drivers/tty/serial/timbuart.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * timbuart.c timberdale FPGA UART driver
   4  * Copyright (c) 2009 Intel Corporation
   5  */
   6
   7 /* Supports:
   8  * Timberdale FPGA UART
   9  */
  10
  11 #include <linux/pci.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/serial_core.h>
  14 #include <linux/tty.h>
  15 #include <linux/tty_flip.h>
  16 #include <linux/kernel.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/ioport.h>
  19 #include <linux/slab.h>
  20 #include <linux/module.h>
  21
  22 #include "timbuart.h"
  23
  24 struct timbuart_port {
  25         struct uart_port        port;
  26         struct tasklet_struct   tasklet;
  27         int                     usedma;
  28         u32                     last_ier;
  29         struct platform_device  *dev;
  30 };
  31
  32 static int baudrates[] = {9600, 19200, 38400, 57600, 115200, 230400, 460800,
  33         921600, 1843200, 3250000};
  34
  35 static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier);
  36
  37 static irqreturn_t timbuart_handleinterrupt(int irq, void *devid);
  38
  39 static void timbuart_stop_rx(struct uart_port *port)
  40 {
  41         /* spin lock held by upper layer, disable all RX interrupts */
  42         u32 ier = ioread32(port->membase + TIMBUART_IER) & ~RXFLAGS;
  43         iowrite32(ier, port->membase + TIMBUART_IER);
  44 }
  45
  46 static void timbuart_stop_tx(struct uart_port *port)
  47 {
  48         /* spinlock held by upper layer, disable TX interrupt */
  49         u32 ier = ioread32(port->membase + TIMBUART_IER) & ~TXBAE;
  50         iowrite32(ier, port->membase + TIMBUART_IER);
  51 }
  52
  53 static void timbuart_start_tx(struct uart_port *port)
  54 {
  55         struct timbuart_port *uart =
  56                 container_of(port, struct timbuart_port, port);
  57
  58         /* do not transfer anything here -> fire off the tasklet */
  59         tasklet_schedule(&uart->tasklet);
  60 }
  61
  62 static unsigned int timbuart_tx_empty(struct uart_port *port)
  63 {
  64         u32 isr = ioread32(port->membase + TIMBUART_ISR);
  65
  66         return (isr & TXBE) ? TIOCSER_TEMT : 0;
  67 }
  68
  69 static void timbuart_flush_buffer(struct uart_port *port)
  70 {
  71         if (!timbuart_tx_empty(port)) {
  72                 u8 ctl = ioread8(port->membase + TIMBUART_CTRL) |
  73                         TIMBUART_CTRL_FLSHTX;
  74
  75                 iowrite8(ctl, port->membase + TIMBUART_CTRL);
  76                 iowrite32(TXBF, port->membase + TIMBUART_ISR);
  77         }
  78 }
  79
  80 static void timbuart_rx_chars(struct uart_port *port)
  81 {
  82         struct tty_port *tport = &port->state->port;
  83
  84         while (ioread32(port->membase + TIMBUART_ISR) & RXDP) {
  85                 u8 ch = ioread8(port->membase + TIMBUART_RXFIFO);
  86                 port->icount.rx++;
  87                 tty_insert_flip_char(tport, ch, TTY_NORMAL);
  88         }
  89
  90         tty_flip_buffer_push(tport);
  91
  92         dev_dbg(port->dev, "%s - total read %d bytes\n",
  93                 __func__, port->icount.rx);
  94 }
  95
  96 static void timbuart_tx_chars(struct uart_port *port)
  97 {
  98         unsigned char ch;
  99
 100         while (!(ioread32(port->membase + TIMBUART_ISR) & TXBF) &&
 101                         uart_fifo_get(port, &ch))
 102                 iowrite8(ch, port->membase + TIMBUART_TXFIFO);
 103
 104         dev_dbg(port->dev,
 105                 "%s - total written %d bytes, CTL: %x, RTS: %x, baud: %x\n",
 106                  __func__,
 107                 port->icount.tx,
 108                 ioread8(port->membase + TIMBUART_CTRL),
 109                 port->mctrl & TIOCM_RTS,
 110                 ioread8(port->membase + TIMBUART_BAUDRATE));
 111 }
 112
 113 static void timbuart_handle_tx_port(struct uart_port *port, u32 isr, u32 *ier)
 114 {
 115         struct timbuart_port *uart =
 116                 container_of(port, struct timbuart_port, port);
 117         struct tty_port *tport = &port->state->port;
 118
 119         if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port))
 120                 return;
 121
 122         if (port->x_char)
 123                 return;
 124
 125         if (isr & TXFLAGS) {
 126                 timbuart_tx_chars(port);
 127                 /* clear all TX interrupts */
 128                 iowrite32(TXFLAGS, port->membase + TIMBUART_ISR);
 129
 130                 if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
 131                         uart_write_wakeup(port);
 132         } else
 133                 /* Re-enable any tx interrupt */
 134                 *ier |= uart->last_ier & TXFLAGS;
 135
 136         /* enable interrupts if there are chars in the transmit buffer,
 137          * Or if we delivered some bytes and want the almost empty interrupt
 138          * we wake up the upper layer later when we got the interrupt
 139          * to give it some time to go out...
