linux/drivers/tty/serial/uartlite.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * uartlite.c: Serial driver for Xilinx uartlite serial controller
   4 *
   5 * Copyright (C) 2006 Peter Korsgaard <jacmet@sunsite.dk>
   6 * Copyright (C) 2007 Secret Lab Technologies Ltd.
   7 */
   8
   9#include <linux/platform_device.h>
  10#include <linux/module.h>
  11#include <linux/console.h>
  12#include <linux/serial.h>
  13#include <linux/serial_core.h>
  14#include <linux/tty.h>
  15#include <linux/tty_flip.h>
  16#include <linux/delay.h>
  17#include <linux/interrupt.h>
  18#include <linux/init.h>
  19#include <linux/io.h>
  20#include <linux/of.h>
  21#include <linux/of_address.h>
  22#include <linux/of_device.h>
  23#include <linux/of_platform.h>
  24#include <linux/clk.h>
  25
  26#define ULITE_NAME              "ttyUL"
  27#define ULITE_MAJOR             204
  28#define ULITE_MINOR             187
  29#define ULITE_NR_UARTS          CONFIG_SERIAL_UARTLITE_NR_UARTS
  30
  31/* ---------------------------------------------------------------------
  32 * Register definitions
  33 *
  34 * For register details see datasheet:
  35 * https://www.xilinx.com/support/documentation/ip_documentation/opb_uartlite.pdf
  36 */
  37
  38#define ULITE_RX                0x00
  39#define ULITE_TX                0x04
  40#define ULITE_STATUS            0x08
  41#define ULITE_CONTROL           0x0c
  42
  43#define ULITE_REGION            16
  44
  45#define ULITE_STATUS_RXVALID    0x01
  46#define ULITE_STATUS_RXFULL     0x02
  47#define ULITE_STATUS_TXEMPTY    0x04
  48#define ULITE_STATUS_TXFULL     0x08
  49#define ULITE_STATUS_IE         0x10
  50#define ULITE_STATUS_OVERRUN    0x20
  51#define ULITE_STATUS_FRAME      0x40
  52#define ULITE_STATUS_PARITY     0x80
  53
  54#define ULITE_CONTROL_RST_TX    0x01
  55#define ULITE_CONTROL_RST_RX    0x02
  56#define ULITE_CONTROL_IE        0x10
  57
  58/* Static pointer to console port */
  59#ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
  60static struct uart_port *console_port;
  61#endif
  62
  63struct uartlite_data {
  64        const struct uartlite_reg_ops *reg_ops;
  65        struct clk *clk;
  66};
  67
  68struct uartlite_reg_ops {
  69        u32 (*in)(void __iomem *addr);
  70        void (*out)(u32 val, void __iomem *addr);
  71};
  72
  73static u32 uartlite_inbe32(void __iomem *addr)
  74{
  75        return ioread32be(addr);
  76}
  77
  78static void uartlite_outbe32(u32 val, void __iomem *addr)
  79{
  80        iowrite32be(val, addr);
  81}
  82
  83static const struct uartlite_reg_ops uartlite_be = {
  84        .in = uartlite_inbe32,
  85        .out = uartlite_outbe32,
  86};
  87
  88static u32 uartlite_inle32(void __iomem *addr)
  89{
  90        return ioread32(addr);
  91}
  92
  93static void uartlite_outle32(u32 val, void __iomem *addr)
  94{
  95        iowrite32(val, addr);
  96}
  97
  98static const struct uartlite_reg_ops uartlite_le = {
  99        .in = uartlite_inle32,
 100        .out = uartlite_outle32,
 101};
 102
 103static inline u32 uart_in32(u32 offset, struct uart_port *port)
 104{
 105        struct uartlite_data *pdata = port->private_data;
 106
 107        return pdata->reg_ops->in(port->membase + offset);
 108}
 109
 110static inline void uart_out32(u32 val, u32 offset, struct uart_port *port)
 111{
 112        struct uartlite_data *pdata = port->private_data;
 113
 114        pdata->reg_ops->out(val, port->membase + offset);
 115}
 116
 117static struct uart_port ulite_ports[ULITE_NR_UARTS];
 118
 119/* ---------------------------------------------------------------------
 120 * Core UART driver operations
 121 */
 122
