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 31struct nwpserial_port { 32 struct uart_port port; 33 dcr_host_t dcr_host; 34 unsigned int ier; 35 unsigned int mcr; 36}; 37 38static DEFINE_MUTEX(nwpserial_mutex); 39static struct nwpserial_port nwpserial_ports[NWPSERIAL_NR]; 40 41static 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 56static 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 66static void 67nwpserial_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 empty */ 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 95static struct uart_driver nwpserial_reg; 96static 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 111static int nwpserial_request_port(struct uart_port *port) 112{ 113 return 0; 114} 115 116static void nwpserial_release_port(struct uart_port *port) 117{ 118 /* N/A */ 119} 120 121static void nwpserial_config_port(struct uart_port *port, int flags) 122{ 123 port->type = PORT_NWPSERIAL; 124} 125 126static irqreturn_t nwpserial_interrupt(int irq, void *dev_id) 127{ 128 struct nwpserial_port *up = dev_id; 129 struct tty_struct *tty = up->port.state->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); 155out: 156 spin_unlock(&up->port.lock); 157 return ret; 158} 159 160static 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 187static 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 203static int nwpserial_verify_port(struct uart_port *port, 204 struct serial_struct *ser) 205{ 206 return -EINVAL; 207} 208 209static const char *nwpserial_type(struct uart_port *port) 210{ 211 return port->type == PORT_NWPSERIAL ? "nwpserial" : NULL; 212} 213 214static 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 233static void nwpserial_break_ctl(struct uart_port *port, int ctl) 234{ 235 /* N/A */ 236} 237 238static void nwpserial_enable_ms(struct uart_port *port) 239{ 240 /* N/A */ 241} 242 243static 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 251static 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 259static 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.state->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 277static unsigned int nwpserial_get_mctrl(struct uart_port *port) 278{ 279 return 0; 280} 281 282static void nwpserial_set_mctrl(struct uart_port *port, unsigned int mctrl) 283{ 284 /* N/A */ 285} 286 287static void nwpserial_stop_tx(struct uart_port *port) 288{ 289 /* N/A */ 290} 291 292static 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 306static 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 325static 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 335int 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 = port->dev->of_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 412out: 413 mutex_unlock(&nwpserial_mutex); 414 415 return ret; 416} 417EXPORT_SYMBOL(nwpserial_register_port); 418 419void 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} 429EXPORT_SYMBOL(nwpserial_unregister_port); 430 431#ifdef CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE 432static 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} 476console_initcall(nwpserial_console_init); 477#endif /* CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL_CONSOLE */ 478