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_LSR) & UART_LSR_DR);
 149
 150         tty_flip_buffer_push(tty);
 151         ret = IRQ_HANDLED;
 152
 153         /* clear interrupt */
 154         dcr_write(up->dcr_host, UART_IIR, 1);
 155 out:
 156         spin_unlock(&up->port.lock);
 157         return ret;
 158 }
 159
 160 static int nwpserial_startup(struct uart_port *port)
 161 {
 162         struct nwpserial_port *up;
 163         int err;
 164
 165         up = container_of(port, struct nwpserial_port, port);
 166
 167         /* disable flow control by default */
 168         up->mcr = dcr_read(up->dcr_host, UART_MCR) & ~UART_MCR_AFE;
 169         dcr_write(up->dcr_host, UART_MCR, up->mcr);
 170
 171         /* register interrupt handler */
 172         err = request_irq(up->port.irq, nwpserial_interrupt,
 173                         IRQF_SHARED, "nwpserial", up);
 174         if (err)
 175                 return err;
 176
 177         /* enable interrupts */
 178         up->ier = UART_IER_RDI;
 179         dcr_write(up->dcr_host, UART_IER, up->ier);
 180
 181         /* enable receiving */
 182         up->port.ignore_status_mask &= ~NWPSERIAL_STATUS_RXVALID;
 183
 184         return 0;
 185 }
 186
 187 static void nwpserial_shutdown(struct uart_port *port)
 188 {
 189         struct nwpserial_port *up;
 190         up = container_of(port, struct nwpserial_port, port);
 191
 192         /* disable receiving */
 193         up->port.ignore_status_mask |= NWPSERIAL_STATUS_RXVALID;
 194
 195         /* disable interrupts from this port */
 196         up->ier = 0;
 197         dcr_write(up->dcr_host, UART_IER, up->ier);
 198
 199         /* free irq */
 200         free_irq(up->port.irq, port);
 201 }
 202
 203 static int nwpserial_verify_port(struct uart_port *port,
 204                         struct serial_struct *ser)
 205 {
 206         return -EINVAL;
 207 }
 208
 209 static const char *nwpserial_type(struct uart_port *port)
 210 {
 211         return port->type == PORT_NWPSERIAL ? "nwpserial" : NULL;
 212 }
 213
 214 static void nwpserial_set_termios(struct uart_port *port,
 215                         struct ktermios *termios, struct ktermios *old)
 216 {
 217         struct nwpserial_port *up;
 218         up = container_of(port, struct nwpserial_port, port);
 219
 220         up->port.read_status_mask = NWPSERIAL_STATUS_RXVALID
 221                                 | NWPSERIAL_STATUS_TXFULL;
 222
 223         up->port.ignore_status_mask = 0;
 224         /* ignore all characters if CREAD is not set */
 225         if ((termios->c_cflag & CREAD) == 0)
 226                 up->port.ignore_status_mask |= NWPSERIAL_STATUS_RXVALID;
 227
 228         /* Copy back the old hardware settings */
 229         if (old)
 230                 tty_termios_copy_hw(termios, old);
 231 }
 232
 233 static void nwpserial_break_ctl(struct uart_port *port, int ctl)
 234 {
 235         /* N/A */
 236 }
 237
 238 static void nwpserial_enable_ms(struct uart_port *port)
 239 {
 240         /* N/A */
 241 }
 242
 243 static void nwpserial_stop_rx(struct uart_port *port)
 244 {
 245         struct nwpserial_port *up;
 246         up = container_of(port, struct nwpserial_port, port);
 247         /* don't forward any more data (like !CREAD) */
 248         up->port.ignore_status_mask = NWPSERIAL_STATUS_RXVALID;
 249 }
 250
 251 static void nwpserial_putchar(struct nwpserial_port *up, unsigned char c)
 252 {
 253         /* check if tx buffer is full */
 254         wait_for_bits(up, UART_LSR_THRE);
 255         dcr_write(up->dcr_host, UART_TX, c);
 256         up->port.icount.tx++;
 257 }
 258
 259 static void nwpserial_start_tx(struct uart_port *port)
 260 {
 261         struct nwpserial_port *up;
