drivers/tty/serial/nwpserial.c

   1 /*
   2  *  Serial Port driver for a NWP uart device
   3  *
   4  *    Copyright (C) 2008 IBM Corp., Benjamin Krill <ben@codiert.org>
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  as published by the Free Software Foundation; either version
   9  *  2 of the License, or (at your option) any later version.
  10  *
  11  */
  12 #include <linux/init.h>
  13 #include <linux/export.h>
  14 #include <linux/console.h>
  15 #include <linux/serial.h>
  16 #include <linux/serial_reg.h>
  17 #include <linux/serial_core.h>
  18 #include <linux/tty.h>
  19 #include <linux/tty_flip.h>
  20 #include <linux/irqreturn.h>
  21 #include <linux/mutex.h>
  22 #include <linux/of_platform.h>
  23 #include <linux/of_device.h>
  24 #include <linux/nwpserial.h>
  25 #include <asm/prom.h>
  26 #include <asm/dcr.h>
  27
  28 #define NWPSERIAL_NR               2
  29
  30 #define NWPSERIAL_STATUS_RXVALID 0x1
  31 #define NWPSERIAL_STATUS_TXFULL  0x2
  32
  33 struct nwpserial_port {
  34         struct uart_port port;
  35         dcr_host_t dcr_host;
  36         unsigned int ier;
  37         unsigned int mcr;
  38 };
  39
  40 static DEFINE_MUTEX(nwpserial_mutex);
  41 static struct nwpserial_port nwpserial_ports[NWPSERIAL_NR];
  42
  43 static void wait_for_bits(struct nwpserial_port *up, int bits)
  44 {
  45         unsigned int status, tmout = 10000;
  46
  47         /* Wait up to 10ms for the character(s) to be sent. */
  48         do {
  49                 status = dcr_read(up->dcr_host, UART_LSR);
  50
  51                 if (--tmout == 0)
  52                         break;
  53                 udelay(1);
  54         } while ((status & bits) != bits);
  55 }
  56
  57 #ifdef CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE
  58 static void nwpserial_console_putchar(struct uart_port *port, int c)
  59 {
  60         struct nwpserial_port *up;
  61         up = container_of(port, struct nwpserial_port, port);
  62         /* check if tx buffer is full */
  63         wait_for_bits(up, UART_LSR_THRE);
  64         dcr_write(up->dcr_host, UART_TX, c);
  65         up->port.icount.tx++;
  66 }
  67
  68 static void
  69 nwpserial_console_write(struct console *co, const char *s, unsigned int count)
  70 {
  71         struct nwpserial_port *up = &nwpserial_ports[co->index];
  72         unsigned long flags;
  73         int locked = 1;
  74
  75         if (oops_in_progress)
  76                 locked = spin_trylock_irqsave(&up->port.lock, flags);
  77         else
  78                 spin_lock_irqsave(&up->port.lock, flags);
  79
  80         /* save and disable interrupt */
  81         up->ier = dcr_read(up->dcr_host, UART_IER);
  82         dcr_write(up->dcr_host, UART_IER, up->ier & ~UART_IER_RDI);
  83
  84         uart_console_write(&up->port, s, count, nwpserial_console_putchar);
  85
  86         /* wait for transmitter to become empty */
  87         while ((dcr_read(up->dcr_host, UART_LSR) & UART_LSR_THRE) == 0)
  88                 cpu_relax();
  89
  90         /* restore interrupt state */
  91         dcr_write(up->dcr_host, UART_IER, up->ier);
  92
  93         if (locked)
  94                 spin_unlock_irqrestore(&up->port.lock, flags);
  95 }
  96
  97 static struct uart_driver nwpserial_reg;
  98 static struct console nwpserial_console = {
  99         .name           = "ttySQ",
 100         .write          = nwpserial_console_write,
 101         .device         = uart_console_device,
 102         .flags          = CON_PRINTBUFFER,
 103         .index          = -1,
 104         .data           = &nwpserial_reg,
 105 };
 106 #define NWPSERIAL_CONSOLE       (&nwpserial_console)
 107 #else
 108 #define NWPSERIAL_CONSOLE       NULL
 109 #endif /* CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE */
 110
 111 /**************************************************************************/
 112
 113 static int nwpserial_request_port(struct uart_port *port)
 114 {
 115         return 0;
 116 }
 117
 118 static void nwpserial_release_port(struct uart_port *port)
 119 {
