PARISC: led.c - fix potential stack overflow in led_proc_write()

[linux-2.6/x86.git] / drivers / parisc / led.c

/*
 *    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 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 =        40,
        .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 );

        /* 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;
        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 unsigned long rx_total_last, tx_total_last;
        unsigned long 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 net_device_stats *stats;
            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);
            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);
                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