc->zlock);
 654
 655         /* Get status from Read Register 0.  */
 656         status = read_zsreg(zport, R0);
 657
 658         if (zport->regs[15] & BRKIE) {
 659                 brk = status & BRK_ABRT;
 660                 if (brk && !zport->brk) {
 661                         spin_unlock(&scc->zlock);
 662                         if (uart_handle_break(uport))
 663                                 zport->tty_break = Rx_SYS;
 664                         else
 665                                 zport->tty_break = Rx_BRK;
 666                         spin_lock(&scc->zlock);
 667                 }
 668                 zport->brk = brk;
 669         }
 670
 671         if (zport != zport_a) {
 672                 delta = zs_raw_xor_mctrl(zport);
 673                 spin_unlock(&scc->zlock);
 674
 675                 if (delta & TIOCM_CTS)
 676                         uart_handle_cts_change(uport,
 677                                                zport->mctrl & TIOCM_CTS);
 678                 if (delta & TIOCM_CAR)
 679                         uart_handle_dcd_change(uport,
 680                                                zport->mctrl & TIOCM_CAR);
 681                 if (delta & TIOCM_RNG)
 682                         uport->icount.dsr++;
 683                 if (delta & TIOCM_DSR)
 684                         uport->icount.rng++;
 685
 686                 if (delta)
 687                         wake_up_interruptible(&uport->state->port.delta_msr_wait);
 688
 689                 spin_lock(&scc->zlock);
 690         }
 691
 692         /* Clear the status condition...  */
 693         write_zsreg(zport, R0, RES_EXT_INT);
 694
 695         spin_unlock(&scc->zlock);
 696 }
 697
 698 /*
 699  * This is the Z85C30 driver's generic interrupt routine.
 700  */
 701 static irqreturn_t zs_interrupt(int irq, void *dev_id)
 702 {
 703         struct zs_scc *scc = dev_id;
 704         struct zs_port *zport_a = &scc->zport[ZS_CHAN_A];
 705         struct zs_port *zport_b = &scc->zport[ZS_CHAN_B];
 706         irqreturn_t status = IRQ_NONE;
 707         u8 zs_intreg;
 708         int count;
 709
 710         /*
 711          * NOTE: The read register 3, which holds the irq status,
 712          *       does so for both channels on each chip.  Although
 713          *       the status value itself must be read from the A
 714          *       channel and is only valid when read from channel A.
 715          *       Yes... broken hardware...
 716          */
 717         for (count = 16; count; count--) {
 718                 spin_lock(&scc->zlock);
 719                 zs_intreg = read_zsreg(zport_a, R3);
 720                 spin_unlock(&scc->zlock);
 721                 if (!zs_intreg)
 722                         break;
 723
 724                 /*
 725                  * We do not like losing characters, so we prioritise
 726                  * interrupt sources a little bit differently than
 727                  * the SCC would, was it allowed to.
 728                  */
 729                 if (zs_intreg & CHBRxIP)
 730                         zs_receive_chars(zport_b);
 731                 if (zs_intreg & CHARxIP)
 732                         zs_receive_chars(zport_a);
 733                 if (zs_intreg & CHBEXT)
 734                         zs_status_handle(zport_b, zport_a);
 735                 if (zs_intreg & CHAEXT)
 736                         zs_status_handle(zport_a, zport_a);
 737                 if (zs_intreg & CHBTxIP)
 738                         zs_transmit_chars(zport_b);
 739                 if (zs_intreg & CHATxIP)
 740                         zs_transmit_chars(zport_a);
 741
 742                 status = IRQ_HANDLED;
 743         }
 744
 745         return status;
 746 }
 747
 748
 749 /*
 750  * Finally, routines used to initialize the serial port.