 120         /* N/A */
 121 }
 122
 123 static void nwpserial_config_port(struct uart_port *port, int flags)
 124 {
 125         port->type = PORT_NWPSERIAL;
 126 }
 127
 128 static irqreturn_t nwpserial_interrupt(int irq, void *dev_id)
 129 {
 130         struct nwpserial_port *up = dev_id;
 131         struct tty_port *port = &up->port.state->port;
 132         irqreturn_t ret;
 133         unsigned int iir;
 134         unsigned char ch;
 135
 136         spin_lock(&up->port.lock);
 137
 138         /* check if the uart was the interrupt source. */
 139         iir = dcr_read(up->dcr_host, UART_IIR);
 140         if (!iir) {
 141                 ret = IRQ_NONE;
 142                 goto out;
 143         }
 144
 145         do {
 146                 up->port.icount.rx++;
 147                 ch = dcr_read(up->dcr_host, UART_RX);
 148                 if (up->port.ignore_status_mask != NWPSERIAL_STATUS_RXVALID)
 149                         tty_insert_flip_char(port, ch, TTY_NORMAL);
 150         } while (dcr_read(up->dcr_host, UART_LSR) & UART_LSR_DR);
 151
 152         tty_flip_buffer_push(port);
 153         ret = IRQ_HANDLED;
 154
 155         /* clear interrupt */
 156         dcr_write(up->dcr_host, UART_IIR, 1);
 157 out:
 158         spin_unlock(&up->port.lock);
 159         return ret;
 160 }
 161
 162 static int nwpserial_startup(struct uart_port *port)
 163 {
 164         struct nwpserial_port *up;
 165         int err;
 166
 167         up = container_of(port, struct nwpserial_port, port);
 168
 169         /* disable flow control by default */
 170         up->mcr = dcr_read(up->dcr_host, UART_MCR) & ~UART_MCR_AFE;
 171         dcr_write(up->dcr_host, UART_MCR, up->mcr);
 172
 173         /* register interrupt handler */
 174         err = request_irq(up->port.irq, nwpserial_interrupt,
 175                         IRQF_SHARED, "nwpserial", up);
 176         if (err)
 177                 return err;
 178
 179         /* enable interrupts */
 180         up->ier = UART_IER_RDI;
 181         dcr_write(up->dcr_host, UART_IER, up->ier);
 182
 183         /* enable receiving */
 184         up->port.ignore_status_mask &= ~NWPSERIAL_STATUS_RXVALID;
 185
 186         return 0;
 187 }
 188
 189 static void nwpserial_shutdown(struct uart_port *port)
 190 {
 191         struct nwpserial_port *up;
 192         up = container_of(port, struct nwpserial_port, port);
 193
 194         /* disable receiving */
 195         up->port.ignore_status_mask |= NWPSERIAL_STATUS_RXVALID;
 196
 197         /* disable interrupts from this port */
 198         up->ier = 0;
 199         dcr_write(up->dcr_host, UART_IER, up->ier);
 200
 201         /* free irq */
 202         free_irq(up->port.irq, up);
 203 }
 204
 205 static int nwpserial_verify_port(struct uart_port *port,
 206                         struct serial_struct *ser)
 207 {
 208         return -EINVAL;
 209 }
 210
 211 static const char *nwpserial_type(struct uart_port *port)
 212 {
 213         return port->type == PORT_NWPSERIAL ? "nwpserial" : NULL;
 214 }
 215
 216 static void nwpserial_set_termios(struct uart_port *port,
 217                         struct ktermios *termios, struct ktermios *old)
 218 {
 219         struct nwpserial_port *up;
 220         up = container_of(port, struct nwpserial_port, port);
 221
 222         up->port.read_status_mask = NWPSERIAL_STATUS_RXVALID
 223                                 | NWPSERIAL_STATUS_TXFULL;
 224
 225         up->port.ignore_status_mask = 0;
 226         /* ignore all characters if CREAD is not set */
 227         if ((termios->c_cflag & CREAD) == 0)
 228                 up->port.ignore_status_mask |= NWPSERIAL_STATUS_RXVALID;
 229
 230         /* Copy back the old hardware settings */
 231         if (old)
 232                 tty_termios_copy_hw(termios, old);
 233 }
 234
 235 static void nwpserial_break_ctl(struct uart_port *port, int ctl)
 236 {
 237         /* N/A */
 238 }
 239
 240 static void nwpserial_enable_ms(struct uart_port *port)
 241 {
 242         /* N/A */
 243 }
 244
 245 static void nwpserial_stop_rx(struct uart_port *port)