 123static int ulite_receive(struct uart_port *port, int stat)
 124{
 125        struct tty_port *tport = &port->state->port;
 126        unsigned char ch = 0;
 127        char flag = TTY_NORMAL;
 128
 129        if ((stat & (ULITE_STATUS_RXVALID | ULITE_STATUS_OVERRUN
 130                     | ULITE_STATUS_FRAME)) == 0)
 131                return 0;
 132
 133        /* stats */
 134        if (stat & ULITE_STATUS_RXVALID) {
 135                port->icount.rx++;
 136                ch = uart_in32(ULITE_RX, port);
 137
 138                if (stat & ULITE_STATUS_PARITY)
 139                        port->icount.parity++;
 140        }
 141
 142        if (stat & ULITE_STATUS_OVERRUN)
 143                port->icount.overrun++;
 144
 145        if (stat & ULITE_STATUS_FRAME)
 146                port->icount.frame++;
 147
 148
 149        /* drop byte with parity error if IGNPAR specificed */
 150        if (stat & port->ignore_status_mask & ULITE_STATUS_PARITY)
 151                stat &= ~ULITE_STATUS_RXVALID;
 152
 153        stat &= port->read_status_mask;
 154
 155        if (stat & ULITE_STATUS_PARITY)
 156                flag = TTY_PARITY;
 157
 158
 159        stat &= ~port->ignore_status_mask;
 160
 161        if (stat & ULITE_STATUS_RXVALID)
 162                tty_insert_flip_char(tport, ch, flag);
 163
 164        if (stat & ULITE_STATUS_FRAME)
 165                tty_insert_flip_char(tport, 0, TTY_FRAME);
 166
 167        if (stat & ULITE_STATUS_OVERRUN)
 168                tty_insert_flip_char(tport, 0, TTY_OVERRUN);
 169
 170        return 1;
 171}
 172
 173static int ulite_transmit(struct uart_port *port, int stat)
 174{
 175        struct circ_buf *xmit  = &port->state->xmit;
 176
 177        if (stat & ULITE_STATUS_TXFULL)
 178                return 0;
 179
 180        if (port->x_char) {
 181                uart_out32(port->x_char, ULITE_TX, port);
 182                port->x_char = 0;
 183                port->icount.tx++;
 184                return 1;
 185        }
 186
 187        if (uart_circ_empty(xmit) || uart_tx_stopped(port))
 188                return 0;
 189
 190        uart_out32(xmit->buf[xmit->tail], ULITE_TX, port);
 191        xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE-1);
 192        port->icount.tx++;
 193
 194        /* wake up */
 195        if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 196                uart_write_wakeup(port);
 197
 198        return 1;
 199}
 200
 201static irqreturn_t ulite_isr(int irq, void *dev_id)
 202{
 203        struct uart_port *port = dev_id;
 204        int stat, busy, n = 0;
 205        unsigned long flags;
 206
 207        do {
 208                spin_lock_irqsave(&port->lock, flags);
 209                stat = uart_in32(ULITE_STATUS, port);
 210                busy  = ulite_receive(port, stat);
 211                busy |= ulite_transmit(port, stat);
 212                spin_unlock_irqrestore(&port->lock, flags);
 213                n++;
 214        } while (busy);
 215
 216        /* work done? */
 217        if (n > 1) {
 218                tty_flip_buffer_push(&port->state->port);
 219                return IRQ_HANDLED;
 220        } else {
 221                return IRQ_NONE;
 222        }
 223}
 224
 225static unsigned int ulite_tx_empty(struct uart_port *port)
 226{
 227        unsigned long flags;
 228        unsigned int ret;
 229
 230        spin_lock_irqsave(&port->lock, flags);
 231        ret = uart_in32(ULITE_STATUS, port);
 232        spin_unlock_irqrestore(&port->lock, flags);
 233
 234        return ret & ULITE_STATUS_TXEMPTY ? TIOCSER_TEMT : 0;
 235}
 236
 237static unsigned int ulite_get_mctrl(struct uart_port *port)
 238{
