drivers/tty/serial/sprd_serial.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2012-2015 Spreadtrum Communications Inc.
   4  */
   5
   6 #if defined(CONFIG_SERIAL_SPRD_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
   7 #define SUPPORT_SYSRQ
   8 #endif
   9
  10 #include <linux/clk.h>
  11 #include <linux/console.h>
  12 #include <linux/delay.h>
  13 #include <linux/io.h>
  14 #include <linux/ioport.h>
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/of.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/serial_core.h>
  20 #include <linux/serial.h>
  21 #include <linux/slab.h>
  22 #include <linux/tty.h>
  23 #include <linux/tty_flip.h>
  24
  25 /* device name */
  26 #define UART_NR_MAX             8
  27 #define SPRD_TTY_NAME           "ttyS"
  28 #define SPRD_FIFO_SIZE          128
  29 #define SPRD_DEF_RATE           26000000
  30 #define SPRD_BAUD_IO_LIMIT      3000000
  31 #define SPRD_TIMEOUT            256000
  32
  33 /* the offset of serial registers and BITs for them */
  34 /* data registers */
  35 #define SPRD_TXD                0x0000
  36 #define SPRD_RXD                0x0004
  37
  38 /* line status register and its BITs  */
  39 #define SPRD_LSR                0x0008
  40 #define SPRD_LSR_OE             BIT(4)
  41 #define SPRD_LSR_FE             BIT(3)
  42 #define SPRD_LSR_PE             BIT(2)
  43 #define SPRD_LSR_BI             BIT(7)
  44 #define SPRD_LSR_TX_OVER        BIT(15)
  45
  46 /* data number in TX and RX fifo */
  47 #define SPRD_STS1               0x000C
  48
  49 /* interrupt enable register and its BITs */
  50 #define SPRD_IEN                0x0010
  51 #define SPRD_IEN_RX_FULL        BIT(0)
  52 #define SPRD_IEN_TX_EMPTY       BIT(1)
  53 #define SPRD_IEN_BREAK_DETECT   BIT(7)
  54 #define SPRD_IEN_TIMEOUT        BIT(13)
  55
  56 /* interrupt clear register */
  57 #define SPRD_ICLR               0x0014
  58 #define SPRD_ICLR_TIMEOUT       BIT(13)
  59
  60 /* line control register */
  61 #define SPRD_LCR                0x0018
  62 #define SPRD_LCR_STOP_1BIT      0x10
  63 #define SPRD_LCR_STOP_2BIT      0x30
  64 #define SPRD_LCR_DATA_LEN       (BIT(2) | BIT(3))
  65 #define SPRD_LCR_DATA_LEN5      0x0
  66 #define SPRD_LCR_DATA_LEN6      0x4
  67 #define SPRD_LCR_DATA_LEN7      0x8
  68 #define SPRD_LCR_DATA_LEN8      0xc
  69 #define SPRD_LCR_PARITY (BIT(0) | BIT(1))
  70 #define SPRD_LCR_PARITY_EN      0x2
  71 #define SPRD_LCR_EVEN_PAR       0x0
  72 #define SPRD_LCR_ODD_PAR        0x1
  73
  74 /* control register 1 */
  75 #define SPRD_CTL1                       0x001C
  76 #define RX_HW_FLOW_CTL_THLD     BIT(6)
  77 #define RX_HW_FLOW_CTL_EN       BIT(7)
  78 #define TX_HW_FLOW_CTL_EN       BIT(8)
  79 #define RX_TOUT_THLD_DEF        0x3E00
  80 #define RX_HFC_THLD_DEF 0x40
  81
  82 /* fifo threshold register */
  83 #define SPRD_CTL2               0x0020
  84 #define THLD_TX_EMPTY   0x40
  85 #define THLD_RX_FULL    0x40
  86
  87 /* config baud rate register */
  88 #define SPRD_CLKD0              0x0024
  89 #define SPRD_CLKD1              0x0028
  90
  91 /* interrupt mask status register */
  92 #define SPRD_IMSR                       0x002C
  93 #define SPRD_IMSR_RX_FIFO_FULL          BIT(0)
  94 #define SPRD_IMSR_TX_FIFO_EMPTY BIT(1)
  95 #define SPRD_IMSR_BREAK_DETECT          BIT(7)
  96 #define SPRD_IMSR_TIMEOUT               BIT(13)
  97
  98 struct reg_backup {
  99         u32 ien;
 100         u32 ctrl0;
 101         u32 ctrl1;
 102         u32 ctrl2;
 103         u32 clkd0;
 104         u32 clkd1;
 105         u32 dspwait;
 106 };
 107
 108 struct sprd_uart_port {
 109         struct uart_port port;
 110         struct reg_backup reg_bak;
 111         char name[16];