 246 {
 247         struct nwpserial_port *up;
 248         up = container_of(port, struct nwpserial_port, port);
 249         /* don't forward any more data (like !CREAD) */
 250         up->port.ignore_status_mask = NWPSERIAL_STATUS_RXVALID;
 251 }
 252
 253 static void nwpserial_putchar(struct nwpserial_port *up, unsigned char c)
 254 {
 255         /* check if tx buffer is full */
 256         wait_for_bits(up, UART_LSR_THRE);
 257         dcr_write(up->dcr_host, UART_TX, c);
 258         up->port.icount.tx++;
 259 }
 260
 261 static void nwpserial_start_tx(struct uart_port *port)
 262 {
 263         struct nwpserial_port *up;
 264         struct circ_buf *xmit;
 265         up = container_of(port, struct nwpserial_port, port);
 266         xmit  = &up->port.state->xmit;
 267
 268         if (port->x_char) {
 269                 nwpserial_putchar(up, up->port.x_char);
 270                 port->x_char = 0;
 271         }
 272
 273         while (!(uart_circ_empty(xmit) || uart_tx_stopped(&up->port))) {
 274                 nwpserial_putchar(up, xmit->buf[xmit->tail]);
 275                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE-1);
 276         }
 277 }
 278
 279 static unsigned int nwpserial_get_mctrl(struct uart_port *port)
 280 {
 281         return 0;
 282 }
 283
 284 static void nwpserial_set_mctrl(struct uart_port *port, unsigned int mctrl)
 285 {
 286         /* N/A */
 287 }
 288
 289 static void nwpserial_stop_tx(struct uart_port *port)
 290 {
 291         /* N/A */
 292 }
 293
 294 static unsigned int nwpserial_tx_empty(struct uart_port *port)
 295 {
 296         struct nwpserial_port *up;
 297         unsigned long flags;
 298         int ret;
 299         up = container_of(port, struct nwpserial_port, port);
 300
 301         spin_lock_irqsave(&up->port.lock, flags);
 302         ret = dcr_read(up->dcr_host, UART_LSR);
 303         spin_unlock_irqrestore(&up->port.lock, flags);
 304
 305         return ret & UART_LSR_TEMT ? TIOCSER_TEMT : 0;
 306 }
 307
 308 static struct uart_ops nwpserial_pops = {
 309         .tx_empty     = nwpserial_tx_empty,
 310         .set_mctrl    = nwpserial_set_mctrl,
 311         .get_mctrl    = nwpserial_get_mctrl,
 312         .stop_tx      = nwpserial_stop_tx,
 313         .start_tx     = nwpserial_start_tx,
 314         .stop_rx      = nwpserial_stop_rx,
 315         .enable_ms    = nwpserial_enable_ms,
 316         .break_ctl    = nwpserial_break_ctl,
 317         .startup      = nwpserial_startup,
 318         .shutdown     = nwpserial_shutdown,
 319         .set_termios  = nwpserial_set_termios,
 320         .type         = nwpserial_type,
 321         .release_port = nwpserial_release_port,
 322         .request_port = nwpserial_request_port,
 323         .config_port  = nwpserial_config_port,
 324         .verify_port  = nwpserial_verify_port,
 325 };
 326
 327 static struct uart_driver nwpserial_reg = {
 328         .owner       = THIS_MODULE,
 329         .driver_name = "nwpserial",
 330         .dev_name    = "ttySQ",
 331         .major       = TTY_MAJOR,
 332         .minor       = 68,
 333         .nr          = NWPSERIAL_NR,
 334         .cons        = NWPSERIAL_CONSOLE,
 335 };
 336
 337 int nwpserial_register_port(struct uart_port *port)
 338 {
 339         struct nwpserial_port *up = NULL;
 340         int ret = -1;
 341         int i;
 342         static int first = 1;
 343         int dcr_len;
 344         int dcr_base;
 345         struct device_node *dn;
 346
 347         mutex_lock(&nwpserial_mutex);
 348
 349         dn = port->dev->of_node;
 350         if (dn == NULL)
 351                 goto out;
 352
 353         /* get dcr base. */
 354         dcr_base = dcr_resource_start(dn, 0);
 355
 356         /* find matching entry */
 357         for (i = 0; i < NWPSERIAL_NR; i++)
 358                 if (nwpserial_ports[i].port.iobase == dcr_base) {
 359                         up = &nwpserial_ports[i];
 360                         break;
 361                 }
 362
 363         /* we didn't find a mtching entry, search for a free port */
