2 * C-Brick Serial Port (and console) driver for SGI Altix machines.
4 * This driver is NOT suitable for talking to the l1-controller for
5 * anything other than 'console activities' --- please use the l1
9 * Copyright (c) 2004-2006 Silicon Graphics, Inc. All Rights Reserved.
11 * This program is free software; you can redistribute it and/or modify it
12 * under the terms of version 2 of the GNU General Public License
13 * as published by the Free Software Foundation.
15 * This program is distributed in the hope that it would be useful, but
16 * WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
19 * Further, this software is distributed without any warranty that it is
20 * free of the rightful claim of any third person regarding infringement
21 * or the like. Any license provided herein, whether implied or
22 * otherwise, applies only to this software file. Patent licenses, if
23 * any, provided herein do not apply to combinations of this program with
24 * other software, or any other product whatsoever.
26 * You should have received a copy of the GNU General Public
27 * License along with this program; if not, write the Free Software
28 * Foundation, Inc., 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
30 * Contact information: Silicon Graphics, Inc., 1500 Crittenden Lane,
31 * Mountain View, CA 94043, or:
35 * For further information regarding this notice, see:
37 * http://oss.sgi.com/projects/GenInfo/NoticeExplan
40 #include <linux/interrupt.h>
41 #include <linux/tty.h>
42 #include <linux/tty_flip.h>
43 #include <linux/serial.h>
44 #include <linux/console.h>
45 #include <linux/module.h>
46 #include <linux/sysrq.h>
47 #include <linux/circ_buf.h>
48 #include <linux/serial_reg.h>
49 #include <linux/delay.h> /* for mdelay */
50 #include <linux/miscdevice.h>
51 #include <linux/serial_core.h>
54 #include <asm/sn/simulator.h>
55 #include <asm/sn/sn_sal.h>
57 /* number of characters we can transmit to the SAL console at a time */
58 #define SN_SAL_MAX_CHARS 120
60 /* 64K, when we're asynch, it must be at least printk's LOG_BUF_LEN to
61 * avoid losing chars, (always has to be a power of 2) */
62 #define SN_SAL_BUFFER_SIZE (64 * (1 << 10))
64 #define SN_SAL_UART_FIFO_DEPTH 16
65 #define SN_SAL_UART_FIFO_SPEED_CPS (9600/10)
67 /* sn_transmit_chars() calling args */
68 #define TRANSMIT_BUFFERED 0
69 #define TRANSMIT_RAW 1
71 /* To use dynamic numbers only and not use the assigned major and minor,
72 * define the following.. */
73 /* #define USE_DYNAMIC_MINOR 1 *//* use dynamic minor number */
74 #define USE_DYNAMIC_MINOR 0 /* Don't rely on misc_register dynamic minor */
76 /* Device name we're using */
77 #define DEVICE_NAME "ttySG"
78 #define DEVICE_NAME_DYNAMIC "ttySG0" /* need full name for misc_register */
79 /* The major/minor we are using, ignored for USE_DYNAMIC_MINOR */
80 #define DEVICE_MAJOR 204
81 #define DEVICE_MINOR 40
83 #ifdef CONFIG_MAGIC_SYSRQ
84 static char sysrq_serial_str[] = "\eSYS";
85 static char *sysrq_serial_ptr = sysrq_serial_str;
86 static unsigned long sysrq_requested;
87 #endif /* CONFIG_MAGIC_SYSRQ */
90 * Port definition - this kinda drives it all
93 struct timer_list sc_timer;
94 struct uart_port sc_port;
96 int (*sal_puts_raw) (const char *s, int len);
97 int (*sal_puts) (const char *s, int len);
98 int (*sal_getc) (void);
99 int (*sal_input_pending) (void);
100 void (*sal_wakeup_transmit) (struct sn_cons_port *, int);
102 unsigned long sc_interrupt_timeout;