 140          */
 141         if (!kfifo_is_empty(&tport->xmit_fifo))
 142                 *ier |= TXBAE;
 143
 144         dev_dbg(port->dev, "%s - leaving\n", __func__);
 145 }
 146
 147 static void timbuart_handle_rx_port(struct uart_port *port, u32 isr, u32 *ier)
 148 {
 149         if (isr & RXFLAGS) {
 150                 /* Some RX status is set */
 151                 if (isr & RXBF) {
 152                         u8 ctl = ioread8(port->membase + TIMBUART_CTRL) |
 153                                 TIMBUART_CTRL_FLSHRX;
 154                         iowrite8(ctl, port->membase + TIMBUART_CTRL);
 155                         port->icount.overrun++;
 156                 } else if (isr & (RXDP))
 157                         timbuart_rx_chars(port);
 158
 159                 /* ack all RX interrupts */
 160                 iowrite32(RXFLAGS, port->membase + TIMBUART_ISR);
 161         }
 162
 163         /* always have the RX interrupts enabled */
 164         *ier |= RXBAF | RXBF | RXTT;
 165
 166         dev_dbg(port->dev, "%s - leaving\n", __func__);
 167 }
 168
 169 static void timbuart_tasklet(struct tasklet_struct *t)
 170 {
 171         struct timbuart_port *uart = from_tasklet(uart, t, tasklet);
 172         u32 isr, ier = 0;
 173
 174         uart_port_lock(&uart->port);
 175
 176         isr = ioread32(uart->port.membase + TIMBUART_ISR);
 177         dev_dbg(uart->port.dev, "%s ISR: %x\n", __func__, isr);
 178
 179         if (!uart->usedma)
 180                 timbuart_handle_tx_port(&uart->port, isr, &ier);
 181
 182         timbuart_mctrl_check(&uart->port, isr, &ier);
 183
 184         if (!uart->usedma)
 185                 timbuart_handle_rx_port(&uart->port, isr, &ier);
 186
 187         iowrite32(ier, uart->port.membase + TIMBUART_IER);
 188
 189         uart_port_unlock(&uart->port);
 190         dev_dbg(uart->port.dev, "%s leaving\n", __func__);
 191 }
 192
 193 static unsigned int timbuart_get_mctrl(struct uart_port *port)
 194 {
 195         u8 cts = ioread8(port->membase + TIMBUART_CTRL);
 196         dev_dbg(port->dev, "%s - cts %x\n", __func__, cts);
 197
 198         if (cts & TIMBUART_CTRL_CTS)
 199                 return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
 200         else
 201                 return TIOCM_DSR | TIOCM_CAR;
 202 }
 203
 204 static void timbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 205 {
 206         dev_dbg(port->dev, "%s - %x\n", __func__, mctrl);
 207
 208         if (mctrl & TIOCM_RTS)
 209                 iowrite8(TIMBUART_CTRL_RTS, port->membase + TIMBUART_CTRL);
 210         else
 211                 iowrite8(0, port->membase + TIMBUART_CTRL);
 212 }
 213
 214 static void timbuart_mctrl_check(struct uart_port *port, u32 isr, u32 *ier)
 215 {
 216         unsigned int cts;
 217
 218         if (isr & CTS_DELTA) {
 219                 /* ack */
 220                 iowrite32(CTS_DELTA, port->membase + TIMBUART_ISR);
 221                 cts = timbuart_get_mctrl(port);
 222                 uart_handle_cts_change(port, cts & TIOCM_CTS);
 223                 wake_up_interruptible(&port->state->port.delta_msr_wait);
 224         }
 225
 226         *ier |= CTS_DELTA;
 227 }
 228
 229 static void timbuart_break_ctl(struct uart_port *port, int ctl)
 230 {
 231         /* N/A */
 232 }
 233
 234 static int timbuart_startup(struct uart_port *port)
 235 {
 236         struct timbuart_port *uart =
 237                 container_of(port, struct timbuart_port, port);
 238
 239         dev_dbg(port->dev, "%s\n", __func__);
 240
 241         iowrite8(TIMBUART_CTRL_FLSHRX, port->membase + TIMBUART_CTRL);
 242         iowrite32(0x1ff, port->membase + TIMBUART_ISR);
 243         /* Enable all but TX interrupts */
 244         iowrite32(RXBAF | RXBF | RXTT | CTS_DELTA,
 245                 port->membase + TIMBUART_IER);
 246
 247         return request_irq(port->irq, timbuart_handleinterrupt, IRQF_SHARED,
 248                 "timb-uart", uart);
