linux/drivers/tty/serial/digicolor-usart.c
<<
>>
Prefs
   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 *  Driver for Conexant Digicolor serial ports (USART)
   4 *
   5 * Author: Baruch Siach <baruch@tkos.co.il>
   6 *
   7 * Copyright (C) 2014 Paradox Innovation Ltd.
   8 */
   9
  10#include <linux/module.h>
  11#include <linux/console.h>
  12#include <linux/serial_core.h>
  13#include <linux/serial.h>
  14#include <linux/clk.h>
  15#include <linux/io.h>
  16#include <linux/tty.h>
  17#include <linux/tty_flip.h>
  18#include <linux/of.h>
  19#include <linux/platform_device.h>
  20#include <linux/workqueue.h>
  21
  22#define UA_ENABLE                       0x00
  23#define UA_ENABLE_ENABLE                BIT(0)
  24
  25#define UA_CONTROL                      0x01
  26#define UA_CONTROL_RX_ENABLE            BIT(0)
  27#define UA_CONTROL_TX_ENABLE            BIT(1)
  28#define UA_CONTROL_SOFT_RESET           BIT(2)
  29
  30#define UA_STATUS                       0x02
  31#define UA_STATUS_PARITY_ERR            BIT(0)
  32#define UA_STATUS_FRAME_ERR             BIT(1)
  33#define UA_STATUS_OVERRUN_ERR           BIT(2)
  34#define UA_STATUS_TX_READY              BIT(6)
  35
  36#define UA_CONFIG                       0x03
  37#define UA_CONFIG_CHAR_LEN              BIT(0)
  38#define UA_CONFIG_STOP_BITS             BIT(1)
  39#define UA_CONFIG_PARITY                BIT(2)
  40#define UA_CONFIG_ODD_PARITY            BIT(4)
  41
  42#define UA_EMI_REC                      0x04
  43
  44#define UA_HBAUD_LO                     0x08
  45#define UA_HBAUD_HI                     0x09
  46
  47#define UA_STATUS_FIFO                  0x0a
  48#define UA_STATUS_FIFO_RX_EMPTY         BIT(2)
  49#define UA_STATUS_FIFO_RX_INT_ALMOST    BIT(3)
  50#define UA_STATUS_FIFO_TX_FULL          BIT(4)
  51#define UA_STATUS_FIFO_TX_INT_ALMOST    BIT(7)
  52
  53#define UA_CONFIG_FIFO                  0x0b
  54#define UA_CONFIG_FIFO_RX_THRESH        7
  55#define UA_CONFIG_FIFO_RX_FIFO_MODE     BIT(3)
  56#define UA_CONFIG_FIFO_TX_FIFO_MODE     BIT(7)
  57
  58#define UA_INTFLAG_CLEAR                0x1c
  59#define UA_INTFLAG_SET                  0x1d
  60#define UA_INT_ENABLE                   0x1e
  61#define UA_INT_STATUS                   0x1f
  62
  63#define UA_INT_TX                       BIT(0)
  64#define UA_INT_RX                       BIT(1)
  65
  66#define DIGICOLOR_USART_NR              3
  67
  68/*
  69 * We use the 16 bytes hardware FIFO to buffer Rx traffic. Rx interrupt is
  70 * only produced when the FIFO is filled more than a certain configurable
  71 * threshold. Unfortunately, there is no way to set this threshold below half
  72 * FIFO. This means that we must periodically poll the FIFO status register to
  73 * see whether there are waiting Rx bytes.