 751  */
 752 static int zs_startup(struct uart_port *uport)
 753 {
 754         struct zs_port *zport = to_zport(uport);
 755         struct zs_scc *scc = zport->scc;
 756         unsigned long flags;
 757         int irq_guard;
 758         int ret;
 759
 760         irq_guard = atomic_add_return(1, &scc->irq_guard);
 761         if (irq_guard == 1) {
 762                 ret = request_irq(zport->port.irq, zs_interrupt,
 763                                   IRQF_SHARED, "scc", scc);
 764                 if (ret) {
 765                         atomic_add(-1, &scc->irq_guard);
 766                         printk(KERN_ERR "zs: can't get irq %d\n",
 767                                zport->port.irq);
 768                         return ret;
 769                 }
 770         }
 771
 772         spin_lock_irqsave(&scc->zlock, flags);
 773
 774         /* Clear the receive FIFO.  */
 775         zs_receive_drain(zport);
 776
 777         /* Clear the interrupt registers.  */
 778         write_zsreg(zport, R0, ERR_RES);
 779         write_zsreg(zport, R0, RES_Tx_P);
 780         /* But Ext only if not being handled already.  */
 781         if (!(zport->regs[1] & EXT_INT_ENAB))
 782                 write_zsreg(zport, R0, RES_EXT_INT);
 783
 784         /* Finally, enable sequencing and interrupts.  */
 785         zport->regs[1] &= ~RxINT_MASK;
 786         zport->regs[1] |= RxINT_ALL | TxINT_ENAB | EXT_INT_ENAB;
 787         zport->regs[3] |= RxENABLE;
 788         zport->regs[15] |= BRKIE;
 789         write_zsreg(zport, R1, zport->regs[1]);
 790         write_zsreg(zport, R3, zport->regs[3]);
 791         write_zsreg(zport, R5, zport->regs[5]);
 792         write_zsreg(zport, R15, zport->regs[15]);
 793
 794         /* Record the current state of RR0.  */
 795         zport->mctrl = zs_raw_get_mctrl(zport);
 796         zport->brk = read_zsreg(zport, R0) & BRK_ABRT;
 797
 798         zport->tx_stopped = 1;
 799
 800         spin_unlock_irqrestore(&scc->zlock, flags);
 801
 802         return 0;
 803 }
 804
 805 static void zs_shutdown(struct uart_port *uport)
 806 {
 807         struct zs_port *zport = to_zport(uport);
 808         struct zs_scc *scc = zport->scc;
 809         unsigned long flags;
 810         int irq_guard;
 811
 812         spin_lock_irqsave(&scc->zlock, flags);
 813
 814         zport->regs[3] &= ~RxENABLE;
 815         write_zsreg(zport, R5, zport->regs[5]);
 816         write_zsreg(zport, R3, zport->regs[3]);
 817
 818         spin_unlock_irqrestore(&scc->zlock, flags);
 819
 820         irq_guard = atomic_add_return(-1, &scc->irq_guard);
 821         if (!irq_guard)
 822                 free_irq(zport->port.irq, scc);
 823 }
 824
 825
 826 static void zs_reset(struct zs_port *zport)
 827 {
 828         struct zs_scc *scc = zport->scc;
 829         int irq;
 830         unsigned long flags;
 831
 832         spin_lock_irqsave(&scc->zlock, flags);
 833         irq = !irqs_disabled_flags(flags);
 834         if (!scc->initialised) {
 835                 /* Reset the pointer first, just in case...  */
 836                 read_zsreg(zport, R0);
 837                 /* And let the current transmission finish.  */
 838                 zs_line_drain(zport, irq);
 839                 write_zsreg(zport, R9, FHWRES);
 840                 udelay(10);
 841                 write_zsreg(zport, R9, 0);
 842                 scc->initialised = 1;
 843         }
 844         load_zsregs(zport, zport->regs, irq);
 845         spin_unlock_irqrestore(&scc->zlock, flags);
 846 }
 847
 848 static void zs_set_termios(struct uart_port *uport, struct ktermios *termios,
 849                            struct ktermios *old_termios)
 850 {
 851         struct zs_port *zport = to_zport(uport);
 852         struct zs_scc *scc = zport->scc;
 853         struct zs_port *zport_a = &scc->zport[ZS_CHAN_A];
 854         int irq;
 855         unsigned int baud, brg;