 239        return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
 240}
 241
 242static void ulite_set_mctrl(struct uart_port *port, unsigned int mctrl)
 243{
 244        /* N/A */
 245}
 246
 247static void ulite_stop_tx(struct uart_port *port)
 248{
 249        /* N/A */
 250}
 251
 252static void ulite_start_tx(struct uart_port *port)
 253{
 254        ulite_transmit(port, uart_in32(ULITE_STATUS, port));
 255}
 256
 257static void ulite_stop_rx(struct uart_port *port)
 258{
 259        /* don't forward any more data (like !CREAD) */
 260        port->ignore_status_mask = ULITE_STATUS_RXVALID | ULITE_STATUS_PARITY
 261                | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
 262}
 263
 264static void ulite_break_ctl(struct uart_port *port, int ctl)
 265{
 266        /* N/A */
 267}
 268
 269static int ulite_startup(struct uart_port *port)
 270{
 271        struct uartlite_data *pdata = port->private_data;
 272        int ret;
 273
 274        ret = clk_enable(pdata->clk);
 275        if (ret) {
 276                dev_err(port->dev, "Failed to enable clock\n");
 277                return ret;
 278        }
 279
 280        ret = request_irq(port->irq, ulite_isr, IRQF_SHARED | IRQF_TRIGGER_RISING,
 281                          "uartlite", port);
 282        if (ret)
 283                return ret;
 284
 285        uart_out32(ULITE_CONTROL_RST_RX | ULITE_CONTROL_RST_TX,
 286                ULITE_CONTROL, port);
 287        uart_out32(ULITE_CONTROL_IE, ULITE_CONTROL, port);
 288
 289        return 0;
 290}
 291
 292static void ulite_shutdown(struct uart_port *port)
 293{
 294        struct uartlite_data *pdata = port->private_data;
 295
 296        uart_out32(0, ULITE_CONTROL, port);
 297        uart_in32(ULITE_CONTROL, port); /* dummy */
 298        free_irq(port->irq, port);
 299        clk_disable(pdata->clk);
 300}
 301
 302static void ulite_set_termios(struct uart_port *port, struct ktermios *termios,
 303                              struct ktermios *old)
 304{
 305        unsigned long flags;
 306        unsigned int baud;
 307
 308        spin_lock_irqsave(&port->lock, flags);
 309
 310        port->read_status_mask = ULITE_STATUS_RXVALID | ULITE_STATUS_OVERRUN
 311                | ULITE_STATUS_TXFULL;
 312
 313        if (termios->c_iflag & INPCK)
 314                port->read_status_mask |=
 315                        ULITE_STATUS_PARITY | ULITE_STATUS_FRAME;
 316
 317        port->ignore_status_mask = 0;
 318        if (termios->c_iflag & IGNPAR)
 319                port->ignore_status_mask |= ULITE_STATUS_PARITY
 320                        | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
 321
 322        /* ignore all characters if CREAD is not set */
 323        if ((termios->c_cflag & CREAD) == 0)
 324                port->ignore_status_mask |=
 325                        ULITE_STATUS_RXVALID | ULITE_STATUS_PARITY
 326                        | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
 327
 328        /* update timeout */
 329        baud = uart_get_baud_rate(port, termios, old, 0, 460800);
 330        uart_update_timeout(port, termios->c_cflag, baud);
 331
 332        spin_unlock_irqrestore(&port->lock, flags);
 333}
 334
 335static const char *ulite_type(struct uart_port *port)
 336{
 337        return port->type == PORT_UARTLITE ? "uartlite" : NULL;
 338}
 339
 340static void ulite_release_port(struct uart_port *port)
 341{
 342        release_mem_region(port->mapbase, ULITE_REGION);
 343        iounmap(port->membase);
 344        port->membase = NULL;
 345}
 346
 347static int ulite_request_port(struct uart_port *port)
 348{
 349        struct uartlite_data *pdata = port->private_data;