  74 */
  75
  76struct digicolor_port {
  77        struct uart_port port;
  78        struct delayed_work rx_poll_work;
  79};
  80
  81static struct uart_port *digicolor_ports[DIGICOLOR_USART_NR];
  82
  83static bool digicolor_uart_tx_full(struct uart_port *port)
  84{
  85        return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &
  86                  UA_STATUS_FIFO_TX_FULL);
  87}
  88
  89static bool digicolor_uart_rx_empty(struct uart_port *port)
  90{
  91        return !!(readb_relaxed(port->membase + UA_STATUS_FIFO) &
  92                  UA_STATUS_FIFO_RX_EMPTY);
  93}
  94
  95static void digicolor_uart_stop_tx(struct uart_port *port)
  96{
  97        u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);
  98
  99        int_enable &= ~UA_INT_TX;
 100        writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
 101}
 102
 103static void digicolor_uart_start_tx(struct uart_port *port)
 104{
 105        u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);
 106
 107        int_enable |= UA_INT_TX;
 108        writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
 109}
 110
 111static void digicolor_uart_stop_rx(struct uart_port *port)
 112{
 113        u8 int_enable = readb_relaxed(port->membase + UA_INT_ENABLE);
 114
 115        int_enable &= ~UA_INT_RX;
 116        writeb_relaxed(int_enable, port->membase + UA_INT_ENABLE);
 117}
 118
 119static void digicolor_rx_poll(struct work_struct *work)
 120{
 121        struct digicolor_port *dp =
 122                container_of(to_delayed_work(work),
 123                             struct digicolor_port, rx_poll_work);
 124
 125        if (!digicolor_uart_rx_empty(&dp->port))
 126                /* force RX interrupt */
 127                writeb_relaxed(UA_INT_RX, dp->port.membase + UA_INTFLAG_SET);
 128
 129        schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));
 130}
 131
 132static void digicolor_uart_rx(struct uart_port *port)
 133{
 134        unsigned long flags;
 135
 136        spin_lock_irqsave(&port->lock, flags);
 137
 138        while (1) {
 139                u8 status, ch;
 140                unsigned int ch_flag;
 141
 142                if (digicolor_uart_rx_empty(port))
 143                        break;
 144
 145                ch = readb_relaxed(port->membase + UA_EMI_REC);
 146                status = readb_relaxed(port->membase + UA_STATUS);
 147
 148                port->icount.rx++;
 149                ch_flag = TTY_NORMAL;
 150
 151                if (status) {
 152                        if (status & UA_STATUS_PARITY_ERR)
 153                                port->icount.parity++;
 154                        else if (status & UA_STATUS_FRAME_ERR)
 155                                port->icount.frame++;
 156                        else if (status & UA_STATUS_OVERRUN_ERR)
 157                                port->icount.overrun++;
 158
 159                        status &= port->read_status_mask;
 160
 161                        if (status & UA_STATUS_PARITY_ERR)
 162                                ch_flag = TTY_PARITY;
 163                        else if (status & UA_STATUS_FRAME_ERR)
 164                                ch_flag = TTY_FRAME;
 165                        else if (status & UA_STATUS_OVERRUN_ERR)
 166                                ch_flag = TTY_OVERRUN;
 167                }
 168
 169                if (status & port->ignore_status_mask)
 170                        continue;
 171
 172                uart_insert_char(port, status, UA_STATUS_OVERRUN_ERR, ch,
 173                                 ch_flag);
 174        }
 175
 176        spin_unlock_irqrestore(&port->lock, flags);
 177
 178        tty_flip_buffer_push(&port->state->port);
 179}
 180
 181static void digicolor_uart_tx(struct uart_port *port)
 182{
 183        struct circ_buf *xmit = &port->state->xmit;
 184        unsigned long flags;
 185
 186        if (digicolor_uart_tx_full(port))
 187                return;
 188
 189        spin_lock_irqsave(&port->lock, flags);
 190
 191        if (port->x_char) {
 192                writeb_relaxed(port->x_char, port->membase + UA_EMI_REC);
 193                port->icount.tx++;
 194                port->x_char = 0;
 195                goto out;
 196        }
 197
