drivers/pci/hotplug/acpiphp_ibm.c - third_party/kernel - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * ACPI PCI Hot Plug IBM Extension
  *
  * Copyright (C) 2004 Vernon Mauery <vernux@us.ibm.com>
  * Copyright (C) 2004 IBM Corp.
  *
  * All rights reserved.
  *
  * Send feedback to <vernux@us.ibm.com>
  *
  */

 #define pr_fmt(fmt) "acpiphp_ibm: " fmt

 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/sysfs.h>
 #include <linux/kobject.h>
 #include <linux/moduleparam.h>
 #include <linux/pci.h>
 #include <linux/uaccess.h>

 #include "acpiphp.h"
 #include "../pci.h"

 #define DRIVER_VERSION	"1.0.1"
 #define DRIVER_AUTHOR	"Irene Zubarev <zubarev@us.ibm.com>, Vernon Mauery <vernux@us.ibm.com>"
 #define DRIVER_DESC	"ACPI Hot Plug PCI Controller Driver IBM extension"


 MODULE_AUTHOR(DRIVER_AUTHOR);
 MODULE_DESCRIPTION(DRIVER_DESC);
 MODULE_LICENSE("GPL");
 MODULE_VERSION(DRIVER_VERSION);

 #define FOUND_APCI 0x61504349
 /* these are the names for the IBM ACPI pseudo-device */
 #define IBM_HARDWARE_ID1 "IBM37D0"
 #define IBM_HARDWARE_ID2 "IBM37D4"

 #define hpslot_to_sun(A) (to_slot(A)->sun)

 /* union apci_descriptor - allows access to the
  * various device descriptors that are embedded in the
  * aPCI table
  */
 union apci_descriptor {
 	struct {
 		char sig[4];
 		u8   len;
 	} header;
 	struct {
 		u8  type;
 		u8  len;
 		u16 slot_id;
 		u8  bus_id;
 		u8  dev_num;
 		u8  slot_num;
 		u8  slot_attr[2];
 		u8  attn;
 		u8  status[2];
 		u8  sun;
 		u8  res[3];
 	} slot;
 	struct {
 		u8 type;
 		u8 len;
 	} generic;
 };

 /* struct notification - keeps info about the device
  * that cause the ACPI notification event
  */
 struct notification {
 	struct acpi_device *device;
 	u8                  event;
 };

 static int ibm_set_attention_status(struct hotplug_slot *slot, u8 status);
 static int ibm_get_attention_status(struct hotplug_slot *slot, u8 *status);
 static void ibm_handle_events(acpi_handle handle, u32 event, void *context);
 static int ibm_get_table_from_acpi(char **bufp);
 static ssize_t ibm_read_apci_table(struct file *filp, struct kobject *kobj,
 				   struct bin_attribute *bin_attr,
 				   char *buffer, loff_t pos, size_t size);
 static acpi_status __init ibm_find_acpi_device(acpi_handle handle,
 		u32 lvl, void *context, void **rv);
 static int __init ibm_acpiphp_init(void);
 static void __exit ibm_acpiphp_exit(void);

 static acpi_handle ibm_acpi_handle;
 static struct notification ibm_note;
 static struct bin_attribute ibm_apci_table_attr __ro_after_init = {
 	    .attr = {
 		    .name = "apci_table",
 		    .mode = S_IRUGO,
 	    },
 	    .read = ibm_read_apci_table,
 	    .write = NULL,
 };
 static struct acpiphp_attention_info ibm_attention_info =
 {
 	.set_attn = ibm_set_attention_status,
 	.get_attn = ibm_get_attention_status,
 	.owner = THIS_MODULE,
 };

 /**
  * ibm_slot_from_id - workaround for bad ibm hardware
  * @id: the slot number that linux refers to the slot by
  *
  * Description: This method returns the aCPI slot descriptor
  * corresponding to the Linux slot number.  This descriptor
  * has info about the aPCI slot id and attention status.
  * This descriptor must be freed using kfree when done.
  */
 static union apci_descriptor *ibm_slot_from_id(int id)
 {
 	int ind = 0, size;
 	union apci_descriptor *ret = NULL, *des;
 	char *table;

 	size = ibm_get_table_from_acpi(&table);
 	if (size < 0)
 		return NULL;
 	des = (union apci_descriptor *)table;
 	if (memcmp(des->header.sig, "aPCI", 4) != 0)
 		goto ibm_slot_done;

 	des = (union apci_descriptor *)&table[ind += des->header.len];
 	while (ind < size && (des->generic.type != 0x82 ||
 			des->slot.slot_num != id)) {
 		des = (union apci_descriptor *)&table[ind += des->generic.len];
 	}

 	if (ind < size && des->slot.slot_num == id)
 		ret = des;

 ibm_slot_done:
 	if (ret) {
 		ret = kmalloc(sizeof(union apci_descriptor), GFP_KERNEL);
 		if (ret)
 			memcpy(ret, des, sizeof(union apci_descriptor));
 	}
 	kfree(table);
 	return ret;
 }