 350        int ret;
 351
 352        pr_debug("ulite console: port=%p; port->mapbase=%llx\n",
 353                 port, (unsigned long long) port->mapbase);
 354
 355        if (!request_mem_region(port->mapbase, ULITE_REGION, "uartlite")) {
 356                dev_err(port->dev, "Memory region busy\n");
 357                return -EBUSY;
 358        }
 359
 360        port->membase = ioremap(port->mapbase, ULITE_REGION);
 361        if (!port->membase) {
 362                dev_err(port->dev, "Unable to map registers\n");
 363                release_mem_region(port->mapbase, ULITE_REGION);
 364                return -EBUSY;
 365        }
 366
 367        pdata->reg_ops = &uartlite_be;
 368        ret = uart_in32(ULITE_CONTROL, port);
 369        uart_out32(ULITE_CONTROL_RST_TX, ULITE_CONTROL, port);
 370        ret = uart_in32(ULITE_STATUS, port);
 371        /* Endianess detection */
 372        if ((ret & ULITE_STATUS_TXEMPTY) != ULITE_STATUS_TXEMPTY)
 373                pdata->reg_ops = &uartlite_le;
 374
 375        return 0;
 376}
 377
 378static void ulite_config_port(struct uart_port *port, int flags)
 379{
 380        if (!ulite_request_port(port))
 381                port->type = PORT_UARTLITE;
 382}
 383
 384static int ulite_verify_port(struct uart_port *port, struct serial_struct *ser)
 385{
 386        /* we don't want the core code to modify any port params */
 387        return -EINVAL;
 388}
 389
 390static void ulite_pm(struct uart_port *port, unsigned int state,
 391                     unsigned int oldstate)
 392{
 393        struct uartlite_data *pdata = port->private_data;
 394
 395        if (!state)
 396                clk_enable(pdata->clk);
 397        else
 398                clk_disable(pdata->clk);
 399}
 400
 401#ifdef CONFIG_CONSOLE_POLL
 402static int ulite_get_poll_char(struct uart_port *port)
 403{
 404        if (!(uart_in32(ULITE_STATUS, port) & ULITE_STATUS_RXVALID))
 405                return NO_POLL_CHAR;
 406
 407        return uart_in32(ULITE_RX, port);
 408}
 409
 410static void ulite_put_poll_char(struct uart_port *port, unsigned char ch)
 411{
 412        while (uart_in32(ULITE_STATUS, port) & ULITE_STATUS_TXFULL)
 413                cpu_relax();
 414
 415        /* write char to device */
 416        uart_out32(ch, ULITE_TX, port);
 417}
 418#endif
 419
 420static const struct uart_ops ulite_ops = {
 421        .tx_empty       = ulite_tx_empty,
 422        .set_mctrl      = ulite_set_mctrl,
 423        .get_mctrl      = ulite_get_mctrl,
 424        .stop_tx        = ulite_stop_tx,
 425        .start_tx       = ulite_start_tx,
 426        .stop_rx        = ulite_stop_rx,
 427        .break_ctl      = ulite_break_ctl,
 428        .startup        = ulite_startup,
 429        .shutdown       = ulite_shutdown,
 430        .set_termios    = ulite_set_termios,
 431        .type           = ulite_type,
 432        .release_port   = ulite_release_port,
 433        .request_port   = ulite_request_port,
 434        .config_port    = ulite_config_port,
 435        .verify_port    = ulite_verify_port,
 436        .pm             = ulite_pm,
 437#ifdef CONFIG_CONSOLE_POLL
 438        .poll_get_char  = ulite_get_poll_char,
 439        .poll_put_char  = ulite_put_poll_char,
 440#endif
 441};
 442
 443/* ---------------------------------------------------------------------
 444 * Console driver operations
 445 */
 446
 447#ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
 448static void ulite_console_wait_tx(struct uart_port *port)
 449{
 450        u8 val;
 451        unsigned long timeout;
 452
 453        /*
 454         * Spin waiting for TX fifo to have space available.
 455         * When using the Microblaze Debug Module this can take up to 1s
 456         */
 457        timeout = jiffies + msecs_to_jiffies(1000);
 458        while (1) {
 459                val = uart_in32(ULITE_STATUS, port);
 460                if ((val & ULITE_STATUS_TXFULL) == 0)
 461                        break;
 462                if (time_after(jiffies, timeout)) {
 463                        dev_warn(port->dev,
 464                                 "timeout waiting for TX buffer empty\n");
 465                        break;
 466                }
 467                cpu_relax();
 468        }
 469}
 470
 471static void ulite_console_putchar(struct uart_port *port, int ch)
 472{
 473        ulite_console_wait_tx(port);
 474        uart_out32(ch, ULITE_TX, port);
 475}
 476
 477static void ulite_console_write(struct console *co, const char *s,
 478                                unsigned int count)
 479{
 480        struct uart_port *port = console_port;
 481        unsigned long flags;
 482        unsigned int ier;
 483        int locked = 1;
 484
 485        if (oops_in_progress) {
 486                locked = spin_trylock_irqsave(&port->lock, flags);
 487        } else
 488                spin_lock_irqsave(&port->lock, flags);
 489
 490        /* save and disable interrupt */
 491        ier = uart_in32(ULITE_STATUS, port) & ULITE_STATUS_IE;
 492        uart_out32(0, ULITE_CONTROL, port);
 493
 494        uart_console_write(port, s, count, ulite_console_putchar);
 495
 496        ulite_console_wait_tx(port);
 497
 498        /* restore interrupt state */
 499        if (ier)
 500                uart_out32(ULITE_CONTROL_IE, ULITE_CONTROL, port);
 501
 502        if (locked)
 503                spin_unlock_irqrestore(&port->lock, flags);
 504}
 505
 506static int ulite_console_setup(struct console *co, char *options)
 507{
 508        struct uart_port *port = NULL;
 509        int baud = 9600;
 510        int bits = 8;
 511        int parity = 'n';
 512        int flow = 'n';
 513
 514        if (co->index >= 0 && co->index < ULITE_NR_UARTS)
 515                port = ulite_ports + co->index;
 516
 517        /* Has the device been initialized yet? */
 518        if (!port || !port->mapbase) {
 519                pr_debug("console on ttyUL%i not present\n", co->index);
 520                return -ENODEV;
 521        }
 522
 523        console_port = port;
 524
 525        /* not initialized yet? */
 526        if (!port->membase) {
 527                if (ulite_request_port(port))
 528                        return -ENODEV;
 529        }
 530
 531        if (options)
 532                uart_parse_options(options, &baud, &parity, &bits, &flow);
 533
 534        return uart_set_options(port, co, baud, parity, bits, flow);
 535}
 536
 537static struct uart_driver ulite_uart_driver;
 538
 539static struct console ulite_console = {
 540        .name   = ULITE_NAME,
 541        .write  = ulite_console_write,
 542        .device = uart_console_device,
 543        .setup  = ulite_console_setup,
 544        .flags  = CON_PRINTBUFFER,
 545        .index  = -1, /* Specified on the cmdline (e.g. console=ttyUL0 ) */
 546        .data   = &ulite_uart_driver,
 547};
 548
 549static void early_uartlite_putc(struct uart_port *port, int c)
 550{
 551        /*
 552         * Limit how many times we'll spin waiting for TX FIFO status.
 553         * This will prevent lockups if the base address is incorrectly
 554         * set, or any other issue on the UARTLITE.
 555         * This limit is pretty arbitrary, unless we are at about 10 baud
 556         * we'll never timeout on a working UART.
 557         */
 558
 559        unsigned retries = 1000000;
 560        /* read status bit - 0x8 offset */
 561        while (--retries && (readl(port->membase + 8) & (1 << 3)))
 562                ;
 563
 564        /* Only attempt the iowrite if we didn't timeout */
 565        /* write to TX_FIFO - 0x4 offset */
 566        if (retries)
 567                writel(c & 0xff, port->membase + 4);
 568}
 569
 570static void early_uartlite_write(struct console *console,
 571                                 const char *s, unsigned n)
 572{
 573        struct earlycon_device *device = console->data;
 574        uart_console_write(&device->port, s, n, early_uartlite_putc);
 575}
 576
 577static int __init early_uartlite_setup(struct earlycon_device *device,
