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bay.c

/*
 *  bay.c - ACPI removable drive bay driver
 *
 *  Copyright (C) 2006 Kristen Carlson Accardi <kristen.c.accardi@intel.com>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  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.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/notifier.h>
#include <acpi/acpi_bus.h>
#include <acpi/acpi_drivers.h>
#include <linux/seq_file.h>
#include <asm/uaccess.h>
#include <linux/platform_device.h>

ACPI_MODULE_NAME("bay");
MODULE_AUTHOR("Kristen Carlson Accardi");
MODULE_DESCRIPTION("ACPI Removable Drive Bay Driver");
MODULE_LICENSE("GPL");
#define ACPI_BAY_CLASS "bay"
#define ACPI_BAY_COMPONENT    0x10000000
#define _COMPONENT ACPI_BAY_COMPONENT
#define bay_dprintk(h,s) {\
      char prefix[80] = {'\0'};\
      struct acpi_buffer buffer = {sizeof(prefix), prefix};\
      acpi_get_name(h, ACPI_FULL_PATHNAME, &buffer);\
      printk(KERN_DEBUG PREFIX "%s: %s\n", prefix, s); }
static void bay_notify(acpi_handle handle, u32 event, void *data);

struct bay {
      acpi_handle handle;
      char *name;
      struct list_head list;
      struct platform_device *pdev;
};

static LIST_HEAD(drive_bays);


/*****************************************************************************
 *                         Drive Bay functions                               *
 *****************************************************************************/
/**
 * is_ejectable - see if a device is ejectable
 * @handle: acpi handle of the device
 *
 * If an acpi object has a _EJ0 method, then it is ejectable
 */
static int is_ejectable(acpi_handle handle)
{
      acpi_status status;
      acpi_handle tmp;

      status = acpi_get_handle(handle, "_EJ0", &tmp);
      if (ACPI_FAILURE(status))
            return 0;
      return 1;
}

/**
 * bay_present - see if the bay device is present
 * @bay: the drive bay
 *
 * execute the _STA method.
 */
static int bay_present(struct bay *bay)
{
      unsigned long sta;
      acpi_status status;

      if (bay) {
            status = acpi_evaluate_integer(bay->handle, "_STA", NULL, &sta);
            if (ACPI_SUCCESS(status) && sta)
                  return 1;
      }
      return 0;
}

/**
 * eject_device - respond to an eject request
 * @handle - the device to eject
 *
 * Call this devices _EJ0 method.
 */
static void eject_device(acpi_handle handle)
{
      struct acpi_object_list arg_list;
      union acpi_object arg;

      bay_dprintk(handle, "Ejecting device");

      arg_list.count = 1;
      arg_list.pointer = &arg;
      arg.type = ACPI_TYPE_INTEGER;
      arg.integer.value = 1;

      if (ACPI_FAILURE(acpi_evaluate_object(handle, "_EJ0",
                                    &arg_list, NULL)))
            pr_debug("Failed to evaluate _EJ0!\n");
}

/*
 * show_present - read method for "present" file in sysfs
 */
static ssize_t show_present(struct device *dev,
                     struct device_attribute *attr, char *buf)
{
      struct bay *bay = dev_get_drvdata(dev);
      return snprintf(buf, PAGE_SIZE, "%d\n", bay_present(bay));

}
DEVICE_ATTR(present, S_IRUGO, show_present, NULL);

/*
 * write_eject - write method for "eject" file in sysfs
 */
static ssize_t write_eject(struct device *dev, struct device_attribute *attr,
                     const char *buf, size_t count)
{
      struct bay *bay = dev_get_drvdata(dev);

      if (!count)
            return -EINVAL;

      eject_device(bay->handle);
      return count;
}
DEVICE_ATTR(eject, S_IWUSR, NULL, write_eject);

/**
 * is_ata - see if a device is an ata device
 * @handle: acpi handle of the device
 *
 * If an acpi object has one of 4 ATA ACPI methods defined,
 * then it is an ATA device
 */
static int is_ata(acpi_handle handle)
{
      acpi_handle tmp;

      if ((ACPI_SUCCESS(acpi_get_handle(handle, "_GTF", &tmp))) ||
         (ACPI_SUCCESS(acpi_get_handle(handle, "_GTM", &tmp))) ||
         (ACPI_SUCCESS(acpi_get_handle(handle, "_STM", &tmp))) ||
         (ACPI_SUCCESS(acpi_get_handle(handle, "_SDD", &tmp))))
            return 1;

      return 0;
}

/**
 * parent_is_ata(acpi_handle handle)
 *
 */
static int parent_is_ata(acpi_handle handle)
{
      acpi_handle phandle;

      if (acpi_get_parent(handle, &phandle))
            return 0;

      return is_ata(phandle);
}

/**
 * is_ejectable_bay - see if a device is an ejectable drive bay
 * @handle: acpi handle of the device
 *
 * If an acpi object is ejectable and has one of the ACPI ATA
 * methods defined, then we can safely call it an ejectable
 * drive bay
 */
static int is_ejectable_bay(acpi_handle handle)
{
      if ((is_ata(handle) || parent_is_ata(handle)) && is_ejectable(handle))
            return 1;
      return 0;
}

/**
 * eject_removable_drive - try to eject this drive
 * @dev : the device structure of the drive
 *
 * If a device is a removable drive that requires an _EJ0 method
 * to be executed in order to safely remove from the system, do
 * it.  ATM - always returns success
 */
int eject_removable_drive(struct device *dev)
{
      acpi_handle handle = DEVICE_ACPI_HANDLE(dev);

      if (handle) {
            bay_dprintk(handle, "Got device handle");
            if (is_ejectable_bay(handle))
                  eject_device(handle);
      } else {
            printk("No acpi handle for device\n");
      }

      /* should I return an error code? */
      return 0;
}
EXPORT_SYMBOL_GPL(eject_removable_drive);

static int acpi_bay_add_fs(struct bay *bay)
{
      int ret;
      struct device *dev = &bay->pdev->dev;

      ret = device_create_file(dev, &dev_attr_present);
      if (ret)
            goto add_fs_err;
      ret = device_create_file(dev, &dev_attr_eject);
      if (ret) {
            device_remove_file(dev, &dev_attr_present);
            goto add_fs_err;
      }
      return 0;

 add_fs_err:
      bay_dprintk(bay->handle, "Error adding sysfs files\n");
      return ret;
}

static void acpi_bay_remove_fs(struct bay *bay)
{
      struct device *dev = &bay->pdev->dev;

      /* cleanup sysfs */
      device_remove_file(dev, &dev_attr_present);
      device_remove_file(dev, &dev_attr_eject);
}

static int bay_is_dock_device(acpi_handle handle)
{
      acpi_handle parent;

      acpi_get_parent(handle, &parent);

      /* if the device or it's parent is dependent on the
       * dock, then we are a dock device
       */
      return (is_dock_device(handle) || is_dock_device(parent));
}

static int bay_add(acpi_handle handle, int id)
{
      acpi_status status;
      struct bay *new_bay;
      struct platform_device *pdev;
      struct acpi_buffer nbuffer = {ACPI_ALLOCATE_BUFFER, NULL};
      acpi_get_name(handle, ACPI_FULL_PATHNAME, &nbuffer);

      bay_dprintk(handle, "Adding notify handler");

      /*
       * Initialize bay device structure
       */
      new_bay = kzalloc(sizeof(*new_bay), GFP_ATOMIC);
      INIT_LIST_HEAD(&new_bay->list);
      new_bay->handle = handle;
      new_bay->name = (char *)nbuffer.pointer;

      /* initialize platform device stuff */
      pdev = platform_device_register_simple(ACPI_BAY_CLASS, id, NULL, 0);
      if (IS_ERR(pdev)) {
            printk(KERN_ERR PREFIX "Error registering bay device\n");
            goto bay_add_err;
      }
      new_bay->pdev = pdev;
      platform_set_drvdata(pdev, new_bay);

      /*
       * we want the bay driver to be able to send uevents
       */
      pdev->dev.uevent_suppress = 0;

      if (acpi_bay_add_fs(new_bay)) {
            platform_device_unregister(new_bay->pdev);
            goto bay_add_err;
      }

      /* register for events on this device */
      status = acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
                  bay_notify, new_bay);
      if (ACPI_FAILURE(status)) {
            printk(KERN_ERR PREFIX "Error installing bay notify handler\n");
      }

      /* if we are on a dock station, we should register for dock
       * notifications.
       */
      if (bay_is_dock_device(handle)) {
            bay_dprintk(handle, "Is dependent on dock\n");
            register_hotplug_dock_device(handle, bay_notify, new_bay);
      }
      list_add(&new_bay->list, &drive_bays);
      printk(KERN_INFO PREFIX "Bay [%s] Added\n", new_bay->name);
      return 0;

bay_add_err:
      kfree(new_bay->name);
      kfree(new_bay);
      return -ENODEV;
}

/**
 * bay_notify - act upon an acpi bay notification
 * @handle: the bay handle
 * @event: the acpi event
 * @data: our driver data struct
 *
 */
static void bay_notify(acpi_handle handle, u32 event, void *data)
{
      struct bay *bay_dev = (struct bay *)data;
      struct device *dev = &bay_dev->pdev->dev;
      char event_string[12];
      char *envp[] = { event_string, NULL };

      bay_dprintk(handle, "Bay event");
      sprintf(event_string, "BAY_EVENT=%d", event);
      kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);
}

static acpi_status
find_bay(acpi_handle handle, u32 lvl, void *context, void **rv)
{
      int *count = (int *)context;

      /*
       * there could be more than one ejectable bay.
       * so, just return AE_OK always so that every object
       * will be checked.
       */
      if (is_ejectable_bay(handle)) {
            bay_dprintk(handle, "found ejectable bay");
            if (!bay_add(handle, *count))
                  (*count)++;
      }
      return AE_OK;
}

static int __init bay_init(void)
{
      int bays = 0;

      INIT_LIST_HEAD(&drive_bays);

      /* look for dockable drive bays */
      acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
            ACPI_UINT32_MAX, find_bay, &bays, NULL);

      if (!bays)
            return -ENODEV;

      return 0;
}

static void __exit bay_exit(void)
{
      struct bay *bay, *tmp;

      list_for_each_entry_safe(bay, tmp, &drive_bays, list) {
            if (is_dock_device(bay->handle))
                  unregister_hotplug_dock_device(bay->handle);
            acpi_bay_remove_fs(bay);
            acpi_remove_notify_handler(bay->handle, ACPI_SYSTEM_NOTIFY,
                  bay_notify);
            platform_device_unregister(bay->pdev);
            kfree(bay->name);
            kfree(bay);
      }
}

postcore_initcall(bay_init);
module_exit(bay_exit);


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