 856         unsigned long flags;
 857
 858         spin_lock_irqsave(&scc->zlock, flags);
 859         irq = !irqs_disabled_flags(flags);
 860
 861         /* Byte size.  */
 862         zport->regs[3] &= ~RxNBITS_MASK;
 863         zport->regs[5] &= ~TxNBITS_MASK;
 864         switch (termios->c_cflag & CSIZE) {
 865         case CS5:
 866                 zport->regs[3] |= Rx5;
 867                 zport->regs[5] |= Tx5;
 868                 break;
 869         case CS6:
 870                 zport->regs[3] |= Rx6;
 871                 zport->regs[5] |= Tx6;
 872                 break;
 873         case CS7:
 874                 zport->regs[3] |= Rx7;
 875                 zport->regs[5] |= Tx7;
 876                 break;
 877         case CS8:
 878         default:
 879                 zport->regs[3] |= Rx8;
 880                 zport->regs[5] |= Tx8;
 881                 break;
 882         }
 883
 884         /* Parity and stop bits.  */
 885         zport->regs[4] &= ~(XCLK_MASK | SB_MASK | PAR_ENA | PAR_EVEN);
 886         if (termios->c_cflag & CSTOPB)
 887                 zport->regs[4] |= SB2;
 888         else
 889                 zport->regs[4] |= SB1;
 890         if (termios->c_cflag & PARENB)
 891                 zport->regs[4] |= PAR_ENA;
 892         if (!(termios->c_cflag & PARODD))
 893                 zport->regs[4] |= PAR_EVEN;
 894         switch (zport->clk_mode) {
 895         case 64:
 896                 zport->regs[4] |= X64CLK;
 897                 break;
 898         case 32:
 899                 zport->regs[4] |= X32CLK;
 900                 break;
 901         case 16:
 902                 zport->regs[4] |= X16CLK;
 903                 break;
 904         case 1:
 905                 zport->regs[4] |= X1CLK;
 906                 break;
 907         default:
 908                 BUG();
 909         }
 910
 911         baud = uart_get_baud_rate(uport, termios, old_termios, 0,
 912                                   uport->uartclk / zport->clk_mode / 4);
 913
 914         brg = ZS_BPS_TO_BRG(baud, uport->uartclk / zport->clk_mode);
 915         zport->regs[12] = brg & 0xff;
 916         zport->regs[13] = (brg >> 8) & 0xff;
 917
 918         uart_update_timeout(uport, termios->c_cflag, baud);
 919
 920         uport->read_status_mask = Rx_OVR;
 921         if (termios->c_iflag & INPCK)
 922                 uport->read_status_mask |= FRM_ERR | PAR_ERR;
 923         if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
 924                 uport->read_status_mask |= Rx_BRK;
 925
 926         uport->ignore_status_mask = 0;
 927         if (termios->c_iflag & IGNPAR)
 928                 uport->ignore_status_mask |= FRM_ERR | PAR_ERR;
 929         if (termios->c_iflag & IGNBRK) {
 930                 uport->ignore_status_mask |= Rx_BRK;
 931                 if (termios->c_iflag & IGNPAR)
 932                         uport->ignore_status_mask |= Rx_OVR;
 933         }
 934
 935         if (termios->c_cflag & CREAD)
 936                 zport->regs[3] |= RxENABLE;
 937         else
 938                 zport->regs[3] &= ~RxENABLE;
 939
 940         if (zport != zport_a) {
 941                 if (!(termios->c_cflag & CLOCAL)) {
 942                         zport->regs[15] |= DCDIE;
 943                 } else
 944                         zport->regs[15] &= ~DCDIE;
 945                 if (termios->c_cflag & CRTSCTS) {
 946                         zport->regs[15] |= CTSIE;
 947                 } else
 948                         zport->regs[15] &= ~CTSIE;
 949                 zs_raw_xor_mctrl(zport);
 950         }
 951
 952         /* Load up the new values.  */
 953         load_zsregs(zport, zport->regs, irq);
 954
 955         spin_unlock_irqrestore(&scc->zlock, flags);
 956 }
 957
 958 /*
 959  * Hack alert!
 960  * Required solely so that the initial PROM-based console
 961  * works undisturbed in parallel with this one.