 /**
  * ibm_set_attention_status - callback method to set the attention LED
  * @slot: the hotplug_slot to work with
  * @status: what to set the LED to (0 or 1)
  *
  * Description: This method is registered with the acpiphp module as a
  * callback to do the device specific task of setting the LED status.
  */
 static int ibm_set_attention_status(struct hotplug_slot *slot, u8 status)
 {
 	union acpi_object args[2];
 	struct acpi_object_list params = { .pointer = args, .count = 2 };
 	acpi_status stat;
 	unsigned long long rc;
 	union apci_descriptor *ibm_slot;
 	int id = hpslot_to_sun(slot);

 	ibm_slot = ibm_slot_from_id(id);
 	if (!ibm_slot) {
 		pr_err("APLS null ACPI descriptor for slot %d\n", id);
 		return -ENODEV;
 	}

 	pr_debug("%s: set slot %d (%d) attention status to %d\n", __func__,
 			ibm_slot->slot.slot_num, ibm_slot->slot.slot_id,
 			(status ? 1 : 0));

 	args[0].type = ACPI_TYPE_INTEGER;
 	args[0].integer.value = ibm_slot->slot.slot_id;
 	args[1].type = ACPI_TYPE_INTEGER;
 	args[1].integer.value = (status) ? 1 : 0;

 	kfree(ibm_slot);

 	stat = acpi_evaluate_integer(ibm_acpi_handle, "APLS", &params, &rc);
 	if (ACPI_FAILURE(stat)) {
 		pr_err("APLS evaluation failed:  0x%08x\n", stat);
 		return -ENODEV;
 	} else if (!rc) {
 		pr_err("APLS method failed:  0x%08llx\n", rc);
 		return -ERANGE;
 	}
 	return 0;
 }

 /**
  * ibm_get_attention_status - callback method to get attention LED status
  * @slot: the hotplug_slot to work with
  * @status: returns what the LED is set to (0 or 1)
  *
  * Description: This method is registered with the acpiphp module as a
  * callback to do the device specific task of getting the LED status.
  *
  * Because there is no direct method of getting the LED status directly
  * from an ACPI call, we read the aPCI table and parse out our
  * slot descriptor to read the status from that.
  */
 static int ibm_get_attention_status(struct hotplug_slot *slot, u8 *status)
 {
 	union apci_descriptor *ibm_slot;
 	int id = hpslot_to_sun(slot);

 	ibm_slot = ibm_slot_from_id(id);
 	if (!ibm_slot) {
 		pr_err("APLS null ACPI descriptor for slot %d\n", id);
 		return -ENODEV;
 	}

 	if (ibm_slot->slot.attn & 0xa0 || ibm_slot->slot.status[1] & 0x08)
 		*status = 1;
 	else
 		*status = 0;

 	pr_debug("%s: get slot %d (%d) attention status is %d\n", __func__,
 			ibm_slot->slot.slot_num, ibm_slot->slot.slot_id,
 			*status);

 	kfree(ibm_slot);
 	return 0;
 }

 /**
  * ibm_handle_events - listens for ACPI events for the IBM37D0 device
  * @handle: an ACPI handle to the device that caused the event
  * @event: the event info (device specific)
  * @context: passed context (our notification struct)
  *
  * Description: This method is registered as a callback with the ACPI
  * subsystem it is called when this device has an event to notify the OS of.
  *
  * The events actually come from the device as two events that get
  * synthesized into one event with data by this function.  The event
  * ID comes first and then the slot number that caused it.  We report
  * this as one event to the OS.
  *
  * From section 5.6.2.2 of the ACPI 2.0 spec, I understand that the OSPM will
  * only re-enable the interrupt that causes this event AFTER this method
  * has returned, thereby enforcing serial access for the notification struct.
  */
 static void ibm_handle_events(acpi_handle handle, u32 event, void *context)
 {
 	u8 detail = event & 0x0f;
 	u8 subevent = event & 0xf0;
 	struct notification *note = context;

 	pr_debug("%s: Received notification %02x\n", __func__, event);

 	if (subevent == 0x80) {
 		pr_debug("%s: generating bus event\n", __func__);
 		acpi_bus_generate_netlink_event(note->device->pnp.device_class,
 						  dev_name(&note->device->dev),
 						  note->event, detail);
 	} else
 		note->event = event;
 }

