// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   *    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>
   *

   * 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 <linux/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
  ", led_heartbeat);
  		seq_printf(m, "Disk IO: %d
  ", led_diskio);
  		seq_printf(m, "LAN Rx/Tx: %d
  ", led_lanrxtx);

  		break;
  	case LED_HASLCD:

  		seq_printf(m, "%s
  ", 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_DATA(inode));

  }

  static ssize_t led_proc_write(struct file *file, const char __user *buf,

  	size_t count, loff_t *pos)

  {

  	void *data = PDE_DATA(file_inode(file));

  	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] == '
  ')
  			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,
  disk io and lan tx/rx indicators
  ");
  	return -EINVAL;
  }

  static const struct proc_ops led_proc_ops = {
  	.proc_open	= led_proc_open,
  	.proc_read	= seq_read,
  	.proc_lseek	= seq_lseek,
  	.proc_release	= single_release,
  	.proc_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", NULL);

  	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_ops, (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_ops, (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
  ", 
  			LCD_CMD_REG , LCD_DATA_REG);
  		led_func_ptr = led_LCD_driver;

  		led_type = LED_HASLCD;
  		break;
  
  	case DISPLAY_MODEL_LASI:

  		/* Skip to register LED in QEMU */
  		if (running_on_qemu)
  			return 1;

  		LED_DATA_REG = data_reg;
  		led_func_ptr = led_LASI_driver;
  		printk(KERN_INFO "LED display at %lx registered
  ", 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
  ", 
  		    LED_DATA_REG);
  		led_type = LED_NOLCD;
  		break;
  
  	default:
  		printk(KERN_ERR "%s: Wrong LCD/LED model %d !
  ",

  		       __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.
  ", __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,
  "
  			 "%s: sizecnt=%d, actcnt=%ld, maxcnt=%ld
  ",
  		         __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
  ",
  			__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.
  "));
  				goto not_found;
  			}
  			break;
  
  		case DISPLAY_MODEL_NONE:	/* no LED or LCD available */
  			printk(KERN_INFO "PDC reported no LCD or LED.
  ");
  			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
  ",
  			       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
  ", 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