 112 };
 113
 114 static struct sprd_uart_port *sprd_port[UART_NR_MAX];
 115 static int sprd_ports_num;
 116
 117 static inline unsigned int serial_in(struct uart_port *port, int offset)
 118 {
 119         return readl_relaxed(port->membase + offset);
 120 }
 121
 122 static inline void serial_out(struct uart_port *port, int offset, int value)
 123 {
 124         writel_relaxed(value, port->membase + offset);
 125 }
 126
 127 static unsigned int sprd_tx_empty(struct uart_port *port)
 128 {
 129         if (serial_in(port, SPRD_STS1) & 0xff00)
 130                 return 0;
 131         else
 132                 return TIOCSER_TEMT;
 133 }
 134
 135 static unsigned int sprd_get_mctrl(struct uart_port *port)
 136 {
 137         return TIOCM_DSR | TIOCM_CTS;
 138 }
 139
 140 static void sprd_set_mctrl(struct uart_port *port, unsigned int mctrl)
 141 {
 142         /* nothing to do */
 143 }
 144
 145 static void sprd_stop_tx(struct uart_port *port)
 146 {
 147         unsigned int ien, iclr;
 148
 149         iclr = serial_in(port, SPRD_ICLR);
 150         ien = serial_in(port, SPRD_IEN);
 151
 152         iclr |= SPRD_IEN_TX_EMPTY;
 153         ien &= ~SPRD_IEN_TX_EMPTY;
 154
 155         serial_out(port, SPRD_ICLR, iclr);
 156         serial_out(port, SPRD_IEN, ien);
 157 }
 158
 159 static void sprd_start_tx(struct uart_port *port)
 160 {
 161         unsigned int ien;
 162
 163         ien = serial_in(port, SPRD_IEN);
 164         if (!(ien & SPRD_IEN_TX_EMPTY)) {
 165                 ien |= SPRD_IEN_TX_EMPTY;
 166                 serial_out(port, SPRD_IEN, ien);
 167         }
 168 }
 169
 170 static void sprd_stop_rx(struct uart_port *port)
 171 {
 172         unsigned int ien, iclr;
 173
 174         iclr = serial_in(port, SPRD_ICLR);
 175         ien = serial_in(port, SPRD_IEN);
 176
 177         ien &= ~(SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT);
 178         iclr |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT;
 179
 180         serial_out(port, SPRD_IEN, ien);
 181         serial_out(port, SPRD_ICLR, iclr);
 182 }
 183
 184 /* The Sprd serial does not support this function. */
 185 static void sprd_break_ctl(struct uart_port *port, int break_state)
 186 {
 187         /* nothing to do */
 188 }
 189
 190 static int handle_lsr_errors(struct uart_port *port,
 191                              unsigned int *flag,
 192                              unsigned int *lsr)
 193 {
 194         int ret = 0;
 195
 196         /* statistics */
 197         if (*lsr & SPRD_LSR_BI) {
 198                 *lsr &= ~(SPRD_LSR_FE | SPRD_LSR_PE);
 199                 port->icount.brk++;
 200                 ret = uart_handle_break(port);
 201                 if (ret)
 202                         return ret;
 203         } else if (*lsr & SPRD_LSR_PE)
 204                 port->icount.parity++;
 205         else if (*lsr & SPRD_LSR_FE)
 206                 port->icount.frame++;
 207         if (*lsr & SPRD_LSR_OE)
 208                 port->icount.overrun++;
 209
 210         /* mask off conditions which should be ignored */
 211         *lsr &= port->read_status_mask;
 212         if (*lsr & SPRD_LSR_BI)
 213                 *flag = TTY_BREAK;
 214         else if (*lsr & SPRD_LSR_PE)
 215                 *flag = TTY_PARITY;
 216         else if (*lsr & SPRD_LSR_FE)
 217                 *flag = TTY_FRAME;
 218
 219         return ret;
 220 }
 221
 222 static inline void sprd_rx(struct uart_port *port)
 223 {
 224         struct tty_port *tty = &port->state->port;
 225         unsigned int ch, flag, lsr, max_count = SPRD_TIMEOUT;
 226
 227         while ((serial_in(port, SPRD_STS1) & 0x00ff) && max_count--) {
 228                 lsr = serial_in(port, SPRD_LSR);
