Free Electrons

Embedded Linux Experts

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
/*
 *    Chassis LCD/LED driver for HP-PARISC workstations
 *
 *      (c) Copyright 2000 Red Hat Software
 *      (c) Copyright 2000 Helge Deller <hdeller@redhat.com>
 *      (c) Copyright 2001-2009 Helge Deller <deller@gmx.de>
 *      (c) Copyright 2001 Randolph Chung <tausq@debian.org>
 *
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2 of the License, or
 *      (at your option) any later version.
 *
 * TODO:
 *	- speed-up calculations with inlined assembler
 *	- interface to write to second row of LCD from /proc (if technically possible)
 *
 * Changes:
 *      - Audit copy_from_user in led_proc_write.
 *                                Daniele Bellucci <bellucda@tiscali.it>
 *	- Switch from using a tasklet to a work queue, so the led_LCD_driver
 *	  	can sleep.
 *	  			  David Pye <dmp@davidmpye.dyndns.org>
 */

#include <linux/module.h>
#include <linux/stddef.h>	/* for offsetof() */
#include <linux/init.h>
#include <linux/types.h>
#include <linux/ioport.h>
#include <linux/utsname.h>
#include <linux/capability.h>
#include <linux/delay.h>
#include <linux/netdevice.h>
#include <linux/inetdevice.h>
#include <linux/in.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/reboot.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/ctype.h>
#include <linux/blkdev.h>
#include <linux/workqueue.h>
#include <linux/rcupdate.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/hardware.h>
#include <asm/param.h>		/* HZ */
#include <asm/led.h>
#include <asm/pdc.h>
#include <asm/uaccess.h>

/* The control of the LEDs and LCDs on PARISC-machines have to be done 
   completely in software. The necessary calculations are done in a work queue
   task which is scheduled regularly, and since the calculations may consume a 
   relatively large amount of CPU time, some of the calculations can be 
   turned off with the following variables (controlled via procfs) */

static int led_type __read_mostly = -1;
static unsigned char lastleds;	/* LED state from most recent update */
static unsigned int led_heartbeat __read_mostly = 1;
static unsigned int led_diskio    __read_mostly = 1;
static unsigned int led_lanrxtx   __read_mostly = 1;
static char lcd_text[32]          __read_mostly;
static char lcd_text_default[32]  __read_mostly;
static int  lcd_no_led_support    __read_mostly = 0; /* KittyHawk doesn't support LED on its LCD */


static struct workqueue_struct *led_wq;
static void led_work_func(struct work_struct *);
static DECLARE_DELAYED_WORK(led_task, led_work_func);

#if 0
#define DPRINTK(x)	printk x
#else
#define DPRINTK(x)
#endif

struct lcd_block {
	unsigned char command;	/* stores the command byte      */
	unsigned char on;	/* value for turning LED on     */
	unsigned char off;	/* value for turning LED off    */
};

/* Structure returned by PDC_RETURN_CHASSIS_INFO */
/* NOTE: we use unsigned long:16 two times, since the following member 
   lcd_cmd_reg_addr needs to be 64bit aligned on 64bit PA2.0-machines */
struct pdc_chassis_lcd_info_ret_block {
	unsigned long model:16;		/* DISPLAY_MODEL_XXXX */
	unsigned long lcd_width:16;	/* width of the LCD in chars (DISPLAY_MODEL_LCD only) */
	unsigned long lcd_cmd_reg_addr;	/* ptr to LCD cmd-register & data ptr for LED */
	unsigned long lcd_data_reg_addr; /* ptr to LCD data-register (LCD only) */
	unsigned int min_cmd_delay;	/* delay in uS after cmd-write (LCD only) */
	unsigned char reset_cmd1;	/* command #1 for writing LCD string (LCD only) */
	unsigned char reset_cmd2;	/* command #2 for writing LCD string (LCD only) */
	unsigned char act_enable;	/* 0 = no activity (LCD only) */
	struct lcd_block heartbeat;
	struct lcd_block disk_io;
	struct lcd_block lan_rcv;
	struct lcd_block lan_tx;
	char _pad;
};


/* LCD_CMD and LCD_DATA for KittyHawk machines */
#define KITTYHAWK_LCD_CMD  F_EXTEND(0xf0190000UL) /* 64bit-ready */
#define KITTYHAWK_LCD_DATA (KITTYHAWK_LCD_CMD+1)

/* lcd_info is pre-initialized to the values needed to program KittyHawk LCD's 
 * HP seems to have used Sharp/Hitachi HD44780 LCDs most of the time. */
static struct pdc_chassis_lcd_info_ret_block
lcd_info __attribute__((aligned(8))) __read_mostly =
{
	.model =		DISPLAY_MODEL_LCD,
	.lcd_width =		16,
	.lcd_cmd_reg_addr =	KITTYHAWK_LCD_CMD,
	.lcd_data_reg_addr =	KITTYHAWK_LCD_DATA,
	.min_cmd_delay =	80,
	.reset_cmd1 =		0x80,
	.reset_cmd2 =		0xc0,
};


/* direct access to some of the lcd_info variables */
#define LCD_CMD_REG	lcd_info.lcd_cmd_reg_addr	 
#define LCD_DATA_REG	lcd_info.lcd_data_reg_addr	 
#define LED_DATA_REG	lcd_info.lcd_cmd_reg_addr	/* LASI & ASP only */

#define LED_HASLCD 1
#define LED_NOLCD  0

/* The workqueue must be created at init-time */
static int start_task(void) 
{	
	/* Display the default text now */
	if (led_type == LED_HASLCD) lcd_print( lcd_text_default );

	/* KittyHawk has no LED support on its LCD */
	if (lcd_no_led_support) return 0;

	/* Create the work queue and queue the LED task */
	led_wq = create_singlethread_workqueue("led_wq");	
	queue_delayed_work(led_wq, &led_task, 0);

	return 0;
}

device_initcall(start_task);

/* ptr to LCD/LED-specific function */
static void (*led_func_ptr) (unsigned char) __read_mostly;

#ifdef CONFIG_PROC_FS
static int led_proc_show(struct seq_file *m, void *v)
{
	switch ((long)m->private)
	{
	case LED_NOLCD:
		seq_printf(m, "Heartbeat: %d\n", led_heartbeat);
		seq_printf(m, "Disk IO: %d\n", led_diskio);
		seq_printf(m, "LAN Rx/Tx: %d\n", led_lanrxtx);
		break;
	case LED_HASLCD:
		seq_printf(m, "%s\n", lcd_text);
		break;
	default:
		return 0;
	}
	return 0;
}

static int led_proc_open(struct inode *inode, struct file *file)
{
	return single_open(file, led_proc_show, PDE(inode)->data);
}


static ssize_t led_proc_write(struct file *file, const char *buf,
	size_t count, loff_t *pos)
{
	void *data = PDE(file->f_path.dentry->d_inode)->data;
	char *cur, lbuf[32];
	int d;

	if (!capable(CAP_SYS_ADMIN))
		return -EACCES;

	if (count >= sizeof(lbuf))
		count = sizeof(lbuf)-1;

	if (copy_from_user(lbuf, buf, count))
		return -EFAULT;
	lbuf[count] = 0;

	cur = lbuf;

	switch ((long)data)
	{
	case LED_NOLCD:
		d = *cur++ - '0';
		if (d != 0 && d != 1) goto parse_error;
		led_heartbeat = d;

		if (*cur++ != ' ') goto parse_error;

		d = *cur++ - '0';
		if (d != 0 && d != 1) goto parse_error;
		led_diskio = d;

		if (*cur++ != ' ') goto parse_error;

		d = *cur++ - '0';
		if (d != 0 && d != 1) goto parse_error;
		led_lanrxtx = d;

		break;
	case LED_HASLCD:
		if (*cur && cur[strlen(cur)-1] == '\n')
			cur[strlen(cur)-1] = 0;
		if (*cur == 0) 
			cur = lcd_text_default;
		lcd_print(cur);
		break;
	default:
		return 0;
	}
	
	return count;

parse_error:
	if ((long)data == LED_NOLCD)
		printk(KERN_CRIT "Parse error: expect \"n n n\" (n == 0 or 1) for heartbeat,\ndisk io and lan tx/rx indicators\n");
	return -EINVAL;
}

static const struct file_operations led_proc_fops = {
	.owner		= THIS_MODULE,
	.open		= led_proc_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
	.write		= led_proc_write,
};

static int __init led_create_procfs(void)
{
	struct proc_dir_entry *proc_pdc_root = NULL;
	struct proc_dir_entry *ent;

	if (led_type == -1) return -1;

	proc_pdc_root = proc_mkdir("pdc", 0);
	if (!proc_pdc_root) return -1;

	if (!lcd_no_led_support)
	{
		ent = proc_create_data("led", S_IRUGO|S_IWUSR, proc_pdc_root,
					&led_proc_fops, (void *)LED_NOLCD); /* LED */
		if (!ent) return -1;
	}

	if (led_type == LED_HASLCD)
	{
		ent = proc_create_data("lcd", S_IRUGO|S_IWUSR, proc_pdc_root,
					&led_proc_fops, (void *)LED_HASLCD); /* LCD */
		if (!ent) return -1;
	}

	return 0;
}
#endif

/*
   ** 
   ** led_ASP_driver()
   ** 
 */
#define	LED_DATA	0x01	/* data to shift (0:on 1:off) */
#define	LED_STROBE	0x02	/* strobe to clock data */
static void led_ASP_driver(unsigned char leds)
{
	int i;

	leds = ~leds;
	for (i = 0; i < 8; i++) {
		unsigned char value;
		value = (leds & 0x80) >> 7;
		gsc_writeb( value,		 LED_DATA_REG );
		gsc_writeb( value | LED_STROBE,	 LED_DATA_REG );
		leds <<= 1;
	}
}


/*
   ** 
   ** led_LASI_driver()
   ** 
 */
static void led_LASI_driver(unsigned char leds)
{
	leds = ~leds;
	gsc_writeb( leds, LED_DATA_REG );
}


/*
   ** 
   ** led_LCD_driver()
   **   
 */
static void led_LCD_driver(unsigned char leds)
{
	static int i;
	static unsigned char mask[4] = { LED_HEARTBEAT, LED_DISK_IO,
		LED_LAN_RCV, LED_LAN_TX };
	
	static struct lcd_block * blockp[4] = {
		&lcd_info.heartbeat,
		&lcd_info.disk_io,
		&lcd_info.lan_rcv,
		&lcd_info.lan_tx
	};

	/* Convert min_cmd_delay to milliseconds */
	unsigned int msec_cmd_delay = 1 + (lcd_info.min_cmd_delay / 1000);
	
	for (i=0; i<4; ++i) 
	{
		if ((leds & mask[i]) != (lastleds & mask[i])) 
		{
			gsc_writeb( blockp[i]->command, LCD_CMD_REG );
			msleep(msec_cmd_delay);
			
			gsc_writeb( leds & mask[i] ? blockp[i]->on : 
					blockp[i]->off, LCD_DATA_REG );
			msleep(msec_cmd_delay);
		}
	}
}


/*
   ** 
   ** led_get_net_activity()
   ** 
   ** calculate if there was TX- or RX-throughput on the network interfaces
   ** (analog to dev_get_info() from net/core/dev.c)
   **   
 */
static __inline__ int led_get_net_activity(void)
{ 
#ifndef CONFIG_NET
	return 0;
#else
	static u64 rx_total_last, tx_total_last;
	u64 rx_total, tx_total;
	struct net_device *dev;
	int retval;

	rx_total = tx_total = 0;
	
	/* we are running as a workqueue task, so we can use an RCU lookup */
	rcu_read_lock();
	for_each_netdev_rcu(&init_net, dev) {
	    const struct rtnl_link_stats64 *stats;
	    struct rtnl_link_stats64 temp;
	    struct in_device *in_dev = __in_dev_get_rcu(dev);
	    if (!in_dev || !in_dev->ifa_list)
		continue;
	    if (ipv4_is_loopback(in_dev->ifa_list->ifa_local))
		continue;
	    stats = dev_get_stats(dev, &temp);
	    rx_total += stats->rx_packets;
	    tx_total += stats->tx_packets;
	}
	rcu_read_unlock();

	retval = 0;

	if (rx_total != rx_total_last) {
		rx_total_last = rx_total;
		retval |= LED_LAN_RCV;
	}

	if (tx_total != tx_total_last) {
		tx_total_last = tx_total;
		retval |= LED_LAN_TX;
	}

	return retval;
#endif
}


/*
   ** 
   ** led_get_diskio_activity()
   ** 
   ** calculate if there was disk-io in the system
   **   
 */
static __inline__ int led_get_diskio_activity(void)
{	
	static unsigned long last_pgpgin, last_pgpgout;
	unsigned long events[NR_VM_EVENT_ITEMS];
	int changed;

	all_vm_events(events);

	/* Just use a very simple calculation here. Do not care about overflow,
	   since we only want to know if there was activity or not. */
	changed = (events[PGPGIN] != last_pgpgin) ||
		  (events[PGPGOUT] != last_pgpgout);
	last_pgpgin  = events[PGPGIN];
	last_pgpgout = events[PGPGOUT];

	return (changed ? LED_DISK_IO : 0);
}



/*
   ** led_work_func()
   ** 
   ** manages when and which chassis LCD/LED gets updated

    TODO:
    - display load average (older machines like 715/64 have 4 "free" LED's for that)
    - optimizations
 */

#define HEARTBEAT_LEN (HZ*10/100)
#define HEARTBEAT_2ND_RANGE_START (HZ*28/100)
#define HEARTBEAT_2ND_RANGE_END   (HEARTBEAT_2ND_RANGE_START + HEARTBEAT_LEN)

#define LED_UPDATE_INTERVAL (1 + (HZ*19/1000))

static void led_work_func (struct work_struct *unused)
{
	static unsigned long last_jiffies;
	static unsigned long count_HZ; /* counter in range 0..HZ */
	unsigned char currentleds = 0; /* stores current value of the LEDs */

	/* exit if not initialized */
	if (!led_func_ptr)
	    return;

	/* increment the heartbeat timekeeper */
	count_HZ += jiffies - last_jiffies;
	last_jiffies = jiffies;
	if (count_HZ >= HZ)
	    count_HZ = 0;

	if (likely(led_heartbeat))
	{
		/* flash heartbeat-LED like a real heart
		 * (2 x short then a long delay)
		 */
		if (count_HZ < HEARTBEAT_LEN || 
				(count_HZ >= HEARTBEAT_2ND_RANGE_START &&
				count_HZ < HEARTBEAT_2ND_RANGE_END)) 
			currentleds |= LED_HEARTBEAT;
	}

	if (likely(led_lanrxtx))  currentleds |= led_get_net_activity();
	if (likely(led_diskio))   currentleds |= led_get_diskio_activity();

	/* blink LEDs if we got an Oops (HPMC) */
	if (unlikely(oops_in_progress)) {
		if (boot_cpu_data.cpu_type >= pcxl2) {
			/* newer machines don't have loadavg. LEDs, so we
			 * let all LEDs blink twice per second instead */
			currentleds = (count_HZ <= (HZ/2)) ? 0 : 0xff;
		} else {
			/* old machines: blink loadavg. LEDs twice per second */
			if (count_HZ <= (HZ/2))
				currentleds &= ~(LED4|LED5|LED6|LED7);
			else
				currentleds |= (LED4|LED5|LED6|LED7);
		}
	}

	if (currentleds != lastleds)
	{
		led_func_ptr(currentleds);	/* Update the LCD/LEDs */
		lastleds = currentleds;
	}

	queue_delayed_work(led_wq, &led_task, LED_UPDATE_INTERVAL);
}

/*
   ** led_halt()
   ** 
   ** called by the reboot notifier chain at shutdown and stops all
   ** LED/LCD activities.
   ** 
 */

static int led_halt(struct notifier_block *, unsigned long, void *);

static struct notifier_block led_notifier = {
	.notifier_call = led_halt,
};
static int notifier_disabled = 0;

static int led_halt(struct notifier_block *nb, unsigned long event, void *buf) 
{
	char *txt;

	if (notifier_disabled)
		return NOTIFY_OK;

	notifier_disabled = 1;
	switch (event) {
	case SYS_RESTART:	txt = "SYSTEM RESTART";
				break;
	case SYS_HALT:		txt = "SYSTEM HALT";
				break;
	case SYS_POWER_OFF:	txt = "SYSTEM POWER OFF";
				break;
	default:		return NOTIFY_DONE;
	}
	
	/* Cancel the work item and delete the queue */
	if (led_wq) {
		cancel_delayed_work_sync(&led_task);
		destroy_workqueue(led_wq);
		led_wq = NULL;
	}
 
	if (lcd_info.model == DISPLAY_MODEL_LCD)
		lcd_print(txt);
	else
		if (led_func_ptr)
			led_func_ptr(0xff); /* turn all LEDs ON */
	
	return NOTIFY_OK;
}

/*
   ** register_led_driver()
   ** 
   ** registers an external LED or LCD for usage by this driver.
   ** currently only LCD-, LASI- and ASP-style LCD/LED's are supported.
   ** 
 */

int __init register_led_driver(int model, unsigned long cmd_reg, unsigned long data_reg)
{
	static int initialized;
	
	if (initialized || !data_reg)
		return 1;
	
	lcd_info.model = model;		/* store the values */
	LCD_CMD_REG = (cmd_reg == LED_CMD_REG_NONE) ? 0 : cmd_reg;

	switch (lcd_info.model) {
	case DISPLAY_MODEL_LCD:
		LCD_DATA_REG = data_reg;
		printk(KERN_INFO "LCD display at %lx,%lx registered\n", 
			LCD_CMD_REG , LCD_DATA_REG);
		led_func_ptr = led_LCD_driver;
		led_type = LED_HASLCD;
		break;

	case DISPLAY_MODEL_LASI:
		LED_DATA_REG = data_reg;
		led_func_ptr = led_LASI_driver;
		printk(KERN_INFO "LED display at %lx registered\n", LED_DATA_REG);
		led_type = LED_NOLCD;
		break;

	case DISPLAY_MODEL_OLD_ASP:
		LED_DATA_REG = data_reg;
		led_func_ptr = led_ASP_driver;
		printk(KERN_INFO "LED (ASP-style) display at %lx registered\n", 
		    LED_DATA_REG);
		led_type = LED_NOLCD;
		break;

	default:
		printk(KERN_ERR "%s: Wrong LCD/LED model %d !\n",
		       __func__, lcd_info.model);
		return 1;
	}
	
	/* mark the LCD/LED driver now as initialized and 
	 * register to the reboot notifier chain */
	initialized++;
	register_reboot_notifier(&led_notifier);

	/* Ensure the work is queued */
	if (led_wq) {
		queue_delayed_work(led_wq, &led_task, 0);
	}

	return 0;
}

/*
   ** register_led_regions()
   ** 
   ** register_led_regions() registers the LCD/LED regions for /procfs.
   ** At bootup - where the initialisation of the LCD/LED normally happens - 
   ** not all internal structures of request_region() are properly set up,
   ** so that we delay the led-registration until after busdevices_init() 
   ** has been executed.
   **
 */

void __init register_led_regions(void)
{
	switch (lcd_info.model) {
	case DISPLAY_MODEL_LCD:
		request_mem_region((unsigned long)LCD_CMD_REG,  1, "lcd_cmd");
		request_mem_region((unsigned long)LCD_DATA_REG, 1, "lcd_data");
		break;
	case DISPLAY_MODEL_LASI:
	case DISPLAY_MODEL_OLD_ASP:
		request_mem_region((unsigned long)LED_DATA_REG, 1, "led_data");
		break;
	}
}


/*
   ** 
   ** lcd_print()
   ** 
   ** Displays the given string on the LCD-Display of newer machines.
   ** lcd_print() disables/enables the timer-based led work queue to
   ** avoid a race condition while writing the CMD/DATA register pair.
   **
 */
int lcd_print( const char *str )
{
	int i;

	if (!led_func_ptr || lcd_info.model != DISPLAY_MODEL_LCD)
	    return 0;
	
	/* temporarily disable the led work task */
	if (led_wq)
		cancel_delayed_work_sync(&led_task);

	/* copy display string to buffer for procfs */
	strlcpy(lcd_text, str, sizeof(lcd_text));

	/* Set LCD Cursor to 1st character */
	gsc_writeb(lcd_info.reset_cmd1, LCD_CMD_REG);
	udelay(lcd_info.min_cmd_delay);

	/* Print the string */
	for (i=0; i < lcd_info.lcd_width; i++) {
	    if (str && *str)
		gsc_writeb(*str++, LCD_DATA_REG);
	    else
		gsc_writeb(' ', LCD_DATA_REG);
	    udelay(lcd_info.min_cmd_delay);
	}
	
	/* re-queue the work */
	if (led_wq) {
		queue_delayed_work(led_wq, &led_task, 0);
	}

	return lcd_info.lcd_width;
}

/*
   ** led_init()
   ** 
   ** led_init() is called very early in the bootup-process from setup.c 
   ** and asks the PDC for an usable chassis LCD or LED.
   ** If the PDC doesn't return any info, then the LED
   ** is detected by lasi.c or asp.c and registered with the
   ** above functions lasi_led_init() or asp_led_init().
   ** KittyHawk machines have often a buggy PDC, so that
   ** we explicitly check for those machines here.
 */

int __init led_init(void)
{
	struct pdc_chassis_info chassis_info;
	int ret;

	snprintf(lcd_text_default, sizeof(lcd_text_default),
		"Linux %s", init_utsname()->release);

	/* Work around the buggy PDC of KittyHawk-machines */
	switch (CPU_HVERSION) {
	case 0x580:		/* KittyHawk DC2-100 (K100) */
	case 0x581:		/* KittyHawk DC3-120 (K210) */
	case 0x582:		/* KittyHawk DC3 100 (K400) */
	case 0x583:		/* KittyHawk DC3 120 (K410) */
	case 0x58B:		/* KittyHawk DC2 100 (K200) */
		printk(KERN_INFO "%s: KittyHawk-Machine (hversion 0x%x) found, "
				"LED detection skipped.\n", __FILE__, CPU_HVERSION);
		lcd_no_led_support = 1;
		goto found;	/* use the preinitialized values of lcd_info */
	}

	/* initialize the struct, so that we can check for valid return values */
	lcd_info.model = DISPLAY_MODEL_NONE;
	chassis_info.actcnt = chassis_info.maxcnt = 0;

	ret = pdc_chassis_info(&chassis_info, &lcd_info, sizeof(lcd_info));
	if (ret == PDC_OK) {
		DPRINTK((KERN_INFO "%s: chassis info: model=%d (%s), "
			 "lcd_width=%d, cmd_delay=%u,\n"
			 "%s: sizecnt=%d, actcnt=%ld, maxcnt=%ld\n",
		         __FILE__, lcd_info.model,
			 (lcd_info.model==DISPLAY_MODEL_LCD) ? "LCD" :
			  (lcd_info.model==DISPLAY_MODEL_LASI) ? "LED" : "unknown",
			 lcd_info.lcd_width, lcd_info.min_cmd_delay,
			 __FILE__, sizeof(lcd_info), 
			 chassis_info.actcnt, chassis_info.maxcnt));
		DPRINTK((KERN_INFO "%s: cmd=%p, data=%p, reset1=%x, reset2=%x, act_enable=%d\n",
			__FILE__, lcd_info.lcd_cmd_reg_addr, 
			lcd_info.lcd_data_reg_addr, lcd_info.reset_cmd1,  
			lcd_info.reset_cmd2, lcd_info.act_enable ));
	
		/* check the results. Some machines have a buggy PDC */
		if (chassis_info.actcnt <= 0 || chassis_info.actcnt != chassis_info.maxcnt)
			goto not_found;

		switch (lcd_info.model) {
		case DISPLAY_MODEL_LCD:		/* LCD display */
			if (chassis_info.actcnt < 
				offsetof(struct pdc_chassis_lcd_info_ret_block, _pad)-1)
				goto not_found;
			if (!lcd_info.act_enable) {
				DPRINTK((KERN_INFO "PDC prohibited usage of the LCD.\n"));
				goto not_found;
			}
			break;

		case DISPLAY_MODEL_NONE:	/* no LED or LCD available */
			printk(KERN_INFO "PDC reported no LCD or LED.\n");
			goto not_found;

		case DISPLAY_MODEL_LASI:	/* Lasi style 8 bit LED display */
			if (chassis_info.actcnt != 8 && chassis_info.actcnt != 32)
				goto not_found;
			break;

		default:
			printk(KERN_WARNING "PDC reported unknown LCD/LED model %d\n",
			       lcd_info.model);
			goto not_found;
		} /* switch() */

found:
		/* register the LCD/LED driver */
		register_led_driver(lcd_info.model, LCD_CMD_REG, LCD_DATA_REG);
		return 0;

	} else { /* if() */
		DPRINTK((KERN_INFO "pdc_chassis_info call failed with retval = %d\n", ret));
	}

not_found:
	lcd_info.model = DISPLAY_MODEL_NONE;
	return 1;
}

static void __exit led_exit(void)
{
	unregister_reboot_notifier(&led_notifier);
	return;
}

#ifdef CONFIG_PROC_FS
module_init(led_create_procfs)
#endif