 262         struct circ_buf *xmit;
 263         up = container_of(port, struct nwpserial_port, port);
 264         xmit  = &up->port.info->xmit;
 265
 266         if (port->x_char) {
 267                 nwpserial_putchar(up, up->port.x_char);
 268                 port->x_char = 0;
 269         }
 270
 271         while (!(uart_circ_empty(xmit) || uart_tx_stopped(&up->port))) {
 272                 nwpserial_putchar(up, xmit->buf[xmit->tail]);
 273                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE-1);
 274         }
 275 }
 276
 277 static unsigned int nwpserial_get_mctrl(struct uart_port *port)
 278 {
 279         return 0;
 280 }
 281
 282 static void nwpserial_set_mctrl(struct uart_port *port, unsigned int mctrl)
 283 {
 284         /* N/A */
 285 }
 286
 287 static void nwpserial_stop_tx(struct uart_port *port)
 288 {
 289         /* N/A */
 290 }
 291
 292 static unsigned int nwpserial_tx_empty(struct uart_port *port)
 293 {
 294         struct nwpserial_port *up;
 295         unsigned long flags;
 296         int ret;
 297         up = container_of(port, struct nwpserial_port, port);
 298
 299         spin_lock_irqsave(&up->port.lock, flags);
 300         ret = dcr_read(up->dcr_host, UART_LSR);
 301         spin_unlock_irqrestore(&up->port.lock, flags);
 302
 303         return ret & UART_LSR_TEMT ? TIOCSER_TEMT : 0;
 304 }
 305
 306 static struct uart_ops nwpserial_pops = {
 307         .tx_empty     = nwpserial_tx_empty,
 308         .set_mctrl    = nwpserial_set_mctrl,
 309         .get_mctrl    = nwpserial_get_mctrl,
 310         .stop_tx      = nwpserial_stop_tx,
 311         .start_tx     = nwpserial_start_tx,
 312         .stop_rx      = nwpserial_stop_rx,
 313         .enable_ms    = nwpserial_enable_ms,
 314         .break_ctl    = nwpserial_break_ctl,
 315         .startup      = nwpserial_startup,
 316         .shutdown     = nwpserial_shutdown,
 317         .set_termios  = nwpserial_set_termios,
 318         .type         = nwpserial_type,
 319         .release_port = nwpserial_release_port,
 320         .request_port = nwpserial_request_port,
 321         .config_port  = nwpserial_config_port,
 322         .verify_port  = nwpserial_verify_port,
 323 };
 324
 325 static struct uart_driver nwpserial_reg = {
 326         .owner       = THIS_MODULE,
 327         .driver_name = "nwpserial",
 328         .dev_name    = "ttySQ",
 329         .major       = TTY_MAJOR,
 330         .minor       = 68,
 331         .nr          = NWPSERIAL_NR,
 332         .cons        = NWPSERIAL_CONSOLE,
 333 };
 334
 335 int nwpserial_register_port(struct uart_port *port)
 336 {
 337         struct nwpserial_port *up = NULL;
 338         int ret = -1;
 339         int i;
 340         static int first = 1;
 341         int dcr_len;
 342         int dcr_base;
 343         struct device_node *dn;
 344
 345         mutex_lock(&nwpserial_mutex);
 346
 347         dn = to_of_device(port->dev)->node;
 348         if (dn == NULL)
 349                 goto out;
 350
 351         /* get dcr base. */
 352         dcr_base = dcr_resource_start(dn, 0);
 353
 354         /* find matching entry */
 355         for (i = 0; i < NWPSERIAL_NR; i++)
 356                 if (nwpserial_ports[i].port.iobase == dcr_base) {
 357                         up = &nwpserial_ports[i];
 358                         break;
 359                 }
 360
 361         /* we didn't find a mtching entry, search for a free port */
 362         if (up == NULL)
 363                 for (i = 0; i < NWPSERIAL_NR; i++)
 364                         if (nwpserial_ports[i].port.type == PORT_UNKNOWN &&
 365                                 nwpserial_ports[i].port.iobase == 0) {
 366                                 up = &nwpserial_ports[i];
 367                                 break;