 229                 ch = serial_in(port, SPRD_RXD);
 230                 flag = TTY_NORMAL;
 231                 port->icount.rx++;
 232
 233                 if (lsr & (SPRD_LSR_BI | SPRD_LSR_PE |
 234                         SPRD_LSR_FE | SPRD_LSR_OE))
 235                         if (handle_lsr_errors(port, &lsr, &flag))
 236                                 continue;
 237                 if (uart_handle_sysrq_char(port, ch))
 238                         continue;
 239
 240                 uart_insert_char(port, lsr, SPRD_LSR_OE, ch, flag);
 241         }
 242
 243         tty_flip_buffer_push(tty);
 244 }
 245
 246 static inline void sprd_tx(struct uart_port *port)
 247 {
 248         struct circ_buf *xmit = &port->state->xmit;
 249         int count;
 250
 251         if (port->x_char) {
 252                 serial_out(port, SPRD_TXD, port->x_char);
 253                 port->icount.tx++;
 254                 port->x_char = 0;
 255                 return;
 256         }
 257
 258         if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
 259                 sprd_stop_tx(port);
 260                 return;
 261         }
 262
 263         count = THLD_TX_EMPTY;
 264         do {
 265                 serial_out(port, SPRD_TXD, xmit->buf[xmit->tail]);
 266                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 267                 port->icount.tx++;
 268                 if (uart_circ_empty(xmit))
 269                         break;
 270         } while (--count > 0);
 271
 272         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 273                 uart_write_wakeup(port);
 274
 275         if (uart_circ_empty(xmit))
 276                 sprd_stop_tx(port);
 277 }
 278
 279 /* this handles the interrupt from one port */
 280 static irqreturn_t sprd_handle_irq(int irq, void *dev_id)
 281 {
 282         struct uart_port *port = dev_id;
 283         unsigned int ims;
 284
 285         spin_lock(&port->lock);
 286
 287         ims = serial_in(port, SPRD_IMSR);
 288
 289         if (!ims) {
 290                 spin_unlock(&port->lock);
 291                 return IRQ_NONE;
 292         }
 293
 294         if (ims & SPRD_IMSR_TIMEOUT)
 295                 serial_out(port, SPRD_ICLR, SPRD_ICLR_TIMEOUT);
 296
 297         if (ims & (SPRD_IMSR_RX_FIFO_FULL |
 298                 SPRD_IMSR_BREAK_DETECT | SPRD_IMSR_TIMEOUT))
 299                 sprd_rx(port);
 300
 301         if (ims & SPRD_IMSR_TX_FIFO_EMPTY)
 302                 sprd_tx(port);
 303
 304         spin_unlock(&port->lock);
 305
 306         return IRQ_HANDLED;
 307 }
 308
 309 static int sprd_startup(struct uart_port *port)
 310 {
 311         int ret = 0;
 312         unsigned int ien, fc;
 313         unsigned int timeout;
 314         struct sprd_uart_port *sp;
 315         unsigned long flags;
 316
 317         serial_out(port, SPRD_CTL2, ((THLD_TX_EMPTY << 8) | THLD_RX_FULL));
 318
 319         /* clear rx fifo */
 320         timeout = SPRD_TIMEOUT;
 321         while (timeout-- && serial_in(port, SPRD_STS1) & 0x00ff)
 322                 serial_in(port, SPRD_RXD);
 323
 324         /* clear tx fifo */
 325         timeout = SPRD_TIMEOUT;
 326         while (timeout-- && serial_in(port, SPRD_STS1) & 0xff00)
 327                 cpu_relax();
 328
 329         /* clear interrupt */
 330         serial_out(port, SPRD_IEN, 0);
 331         serial_out(port, SPRD_ICLR, ~0);
 332
 333         /* allocate irq */
 334         sp = container_of(port, struct sprd_uart_port, port);
 335         snprintf(sp->name, sizeof(sp->name), "sprd_serial%d", port->line);
 336         ret = devm_request_irq(port->dev, port->irq, sprd_handle_irq,