 198        if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
 199                digicolor_uart_stop_tx(port);
 200                goto out;
 201        }
 202
 203        while (!uart_circ_empty(xmit)) {
 204                writeb(xmit->buf[xmit->tail], port->membase + UA_EMI_REC);
 205                xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 206                port->icount.tx++;
 207
 208                if (digicolor_uart_tx_full(port))
 209                        break;
 210        }
 211
 212        if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 213                uart_write_wakeup(port);
 214
 215out:
 216        spin_unlock_irqrestore(&port->lock, flags);
 217}
 218
 219static irqreturn_t digicolor_uart_int(int irq, void *dev_id)
 220{
 221        struct uart_port *port = dev_id;
 222        u8 int_status = readb_relaxed(port->membase + UA_INT_STATUS);
 223
 224        writeb_relaxed(UA_INT_RX | UA_INT_TX,
 225                       port->membase + UA_INTFLAG_CLEAR);
 226
 227        if (int_status & UA_INT_RX)
 228                digicolor_uart_rx(port);
 229        if (int_status & UA_INT_TX)
 230                digicolor_uart_tx(port);
 231
 232        return IRQ_HANDLED;
 233}
 234
 235static unsigned int digicolor_uart_tx_empty(struct uart_port *port)
 236{
 237        u8 status = readb_relaxed(port->membase + UA_STATUS);
 238
 239        return (status & UA_STATUS_TX_READY) ? TIOCSER_TEMT : 0;
 240}
 241
 242static unsigned int digicolor_uart_get_mctrl(struct uart_port *port)
 243{
 244        return TIOCM_CTS;
 245}
 246
 247static void digicolor_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 248{
 249}
 250
 251static void digicolor_uart_break_ctl(struct uart_port *port, int state)
 252{
 253}
 254
 255static int digicolor_uart_startup(struct uart_port *port)
 256{
 257        struct digicolor_port *dp =
 258                container_of(port, struct digicolor_port, port);
 259
 260        writeb_relaxed(UA_ENABLE_ENABLE, port->membase + UA_ENABLE);
 261        writeb_relaxed(UA_CONTROL_SOFT_RESET, port->membase + UA_CONTROL);
 262        writeb_relaxed(0, port->membase + UA_CONTROL);
 263
 264        writeb_relaxed(UA_CONFIG_FIFO_RX_FIFO_MODE
 265                       | UA_CONFIG_FIFO_TX_FIFO_MODE | UA_CONFIG_FIFO_RX_THRESH,
 266                       port->membase + UA_CONFIG_FIFO);
 267        writeb_relaxed(UA_STATUS_FIFO_RX_INT_ALMOST,
 268                       port->membase + UA_STATUS_FIFO);
 269        writeb_relaxed(UA_CONTROL_RX_ENABLE | UA_CONTROL_TX_ENABLE,
 270                       port->membase + UA_CONTROL);
 271        writeb_relaxed(UA_INT_TX | UA_INT_RX,
 272                       port->membase + UA_INT_ENABLE);
 273
 274        schedule_delayed_work(&dp->rx_poll_work, msecs_to_jiffies(100));
 275
 276        return 0;
 277}
 278
 279static void digicolor_uart_shutdown(struct uart_port *port)
 280{
 281        struct digicolor_port *dp =
 282                container_of(port, struct digicolor_port, port);
 283
 284        writeb_relaxed(0, port->membase + UA_ENABLE);
 285        cancel_delayed_work_sync(&dp->rx_poll_work);
 286}
 287
 288static void digicolor_uart_set_termios(struct uart_port *port,
 289                                       struct ktermios *termios,
 290                                       struct ktermios *old)
 291{
 292        unsigned int baud, divisor;
 293        u8 config = 0;
 294        unsigned long flags;
 295
 296        /* Mask termios capabilities we don't support */
 297        termios->c_cflag &= ~CMSPAR;
 298        termios->c_iflag &= ~(BRKINT | IGNBRK);
 299
 300        /* Limit baud rates so that we don't need the fractional divider */
 301        baud = uart_get_baud_rate(port, termios, old,
 302                                  port->uartclk / (0x10000*16),
 303                                  port->uartclk / 256);
 304        divisor = uart_get_divisor(port, baud) - 1;
 305
 306        switch (termios->c_cflag & CSIZE) {
 307        case CS7:
 308                break;
 309        case CS8:
 310        default:
 311                config |= UA_CONFIG_CHAR_LEN;
 312                break;
 313        }
 314
 315        if (termios->c_cflag & CSTOPB)
 316                config |= UA_CONFIG_STOP_BITS;