 249 }
 250
 251 static void timbuart_shutdown(struct uart_port *port)
 252 {
 253         struct timbuart_port *uart =
 254                 container_of(port, struct timbuart_port, port);
 255         dev_dbg(port->dev, "%s\n", __func__);
 256         free_irq(port->irq, uart);
 257         iowrite32(0, port->membase + TIMBUART_IER);
 258
 259         timbuart_flush_buffer(port);
 260 }
 261
 262 static int get_bindex(int baud)
 263 {
 264         int i;
 265
 266         for (i = 0; i < ARRAY_SIZE(baudrates); i++)
 267                 if (baud <= baudrates[i])
 268                         return i;
 269
 270         return -1;
 271 }
 272
 273 static void timbuart_set_termios(struct uart_port *port,
 274                                  struct ktermios *termios,
 275                                  const struct ktermios *old)
 276 {
 277         unsigned int baud;
 278         short bindex;
 279         unsigned long flags;
 280
 281         baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
 282         bindex = get_bindex(baud);
 283         dev_dbg(port->dev, "%s - bindex %d\n", __func__, bindex);
 284
 285         if (bindex < 0)
 286                 bindex = 0;
 287         baud = baudrates[bindex];
 288
 289         /* The serial layer calls into this once with old = NULL when setting
 290            up initially */
 291         if (old)
 292                 tty_termios_copy_hw(termios, old);
 293         tty_termios_encode_baud_rate(termios, baud, baud);
 294
 295         uart_port_lock_irqsave(port, &flags);
 296         iowrite8((u8)bindex, port->membase + TIMBUART_BAUDRATE);
 297         uart_update_timeout(port, termios->c_cflag, baud);
 298         uart_port_unlock_irqrestore(port, flags);
 299 }
 300
 301 static const char *timbuart_type(struct uart_port *port)
 302 {
 303         return port->type == PORT_UNKNOWN ? "timbuart" : NULL;
 304 }
 305
 306 /* We do not request/release mappings of the registers here,
 307  * currently it's done in the proble function.
 308  */
 309 static void timbuart_release_port(struct uart_port *port)
 310 {
 311         struct platform_device *pdev = to_platform_device(port->dev);
 312         int size =
 313                 resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
 314
 315         if (port->flags & UPF_IOREMAP) {
 316                 iounmap(port->membase);
 317                 port->membase = NULL;
 318         }
 319
 320         release_mem_region(port->mapbase, size);
 321 }
 322
 323 static int timbuart_request_port(struct uart_port *port)
 324 {
 325         struct platform_device *pdev = to_platform_device(port->dev);
 326         int size =
 327                 resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
 328
 329         if (!request_mem_region(port->mapbase, size, "timb-uart"))
 330                 return -EBUSY;
 331
 332         if (port->flags & UPF_IOREMAP) {
 333                 port->membase = ioremap(port->mapbase, size);
 334                 if (port->membase == NULL) {
 335                         release_mem_region(port->mapbase, size);
 336                         return -ENOMEM;
 337                 }
 338         }
 339
 340         return 0;
 341 }
 342
 343 static irqreturn_t timbuart_handleinterrupt(int irq, void *devid)
 344 {
 345         struct timbuart_port *uart = (struct timbuart_port *)devid;
 346
 347         if (ioread8(uart->port.membase + TIMBUART_IPR)) {
 348                 uart->last_ier = ioread32(uart->port.membase + TIMBUART_IER);
 349
 350                 /* disable interrupts, the tasklet enables them again */
 351                 iowrite32(0, uart->port.membase + TIMBUART_IER);
 352
 353                 /* fire off bottom half */
 354                 tasklet_schedule(&uart->tasklet);
 355
 356                 return IRQ_HANDLED;
 357         } else
 358                 return IRQ_NONE;
 359 }
 360
 361 /*
 362  * Configure/autoconfigure the port.