 337                                 IRQF_SHARED, sp->name, port);
 338         if (ret) {
 339                 dev_err(port->dev, "fail to request serial irq %d, ret=%d\n",
 340                         port->irq, ret);
 341                 return ret;
 342         }
 343         fc = serial_in(port, SPRD_CTL1);
 344         fc |= RX_TOUT_THLD_DEF | RX_HFC_THLD_DEF;
 345         serial_out(port, SPRD_CTL1, fc);
 346
 347         /* enable interrupt */
 348         spin_lock_irqsave(&port->lock, flags);
 349         ien = serial_in(port, SPRD_IEN);
 350         ien |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT | SPRD_IEN_TIMEOUT;
 351         serial_out(port, SPRD_IEN, ien);
 352         spin_unlock_irqrestore(&port->lock, flags);
 353
 354         return 0;
 355 }
 356
 357 static void sprd_shutdown(struct uart_port *port)
 358 {
 359         serial_out(port, SPRD_IEN, 0);
 360         serial_out(port, SPRD_ICLR, ~0);
 361         devm_free_irq(port->dev, port->irq, port);
 362 }
 363
 364 static void sprd_set_termios(struct uart_port *port,
 365                                     struct ktermios *termios,
 366                                     struct ktermios *old)
 367 {
 368         unsigned int baud, quot;
 369         unsigned int lcr = 0, fc;
 370         unsigned long flags;
 371
 372         /* ask the core to calculate the divisor for us */
 373         baud = uart_get_baud_rate(port, termios, old, 0, SPRD_BAUD_IO_LIMIT);
 374
 375         quot = (unsigned int)((port->uartclk + baud / 2) / baud);
 376
 377         /* set data length */
 378         switch (termios->c_cflag & CSIZE) {
 379         case CS5:
 380                 lcr |= SPRD_LCR_DATA_LEN5;
 381                 break;
 382         case CS6:
 383                 lcr |= SPRD_LCR_DATA_LEN6;
 384                 break;
 385         case CS7:
 386                 lcr |= SPRD_LCR_DATA_LEN7;
 387                 break;
 388         case CS8:
 389         default:
 390                 lcr |= SPRD_LCR_DATA_LEN8;
 391                 break;
 392         }
 393
 394         /* calculate stop bits */
 395         lcr &= ~(SPRD_LCR_STOP_1BIT | SPRD_LCR_STOP_2BIT);
 396         if (termios->c_cflag & CSTOPB)
 397                 lcr |= SPRD_LCR_STOP_2BIT;
 398         else
 399                 lcr |= SPRD_LCR_STOP_1BIT;
 400
 401         /* calculate parity */
 402         lcr &= ~SPRD_LCR_PARITY;
 403         termios->c_cflag &= ~CMSPAR;    /* no support mark/space */
 404         if (termios->c_cflag & PARENB) {
 405                 lcr |= SPRD_LCR_PARITY_EN;
 406                 if (termios->c_cflag & PARODD)
 407                         lcr |= SPRD_LCR_ODD_PAR;
 408                 else
 409                         lcr |= SPRD_LCR_EVEN_PAR;
 410         }
 411
 412         spin_lock_irqsave(&port->lock, flags);
 413
 414         /* update the per-port timeout */
 415         uart_update_timeout(port, termios->c_cflag, baud);
 416
 417         port->read_status_mask = SPRD_LSR_OE;
 418         if (termios->c_iflag & INPCK)
 419                 port->read_status_mask |= SPRD_LSR_FE | SPRD_LSR_PE;
 420         if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
 421                 port->read_status_mask |= SPRD_LSR_BI;
 422
 423         /* characters to ignore */
 424         port->ignore_status_mask = 0;
 425         if (termios->c_iflag & IGNPAR)
 426                 port->ignore_status_mask |= SPRD_LSR_PE | SPRD_LSR_FE;
 427         if (termios->c_iflag & IGNBRK) {
 428                 port->ignore_status_mask |= SPRD_LSR_BI;
 429                 /*
 430                  * If we're ignoring parity and break indicators,
 431                  * ignore overruns too (for real raw support).
