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