 363  */
 364 static void timbuart_config_port(struct uart_port *port, int flags)
 365 {
 366         if (flags & UART_CONFIG_TYPE) {
 367                 port->type = PORT_TIMBUART;
 368                 timbuart_request_port(port);
 369         }
 370 }
 371
 372 static int timbuart_verify_port(struct uart_port *port,
 373         struct serial_struct *ser)
 374 {
 375         /* we don't want the core code to modify any port params */
 376         return -EINVAL;
 377 }
 378
 379 static const struct uart_ops timbuart_ops = {
 380         .tx_empty = timbuart_tx_empty,
 381         .set_mctrl = timbuart_set_mctrl,
 382         .get_mctrl = timbuart_get_mctrl,
 383         .stop_tx = timbuart_stop_tx,
 384         .start_tx = timbuart_start_tx,
 385         .flush_buffer = timbuart_flush_buffer,
 386         .stop_rx = timbuart_stop_rx,
 387         .break_ctl = timbuart_break_ctl,
 388         .startup = timbuart_startup,
 389         .shutdown = timbuart_shutdown,
 390         .set_termios = timbuart_set_termios,
 391         .type = timbuart_type,
 392         .release_port = timbuart_release_port,
 393         .request_port = timbuart_request_port,
 394         .config_port = timbuart_config_port,
 395         .verify_port = timbuart_verify_port
 396 };
 397
 398 static struct uart_driver timbuart_driver = {
 399         .owner = THIS_MODULE,
 400         .driver_name = "timberdale_uart",
 401         .dev_name = "ttyTU",
 402         .major = TIMBUART_MAJOR,
 403         .minor = TIMBUART_MINOR,
 404         .nr = 1
 405 };
 406
 407 static int timbuart_probe(struct platform_device *dev)
 408 {
 409         int err, irq;
 410         struct timbuart_port *uart;
 411         struct resource *iomem;
 412
 413         dev_dbg(&dev->dev, "%s\n", __func__);
 414
 415         uart = kzalloc(sizeof(*uart), GFP_KERNEL);
 416         if (!uart) {
 417                 err = -EINVAL;
 418                 goto err_mem;
 419         }
 420
 421         uart->usedma = 0;
 422
 423         uart->port.uartclk = 3250000 * 16;
 424         uart->port.fifosize  = TIMBUART_FIFO_SIZE;
 425         uart->port.regshift  = 2;
 426         uart->port.iotype  = UPIO_MEM;
 427         uart->port.ops = &timbuart_ops;
 428         uart->port.irq = 0;
 429         uart->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP;
 430         uart->port.line  = 0;
 431         uart->port.dev  = &dev->dev;
 432
 433         iomem = platform_get_resource(dev, IORESOURCE_MEM, 0);
 434         if (!iomem) {
 435                 err = -ENOMEM;
 436                 goto err_register;
 437         }
 438         uart->port.mapbase = iomem->start;
 439         uart->port.membase = NULL;
 440
 441         irq = platform_get_irq(dev, 0);
 442         if (irq < 0) {
 443                 err = -EINVAL;
 444                 goto err_register;
 445         }
 446         uart->port.irq = irq;
 447
 448         tasklet_setup(&uart->tasklet, timbuart_tasklet);
 449
 450         err = uart_register_driver(&timbuart_driver);
 451         if (err)
 452                 goto err_register;
 453
 454         err = uart_add_one_port(&timbuart_driver, &uart->port);
 455         if (err)
 456                 goto err_add_port;
 457
 458         platform_set_drvdata(dev, uart);
 459
 460         return 0;
 461
 462 err_add_port:
 463         uart_unregister_driver(&timbuart_driver);
 464 err_register:
 465         kfree(uart);
 466 err_mem:
 467         printk(KERN_ERR "timberdale: Failed to register Timberdale UART: %d\n",
 468                 err);
 469
 470         return err;
 471 }
 472
 473 static void timbuart_remove(struct platform_device *dev)
 474 {
 475         struct timbuart_port *uart = platform_get_drvdata(dev);
 476
 477         tasklet_kill(&uart->tasklet);
 478         uart_remove_one_port(&timbuart_driver, &uart->port);
 479         uart_unregister_driver(&timbuart_driver);
 480         kfree(uart);
 481 }
 482
 483 static struct platform_driver timbuart_platform_driver = {
 484         .driver = {
 485                 .name   = "timb-uart",
 486         },
 487         .probe          = timbuart_probe,
 488         .remove         = timbuart_remove,
 489 };
 490
 491 module_platform_driver(timbuart_platform_driver);
 492
 493 MODULE_DESCRIPTION("Timberdale UART driver");
 494 MODULE_LICENSE("GPL v2");
 495 MODULE_ALIAS("platform:timb-uart");
 496