 962  */
 963 static void zs_pm(struct uart_port *uport, unsigned int state,
 964                   unsigned int oldstate)
 965 {
 966         struct zs_port *zport = to_zport(uport);
 967
 968         if (state < 3)
 969                 zport->regs[5] |= TxENAB;
 970         else
 971                 zport->regs[5] &= ~TxENAB;
 972         write_zsreg(zport, R5, zport->regs[5]);
 973 }
 974
 975
 976 static const char *zs_type(struct uart_port *uport)
 977 {
 978         return "Z85C30 SCC";
 979 }
 980
 981 static void zs_release_port(struct uart_port *uport)
 982 {
 983         iounmap(uport->membase);
 984         uport->membase = 0;
 985         release_mem_region(uport->mapbase, ZS_CHAN_IO_SIZE);
 986 }
 987
 988 static int zs_map_port(struct uart_port *uport)
 989 {
 990         if (!uport->membase)
 991                 uport->membase = ioremap(uport->mapbase,
 992                                                  ZS_CHAN_IO_SIZE);
 993         if (!uport->membase) {
 994                 printk(KERN_ERR "zs: Cannot map MMIO\n");
 995                 return -ENOMEM;
 996         }
 997         return 0;
 998 }
 999
1000 static int zs_request_port(struct uart_port *uport)
1001 {
1002         int ret;
1003
1004         if (!request_mem_region(uport->mapbase, ZS_CHAN_IO_SIZE, "scc")) {
1005                 printk(KERN_ERR "zs: Unable to reserve MMIO resource\n");
1006                 return -EBUSY;
1007         }
1008         ret = zs_map_port(uport);
1009         if (ret) {
1010                 release_mem_region(uport->mapbase, ZS_CHAN_IO_SIZE);
1011                 return ret;
1012         }
1013         return 0;
1014 }
1015
1016 static void zs_config_port(struct uart_port *uport, int flags)
1017 {
1018         struct zs_port *zport = to_zport(uport);
1019
1020         if (flags & UART_CONFIG_TYPE) {
1021                 if (zs_request_port(uport))
1022                         return;
1023
1024                 uport->type = PORT_ZS;
1025
1026                 zs_reset(zport);
1027         }
1028 }
1029
1030 static int zs_verify_port(struct uart_port *uport, struct serial_struct *ser)
1031 {
1032         struct zs_port *zport = to_zport(uport);
1033         int ret = 0;
1034
1035         if (ser->type != PORT_UNKNOWN && ser->type != PORT_ZS)
1036                 ret = -EINVAL;
1037         if (ser->irq != uport->irq)
1038                 ret = -EINVAL;
1039         if (ser->baud_base != uport->uartclk / zport->clk_mode / 4)
1040                 ret = -EINVAL;
1041         return ret;
1042 }
1043
1044
1045 static const struct uart_ops zs_ops = {
1046         .tx_empty       = zs_tx_empty,
1047         .set_mctrl      = zs_set_mctrl,
1048         .get_mctrl      = zs_get_mctrl,
1049         .stop_tx        = zs_stop_tx,
1050         .start_tx       = zs_start_tx,
1051         .stop_rx        = zs_stop_rx,
1052         .enable_ms      = zs_enable_ms,
1053         .break_ctl      = zs_break_ctl,
1054         .startup        = zs_startup,
1055         .shutdown       = zs_shutdown,
1056         .set_termios    = zs_set_termios,
1057         .pm             = zs_pm,
1058         .type           = zs_type,
1059         .release_port   = zs_release_port,
1060         .request_port   = zs_request_port,
1061         .config_port    = zs_config_port,
1062         .verify_port    = zs_verify_port,
1063 };
1064
1065 /*
1066  * Initialize Z85C30 port structures.