 317
 318        if (termios->c_cflag & PARENB) {
 319                config |= UA_CONFIG_PARITY;
 320                if (termios->c_cflag & PARODD)
 321                        config |= UA_CONFIG_ODD_PARITY;
 322        }
 323
 324        /* Set read status mask */
 325        port->read_status_mask = UA_STATUS_OVERRUN_ERR;
 326        if (termios->c_iflag & INPCK)
 327                port->read_status_mask |= UA_STATUS_PARITY_ERR
 328                        | UA_STATUS_FRAME_ERR;
 329
 330        /* Set status ignore mask */
 331        port->ignore_status_mask = 0;
 332        if (!(termios->c_cflag & CREAD))
 333                port->ignore_status_mask |= UA_STATUS_OVERRUN_ERR
 334                        | UA_STATUS_PARITY_ERR | UA_STATUS_FRAME_ERR;
 335
 336        spin_lock_irqsave(&port->lock, flags);
 337
 338        uart_update_timeout(port, termios->c_cflag, baud);
 339
 340        writeb_relaxed(config, port->membase + UA_CONFIG);
 341        writeb_relaxed(divisor & 0xff, port->membase + UA_HBAUD_LO);
 342        writeb_relaxed(divisor >> 8, port->membase + UA_HBAUD_HI);
 343
 344        spin_unlock_irqrestore(&port->lock, flags);
 345}
 346
 347static const char *digicolor_uart_type(struct uart_port *port)
 348{
 349        return (port->type == PORT_DIGICOLOR) ? "DIGICOLOR USART" : NULL;
 350}
 351
 352static void digicolor_uart_config_port(struct uart_port *port, int flags)
 353{
 354        if (flags & UART_CONFIG_TYPE)
 355                port->type = PORT_DIGICOLOR;
 356}
 357
 358static void digicolor_uart_release_port(struct uart_port *port)
 359{
 360}
 361
 362static int digicolor_uart_request_port(struct uart_port *port)
 363{
 364        return 0;
 365}
 366
 367static const struct uart_ops digicolor_uart_ops = {
 368        .tx_empty       = digicolor_uart_tx_empty,
 369        .set_mctrl      = digicolor_uart_set_mctrl,
 370        .get_mctrl      = digicolor_uart_get_mctrl,
 371        .stop_tx        = digicolor_uart_stop_tx,
 372        .start_tx       = digicolor_uart_start_tx,
 373        .stop_rx        = digicolor_uart_stop_rx,
 374        .break_ctl      = digicolor_uart_break_ctl,
 375        .startup        = digicolor_uart_startup,
 376        .shutdown       = digicolor_uart_shutdown,
 377        .set_termios    = digicolor_uart_set_termios,
 378        .type           = digicolor_uart_type,
 379        .config_port    = digicolor_uart_config_port,
 380        .release_port   = digicolor_uart_release_port,
 381        .request_port   = digicolor_uart_request_port,
 382};
 383
 384static void digicolor_uart_console_putchar(struct uart_port *port, int ch)
 385{
 386        while (digicolor_uart_tx_full(port))
 387                cpu_relax();
 388
 389        writeb_relaxed(ch, port->membase + UA_EMI_REC);
 390}
 391
 392static void digicolor_uart_console_write(struct console *co, const char *c,
 393                                         unsigned n)
 394{
 395        struct uart_port *port = digicolor_ports[co->index];
 396        u8 status;
 397        unsigned long flags;
 398        int locked = 1;
 399
 400        if (oops_in_progress)
 401                locked = spin_trylock_irqsave(&port->lock, flags);
 402        else
 403                spin_lock_irqsave(&port->lock, flags);
 404
 405        uart_console_write(port, c, n, digicolor_uart_console_putchar);
 406
 407        if (locked)
 408                spin_unlock_irqrestore(&port->lock, flags);
 409
 410        /* Wait for transmitter to become empty */
 411        do {
 412                status = readb_relaxed(port->membase + UA_STATUS);
 413        } while ((status & UA_STATUS_TX_READY) == 0);
 414}
 415
 416static int digicolor_uart_console_setup(struct console *co, char *options)
 417{
 418        int baud = 115200, bits = 8, parity = 'n', flow = 'n';
 419        struct uart_port *port;
 420
 421        if (co->index < 0 || co->index >= DIGICOLOR_USART_NR)
 422                return -EINVAL;
 423
 424        port = digicolor_ports[co->index];
 425        if (!port)
 426                return -ENODEV;
 427
 428        if (options)
 429                uart_parse_options(options, &baud, &parity, &bits, &flow);
 430
 431        return uart_set_options(port, co, baud, parity, bits, flow);
 432}
 433
 434static struct console digicolor_console = {
 435        .name   = "ttyS",
 436        .device = uart_console_device,
 437        .write  = digicolor_uart_console_write,
 438        .setup  = digicolor_uart_console_setup,
 439        .flags  = CON_PRINTBUFFER,
 440        .index  = -1,
 441};
 442
 443static struct uart_driver digicolor_uart = {
 444        .driver_name    = "digicolor-usart",
 445        .dev_name       = "ttyS",
 446        .nr             = DIGICOLOR_USART_NR,
 447};
 448
 449static int digicolor_uart_probe(struct platform_device *pdev)
 450{
 451        struct device_node *np = pdev->dev.of_node;
 452        int irq, ret, index;
 453        struct digicolor_port *dp;
 454        struct resource *res;
 455        struct clk *uart_clk;
 456
 457        if (!np) {
 458                dev_err(&pdev->dev, "Missing device tree node\n");
 459                return -ENXIO;
 460        }
 461
 462        index = of_alias_get_id(np, "serial");
 463        if (index < 0 || index >= DIGICOLOR_USART_NR)
 464                return -EINVAL;
 465
 466        dp = devm_kzalloc(&pdev->dev, sizeof(*dp), GFP_KERNEL);
 467        if (!dp)
 468                return -ENOMEM;
 469
 470        uart_clk = devm_clk_get(&pdev->dev, NULL);
 471        if (IS_ERR(uart_clk))
 472                return PTR_ERR(uart_clk);
 473
 474        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 475        dp->port.mapbase = res->start;
 476        dp->port.membase = devm_ioremap_resource(&pdev->dev, res);
 477        if (IS_ERR(dp->port.membase))
 478                return PTR_ERR(dp->port.membase);
 479
 480        irq = platform_get_irq(pdev, 0);
 481        if (irq < 0)
 482                return irq;
 483        dp->port.irq = irq;
 484
 485        dp->port.iotype = UPIO_MEM;
 486        dp->port.uartclk = clk_get_rate(uart_clk);
 487        dp->port.fifosize = 16;
 488        dp->port.dev = &pdev->dev;
 489        dp->port.ops = &digicolor_uart_ops;
 490        dp->port.line = index;
 491        dp->port.type = PORT_DIGICOLOR;
 492        spin_lock_init(&dp->port.lock);
 493
 494        digicolor_ports[index] = &dp->port;
 495        platform_set_drvdata(pdev, &dp->port);
 496
 497        INIT_DELAYED_WORK(&dp->rx_poll_work, digicolor_rx_poll);
 498
 499        ret = devm_request_irq(&pdev->dev, dp->port.irq, digicolor_uart_int, 0,
 500                               dev_name(&pdev->dev), &dp->port);
 501        if (ret)
 502                return ret;
 503
 504        return uart_add_one_port(&digicolor_uart, &dp->port);
 505}
 506
 507static int digicolor_uart_remove(struct platform_device *pdev)
 508{
 509        struct uart_port *port = platform_get_drvdata(pdev);
 510
 511        uart_remove_one_port(&digicolor_uart, port);
 512
 513        return 0;
 514}
 515
 516static const struct of_device_id digicolor_uart_dt_ids[] = {
 517        { .compatible = "cnxt,cx92755-usart", },
 518        { }
 519};
 520MODULE_DEVICE_TABLE(of, digicolor_uart_dt_ids);
 521
 522static struct platform_driver digicolor_uart_platform = {
 523        .driver = {
 524                .name           = "digicolor-usart",
 525                .of_match_table = of_match_ptr(digicolor_uart_dt_ids),
 526        },
 527        .probe  = digicolor_uart_probe,
 528        .remove = digicolor_uart_remove,
 529};
 530
 531static int __init digicolor_uart_init(void)
 532{
 533        int ret;
 534
 535        if (IS_ENABLED(CONFIG_SERIAL_CONEXANT_DIGICOLOR_CONSOLE)) {
 536                digicolor_uart.cons = &digicolor_console;
 537                digicolor_console.data = &digicolor_uart;
 538        }
 539
 540        ret = uart_register_driver(&digicolor_uart);
 541        if (ret)
 542                return ret;
 543
 544        return platform_driver_register(&digicolor_uart_platform);
 545}
 546module_init(digicolor_uart_init);
 547
 548static void __exit digicolor_uart_exit(void)
 549{
 550        platform_driver_unregister(&digicolor_uart_platform);
 551        uart_unregister_driver(&digicolor_uart);
 552}
 553module_exit(digicolor_uart_exit);
 554
 555MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
 556MODULE_DESCRIPTION("Conexant Digicolor USART serial driver");
 557MODULE_LICENSE("GPL");
 558