 /**
  * ibm_get_table_from_acpi - reads the APLS buffer from ACPI
  * @bufp: address to pointer to allocate for the table
  *
  * Description: This method reads the APLS buffer in from ACPI and
  * stores the "stripped" table into a single buffer
  * it allocates and passes the address back in bufp.
  *
  * If NULL is passed in as buffer, this method only calculates
  * the size of the table and returns that without filling
  * in the buffer.
  *
  * Returns < 0 on error or the size of the table on success.
  */
 static int ibm_get_table_from_acpi(char **bufp)
 {
 	union acpi_object *package;
 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 	acpi_status status;
 	char *lbuf = NULL;
 	int i, size = -EIO;

 	status = acpi_evaluate_object(ibm_acpi_handle, "APCI", NULL, &buffer);
 	if (ACPI_FAILURE(status)) {
 		pr_err("%s:  APCI evaluation failed\n", __func__);
 		return -ENODEV;
 	}

 	package = (union acpi_object *) buffer.pointer;
 	if (!(package) ||
 			(package->type != ACPI_TYPE_PACKAGE) ||
 			!(package->package.elements)) {
 		pr_err("%s:  Invalid APCI object\n", __func__);
 		goto read_table_done;
 	}

 	for (size = 0, i = 0; i < package->package.count; i++) {
 		if (package->package.elements[i].type != ACPI_TYPE_BUFFER) {
 			pr_err("%s:  Invalid APCI element %d\n", __func__, i);
 			goto read_table_done;
 		}
 		size += package->package.elements[i].buffer.length;
 	}

 	if (bufp == NULL)
 		goto read_table_done;

 	lbuf = kzalloc(size, GFP_KERNEL);
 	pr_debug("%s: element count: %i, ASL table size: %i, &table = 0x%p\n",
 			__func__, package->package.count, size, lbuf);

 	if (lbuf) {
 		*bufp = lbuf;
 	} else {
 		size = -ENOMEM;
 		goto read_table_done;
 	}

 	size = 0;
 	for (i = 0; i < package->package.count; i++) {
 		memcpy(&lbuf[size],
 				package->package.elements[i].buffer.pointer,
 				package->package.elements[i].buffer.length);
 		size += package->package.elements[i].buffer.length;
 	}

 read_table_done:
 	kfree(buffer.pointer);
 	return size;
 }

 /**
  * ibm_read_apci_table - callback for the sysfs apci_table file
  * @filp: the open sysfs file
  * @kobj: the kobject this binary attribute is a part of
  * @bin_attr: struct bin_attribute for this file
  * @buffer: the kernel space buffer to fill
  * @pos: the offset into the file
  * @size: the number of bytes requested
  *
  * Description: Gets registered with sysfs as the reader callback
  * to be executed when /sys/bus/pci/slots/apci_table gets read.
  *
  * Since we don't get notified on open and close for this file,
  * things get really tricky here...
  * our solution is to only allow reading the table in all at once.
  */
 static ssize_t ibm_read_apci_table(struct file *filp, struct kobject *kobj,
 				   struct bin_attribute *bin_attr,
 				   char *buffer, loff_t pos, size_t size)
 {
 	int bytes_read = -EINVAL;
 	char *table = NULL;

 	pr_debug("%s: pos = %d, size = %zd\n", __func__, (int)pos, size);

 	if (pos == 0) {
 		bytes_read = ibm_get_table_from_acpi(&table);
 		if (bytes_read > 0 && bytes_read <= size)
 			memcpy(buffer, table, bytes_read);
 		kfree(table);
 	}
 	return bytes_read;
 }