 578                                       const char *options)
 579{
 580        if (!device->port.membase)
 581                return -ENODEV;
 582
 583        device->con->write = early_uartlite_write;
 584        return 0;
 585}
 586EARLYCON_DECLARE(uartlite, early_uartlite_setup);
 587OF_EARLYCON_DECLARE(uartlite_b, "xlnx,opb-uartlite-1.00.b", early_uartlite_setup);
 588OF_EARLYCON_DECLARE(uartlite_a, "xlnx,xps-uartlite-1.00.a", early_uartlite_setup);
 589
 590#endif /* CONFIG_SERIAL_UARTLITE_CONSOLE */
 591
 592static struct uart_driver ulite_uart_driver = {
 593        .owner          = THIS_MODULE,
 594        .driver_name    = "uartlite",
 595        .dev_name       = ULITE_NAME,
 596        .major          = ULITE_MAJOR,
 597        .minor          = ULITE_MINOR,
 598        .nr             = ULITE_NR_UARTS,
 599#ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
 600        .cons           = &ulite_console,
 601#endif
 602};
 603
 604/* ---------------------------------------------------------------------
 605 * Port assignment functions (mapping devices to uart_port structures)
 606 */
 607
 608/** ulite_assign: register a uartlite device with the driver
 609 *
 610 * @dev: pointer to device structure
 611 * @id: requested id number.  Pass -1 for automatic port assignment
 612 * @base: base address of uartlite registers
 613 * @irq: irq number for uartlite
 614 * @pdata: private data for uartlite
 615 *
 616 * Returns: 0 on success, <0 otherwise
 617 */
 618static int ulite_assign(struct device *dev, int id, u32 base, int irq,
 619                        struct uartlite_data *pdata)
 620{
 621        struct uart_port *port;
 622        int rc;
 623
 624        /* if id = -1; then scan for a free id and use that */
 625        if (id < 0) {
 626                for (id = 0; id < ULITE_NR_UARTS; id++)
 627                        if (ulite_ports[id].mapbase == 0)
 628                                break;
 629        }
 630        if (id < 0 || id >= ULITE_NR_UARTS) {
 631                dev_err(dev, "%s%i too large\n", ULITE_NAME, id);
 632                return -EINVAL;
 633        }
 634
 635        if ((ulite_ports[id].mapbase) && (ulite_ports[id].mapbase != base)) {
 636                dev_err(dev, "cannot assign to %s%i; it is already in use\n",
 637                        ULITE_NAME, id);
 638                return -EBUSY;
 639        }
 640
 641        port = &ulite_ports[id];
 642
 643        spin_lock_init(&port->lock);
 644        port->fifosize = 16;
 645        port->regshift = 2;
 646        port->iotype = UPIO_MEM;
 647        port->iobase = 1; /* mark port in use */
 648        port->mapbase = base;
 649        port->membase = NULL;
 650        port->ops = &ulite_ops;
 651        port->irq = irq;
 652        port->flags = UPF_BOOT_AUTOCONF;
 653        port->dev = dev;
 654        port->type = PORT_UNKNOWN;
 655        port->line = id;
 656        port->private_data = pdata;
 657
 658        dev_set_drvdata(dev, port);
 659
 660        /* Register the port */
 661        rc = uart_add_one_port(&ulite_uart_driver, port);
 662        if (rc) {
 663                dev_err(dev, "uart_add_one_port() failed; err=%i\n", rc);
 664                port->mapbase = 0;
 665                dev_set_drvdata(dev, NULL);
 666                return rc;
 667        }
 668
 669        return 0;
 670}
 671
 672/** ulite_release: register a uartlite device with the driver
 673 *
 674 * @dev: pointer to device structure
 675 */
 676static int ulite_release(struct device *dev)
 677{
 678        struct uart_port *port = dev_get_drvdata(dev);
 679        int rc = 0;
 680
 681        if (port) {
 682                rc = uart_remove_one_port(&ulite_uart_driver, port);
 683                dev_set_drvdata(dev, NULL);
 684                port->mapbase = 0;
 685        }
 686
 687        return rc;
 688}
 689
 690/**
 691 * ulite_suspend - Stop the device.
 692 *
 693 * @dev: handle to the device structure.
 694 * Return: 0 always.
 695 */
 696static int __maybe_unused ulite_suspend(struct device *dev)
 697{
 698        struct uart_port *port = dev_get_drvdata(dev);
 699
 700        if (port)
 701                uart_suspend_port(&ulite_uart_driver, port);
 702
 703        return 0;
 704}
 705
 706/**
 707 * ulite_resume - Resume the device.
 708 *
 709 * @dev: handle to the device structure.
 710 * Return: 0 on success, errno otherwise.