106 static struct sn_cons_port sal_console_port;
107 static int sn_process_input;
109 /* Only used if USE_DYNAMIC_MINOR is set to 1 */
110 static struct miscdevice misc; /* used with misc_register for dynamic */
112 extern void early_sn_setup(void);
116 static int sn_debug_printf(const char *fmt, ...);
117 #define DPRINTF(x...) sn_debug_printf(x)
119 #define DPRINTF(x...) do { } while (0)
123 static int snt_hw_puts_raw(const char *, int);
124 static int snt_hw_puts_buffered(const char *, int);
125 static int snt_poll_getc(void);
126 static int snt_poll_input_pending(void);
127 static int snt_intr_getc(void);
128 static int snt_intr_input_pending(void);
129 static void sn_transmit_chars(struct sn_cons_port *, int);
131 /* A table for polling:
133 static struct sn_sal_ops poll_ops = {
134 .sal_puts_raw = snt_hw_puts_raw,
135 .sal_puts = snt_hw_puts_raw,
136 .sal_getc = snt_poll_getc,
137 .sal_input_pending = snt_poll_input_pending
140 /* A table for interrupts enabled */
141 static struct sn_sal_ops intr_ops = {
142 .sal_puts_raw = snt_hw_puts_raw,
143 .sal_puts = snt_hw_puts_buffered,
144 .sal_getc = snt_intr_getc,
145 .sal_input_pending = snt_intr_input_pending,
146 .sal_wakeup_transmit = sn_transmit_chars
149 /* the console does output in two distinctly different ways:
150 * synchronous (raw) and asynchronous (buffered). initially, early_printk
151 * does synchronous output. any data written goes directly to the SAL
152 * to be output (incidentally, it is internally buffered by the SAL)
153 * after interrupts and timers are initialized and available for use,
154 * the console init code switches to asynchronous output. this is
155 * also the earliest opportunity to begin polling for console input.
156 * after console initialization, console output and tty (serial port)
157 * output is buffered and sent to the SAL asynchronously (either by
158 * timer callback or by UART interrupt) */
160 /* routines for running the console in polling mode */
163 * snt_poll_getc - Get a character from the console in polling mode
166 static int snt_poll_getc(void)
170 ia64_sn_console_getc(&ch);
175 * snt_poll_input_pending - Check if any input is waiting - polling mode.
178 static int snt_poll_input_pending(void)
182 status = ia64_sn_console_check(&input);
183 return !status && input;
186 /* routines for an interrupt driven console (normal) */
189 * snt_intr_getc - Get a character from the console, interrupt mode
192 static int snt_intr_getc(void)
194 return ia64_sn_console_readc();
198 * snt_intr_input_pending - Check if input is pending, interrupt mode
201 static int snt_intr_input_pending(void)
203 return ia64_sn_console_intr_status() & SAL_CONSOLE_INTR_RECV;
206 /* these functions are polled and interrupt */
209 * snt_hw_puts_raw - Send raw string to the console, polled or interrupt mode
214 static int snt_hw_puts_raw(const char *s, int len)
216 /* this will call the PROM and not return until this is done */
217 return ia64_sn_console_putb(s, len);
221 * snt_hw_puts_buffered - Send string to console, polled or interrupt mode
226 static int snt_hw_puts_buffered(const char *s, int len)
228 /* queue data to the PROM */
229 return ia64_sn_console_xmit_chars((char *)s, len);
232 /* uart interface structs
233 * These functions are associated with the uart_port that the serial core
234 * infrastructure calls.
236 * Note: Due to how the console works, many routines are no-ops.
240 * snp_type - What type of console are we?
241 * @port: Port to operate with (we ignore since we only have one port)
244 static const char *snp_type(struct uart_port *port)
246 return ("SGI SN L1");
250 * snp_tx_empty - Is the transmitter empty? We pretend we're always empty
251 * @port: Port to operate on (we ignore since we only have one port)
254 static unsigned int snp_tx_empty(struct uart_port *port)
260 * snp_stop_tx - stop the transmitter - no-op for us
261 * @port: Port to operat eon - we ignore - no-op function
264 static void snp_stop_tx(struct uart_port *port)
269 * snp_release_port - Free i/o and resources for port - no-op for us
270 * @port: Port to operate on - we ignore - no-op function
273 static void snp_release_port(struct uart_port *port)
278 * snp_enable_ms - Force modem status interrupts on - no-op for us
279 * @port: Port to operate on - we ignore - no-op function
282 static void snp_enable_ms(struct uart_port *port)
287 * snp_shutdown - shut down the port - free irq and disable - no-op for us
288 * @port: Port to shut down - we ignore
291 static void snp_shutdown(struct uart_port *port)
296 * snp_set_mctrl - set control lines (dtr, rts, etc) - no-op for our console
297 * @port: Port to operate on - we ignore
298 * @mctrl: Lines to set/unset - we ignore
301 static void snp_set_mctrl(struct uart_port *port, unsigned int mctrl)
306 * snp_get_mctrl - get contorl line info, we just return a static value
307 * @port: port to operate on - we only have one port so we ignore this
310 static unsigned int snp_get_mctrl(struct uart_port *port)
312 return TIOCM_CAR | TIOCM_RNG | TIOCM_DSR | TIOCM_CTS;
316 * snp_stop_rx - Stop the receiver - we ignor ethis
317 * @port: Port to operate on - we ignore
320 static void snp_stop_rx(struct uart_port *port)
325 * snp_start_tx - Start transmitter
326 * @port: Port to operate on
329 static void snp_start_tx(struct uart_port *port)
331 if (sal_console_port.sc_ops->sal_wakeup_transmit)
332 sal_console_port.sc_ops->sal_wakeup_transmit(&sal_console_port,
338 * snp_break_ctl - handle breaks - ignored by us
339 * @port: Port to operate on
340 * @break_state: Break state
343 static void snp_break_ctl(struct uart_port *port, int break_state)
348 * snp_startup - Start up the serial port - always return 0 (We're always on)
349 * @port: Port to operate on
352 static int snp_startup(struct uart_port *port)
358 * snp_set_termios - set termios stuff - we ignore these
359 * @port: port to operate on
360 * @termios: New settings
365 snp_set_termios(struct uart_port *port, struct ktermios *termios,
366 struct ktermios *old)
371 * snp_request_port - allocate resources for port - ignored by us
372 * @port: port to operate on
375 static int snp_request_port(struct uart_port *port)
381 * snp_config_port - allocate resources, set up - we ignore, we're always on
382 * @port: Port to operate on
383 * @flags: flags used for port setup
386 static void snp_config_port(struct uart_port *port, int flags)
390 /* Associate the uart functions above - given to serial core */
392 static struct uart_ops sn_console_ops = {
393 .tx_empty = snp_tx_empty,
394 .set_mctrl = snp_set_mctrl,
395 .get_mctrl = snp_get_mctrl,
396 .stop_tx = snp_stop_tx,
397 .start_tx = snp_start_tx,
398 .stop_rx = snp_stop_rx,
399 .enable_ms = snp_enable_ms,
400 .break_ctl = snp_break_ctl,
401 .startup = snp_startup,
402 .shutdown = snp_shutdown,
403 .set_termios = snp_set_termios,
406 .release_port = snp_release_port,
407 .request_port = snp_request_port,
408 .config_port = snp_config_port,
412 /* End of uart struct functions and defines */
417 * sn_debug_printf - close to hardware debugging printf
418 * @fmt: printf format
420 * This is as "close to the metal" as we can get, used when the driver
421 * itself may be broken.
424 static int sn_debug_printf(const char *fmt, ...)
426 static char printk_buf[1024];
431 printed_len = vsnprintf(printk_buf, sizeof(printk_buf), fmt, args);
433 if (!sal_console_port.sc_ops) {
434 sal_console_port.sc_ops = &poll_ops;
437 sal_console_port.sc_ops->sal_puts_raw(printk_buf, printed_len);
445 * Interrupt handling routines.
449 * sn_receive_chars - Grab characters, pass them to tty layer
450 * @port: Port to operate on
453 * Note: If we're not registered with the serial core infrastructure yet,
454 * we don't try to send characters to it...