 432                  */
 433                 if (termios->c_iflag & IGNPAR)
 434                         port->ignore_status_mask |= SPRD_LSR_OE;
 435         }
 436
 437         /* flow control */
 438         fc = serial_in(port, SPRD_CTL1);
 439         fc &= ~(RX_HW_FLOW_CTL_THLD | RX_HW_FLOW_CTL_EN | TX_HW_FLOW_CTL_EN);
 440         if (termios->c_cflag & CRTSCTS) {
 441                 fc |= RX_HW_FLOW_CTL_THLD;
 442                 fc |= RX_HW_FLOW_CTL_EN;
 443                 fc |= TX_HW_FLOW_CTL_EN;
 444         }
 445
 446         /* clock divider bit0~bit15 */
 447         serial_out(port, SPRD_CLKD0, quot & 0xffff);
 448
 449         /* clock divider bit16~bit20 */
 450         serial_out(port, SPRD_CLKD1, (quot & 0x1f0000) >> 16);
 451         serial_out(port, SPRD_LCR, lcr);
 452         fc |= RX_TOUT_THLD_DEF | RX_HFC_THLD_DEF;
 453         serial_out(port, SPRD_CTL1, fc);
 454
 455         spin_unlock_irqrestore(&port->lock, flags);
 456
 457         /* Don't rewrite B0 */
 458         if (tty_termios_baud_rate(termios))
 459                 tty_termios_encode_baud_rate(termios, baud, baud);
 460 }
 461
 462 static const char *sprd_type(struct uart_port *port)
 463 {
 464         return "SPX";
 465 }
 466
 467 static void sprd_release_port(struct uart_port *port)
 468 {
 469         /* nothing to do */
 470 }
 471
 472 static int sprd_request_port(struct uart_port *port)
 473 {
 474         return 0;
 475 }
 476
 477 static void sprd_config_port(struct uart_port *port, int flags)
 478 {
 479         if (flags & UART_CONFIG_TYPE)
 480                 port->type = PORT_SPRD;
 481 }
 482
 483 static int sprd_verify_port(struct uart_port *port,
 484                                    struct serial_struct *ser)
 485 {
 486         if (ser->type != PORT_SPRD)
 487                 return -EINVAL;
 488         if (port->irq != ser->irq)
 489                 return -EINVAL;
 490         if (port->iotype != ser->io_type)
 491                 return -EINVAL;
 492         return 0;
 493 }
 494
 495 static const struct uart_ops serial_sprd_ops = {
 496         .tx_empty = sprd_tx_empty,
 497         .get_mctrl = sprd_get_mctrl,
 498         .set_mctrl = sprd_set_mctrl,
 499         .stop_tx = sprd_stop_tx,
 500         .start_tx = sprd_start_tx,
 501         .stop_rx = sprd_stop_rx,
 502         .break_ctl = sprd_break_ctl,
 503         .startup = sprd_startup,
 504         .shutdown = sprd_shutdown,
 505         .set_termios = sprd_set_termios,
 506         .type = sprd_type,
 507         .release_port = sprd_release_port,
 508         .request_port = sprd_request_port,
 509         .config_port = sprd_config_port,
 510         .verify_port = sprd_verify_port,
 511 };
 512
 513 #ifdef CONFIG_SERIAL_SPRD_CONSOLE
 514 static void wait_for_xmitr(struct uart_port *port)
 515 {
 516         unsigned int status, tmout = 10000;
 517
 518         /* wait up to 10ms for the character(s) to be sent */
 519         do {
 520                 status = serial_in(port, SPRD_STS1);
 521                 if (--tmout == 0)
 522                         break;
 523                 udelay(1);
 524         } while (status & 0xff00);
 525 }
 526
 527 static void sprd_console_putchar(struct uart_port *port, int ch)
 528 {
 529         wait_for_xmitr(port);
 530         serial_out(port, SPRD_TXD, ch);
 531 }
 532
 533 static void sprd_console_write(struct console *co, const char *s,
 534                                       unsigned int count)
 535 {
 536         struct uart_port *port = &sprd_port[co->index]->port;
 537         int locked = 1;
 538         unsigned long flags;
 539
 540         if (port->sysrq)
 541                 locked = 0;
 542         else if (oops_in_progress)
 543                 locked = spin_trylock_irqsave(&port->lock, flags);
 544         else
 545                 spin_lock_irqsave(&port->lock, flags);
 546
 547         uart_console_write(port, s, count, sprd_console_putchar);