 368                         }
 369
 370         if (up == NULL) {
 371                 ret = -EBUSY;
 372                 goto out;
 373         }
 374
 375         if (first)
 376                 uart_register_driver(&nwpserial_reg);
 377         first = 0;
 378
 379         up->port.membase      = port->membase;
 380         up->port.irq          = port->irq;
 381         up->port.uartclk      = port->uartclk;
 382         up->port.fifosize     = port->fifosize;
 383         up->port.regshift     = port->regshift;
 384         up->port.iotype       = port->iotype;
 385         up->port.flags        = port->flags;
 386         up->port.mapbase      = port->mapbase;
 387         up->port.private_data = port->private_data;
 388
 389         if (port->dev)
 390                 up->port.dev = port->dev;
 391
 392         if (up->port.iobase != dcr_base) {
 393                 up->port.ops          = &nwpserial_pops;
 394                 up->port.fifosize     = 16;
 395
 396                 spin_lock_init(&up->port.lock);
 397
 398                 up->port.iobase = dcr_base;
 399                 dcr_len = dcr_resource_len(dn, 0);
 400
 401                 up->dcr_host = dcr_map(dn, dcr_base, dcr_len);
 402                 if (!DCR_MAP_OK(up->dcr_host)) {
 403                         printk(KERN_ERR "Cannot map DCR resources for NWPSERIAL");
 404                         goto out;
 405                 }
 406         }
 407
 408         ret = uart_add_one_port(&nwpserial_reg, &up->port);
 409         if (ret == 0)
 410                 ret = up->port.line;
 411
 412 out:
 413         mutex_unlock(&nwpserial_mutex);
 414
 415         return ret;
 416 }
 417 EXPORT_SYMBOL(nwpserial_register_port);
 418
 419 void nwpserial_unregister_port(int line)
 420 {
 421         struct nwpserial_port *up = &nwpserial_ports[line];
 422         mutex_lock(&nwpserial_mutex);
 423         uart_remove_one_port(&nwpserial_reg, &up->port);
 424
 425         up->port.type = PORT_UNKNOWN;
 426
 427         mutex_unlock(&nwpserial_mutex);
 428 }
 429 EXPORT_SYMBOL(nwpserial_unregister_port);
 430
 431 #ifdef CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE
 432 static int __init nwpserial_console_init(void)
 433 {
 434         struct nwpserial_port *up = NULL;
 435         struct device_node *dn;
 436         const char *name;
 437         int dcr_base;
 438         int dcr_len;
 439         int i;
 440
 441         /* search for a free port */
 442         for (i = 0; i < NWPSERIAL_NR; i++)
 443                 if (nwpserial_ports[i].port.type == PORT_UNKNOWN) {
 444                         up = &nwpserial_ports[i];
 445                         break;
 446                 }
 447
 448         if (up == NULL)
 449                 return -1;
 450
 451         name = of_get_property(of_chosen, "linux,stdout-path", NULL);
 452         if (name == NULL)
 453                 return -1;
 454
 455         dn = of_find_node_by_path(name);
 456         if (!dn)
 457                 return -1;
 458
 459         spin_lock_init(&up->port.lock);
 460         up->port.ops = &nwpserial_pops;
 461         up->port.type = PORT_NWPSERIAL;
 462         up->port.fifosize = 16;
 463
 464         dcr_base = dcr_resource_start(dn, 0);
 465         dcr_len = dcr_resource_len(dn, 0);
 466         up->port.iobase = dcr_base;
 467
 468         up->dcr_host = dcr_map(dn, dcr_base, dcr_len);
 469         if (!DCR_MAP_OK(up->dcr_host)) {
 470                 printk("Cannot map DCR resources for SERIAL");
 471                 return -1;
 472         }
 473         register_console(&nwpserial_console);
 474         return 0;
 475 }
 476 console_initcall(nwpserial_console_init);
 477 #endif /* CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE */