[S390] Fix sparse warnings.

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / drivers / s390 / block / dasd_devmap.c

/*
 * File...........: linux/drivers/s390/block/dasd_devmap.c
 * Author(s)......: Holger Smolinski <Holger.Smolinski@de.ibm.com>
 *                  Horst Hummel <Horst.Hummel@de.ibm.com>
 *                  Carsten Otte <Cotte@de.ibm.com>
 *                  Martin Schwidefsky <schwidefsky@de.ibm.com>
 * Bugreports.to..: <Linux390@de.ibm.com>
 * (C) IBM Corporation, IBM Deutschland Entwicklung GmbH, 1999-2001
 *
 * Device mapping and dasd= parameter parsing functions. All devmap
 * functions may not be called from interrupt context. In particular
 * dasd_get_device is a no-no from interrupt context.
 *
 */

#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/module.h>

#include <asm/debug.h>
#include <asm/uaccess.h>

/* This is ugly... */
#define PRINTK_HEADER "dasd_devmap:"

#include "dasd_int.h"

kmem_cache_t *dasd_page_cache;
EXPORT_SYMBOL_GPL(dasd_page_cache);

/*
 * dasd_devmap_t is used to store the features and the relation
 * between device number and device index. To find a dasd_devmap_t
 * that corresponds to a device number of a device index each
 * dasd_devmap_t is added to two linked lists, one to search by
 * the device number and one to search by the device index. As
 * soon as big minor numbers are available the device index list
 * can be removed since the device number will then be identical
 * to the device index.
 */
struct dasd_devmap {
        struct list_head list;
        char bus_id[BUS_ID_SIZE];
        unsigned int devindex;
        unsigned short features;
        struct dasd_device *device;
        struct dasd_uid uid;
};

/*
 * dasd_servermap is used to store the server_id of all storage servers
 * accessed by DASD device driver.
 */
struct dasd_servermap {
        struct list_head list;
        struct server_id {
                char vendor[4];
                char serial[15];
        } sid;
};

static struct list_head dasd_serverlist;

/*
 * Parameter parsing functions for dasd= parameter. The syntax is:
 *   <devno>            : (0x)?[0-9a-fA-F]+
 *   <busid>            : [0-0a-f]\.[0-9a-f]\.(0x)?[0-9a-fA-F]+
 *   <feature>          : ro
 *   <feature_list>     : \(<feature>(:<feature>)*\)
 *   <devno-range>      : <devno>(-<devno>)?<feature_list>?
 *   <busid-range>      : <busid>(-<busid>)?<feature_list>?
 *   <devices>          : <devno-range>|<busid-range>
 *   <dasd_module>      : dasd_diag_mod|dasd_eckd_mod|dasd_fba_mod
 *
 *   <dasd>             : autodetect|probeonly|<devices>(,<devices>)*
 */

int dasd_probeonly =  0;        /* is true, when probeonly mode is active */
int dasd_autodetect = 0;        /* is true, when autodetection is active */
int dasd_nopav = 0;             /* is true, when PAV is disabled */
EXPORT_SYMBOL_GPL(dasd_nopav);

/*
 * char *dasd[] is intended to hold the ranges supplied by the dasd= statement
 * it is named 'dasd' to directly be filled by insmod with the comma separated
 * strings when running as a module.
 */
static char *dasd[256];
module_param_array(dasd, charp, NULL, 0);

/*
 * Single spinlock to protect devmap structures and lists.
 */
static DEFINE_SPINLOCK(dasd_devmap_lock);

/*
 * Hash lists for devmap structures.
 */
static struct list_head dasd_hashlists[256];
int dasd_max_devindex;

static struct dasd_devmap *dasd_add_busid(char *, int);

static inline int
dasd_hash_busid(char *bus_id)
{
        int hash, i;

        hash = 0;
        for (i = 0; (i < BUS_ID_SIZE) && *bus_id; i++, bus_id++)
                hash += *bus_id;
        return hash & 0xff;
}