458 sn_receive_chars(struct sn_cons_port *port, unsigned long flags)
460 struct tty_port *tport = NULL;
462 struct tty_struct *tty;
465 printk(KERN_ERR "sn_receive_chars - port NULL so can't receive\n");
470 printk(KERN_ERR "sn_receive_chars - port->sc_ops NULL so can't receive\n");
474 if (port->sc_port.state) {
475 /* The serial_core stuffs are initialized, use them */
476 tport = &port->sc_port.state->port;
480 /* Not registered yet - can't pass to tty layer. */
484 while (port->sc_ops->sal_input_pending()) {
485 ch = port->sc_ops->sal_getc();
487 printk(KERN_ERR "sn_console: An error occurred while "
488 "obtaining data from the console (0x%0x)\n", ch);
491 #ifdef CONFIG_MAGIC_SYSRQ
492 if (sysrq_requested) {
493 unsigned long sysrq_timeout = sysrq_requested + HZ*5;
496 if (ch && time_before(jiffies, sysrq_timeout)) {
497 spin_unlock_irqrestore(&port->sc_port.lock, flags);
499 spin_lock_irqsave(&port->sc_port.lock, flags);
500 /* ignore actual sysrq command char */
504 if (ch == *sysrq_serial_ptr) {
505 if (!(*++sysrq_serial_ptr)) {
506 sysrq_requested = jiffies;
507 sysrq_serial_ptr = sysrq_serial_str;
510 * ignore the whole sysrq string except for the
517 sysrq_serial_ptr = sysrq_serial_str;
518 #endif /* CONFIG_MAGIC_SYSRQ */
520 /* record the character to pass up to the tty layer */
522 if (tty_insert_flip_char(tport, ch, TTY_NORMAL) == 0)
525 port->sc_port.icount.rx++;
529 tty_flip_buffer_push(tty);
533 * sn_transmit_chars - grab characters from serial core, send off
534 * @port: Port to operate on
535 * @raw: Transmit raw or buffered
537 * Note: If we're early, before we're registered with serial core, the
538 * writes are going through sn_sal_console_write because that's how
539 * register_console has been set up. We currently could have asynch
540 * polls calling this function due to sn_sal_switch_to_asynch but we can
541 * ignore them until we register with the serial core stuffs.
544 static void sn_transmit_chars(struct sn_cons_port *port, int raw)
546 int xmit_count, tail, head, loops, ii;
549 struct circ_buf *xmit;
554 BUG_ON(!port->sc_is_asynch);
556 if (port->sc_port.state) {
557 /* We're initialized, using serial core infrastructure */
558 xmit = &port->sc_port.state->xmit;
560 /* Probably sn_sal_switch_to_asynch has been run but serial core isn't
561 * initialized yet. Just return. Writes are going through
562 * sn_sal_console_write (due to register_console) at this time.
567 if (uart_circ_empty(xmit) || uart_tx_stopped(&port->sc_port)) {
569 ia64_sn_console_intr_disable(SAL_CONSOLE_INTR_XMIT);
575 start = &xmit->buf[tail];
577 /* twice around gets the tail to the end of the buffer and
578 * then to the head, if needed */
579 loops = (head < tail) ? 2 : 1;
581 for (ii = 0; ii < loops; ii++) {
582 xmit_count = (head < tail) ?
583 (UART_XMIT_SIZE - tail) : (head - tail);
585 if (xmit_count > 0) {
586 if (raw == TRANSMIT_RAW)
588 port->sc_ops->sal_puts_raw(start,
592 port->sc_ops->sal_puts(start, xmit_count);
598 xmit_count -= result;
599 port->sc_port.icount.tx += result;
601 tail &= UART_XMIT_SIZE - 1;
603 start = &xmit->buf[tail];
608 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
609 uart_write_wakeup(&port->sc_port);
611 if (uart_circ_empty(xmit))
612 snp_stop_tx(&port->sc_port); /* no-op for us */
616 * sn_sal_interrupt - Handle console interrupts
617 * @irq: irq #, useful for debug statements
618 * @dev_id: our pointer to our port (sn_cons_port which contains the uart port)
621 static irqreturn_t sn_sal_interrupt(int irq, void *dev_id)
623 struct sn_cons_port *port = (struct sn_cons_port *)dev_id;
625 int status = ia64_sn_console_intr_status();
630 spin_lock_irqsave(&port->sc_port.lock, flags);
631 if (status & SAL_CONSOLE_INTR_RECV) {
632 sn_receive_chars(port, flags);
634 if (status & SAL_CONSOLE_INTR_XMIT) {
635 sn_transmit_chars(port, TRANSMIT_BUFFERED);
637 spin_unlock_irqrestore(&port->sc_port.lock, flags);
642 * sn_sal_timer_poll - this function handles polled console mode
643 * @data: A pointer to our sn_cons_port (which contains the uart port)
645 * data is the pointer that init_timer will store for us. This function is
646 * associated with init_timer to see if there is any console traffic.