1067  */
1068 static int __init zs_probe_sccs(void)
1069 {
1070         static int probed;
1071         struct zs_parms zs_parms;
1072         int chip, side, irq;
1073         int n_chips = 0;
1074         int i;
1075
1076         if (probed)
1077                 return 0;
1078
1079         irq = dec_interrupt[DEC_IRQ_SCC0];
1080         if (irq >= 0) {
1081                 zs_parms.scc[n_chips] = IOASIC_SCC0;
1082                 zs_parms.irq[n_chips] = dec_interrupt[DEC_IRQ_SCC0];
1083                 n_chips++;
1084         }
1085         irq = dec_interrupt[DEC_IRQ_SCC1];
1086         if (irq >= 0) {
1087                 zs_parms.scc[n_chips] = IOASIC_SCC1;
1088                 zs_parms.irq[n_chips] = dec_interrupt[DEC_IRQ_SCC1];
1089                 n_chips++;
1090         }
1091         if (!n_chips)
1092                 return -ENXIO;
1093
1094         probed = 1;
1095
1096         for (chip = 0; chip < n_chips; chip++) {
1097                 spin_lock_init(&zs_sccs[chip].zlock);
1098                 for (side = 0; side < ZS_NUM_CHAN; side++) {
1099                         struct zs_port *zport = &zs_sccs[chip].zport[side];
1100                         struct uart_port *uport = &zport->port;
1101
1102                         zport->scc      = &zs_sccs[chip];
1103                         zport->clk_mode = 16;
1104
1105                         uport->has_sysrq = IS_ENABLED(CONFIG_SERIAL_ZS_CONSOLE);
1106                         uport->irq      = zs_parms.irq[chip];
1107                         uport->uartclk  = ZS_CLOCK;
1108                         uport->fifosize = 1;
1109                         uport->iotype   = UPIO_MEM;
1110                         uport->flags    = UPF_BOOT_AUTOCONF;
1111                         uport->ops      = &zs_ops;
1112                         uport->line     = chip * ZS_NUM_CHAN + side;
1113                         uport->mapbase  = dec_kn_slot_base +
1114                                           zs_parms.scc[chip] +
1115                                           (side ^ ZS_CHAN_B) * ZS_CHAN_IO_SIZE;
1116
1117                         for (i = 0; i < ZS_NUM_REGS; i++)
1118                                 zport->regs[i] = zs_init_regs[i];
1119                 }
1120         }
1121
1122         return 0;
1123 }
1124
1125
1126 #ifdef CONFIG_SERIAL_ZS_CONSOLE
1127 static void zs_console_putchar(struct uart_port *uport, int ch)
1128 {
1129         struct zs_port *zport = to_zport(uport);
1130         struct zs_scc *scc = zport->scc;
1131         int irq;
1132         unsigned long flags;
1133
1134         spin_lock_irqsave(&scc->zlock, flags);
1135         irq = !irqs_disabled_flags(flags);
1136         if (zs_transmit_drain(zport, irq))
1137                 write_zsdata(zport, ch);
1138         spin_unlock_irqrestore(&scc->zlock, flags);
1139 }
1140
1141 /*
1142  * Print a string to the serial port trying not to disturb
1143  * any possible real use of the port...
1144  */
1145 static void zs_console_write(struct console *co, const char *s,
1146                              unsigned int count)
1147 {
1148         int chip = co->index / ZS_NUM_CHAN, side = co->index % ZS_NUM_CHAN;
1149         struct zs_port *zport = &zs_sccs[chip].zport[side];
1150         struct zs_scc *scc = zport->scc;
1151         unsigned long flags;
1152         u8 txint, txenb;
1153         int irq;
1154
1155         /* Disable transmit interrupts and enable the transmitter. */
1156         spin_lock_irqsave(&scc->zlock, flags);
1157         txint = zport->regs[1];
1158         txenb = zport->regs[5];
1159         if (txint & TxINT_ENAB) {
1160                 zport->regs[1] = txint & ~TxINT_ENAB;
1161                 write_zsreg(zport, R1, zport->regs[1]);
1162         }
1163         if (!(txenb & TxENAB)) {
1164                 zport->regs[5] = txenb | TxENAB;
1165                 write_zsreg(zport, R5, zport->regs[5]);
1166         }
1167         spin_unlock_irqrestore(&scc->zlock, flags);
1168
1169         uart_console_write(&zport->port, s, count, zs_console_putchar);
1170
1171         /* Restore transmit interrupts and the transmitter enable. */
1172         spin_lock_irqsave(&scc->zlock, flags);
1173         irq = !irqs_disabled_flags(flags);
1174         zs_line_drain(zport, irq);
1175         if (!(txenb & TxENAB)) {
1176                 zport->regs[5] &= ~TxENAB;
1177                 write_zsreg(zport, R5, zport->regs[5]);
1178         }
1179         if (txint & TxINT_ENAB) {
1180                 zport->regs[1] |= TxINT_ENAB;
1181                 write_zsreg(zport, R1, zport->regs[1]);
1182
1183                 /* Resume any transmission as the TxIP bit won't be set.  */
1184                 if (!zport->tx_stopped)
1185                         zs_raw_transmit_chars(zport);
1186         }
1187         spin_unlock_irqrestore(&scc->zlock, flags);
1188 }
1189
1190 /*
1191  * Setup serial console baud/bits/parity.  We do two things here:
1192  * - construct a cflag setting for the first uart_open()
1193  * - initialise the serial port
1194  * Return non-zero if we didn't find a serial port.