#ifndef MODULE
/*
 * The parameter parsing functions for builtin-drivers are called
 * before kmalloc works. Store the pointers to the parameters strings
 * into dasd[] for later processing.
 */
static int __init
dasd_call_setup(char *str)
{
        static int count = 0;

        if (count < 256)
                dasd[count++] = str;
        return 1;
}

__setup ("dasd=", dasd_call_setup);
#endif  /* #ifndef MODULE */

/*
 * Read a device busid/devno from a string.
 */
static inline int
dasd_busid(char **str, int *id0, int *id1, int *devno)
{
        int val, old_style;

        /* check for leading '0x' */
        old_style = 0;
        if ((*str)[0] == '0' && (*str)[1] == 'x') {
                *str += 2;
                old_style = 1;
        }
        if (!isxdigit((*str)[0]))       /* We require at least one hex digit */
                return -EINVAL;
        val = simple_strtoul(*str, str, 16);
        if (old_style || (*str)[0] != '.') {
                *id0 = *id1 = 0;
                if (val < 0 || val > 0xffff)
                        return -EINVAL;
                *devno = val;
                return 0;
        }
        /* New style x.y.z busid */
        if (val < 0 || val > 0xff)
                return -EINVAL;
        *id0 = val;
        (*str)++;
        if (!isxdigit((*str)[0]))       /* We require at least one hex digit */
                return -EINVAL;
        val = simple_strtoul(*str, str, 16);
        if (val < 0 || val > 0xff || (*str)++[0] != '.')
                return -EINVAL;
        *id1 = val;
        if (!isxdigit((*str)[0]))       /* We require at least one hex digit */
                return -EINVAL;
        val = simple_strtoul(*str, str, 16);
        if (val < 0 || val > 0xffff)
                return -EINVAL;
        *devno = val;
        return 0;
}

/*
 * Read colon separated list of dasd features. Currently there is
 * only one: "ro" for read-only devices. The default feature set
 * is empty (value 0).
 */
static inline int
dasd_feature_list(char *str, char **endp)
{
        int features, len, rc;

        rc = 0;
        if (*str != '(') {
                *endp = str;
                return DASD_FEATURE_DEFAULT;
        }
        str++;
        features = 0;

        while (1) {
                for (len = 0;
                     str[len] && str[len] != ':' && str[len] != ')'; len++);
                if (len == 2 && !strncmp(str, "ro", 2))
                        features |= DASD_FEATURE_READONLY;
                else if (len == 4 && !strncmp(str, "diag", 4))
                        features |= DASD_FEATURE_USEDIAG;
                else {
                        MESSAGE(KERN_WARNING,
                                "unsupported feature: %*s, "
                                "ignoring setting", len, str);
                        rc = -EINVAL;
                }
                str += len;
                if (*str != ':')
                        break;
                str++;
        }
        if (*str != ')') {
                MESSAGE(KERN_WARNING, "%s",
                        "missing ')' in dasd parameter string\n");
                rc = -EINVAL;
        } else
                str++;
        *endp = str;
        if (rc != 0)
                return rc;
        return features;
}

/*
 * Try to match the first element on the comma separated parse string
 * with one of the known keywords. If a keyword is found, take the approprate
 * action and return a pointer to the residual string. If the first element
 * could not be matched to any keyword then return an error code.
 */
static char *
dasd_parse_keyword( char *parsestring ) {

        char *nextcomma, *residual_str;
        int length;

        nextcomma = strchr(parsestring,',');
        if (nextcomma) {
                length = nextcomma - parsestring;
                residual_str = nextcomma + 1;
        } else {
                length = strlen(parsestring);
                residual_str = parsestring + length;
        }
        if (strncmp("autodetect", parsestring, length) == 0) {
                dasd_autodetect = 1;
                MESSAGE (KERN_INFO, "%s",
                         "turning to autodetection mode");
                return residual_str;
        }
        if (strncmp("probeonly", parsestring, length) == 0) {
                dasd_probeonly = 1;
                MESSAGE(KERN_INFO, "%s",
                        "turning to probeonly mode");
                return residual_str;
        }
        if (strncmp("nopav", parsestring, length) == 0) {
                dasd_nopav = 1;
                MESSAGE(KERN_INFO, "%s", "disable PAV mode");
                return residual_str;
        }
        if (strncmp("fixedbuffers", parsestring, length) == 0) {
                if (dasd_page_cache)
                        return residual_str;
                dasd_page_cache =
                        kmem_cache_create("dasd_page_cache", PAGE_SIZE, 0,
                                          SLAB_CACHE_DMA, NULL, NULL );
                if (!dasd_page_cache)
                        MESSAGE(KERN_WARNING, "%s", "Failed to create slab, "
                                "fixed buffer mode disabled.");
                else
                        MESSAGE (KERN_INFO, "%s",
                                 "turning on fixed buffer mode");
                return residual_str;
        }
        return ERR_PTR(-EINVAL);
}

/*
 * Try to interprete the first element on the comma separated parse string
 * as a device number or a range of devices. If the interpretation is
 * successfull, create the matching dasd_devmap entries and return a pointer
 * to the residual string.
 * If interpretation fails or in case of an error, return an error code.
 */
static char *
dasd_parse_range( char *parsestring ) {

        struct dasd_devmap *devmap;
        int from, from_id0, from_id1;
        int to, to_id0, to_id1;
        int features, rc;
        char bus_id[BUS_ID_SIZE+1], *str;

        str = parsestring;
        rc = dasd_busid(&str, &from_id0, &from_id1, &from);
        if (rc == 0) {
                to = from;
                to_id0 = from_id0;
                to_id1 = from_id1;
                if (*str == '-') {
                        str++;
                        rc = dasd_busid(&str, &to_id0, &to_id1, &to);
                }
        }
        if (rc == 0 &&
            (from_id0 != to_id0 || from_id1 != to_id1 || from > to))
                rc = -EINVAL;
        if (rc) {
                MESSAGE(KERN_ERR, "Invalid device range %s", parsestring);
                return ERR_PTR(rc);
        }
        features = dasd_feature_list(str, &str);
        if (features < 0)
                return ERR_PTR(-EINVAL);
        /* each device in dasd= parameter should be set initially online */
        features |= DASD_FEATURE_INITIAL_ONLINE;
        while (from <= to) {
                sprintf(bus_id, "%01x.%01x.%04x",
                        from_id0, from_id1, from++);
                devmap = dasd_add_busid(bus_id, features);
                if (IS_ERR(devmap))
                        return (char *)devmap;
        }
        if (*str == ',')
                return str + 1;
        if (*str == '\0')
                return str;
        MESSAGE(KERN_WARNING,
                "junk at end of dasd parameter string: %s\n", str);
        return ERR_PTR(-EINVAL);
}

static inline char *
dasd_parse_next_element( char *parsestring ) {
        char * residual_str;
        residual_str = dasd_parse_keyword(parsestring);
        if (!IS_ERR(residual_str))
                return residual_str;
        residual_str = dasd_parse_range(parsestring);
        return residual_str;
}

/*
 * Parse parameters stored in dasd[]
 * The 'dasd=...' parameter allows to specify a comma separated list of
 * keywords and device ranges. When the dasd driver is build into the kernel,
 * the complete list will be stored as one element of the dasd[] array.
 * When the dasd driver is build as a module, then the list is broken into
 * it's elements and each dasd[] entry contains one element.
 */
int
dasd_parse(void)
{
        int rc, i;
        char *parsestring;

        rc = 0;
        for (i = 0; i < 256; i++) {
                if (dasd[i] == NULL)
                        break;
                parsestring = dasd[i];
                /* loop over the comma separated list in the parsestring */
                while (*parsestring) {
                        parsestring = dasd_parse_next_element(parsestring);
                        if(IS_ERR(parsestring)) {
                                rc = PTR_ERR(parsestring);
                                break;
                        }
                }
                if (rc) {
                        DBF_EVENT(DBF_ALERT, "%s", "invalid range found");
                        break;
                }
        }
        return rc;
}

/*
 * Add a devmap for the device specified by busid. It is possible that
 * the devmap already exists (dasd= parameter). The order of the devices
 * added through this function will define the kdevs for the individual
 * devices.
 */
static struct dasd_devmap *
dasd_add_busid(char *bus_id, int features)
{
        struct dasd_devmap *devmap, *new, *tmp;
        int hash;

        new = (struct dasd_devmap *)
                kzalloc(sizeof(struct dasd_devmap), GFP_KERNEL);
        if (!new)
                return ERR_PTR(-ENOMEM);
        spin_lock(&dasd_devmap_lock);
        devmap = NULL;
        hash = dasd_hash_busid(bus_id);
        list_for_each_entry(tmp, &dasd_hashlists[hash], list)
                if (strncmp(tmp->bus_id, bus_id, BUS_ID_SIZE) == 0) {
                        devmap = tmp;
                        break;
                }
        if (!devmap) {
                /* This bus_id is new. */
                new->devindex = dasd_max_devindex++;
                strncpy(new->bus_id, bus_id, BUS_ID_SIZE);
                new->features = features;
                new->device = NULL;
                list_add(&new->list, &dasd_hashlists[hash]);
                devmap = new;
                new = NULL;
        }
        spin_unlock(&dasd_devmap_lock);
        kfree(new);
        return devmap;
}

/*
 * Find devmap for device with given bus_id.
 */
static struct dasd_devmap *
dasd_find_busid(char *bus_id)
{
        struct dasd_devmap *devmap, *tmp;
        int hash;

        spin_lock(&dasd_devmap_lock);
        devmap = ERR_PTR(-ENODEV);
        hash = dasd_hash_busid(bus_id);
        list_for_each_entry(tmp, &dasd_hashlists[hash], list) {
                if (strncmp(tmp->bus_id, bus_id, BUS_ID_SIZE) == 0) {
                        devmap = tmp;
                        break;
                }
        }
        spin_unlock(&dasd_devmap_lock);
        return devmap;
}

/*
 * Check if busid has been added to the list of dasd ranges.
 */
int
dasd_busid_known(char *bus_id)
{
        return IS_ERR(dasd_find_busid(bus_id)) ? -ENOENT : 0;
}

/*
 * Forget all about the device numbers added so far.
 * This may only be called at module unload or system shutdown.
 */
static void
dasd_forget_ranges(void)
{
        struct dasd_devmap *devmap, *n;
        int i;

        spin_lock(&dasd_devmap_lock);
        for (i = 0; i < 256; i++) {
                list_for_each_entry_safe(devmap, n, &dasd_hashlists[i], list) {
                        BUG_ON(devmap->device != NULL);
                        list_del(&devmap->list);
                        kfree(devmap);
                }
        }
        spin_unlock(&dasd_devmap_lock);
}

/*
 * Find the device struct by its device index.
 */
struct dasd_device *
dasd_device_from_devindex(int devindex)
{
        struct dasd_devmap *devmap, *tmp;
        struct dasd_device *device;
        int i;

        spin_lock(&dasd_devmap_lock);
        devmap = NULL;
        for (i = 0; (i < 256) && !devmap; i++)
                list_for_each_entry(tmp, &dasd_hashlists[i], list)
                        if (tmp->devindex == devindex) {
                                /* Found the devmap for the device. */
                                devmap = tmp;
                                break;
                        }
        if (devmap && devmap->device) {
                device = devmap->device;
                dasd_get_device(device);
        } else
                device = ERR_PTR(-ENODEV);
        spin_unlock(&dasd_devmap_lock);
        return device;
}

/*
 * Return devmap for cdev. If no devmap exists yet, create one and
 * connect it to the cdev.
 */
static struct dasd_devmap *
dasd_devmap_from_cdev(struct ccw_device *cdev)
{
        struct dasd_devmap *devmap;

        devmap = dasd_find_busid(cdev->dev.bus_id);
        if (IS_ERR(devmap))
                devmap = dasd_add_busid(cdev->dev.bus_id,
                                        DASD_FEATURE_DEFAULT);
        return devmap;
}

/*
 * Create a dasd device structure for cdev.
 */
struct dasd_device *
dasd_create_device(struct ccw_device *cdev)
{
        struct dasd_devmap *devmap;
        struct dasd_device *device;
        int rc;

        devmap = dasd_devmap_from_cdev(cdev);
        if (IS_ERR(devmap))
                return (void *) devmap;
        cdev->dev.driver_data = devmap;

        device = dasd_alloc_device();
        if (IS_ERR(device))
                return device;
        atomic_set(&device->ref_count, 2);

        spin_lock(&dasd_devmap_lock);
        if (!devmap->device) {
                devmap->device = device;
                device->devindex = devmap->devindex;
                device->features = devmap->features;
                get_device(&cdev->dev);
                device->cdev = cdev;
                rc = 0;
        } else
                /* Someone else was faster. */
                rc = -EBUSY;
        spin_unlock(&dasd_devmap_lock);

        if (rc) {
                dasd_free_device(device);
                return ERR_PTR(rc);
        }
        return device;
}

/*
 * Wait queue for dasd_delete_device waits.
 */
static DECLARE_WAIT_QUEUE_HEAD(dasd_delete_wq);

/*
 * Remove a dasd device structure. The passed referenced
 * is destroyed.
 */
void
dasd_delete_device(struct dasd_device *device)
{
        struct ccw_device *cdev;
        struct dasd_devmap *devmap;

        /* First remove device pointer from devmap. */
        devmap = dasd_find_busid(device->cdev->dev.bus_id);
        BUG_ON(IS_ERR(devmap));
        spin_lock(&dasd_devmap_lock);
        if (devmap->device != device) {
                spin_unlock(&dasd_devmap_lock);
                dasd_put_device(device);
                return;
        }
        devmap->device = NULL;
        spin_unlock(&dasd_devmap_lock);

        /* Drop ref_count by 2, one for the devmap reference and
         * one for the passed reference. */
        atomic_sub(2, &device->ref_count);

        /* Wait for reference counter to drop to zero. */
        wait_event(dasd_delete_wq, atomic_read(&device->ref_count) == 0);

        /* Disconnect dasd_device structure from ccw_device structure. */
        cdev = device->cdev;
        device->cdev = NULL;

        /* Disconnect dasd_devmap structure from ccw_device structure. */
        cdev->dev.driver_data = NULL;

        /* Put ccw_device structure. */
        put_device(&cdev->dev);

        /* Now the device structure can be freed. */
        dasd_free_device(device);
}

/*
 * Reference counter dropped to zero. Wake up waiter
 * in dasd_delete_device.
 */
void
dasd_put_device_wake(struct dasd_device *device)
{
        wake_up(&dasd_delete_wq);
}

/*
 * Return dasd_device structure associated with cdev.
 */
struct dasd_device *
dasd_device_from_cdev(struct ccw_device *cdev)
{
        struct dasd_devmap *devmap;
        struct dasd_device *device;

        device = ERR_PTR(-ENODEV);
        spin_lock(&dasd_devmap_lock);
        devmap = cdev->dev.driver_data;
        if (devmap && devmap->device) {
                device = devmap->device;
                dasd_get_device(device);
        }
        spin_unlock(&dasd_devmap_lock);
        return device;
}

/*
 * SECTION: files in sysfs
 */

/*
 * readonly controls the readonly status of a dasd
 */
static ssize_t
dasd_ro_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct dasd_devmap *devmap;
        int ro_flag;

        devmap = dasd_find_busid(dev->bus_id);
        if (!IS_ERR(devmap))
                ro_flag = (devmap->features & DASD_FEATURE_READONLY) != 0;
        else
                ro_flag = (DASD_FEATURE_DEFAULT & DASD_FEATURE_READONLY) != 0;
        return snprintf(buf, PAGE_SIZE, ro_flag ? "1\n" : "0\n");
}

static ssize_t
dasd_ro_store(struct device *dev, struct device_attribute *attr,
              const char *buf, size_t count)
{
        struct dasd_devmap *devmap;
        int ro_flag;

        devmap = dasd_devmap_from_cdev(to_ccwdev(dev));
        if (IS_ERR(devmap))
                return PTR_ERR(devmap);
        ro_flag = buf[0] == '1';
        spin_lock(&dasd_devmap_lock);
        if (ro_flag)
                devmap->features |= DASD_FEATURE_READONLY;
        else
                devmap->features &= ~DASD_FEATURE_READONLY;
        if (devmap->device)
                devmap->device->features = devmap->features;
        if (devmap->device && devmap->device->gdp)
                set_disk_ro(devmap->device->gdp, ro_flag);
        spin_unlock(&dasd_devmap_lock);
        return count;
}

static DEVICE_ATTR(readonly, 0644, dasd_ro_show, dasd_ro_store);

/*
 * use_diag controls whether the driver should use diag rather than ssch
 * to talk to the device
 */
static ssize_t
dasd_use_diag_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct dasd_devmap *devmap;
        int use_diag;

        devmap = dasd_find_busid(dev->bus_id);
        if (!IS_ERR(devmap))
                use_diag = (devmap->features & DASD_FEATURE_USEDIAG) != 0;
        else
                use_diag = (DASD_FEATURE_DEFAULT & DASD_FEATURE_USEDIAG) != 0;
        return sprintf(buf, use_diag ? "1\n" : "0\n");
}

static ssize_t
dasd_use_diag_store(struct device *dev, struct device_attribute *attr,
                    const char *buf, size_t count)
{
        struct dasd_devmap *devmap;
        ssize_t rc;
        int use_diag;

        devmap = dasd_devmap_from_cdev(to_ccwdev(dev));
        if (IS_ERR(devmap))
                return PTR_ERR(devmap);
        use_diag = buf[0] == '1';
        spin_lock(&dasd_devmap_lock);
        /* Changing diag discipline flag is only allowed in offline state. */
        rc = count;
        if (!devmap->device) {
                if (use_diag)
                        devmap->features |= DASD_FEATURE_USEDIAG;
                else
                        devmap->features &= ~DASD_FEATURE_USEDIAG;
        } else
                rc = -EPERM;
        spin_unlock(&dasd_devmap_lock);
        return rc;
}

static DEVICE_ATTR(use_diag, 0644, dasd_use_diag_show, dasd_use_diag_store);

static ssize_t
dasd_discipline_show(struct device *dev, struct device_attribute *attr,
                     char *buf)
{
        struct dasd_devmap *devmap;
        char *dname;

        spin_lock(&dasd_devmap_lock);
        dname = "none";
        devmap = dev->driver_data;
        if (devmap && devmap->device && devmap->device->discipline)
                dname = devmap->device->discipline->name;
        spin_unlock(&dasd_devmap_lock);
        return snprintf(buf, PAGE_SIZE, "%s\n", dname);
}

static DEVICE_ATTR(discipline, 0444, dasd_discipline_show, NULL);

static ssize_t
dasd_alias_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct dasd_devmap *devmap;
        int alias;

        devmap = dasd_find_busid(dev->bus_id);
        spin_lock(&dasd_devmap_lock);
        if (!IS_ERR(devmap))
                alias = devmap->uid.alias;
        else
                alias = 0;
        spin_unlock(&dasd_devmap_lock);

        return sprintf(buf, alias ? "1\n" : "0\n");
}

static DEVICE_ATTR(alias, 0444, dasd_alias_show, NULL);

static ssize_t
dasd_vendor_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct dasd_devmap *devmap;
        char *vendor;

        devmap = dasd_find_busid(dev->bus_id);
        spin_lock(&dasd_devmap_lock);
        if (!IS_ERR(devmap) && strlen(devmap->uid.vendor) > 0)
                vendor = devmap->uid.vendor;
        else
                vendor = "";
        spin_unlock(&dasd_devmap_lock);

        return snprintf(buf, PAGE_SIZE, "%s\n", vendor);
}

static DEVICE_ATTR(vendor, 0444, dasd_vendor_show, NULL);

#define UID_STRLEN ( /* vendor */ 3 + 1 + /* serial    */ 14 + 1 +\
                     /* SSID   */ 4 + 1 + /* unit addr */ 2 + 1)

static ssize_t
dasd_uid_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct dasd_devmap *devmap;
        char uid[UID_STRLEN];

        devmap = dasd_find_busid(dev->bus_id);
        spin_lock(&dasd_devmap_lock);
        if (!IS_ERR(devmap) && strlen(devmap->uid.vendor) > 0)
                snprintf(uid, sizeof(uid), "%s.%s.%04x.%02x",
                         devmap->uid.vendor, devmap->uid.serial,
                         devmap->uid.ssid, devmap->uid.unit_addr);
        else
                uid[0] = 0;
        spin_unlock(&dasd_devmap_lock);

        return snprintf(buf, PAGE_SIZE, "%s\n", uid);
}

static DEVICE_ATTR(uid, 0444, dasd_uid_show, NULL);

/*
 * extended error-reporting
 */
static ssize_t
dasd_eer_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct dasd_devmap *devmap;
        int eer_flag;

        devmap = dasd_find_busid(dev->bus_id);
        if (!IS_ERR(devmap) && devmap->device)
                eer_flag = dasd_eer_enabled(devmap->device);
        else
                eer_flag = 0;
        return snprintf(buf, PAGE_SIZE, eer_flag ? "1\n" : "0\n");
}

static ssize_t
dasd_eer_store(struct device *dev, struct device_attribute *attr,
               const char *buf, size_t count)
{
        struct dasd_devmap *devmap;
        int rc;

        devmap = dasd_devmap_from_cdev(to_ccwdev(dev));
        if (IS_ERR(devmap))
                return PTR_ERR(devmap);
        if (!devmap->device)
                return count;
        if (buf[0] == '1') {
                rc = dasd_eer_enable(devmap->device);
                if (rc)
                        return rc;
        } else
                dasd_eer_disable(devmap->device);
        return count;
}

static DEVICE_ATTR(eer_enabled, 0644, dasd_eer_show, dasd_eer_store);

static struct attribute * dasd_attrs[] = {
        &dev_attr_readonly.attr,
        &dev_attr_discipline.attr,
        &dev_attr_alias.attr,
        &dev_attr_vendor.attr,
        &dev_attr_uid.attr,
        &dev_attr_use_diag.attr,
        &dev_attr_eer_enabled.attr,
        NULL,
};

static struct attribute_group dasd_attr_group = {
        .attrs = dasd_attrs,
};

/*
 * Check if the related storage server is already contained in the
 * dasd_serverlist. If server is not contained, create new entry.
 * Return 0 if server was already in serverlist,
 *        1 if the server was added successfully
 *       <0 in case of error.
 */
static int
dasd_add_server(struct dasd_uid *uid)
{
        struct dasd_servermap *new, *tmp;

        /* check if server is already contained */
        list_for_each_entry(tmp, &dasd_serverlist, list)
          // normale cmp?
                if (strncmp(tmp->sid.vendor, uid->vendor,
                            sizeof(tmp->sid.vendor)) == 0
                    && strncmp(tmp->sid.serial, uid->serial,
                               sizeof(tmp->sid.serial)) == 0)
                        return 0;

        new = (struct dasd_servermap *)
                kzalloc(sizeof(struct dasd_servermap), GFP_KERNEL);
        if (!new)
                return -ENOMEM;

        strncpy(new->sid.vendor, uid->vendor, sizeof(new->sid.vendor));
        strncpy(new->sid.serial, uid->serial, sizeof(new->sid.serial));
        list_add(&new->list, &dasd_serverlist);
        return 1;
}


/*
 * Return copy of the device unique identifier.
 */
int
dasd_get_uid(struct ccw_device *cdev, struct dasd_uid *uid)
{
        struct dasd_devmap *devmap;

        devmap = dasd_find_busid(cdev->dev.bus_id);
        if (IS_ERR(devmap))
                return PTR_ERR(devmap);
        spin_lock(&dasd_devmap_lock);
        *uid = devmap->uid;
        spin_unlock(&dasd_devmap_lock);
        return 0;
}

/*
 * Register the given device unique identifier into devmap struct.
 * Return 0 if server was already in serverlist,
 *        1 if the server was added successful
 *       <0 in case of error.
 */
int
dasd_set_uid(struct ccw_device *cdev, struct dasd_uid *uid)
{
        struct dasd_devmap *devmap;
        int rc;

        devmap = dasd_find_busid(cdev->dev.bus_id);
        if (IS_ERR(devmap))
                return PTR_ERR(devmap);
        spin_lock(&dasd_devmap_lock);
        devmap->uid = *uid;
        rc = dasd_add_server(uid);
        spin_unlock(&dasd_devmap_lock);
        return rc;
}
EXPORT_SYMBOL_GPL(dasd_set_uid);

/*
 * Return value of the specified feature.
 */
int
dasd_get_feature(struct ccw_device *cdev, int feature)
{
        struct dasd_devmap *devmap;

        devmap = dasd_find_busid(cdev->dev.bus_id);
        if (IS_ERR(devmap))
                return PTR_ERR(devmap);

        return ((devmap->features & feature) != 0);
}

/*
 * Set / reset given feature.
 * Flag indicates wether to set (!=0) or the reset (=0) the feature.
 */
int
dasd_set_feature(struct ccw_device *cdev, int feature, int flag)
{
        struct dasd_devmap *devmap;

        devmap = dasd_find_busid(cdev->dev.bus_id);
        if (IS_ERR(devmap))
                return PTR_ERR(devmap);

        spin_lock(&dasd_devmap_lock);
        if (flag)
                devmap->features |= feature;
        else
                devmap->features &= ~feature;
        if (devmap->device)
                devmap->device->features = devmap->features;
        spin_unlock(&dasd_devmap_lock);
        return 0;
}


int
dasd_add_sysfs_files(struct ccw_device *cdev)
{
        return sysfs_create_group(&cdev->dev.kobj, &dasd_attr_group);
}

void
dasd_remove_sysfs_files(struct ccw_device *cdev)
{
        sysfs_remove_group(&cdev->dev.kobj, &dasd_attr_group);
}


int
dasd_devmap_init(void)
{
        int i;

        /* Initialize devmap structures. */
        dasd_max_devindex = 0;
        for (i = 0; i < 256; i++)
                INIT_LIST_HEAD(&dasd_hashlists[i]);

        /* Initialize servermap structure. */
        INIT_LIST_HEAD(&dasd_serverlist);
        return 0;
}

void
dasd_devmap_exit(void)
{
        dasd_forget_ranges();
}