647 * Obviously not used in interrupt mode
650 static void sn_sal_timer_poll(unsigned long data)
652 struct sn_cons_port *port = (struct sn_cons_port *)data;
658 if (!port->sc_port.irq) {
659 spin_lock_irqsave(&port->sc_port.lock, flags);
660 if (sn_process_input)
661 sn_receive_chars(port, flags);
662 sn_transmit_chars(port, TRANSMIT_RAW);
663 spin_unlock_irqrestore(&port->sc_port.lock, flags);
664 mod_timer(&port->sc_timer,
665 jiffies + port->sc_interrupt_timeout);
670 * Boot-time initialization code
674 * sn_sal_switch_to_asynch - Switch to async mode (as opposed to synch)
675 * @port: Our sn_cons_port (which contains the uart port)
677 * So this is used by sn_sal_serial_console_init (early on, before we're
678 * registered with serial core). It's also used by sn_sal_module_init
679 * right after we've registered with serial core. The later only happens
680 * if we didn't already come through here via sn_sal_serial_console_init.
683 static void __init sn_sal_switch_to_asynch(struct sn_cons_port *port)
690 DPRINTF("sn_console: about to switch to asynchronous console\n");
692 /* without early_printk, we may be invoked late enough to race
693 * with other cpus doing console IO at this point, however
694 * console interrupts will never be enabled */
695 spin_lock_irqsave(&port->sc_port.lock, flags);
697 /* early_printk invocation may have done this for us */
699 port->sc_ops = &poll_ops;
701 /* we can't turn on the console interrupt (as request_irq
702 * calls kmalloc, which isn't set up yet), so we rely on a
703 * timer to poll for input and push data from the console
706 init_timer(&port->sc_timer);
707 port->sc_timer.function = sn_sal_timer_poll;
708 port->sc_timer.data = (unsigned long)port;
710 if (IS_RUNNING_ON_SIMULATOR())
711 port->sc_interrupt_timeout = 6;
713 /* 960cps / 16 char FIFO = 60HZ
714 * HZ / (SN_SAL_FIFO_SPEED_CPS / SN_SAL_FIFO_DEPTH) */
715 port->sc_interrupt_timeout =
716 HZ * SN_SAL_UART_FIFO_DEPTH / SN_SAL_UART_FIFO_SPEED_CPS;
718 mod_timer(&port->sc_timer, jiffies + port->sc_interrupt_timeout);
720 port->sc_is_asynch = 1;
721 spin_unlock_irqrestore(&port->sc_port.lock, flags);
725 * sn_sal_switch_to_interrupts - Switch to interrupt driven mode
726 * @port: Our sn_cons_port (which contains the uart port)
728 * In sn_sal_module_init, after we're registered with serial core and
729 * the port is added, this function is called to switch us to interrupt
730 * mode. We were previously in asynch/polling mode (using init_timer).
732 * We attempt to switch to interrupt mode here by calling
733 * request_irq. If that works out, we enable receive interrupts.
735 static void __init sn_sal_switch_to_interrupts(struct sn_cons_port *port)
740 DPRINTF("sn_console: switching to interrupt driven console\n");
742 if (request_irq(SGI_UART_VECTOR, sn_sal_interrupt,
744 "SAL console driver", port) >= 0) {
745 spin_lock_irqsave(&port->sc_port.lock, flags);
746 port->sc_port.irq = SGI_UART_VECTOR;
747 port->sc_ops = &intr_ops;
748 irq_set_handler(port->sc_port.irq, handle_level_irq);
750 /* turn on receive interrupts */
751 ia64_sn_console_intr_enable(SAL_CONSOLE_INTR_RECV);
752 spin_unlock_irqrestore(&port->sc_port.lock, flags);
756 "sn_console: console proceeding in polled mode\n");
762 * Kernel console definitions
765 static void sn_sal_console_write(struct console *, const char *, unsigned);
766 static int sn_sal_console_setup(struct console *, char *);
767 static struct uart_driver sal_console_uart;
768 extern struct tty_driver *uart_console_device(struct console *, int *);
770 static struct console sal_console = {
772 .write = sn_sal_console_write,
773 .device = uart_console_device,
774 .setup = sn_sal_console_setup,
775 .index = -1, /* unspecified */
776 .data = &sal_console_uart,
779 #define SAL_CONSOLE &sal_console
781 static struct uart_driver sal_console_uart = {
782 .owner = THIS_MODULE,
783 .driver_name = "sn_console",
784 .dev_name = DEVICE_NAME,
785 .major = 0, /* major/minor set at registration time per USE_DYNAMIC_MINOR */
787 .nr = 1, /* one port */
792 * sn_sal_module_init - When the kernel loads us, get us rolling w/ serial core
794 * Before this is called, we've been printing kernel messages in a special
795 * early mode not making use of the serial core infrastructure. When our
796 * driver is loaded for real, we register the driver and port with serial
797 * core and try to enable interrupt driven mode.