 364         if (up == NULL)
 365                 for (i = 0; i < NWPSERIAL_NR; i++)
 366                         if (nwpserial_ports[i].port.type == PORT_UNKNOWN &&
 367                                 nwpserial_ports[i].port.iobase == 0) {
 368                                 up = &nwpserial_ports[i];
 369                                 break;
 370                         }
 371
 372         if (up == NULL) {
 373                 ret = -EBUSY;
 374                 goto out;
 375         }
 376
 377         if (first)
 378                 uart_register_driver(&nwpserial_reg);
 379         first = 0;
 380
 381         up->port.membase      = port->membase;
 382         up->port.irq          = port->irq;
 383         up->port.uartclk      = port->uartclk;
 384         up->port.fifosize     = port->fifosize;
 385         up->port.regshift     = port->regshift;
 386         up->port.iotype       = port->iotype;
 387         up->port.flags        = port->flags;
 388         up->port.mapbase      = port->mapbase;
 389         up->port.private_data = port->private_data;
 390
 391         if (port->dev)
 392                 up->port.dev = port->dev;
 393
 394         if (up->port.iobase != dcr_base) {
 395                 up->port.ops          = &nwpserial_pops;
 396                 up->port.fifosize     = 16;
 397
 398                 spin_lock_init(&up->port.lock);
 399
 400                 up->port.iobase = dcr_base;
 401                 dcr_len = dcr_resource_len(dn, 0);
 402
 403                 up->dcr_host = dcr_map(dn, dcr_base, dcr_len);
 404                 if (!DCR_MAP_OK(up->dcr_host)) {
 405                         printk(KERN_ERR "Cannot map DCR resources for NWPSERIAL");
 406                         goto out;
 407                 }
 408         }
 409
 410         ret = uart_add_one_port(&nwpserial_reg, &up->port);
 411         if (ret == 0)
 412                 ret = up->port.line;
 413
 414 out:
 415         mutex_unlock(&nwpserial_mutex);
 416
 417         return ret;
 418 }
 419 EXPORT_SYMBOL(nwpserial_register_port);
 420
 421 void nwpserial_unregister_port(int line)
 422 {
 423         struct nwpserial_port *up = &nwpserial_ports[line];
 424         mutex_lock(&nwpserial_mutex);
 425         uart_remove_one_port(&nwpserial_reg, &up->port);
 426
 427         up->port.type = PORT_UNKNOWN;
 428
 429         mutex_unlock(&nwpserial_mutex);
 430 }
 431 EXPORT_SYMBOL(nwpserial_unregister_port);
 432
 433 #ifdef CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE
 434 static int __init nwpserial_console_init(void)
 435 {
 436         struct nwpserial_port *up = NULL;
 437         struct device_node *dn;
 438         const char *name;
 439         int dcr_base;
 440         int dcr_len;
 441         int i;
 442
 443         /* search for a free port */
 444         for (i = 0; i < NWPSERIAL_NR; i++)
 445                 if (nwpserial_ports[i].port.type == PORT_UNKNOWN) {
 446                         up = &nwpserial_ports[i];
 447                         break;
 448                 }
 449
 450         if (up == NULL)
 451                 return -1;
 452
 453         name = of_get_property(of_chosen, "linux,stdout-path", NULL);
 454         if (name == NULL)
 455                 return -1;
 456
 457         dn = of_find_node_by_path(name);
 458         if (!dn)
 459                 return -1;
 460
 461         spin_lock_init(&up->port.lock);
 462         up->port.ops = &nwpserial_pops;
 463         up->port.type = PORT_NWPSERIAL;
 464         up->port.fifosize = 16;
 465
 466         dcr_base = dcr_resource_start(dn, 0);
 467         dcr_len = dcr_resource_len(dn, 0);
 468         up->port.iobase = dcr_base;
 469
 470         up->dcr_host = dcr_map(dn, dcr_base, dcr_len);
 471         if (!DCR_MAP_OK(up->dcr_host)) {
 472                 printk("Cannot map DCR resources for SERIAL");
 473                 return -1;
 474         }
 475         register_console(&nwpserial_console);
 476         return 0;
 477 }
 478 console_initcall(nwpserial_console_init);
 479 #endif /* CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE */