led.c

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/*
 *    Chassis LCD/LED driver for HP-PARISC workstations
 *
 *      (c) Copyright 2000 Red Hat Software
 *      (c) Copyright 2000 Helge Deller <[email protected]>
 *      (c) Copyright 2001-2009 Helge Deller <[email protected]>
 *      (c) Copyright 2001 Randolph Chung <[email protected]>
 *
 *      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 <[email protected]>
 *  - Switch from using a tasklet to a work queue, so the led_LCD_driver
 *      can sleep.
 *                David Pye <[email protected]>
 */

#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