 711 */
 712static int __maybe_unused ulite_resume(struct device *dev)
 713{
 714        struct uart_port *port = dev_get_drvdata(dev);
 715
 716        if (port)
 717                uart_resume_port(&ulite_uart_driver, port);
 718
 719        return 0;
 720}
 721
 722/* ---------------------------------------------------------------------
 723 * Platform bus binding
 724 */
 725
 726static SIMPLE_DEV_PM_OPS(ulite_pm_ops, ulite_suspend, ulite_resume);
 727
 728#if defined(CONFIG_OF)
 729/* Match table for of_platform binding */
 730static const struct of_device_id ulite_of_match[] = {
 731        { .compatible = "xlnx,opb-uartlite-1.00.b", },
 732        { .compatible = "xlnx,xps-uartlite-1.00.a", },
 733        {}
 734};
 735MODULE_DEVICE_TABLE(of, ulite_of_match);
 736#endif /* CONFIG_OF */
 737
 738static int ulite_probe(struct platform_device *pdev)
 739{
 740        struct resource *res;
 741        struct uartlite_data *pdata;
 742        int irq, ret;
 743        int id = pdev->id;
 744#ifdef CONFIG_OF
 745        const __be32 *prop;
 746
 747        prop = of_get_property(pdev->dev.of_node, "port-number", NULL);
 748        if (prop)
 749                id = be32_to_cpup(prop);
 750#endif
 751        pdata = devm_kzalloc(&pdev->dev, sizeof(struct uartlite_data),
 752                             GFP_KERNEL);
 753        if (!pdata)
 754                return -ENOMEM;
 755
 756        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 757        if (!res)
 758                return -ENODEV;
 759
 760        irq = platform_get_irq(pdev, 0);
 761        if (irq < 0)
 762                return irq;
 763
 764        pdata->clk = devm_clk_get(&pdev->dev, "s_axi_aclk");
 765        if (IS_ERR(pdata->clk)) {
 766                if (PTR_ERR(pdata->clk) != -ENOENT)
 767                        return PTR_ERR(pdata->clk);
 768
 769                /*
 770                 * Clock framework support is optional, continue on
 771                 * anyways if we don't find a matching clock.
 772                 */
 773                pdata->clk = NULL;
 774        }
 775
 776        ret = clk_prepare_enable(pdata->clk);
 777        if (ret) {
 778                dev_err(&pdev->dev, "Failed to prepare clock\n");
 779                return ret;
 780        }
 781
 782        if (!ulite_uart_driver.state) {
 783                dev_dbg(&pdev->dev, "uartlite: calling uart_register_driver()\n");
 784                ret = uart_register_driver(&ulite_uart_driver);
 785                if (ret < 0) {
 786                        dev_err(&pdev->dev, "Failed to register driver\n");
 787                        return ret;
 788                }
 789        }
 790
 791        ret = ulite_assign(&pdev->dev, id, res->start, irq, pdata);
 792
 793        clk_disable(pdata->clk);
 794
 795        return ret;
 796}
 797
 798static int ulite_remove(struct platform_device *pdev)
 799{
 800        struct uart_port *port = dev_get_drvdata(&pdev->dev);
 801        struct uartlite_data *pdata = port->private_data;
 802
 803        clk_disable_unprepare(pdata->clk);
 804        return ulite_release(&pdev->dev);
 805}
 806
 807/* work with hotplug and coldplug */
 808MODULE_ALIAS("platform:uartlite");
 809
 810static struct platform_driver ulite_platform_driver = {
 811        .probe = ulite_probe,
 812        .remove = ulite_remove,
 813        .driver = {
 814                .name  = "uartlite",
 815                .of_match_table = of_match_ptr(ulite_of_match),
 816                .pm = &ulite_pm_ops,
 817        },
 818};
 819
 820/* ---------------------------------------------------------------------
 821 * Module setup/teardown
 822 */
 823
 824static int __init ulite_init(void)
 825{
 826
 827        pr_debug("uartlite: calling platform_driver_register()\n");
 828        return platform_driver_register(&ulite_platform_driver);
 829}
 830
 831static void __exit ulite_exit(void)
 832{
 833        platform_driver_unregister(&ulite_platform_driver);
 834        if (ulite_uart_driver.state)
 835                uart_unregister_driver(&ulite_uart_driver);
 836}
 837
 838module_init(ulite_init);
 839module_exit(ulite_exit);
 840
 841MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
 842MODULE_DESCRIPTION("Xilinx uartlite serial driver");
 843MODULE_LICENSE("GPL");
 844