1195  */
1196 static int __init zs_console_setup(struct console *co, char *options)
1197 {
1198         int chip = co->index / ZS_NUM_CHAN, side = co->index % ZS_NUM_CHAN;
1199         struct zs_port *zport = &zs_sccs[chip].zport[side];
1200         struct uart_port *uport = &zport->port;
1201         int baud = 9600;
1202         int bits = 8;
1203         int parity = 'n';
1204         int flow = 'n';
1205         int ret;
1206
1207         ret = zs_map_port(uport);
1208         if (ret)
1209                 return ret;
1210
1211         zs_reset(zport);
1212         zs_pm(uport, 0, -1);
1213
1214         if (options)
1215                 uart_parse_options(options, &baud, &parity, &bits, &flow);
1216         return uart_set_options(uport, co, baud, parity, bits, flow);
1217 }
1218
1219 static struct uart_driver zs_reg;
1220 static struct console zs_console = {
1221         .name   = "ttyS",
1222         .write  = zs_console_write,
1223         .device = uart_console_device,
1224         .setup  = zs_console_setup,
1225         .flags  = CON_PRINTBUFFER,
1226         .index  = -1,
1227         .data   = &zs_reg,
1228 };
1229
1230 /*
1231  *      Register console.
1232  */
1233 static int __init zs_serial_console_init(void)
1234 {
1235         int ret;
1236
1237         ret = zs_probe_sccs();
1238         if (ret)
1239                 return ret;
1240         register_console(&zs_console);
1241
1242         return 0;
1243 }
1244
1245 console_initcall(zs_serial_console_init);
1246
1247 #define SERIAL_ZS_CONSOLE       &zs_console
1248 #else
1249 #define SERIAL_ZS_CONSOLE       NULL
1250 #endif /* CONFIG_SERIAL_ZS_CONSOLE */
1251
1252 static struct uart_driver zs_reg = {
1253         .owner                  = THIS_MODULE,
1254         .driver_name            = "serial",
1255         .dev_name               = "ttyS",
1256         .major                  = TTY_MAJOR,
1257         .minor                  = 64,
1258         .nr                     = ZS_NUM_SCCS * ZS_NUM_CHAN,
1259         .cons                   = SERIAL_ZS_CONSOLE,
1260 };
1261
1262 /* zs_init inits the driver. */
1263 static int __init zs_init(void)
1264 {
1265         int i, ret;
1266
1267         pr_info("%s%s\n", zs_name, zs_version);
1268
1269         /* Find out how many Z85C30 SCCs we have.  */
1270         ret = zs_probe_sccs();
1271         if (ret)
1272                 return ret;
1273
1274         ret = uart_register_driver(&zs_reg);
1275         if (ret)
1276                 return ret;
1277
1278         for (i = 0; i < ZS_NUM_SCCS * ZS_NUM_CHAN; i++) {
1279                 struct zs_scc *scc = &zs_sccs[i / ZS_NUM_CHAN];
1280                 struct zs_port *zport = &scc->zport[i % ZS_NUM_CHAN];
1281                 struct uart_port *uport = &zport->port;
1282
1283                 if (zport->scc)
1284                         uart_add_one_port(&zs_reg, uport);
1285         }
1286
1287         return 0;
1288 }
1289
1290 static void __exit zs_exit(void)
1291 {
1292         int i;
1293
1294         for (i = ZS_NUM_SCCS * ZS_NUM_CHAN - 1; i >= 0; i--) {
1295                 struct zs_scc *scc = &zs_sccs[i / ZS_NUM_CHAN];
1296                 struct zs_port *zport = &scc->zport[i % ZS_NUM_CHAN];
1297                 struct uart_port *uport = &zport->port;
1298
1299                 if (zport->scc)
1300                         uart_remove_one_port(&zs_reg, uport);
1301         }
1302
1303         uart_unregister_driver(&zs_reg);
1304 }
1305
1306 module_init(zs_init);
1307 module_exit(zs_exit);