800 static int __init sn_sal_module_init(void)
804 if (!ia64_platform_is("sn2"))
807 printk(KERN_INFO "sn_console: Console driver init\n");
809 if (USE_DYNAMIC_MINOR == 1) {
810 misc.minor = MISC_DYNAMIC_MINOR;
811 misc.name = DEVICE_NAME_DYNAMIC;
812 retval = misc_register(&misc);
814 printk(KERN_WARNING "Failed to register console "
815 "device using misc_register.\n");
818 sal_console_uart.major = MISC_MAJOR;
819 sal_console_uart.minor = misc.minor;
821 sal_console_uart.major = DEVICE_MAJOR;
822 sal_console_uart.minor = DEVICE_MINOR;
825 /* We register the driver and the port before switching to interrupts
826 * or async above so the proper uart structures are populated */
828 if (uart_register_driver(&sal_console_uart) < 0) {
830 ("ERROR sn_sal_module_init failed uart_register_driver, line %d\n",
835 spin_lock_init(&sal_console_port.sc_port.lock);
837 /* Setup the port struct with the minimum needed */
838 sal_console_port.sc_port.membase = (char *)1; /* just needs to be non-zero */
839 sal_console_port.sc_port.type = PORT_16550A;
840 sal_console_port.sc_port.fifosize = SN_SAL_MAX_CHARS;
841 sal_console_port.sc_port.ops = &sn_console_ops;
842 sal_console_port.sc_port.line = 0;
844 if (uart_add_one_port(&sal_console_uart, &sal_console_port.sc_port) < 0) {
845 /* error - not sure what I'd do - so I'll do nothing */
846 printk(KERN_ERR "%s: unable to add port\n", __func__);
849 /* when this driver is compiled in, the console initialization
850 * will have already switched us into asynchronous operation
851 * before we get here through the module initcalls */
852 if (!sal_console_port.sc_is_asynch) {
853 sn_sal_switch_to_asynch(&sal_console_port);
856 /* at this point (module_init) we can try to turn on interrupts */
857 if (!IS_RUNNING_ON_SIMULATOR()) {
858 sn_sal_switch_to_interrupts(&sal_console_port);
860 sn_process_input = 1;
865 * sn_sal_module_exit - When we're unloaded, remove the driver/port
868 static void __exit sn_sal_module_exit(void)
870 del_timer_sync(&sal_console_port.sc_timer);
871 uart_remove_one_port(&sal_console_uart, &sal_console_port.sc_port);
872 uart_unregister_driver(&sal_console_uart);
873 misc_deregister(&misc);
876 module_init(sn_sal_module_init);
877 module_exit(sn_sal_module_exit);
880 * puts_raw_fixed - sn_sal_console_write helper for adding \r's as required
881 * @puts_raw : puts function to do the writing
885 * We need a \r ahead of every \n for direct writes through
886 * ia64_sn_console_putb (what sal_puts_raw below actually does).
890 static void puts_raw_fixed(int (*puts_raw) (const char *s, int len),
891 const char *s, int count)
895 /* Output '\r' before each '\n' */
896 while ((s1 = memchr(s, '\n', count)) != NULL) {
906 * sn_sal_console_write - Print statements before serial core available
907 * @console: Console to operate on - we ignore since we have just one
911 * This is referenced in the console struct. It is used for early
912 * console printing before we register with serial core and for things
913 * such as kdb. The console_lock must be held when we get here.
915 * This function has some code for trying to print output even if the lock
916 * is held. We try to cover the case where a lock holder could have died.
917 * We don't use this special case code if we're not registered with serial
918 * core yet. After we're registered with serial core, the only time this
919 * function would be used is for high level kernel output like magic sys req,
923 sn_sal_console_write(struct console *co, const char *s, unsigned count)
925 unsigned long flags = 0;
926 struct sn_cons_port *port = &sal_console_port;
927 static int stole_lock = 0;
929 BUG_ON(!port->sc_is_asynch);
931 /* We can't look at the xmit buffer if we're not registered with serial core
932 * yet. So only do the fancy recovery after registering
934 if (!port->sc_port.state) {
935 /* Not yet registered with serial core - simple case */
936 puts_raw_fixed(port->sc_ops->sal_puts_raw, s, count);
940 /* somebody really wants this output, might be an
941 * oops, kdb, panic, etc. make sure they get it. */
942 if (spin_is_locked(&port->sc_port.lock)) {
943 int lhead = port->sc_port.state->xmit.head;
944 int ltail = port->sc_port.state->xmit.tail;
945 int counter, got_lock = 0;
948 * We attempt to determine if someone has died with the
949 * lock. We wait ~20 secs after the head and tail ptrs
950 * stop moving and assume the lock holder is not functional
951 * and plow ahead. If the lock is freed within the time out
952 * period we re-get the lock and go ahead normally. We also
953 * remember if we have plowed ahead so that we don't have
954 * to wait out the time out period again - the asumption
955 * is that we will time out again.
958 for (counter = 0; counter < 150; mdelay(125), counter++) {
959 if (!spin_is_locked(&port->sc_port.lock)
962 spin_lock_irqsave(&port->sc_port.lock,
969 if ((lhead != port->sc_port.state->xmit.head)
971 port->sc_port.state->xmit.tail)) {
973 port->sc_port.state->xmit.head;
975 port->sc_port.state->xmit.tail;
980 /* flush anything in the serial core xmit buffer, raw */
981 sn_transmit_chars(port, 1);
983 spin_unlock_irqrestore(&port->sc_port.lock, flags);
989 puts_raw_fixed(port->sc_ops->sal_puts_raw, s, count);
992 spin_lock_irqsave(&port->sc_port.lock, flags);
993 sn_transmit_chars(port, 1);
994 spin_unlock_irqrestore(&port->sc_port.lock, flags);
996 puts_raw_fixed(port->sc_ops->sal_puts_raw, s, count);
1002 * sn_sal_console_setup - Set up console for early printing
1003 * @co: Console to work with
1004 * @options: Options to set
1006 * Altix console doesn't do anything with baud rates, etc, anyway.
1008 * This isn't required since not providing the setup function in the
1009 * console struct is ok. However, other patches like KDB plop something
1010 * here so providing it is easier.
1013 static int sn_sal_console_setup(struct console *co, char *options)
1019 * sn_sal_console_write_early - simple early output routine
1020 * @co - console struct
1021 * @s - string to print
1024 * Simple function to provide early output, before even
1025 * sn_sal_serial_console_init is called. Referenced in the
1026 * console struct registerd in sn_serial_console_early_setup.
1030 sn_sal_console_write_early(struct console *co, const char *s, unsigned count)
1032 puts_raw_fixed(sal_console_port.sc_ops->sal_puts_raw, s, count);
1035 /* Used for very early console printing - again, before
1036 * sn_sal_serial_console_init is run */
1037 static struct console sal_console_early __initdata = {
1039 .write = sn_sal_console_write_early,
1040 .flags = CON_PRINTBUFFER,
1045 * sn_serial_console_early_setup - Sets up early console output support
1047 * Register a console early on... This is for output before even
1048 * sn_sal_serial_cosnole_init is called. This function is called from
1049 * setup.c. This allows us to do really early polled writes. When
1050 * sn_sal_serial_console_init is called, this console is unregistered
1051 * and a new one registered.
1053 int __init sn_serial_console_early_setup(void)
1055 if (!ia64_platform_is("sn2"))
1058 sal_console_port.sc_ops = &poll_ops;
1059 spin_lock_init(&sal_console_port.sc_port.lock);
1060 early_sn_setup(); /* Find SAL entry points */
1061 register_console(&sal_console_early);
1067 * sn_sal_serial_console_init - Early console output - set up for register
1069 * This function is called when regular console init happens. Because we
1070 * support even earlier console output with sn_serial_console_early_setup
1071 * (called from setup.c directly), this function unregisters the really
1074 * Note: Even if setup.c doesn't register sal_console_early, unregistering
1075 * it here doesn't hurt anything.
1078 static int __init sn_sal_serial_console_init(void)
1080 if (ia64_platform_is("sn2")) {
1081 sn_sal_switch_to_asynch(&sal_console_port);
1082 DPRINTF("sn_sal_serial_console_init : register console\n");
1083 register_console(&sal_console);
1084 unregister_console(&sal_console_early);
1089 console_initcall(sn_sal_serial_console_init);