 /**
  * ibm_find_acpi_device - callback to find our ACPI device
  * @handle: the ACPI handle of the device we are inspecting
  * @lvl: depth into the namespace tree
  * @context: a pointer to our handle to fill when we find the device
  * @rv: a return value to fill if desired
  *
  * Description: Used as a callback when calling acpi_walk_namespace
  * to find our device.  When this method returns non-zero
  * acpi_walk_namespace quits its search and returns our value.
  */
 static acpi_status __init ibm_find_acpi_device(acpi_handle handle,
 		u32 lvl, void *context, void **rv)
 {
 	acpi_handle *phandle = (acpi_handle *)context;
 	unsigned long long current_status = 0;
 	acpi_status status;
 	struct acpi_device_info *info;
 	int retval = 0;

 	status = acpi_get_object_info(handle, &info);
 	if (ACPI_FAILURE(status)) {
 		pr_err("%s:  Failed to get device information status=0x%x\n",
 			__func__, status);
 		return retval;
 	}

 	acpi_bus_get_status_handle(handle, &current_status);

 	if (current_status && (info->valid & ACPI_VALID_HID) &&
 			(!strcmp(info->hardware_id.string, IBM_HARDWARE_ID1) ||
 			 !strcmp(info->hardware_id.string, IBM_HARDWARE_ID2))) {
 		pr_debug("found hardware: %s, handle: %p\n",
 			info->hardware_id.string, handle);
 		*phandle = handle;
 		/* returning non-zero causes the search to stop
 		 * and returns this value to the caller of
 		 * acpi_walk_namespace, but it also causes some warnings
 		 * in the acpi debug code to print...
 		 */
 		retval = FOUND_APCI;
 	}
 	kfree(info);
 	return retval;
 }

 static int __init ibm_acpiphp_init(void)
 {
 	int retval = 0;
 	acpi_status status;
 	struct acpi_device *device;
 	struct kobject *sysdir = &pci_slots_kset->kobj;

 	pr_debug("%s\n", __func__);

 	if (acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 			ACPI_UINT32_MAX, ibm_find_acpi_device, NULL,
 			&ibm_acpi_handle, NULL) != FOUND_APCI) {
 		pr_err("%s: acpi_walk_namespace failed\n", __func__);
 		retval = -ENODEV;
 		goto init_return;
 	}
 	pr_debug("%s: found IBM aPCI device\n", __func__);
 	device = acpi_fetch_acpi_dev(ibm_acpi_handle);
 	if (!device) {
 		pr_err("%s: acpi_fetch_acpi_dev failed\n", __func__);
 		retval = -ENODEV;
 		goto init_return;
 	}
 	if (acpiphp_register_attention(&ibm_attention_info)) {
 		retval = -ENODEV;
 		goto init_return;
 	}

 	ibm_note.device = device;
 	status = acpi_install_notify_handler(ibm_acpi_handle,
 			ACPI_DEVICE_NOTIFY, ibm_handle_events,
 			&ibm_note);
 	if (ACPI_FAILURE(status)) {
 		pr_err("%s: Failed to register notification handler\n",
 				__func__);
 		retval = -EBUSY;
 		goto init_cleanup;
 	}

 	ibm_apci_table_attr.size = ibm_get_table_from_acpi(NULL);
 	retval = sysfs_create_bin_file(sysdir, &ibm_apci_table_attr);

 	return retval;

 init_cleanup:
 	acpiphp_unregister_attention(&ibm_attention_info);
 init_return:
 	return retval;
 }

 static void __exit ibm_acpiphp_exit(void)
 {
 	acpi_status status;
 	struct kobject *sysdir = &pci_slots_kset->kobj;

 	pr_debug("%s\n", __func__);

 	if (acpiphp_unregister_attention(&ibm_attention_info))
 		pr_err("%s: attention info deregistration failed", __func__);

 	status = acpi_remove_notify_handler(
 			   ibm_acpi_handle,
 			   ACPI_DEVICE_NOTIFY,
 			   ibm_handle_events);
 	if (ACPI_FAILURE(status))
 		pr_err("%s: Notification handler removal failed\n", __func__);
 	/* remove the /sys entries */
 	sysfs_remove_bin_file(sysdir, &ibm_apci_table_attr);
 }

 module_init(ibm_acpiphp_init);
 module_exit(ibm_acpiphp_exit);
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* ACPI PCI Hot Plug IBM Extension
	*
	* Copyright (C) 2004 Vernon Mauery <vernux@us.ibm.com>
	* Copyright (C) 2004 IBM Corp.
	*
	* All rights reserved.
	*
	* Send feedback to <vernux@us.ibm.com>
	*
	*/