 548
 549         /* wait for transmitter to become empty */
 550         wait_for_xmitr(port);
 551
 552         if (locked)
 553                 spin_unlock_irqrestore(&port->lock, flags);
 554 }
 555
 556 static int __init sprd_console_setup(struct console *co, char *options)
 557 {
 558         struct uart_port *port;
 559         int baud = 115200;
 560         int bits = 8;
 561         int parity = 'n';
 562         int flow = 'n';
 563
 564         if (co->index >= UART_NR_MAX || co->index < 0)
 565                 co->index = 0;
 566
 567         port = &sprd_port[co->index]->port;
 568         if (port == NULL) {
 569                 pr_info("serial port %d not yet initialized\n", co->index);
 570                 return -ENODEV;
 571         }
 572         if (options)
 573                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 574
 575         return uart_set_options(port, co, baud, parity, bits, flow);
 576 }
 577
 578 static struct uart_driver sprd_uart_driver;
 579 static struct console sprd_console = {
 580         .name = SPRD_TTY_NAME,
 581         .write = sprd_console_write,
 582         .device = uart_console_device,
 583         .setup = sprd_console_setup,
 584         .flags = CON_PRINTBUFFER,
 585         .index = -1,
 586         .data = &sprd_uart_driver,
 587 };
 588
 589 #define SPRD_CONSOLE    (&sprd_console)
 590
 591 /* Support for earlycon */
 592 static void sprd_putc(struct uart_port *port, int c)
 593 {
 594         unsigned int timeout = SPRD_TIMEOUT;
 595
 596         while (timeout-- &&
 597                    !(readl(port->membase + SPRD_LSR) & SPRD_LSR_TX_OVER))
 598                 cpu_relax();
 599
 600         writeb(c, port->membase + SPRD_TXD);
 601 }
 602
 603 static void sprd_early_write(struct console *con, const char *s,
 604                                     unsigned n)
 605 {
 606         struct earlycon_device *dev = con->data;
 607
 608         uart_console_write(&dev->port, s, n, sprd_putc);
 609 }
 610
 611 static int __init sprd_early_console_setup(
 612                                 struct earlycon_device *device,
 613                                 const char *opt)
 614 {
 615         if (!device->port.membase)
 616                 return -ENODEV;
 617
 618         device->con->write = sprd_early_write;
 619         return 0;
 620 }
 621 OF_EARLYCON_DECLARE(sprd_serial, "sprd,sc9836-uart",
 622                     sprd_early_console_setup);
 623
 624 #else /* !CONFIG_SERIAL_SPRD_CONSOLE */
 625 #define SPRD_CONSOLE            NULL
 626 #endif
 627
 628 static struct uart_driver sprd_uart_driver = {
 629         .owner = THIS_MODULE,
 630         .driver_name = "sprd_serial",
 631         .dev_name = SPRD_TTY_NAME,
 632         .major = 0,
 633         .minor = 0,
 634         .nr = UART_NR_MAX,
 635         .cons = SPRD_CONSOLE,
 636 };
 637
 638 static int sprd_probe_dt_alias(int index, struct device *dev)
 639 {
 640         struct device_node *np;
 641         int ret = index;
 642
 643         if (!IS_ENABLED(CONFIG_OF))
 644                 return ret;
 645
 646         np = dev->of_node;
 647         if (!np)
 648                 return ret;
 649
 650         ret = of_alias_get_id(np, "serial");
 651         if (ret < 0)
 652                 ret = index;
 653         else if (ret >= ARRAY_SIZE(sprd_port) || sprd_port[ret] != NULL) {
 654                 dev_warn(dev, "requested serial port %d not available.\n", ret);
 655                 ret = index;
 656         }
 657
 658         return ret;
 659 }
 660
 661 static int sprd_remove(struct platform_device *dev)
 662 {
 663         struct sprd_uart_port *sup = platform_get_drvdata(dev);
 664
 665         if (sup) {
 666                 uart_remove_one_port(&sprd_uart_driver, &sup->port);
 667                 sprd_port[sup->port.line] = NULL;
 668                 sprd_ports_num--;
 669         }
 670
 671         if (!sprd_ports_num)
 672                 uart_unregister_driver(&sprd_uart_driver);
 673
 674         return 0;
 675 }
 676
 677 static int sprd_probe(struct platform_device *pdev)
 678 {
 679         struct resource *res;
 680         struct uart_port *up;
 681         struct clk *clk;
 682         int irq;
 683         int index;
 684         int ret;
 685
 686         for (index = 0; index < ARRAY_SIZE(sprd_port); index++)
 687                 if (sprd_port[index] == NULL)
 688                         break;
 689
 690         if (index == ARRAY_SIZE(sprd_port))
 691                 return -EBUSY;
 692
 693         index = sprd_probe_dt_alias(index, &pdev->dev);
 694
 695         sprd_port[index] = devm_kzalloc(&pdev->dev,
 696                 sizeof(*sprd_port[index]), GFP_KERNEL);
 697         if (!sprd_port[index])
 698                 return -ENOMEM;
 699
 700         up = &sprd_port[index]->port;
 701         up->dev = &pdev->dev;
 702         up->line = index;
 703         up->type = PORT_SPRD;
 704         up->iotype = UPIO_MEM;
 705         up->uartclk = SPRD_DEF_RATE;
 706         up->fifosize = SPRD_FIFO_SIZE;
 707         up->ops = &serial_sprd_ops;
 708         up->flags = UPF_BOOT_AUTOCONF;
 709
 710         clk = devm_clk_get(&pdev->dev, NULL);
 711         if (!IS_ERR_OR_NULL(clk))
 712                 up->uartclk = clk_get_rate(clk);
 713
 714         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 715         if (!res) {
 716                 dev_err(&pdev->dev, "not provide mem resource\n");
 717                 return -ENODEV;
 718         }
 719         up->mapbase = res->start;
 720         up->membase = devm_ioremap_resource(&pdev->dev, res);
 721         if (IS_ERR(up->membase))
 722                 return PTR_ERR(up->membase);
 723
 724         irq = platform_get_irq(pdev, 0);
 725         if (irq < 0) {
 726                 dev_err(&pdev->dev, "not provide irq resource: %d\n", irq);
 727                 return irq;
 728         }
 729         up->irq = irq;
 730
 731         if (!sprd_ports_num) {
 732                 ret = uart_register_driver(&sprd_uart_driver);
 733                 if (ret < 0) {
 734                         pr_err("Failed to register SPRD-UART driver\n");
 735                         return ret;
 736                 }
 737         }
 738         sprd_ports_num++;
 739
 740         ret = uart_add_one_port(&sprd_uart_driver, up);
 741         if (ret) {
 742                 sprd_port[index] = NULL;
 743                 sprd_remove(pdev);
 744         }
 745
 746         platform_set_drvdata(pdev, up);
 747
 748         return ret;
 749 }
 750
 751 #ifdef CONFIG_PM_SLEEP
 752 static int sprd_suspend(struct device *dev)
 753 {
 754         struct sprd_uart_port *sup = dev_get_drvdata(dev);
 755
 756         uart_suspend_port(&sprd_uart_driver, &sup->port);
 757
 758         return 0;
 759 }
 760
 761 static int sprd_resume(struct device *dev)
 762 {
 763         struct sprd_uart_port *sup = dev_get_drvdata(dev);
 764
 765         uart_resume_port(&sprd_uart_driver, &sup->port);
 766
 767         return 0;
 768 }
 769 #endif
 770
 771 static SIMPLE_DEV_PM_OPS(sprd_pm_ops, sprd_suspend, sprd_resume);
 772
 773 static const struct of_device_id serial_ids[] = {
 774         {.compatible = "sprd,sc9836-uart",},
 775         {}
 776 };
 777 MODULE_DEVICE_TABLE(of, serial_ids);
 778
 779 static struct platform_driver sprd_platform_driver = {
 780         .probe          = sprd_probe,
 781         .remove         = sprd_remove,
 782         .driver         = {
 783                 .name   = "sprd_serial",
 784                 .of_match_table = of_match_ptr(serial_ids),
 785                 .pm     = &sprd_pm_ops,
 786         },
 787 };
 788
 789 module_platform_driver(sprd_platform_driver);
 790
 791 MODULE_LICENSE("GPL v2");
 792 MODULE_DESCRIPTION("Spreadtrum SoC serial driver series");