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