	#define pr_fmt(fmt) "acpiphp_ibm: " fmt

	#include <linux/init.h>
	#include <linux/slab.h>
	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <linux/sysfs.h>
	#include <linux/kobject.h>
	#include <linux/moduleparam.h>
	#include <linux/pci.h>
	#include <linux/uaccess.h>

	#include "acpiphp.h"
	#include "../pci.h"

	#define DRIVER_VERSION "1.0.1"
	#define DRIVER_AUTHOR "Irene Zubarev <zubarev@us.ibm.com>, Vernon Mauery <vernux@us.ibm.com>"
	#define DRIVER_DESC "ACPI Hot Plug PCI Controller Driver IBM extension"


	MODULE_AUTHOR(DRIVER_AUTHOR);
	MODULE_DESCRIPTION(DRIVER_DESC);
	MODULE_LICENSE("GPL");
	MODULE_VERSION(DRIVER_VERSION);

	#define FOUND_APCI 0x61504349
	/* these are the names for the IBM ACPI pseudo-device */
	#define IBM_HARDWARE_ID1 "IBM37D0"
	#define IBM_HARDWARE_ID2 "IBM37D4"

	#define hpslot_to_sun(A) (to_slot(A)->sun)

	/* union apci_descriptor - allows access to the
	* various device descriptors that are embedded in the
	* aPCI table
	*/
	union apci_descriptor {
	struct {
	char sig[4];
	u8 len;
	} header;
	struct {
	u8 type;
	u8 len;
	u16 slot_id;
	u8 bus_id;
	u8 dev_num;
	u8 slot_num;
	u8 slot_attr[2];
	u8 attn;
	u8 status[2];
	u8 sun;
	u8 res[3];
	} slot;
	struct {
	u8 type;
	u8 len;
	} generic;
	};

	/* struct notification - keeps info about the device
	* that cause the ACPI notification event
	*/
	struct notification {
	struct acpi_device *device;
	u8 event;
	};

	static int ibm_set_attention_status(struct hotplug_slot *slot, u8 status);
	static int ibm_get_attention_status(struct hotplug_slot slot, u8 status);
	static void ibm_handle_events(acpi_handle handle, u32 event, void *context);
	static int ibm_get_table_from_acpi(char **bufp);
	static ssize_t ibm_read_apci_table(struct file filp, struct kobject kobj,
	struct bin_attribute *bin_attr,
	char *buffer, loff_t pos, size_t size);
	static acpi_status __init ibm_find_acpi_device(acpi_handle handle,
	u32 lvl, void context, void *rv);
	static int __init ibm_acpiphp_init(void);
	static void __exit ibm_acpiphp_exit(void);

	static acpi_handle ibm_acpi_handle;
	static struct notification ibm_note;
	static struct bin_attribute ibm_apci_table_attr __ro_after_init = {
	.attr = {
	.name = "apci_table",
	.mode = S_IRUGO,
	},
	.read = ibm_read_apci_table,
	.write = NULL,
	};
	static struct acpiphp_attention_info ibm_attention_info =
	{
	.set_attn = ibm_set_attention_status,
	.get_attn = ibm_get_attention_status,
	.owner = THIS_MODULE,
	};

	/**
	* ibm_slot_from_id - workaround for bad ibm hardware
	* @id: the slot number that linux refers to the slot by
	*
	* Description: This method returns the aCPI slot descriptor
	* corresponding to the Linux slot number. This descriptor
	* has info about the aPCI slot id and attention status.
	* This descriptor must be freed using kfree when done.
	*/
	static union apci_descriptor *ibm_slot_from_id(int id)
	{
	int ind = 0, size;
	union apci_descriptor ret = NULL, des;
	char *table;

	size = ibm_get_table_from_acpi(&table);
	if (size < 0)
	return NULL;
	des = (union apci_descriptor *)table;
	if (memcmp(des->header.sig, "aPCI", 4) != 0)
	goto ibm_slot_done;

	des = (union apci_descriptor *)&table[ind += des->header.len];
	while (ind < size && (des->generic.type != 0x82 \|\|
	des->slot.slot_num != id)) {
	des = (union apci_descriptor *)&table[ind += des->generic.len];
	}

	if (ind < size && des->slot.slot_num == id)
	ret = des;

	ibm_slot_done:
	if (ret) {
	ret = kmalloc(sizeof(union apci_descriptor), GFP_KERNEL);
	if (ret)
	memcpy(ret, des, sizeof(union apci_descriptor));
	}
	kfree(table);
	return ret;
	}

	/**
	* ibm_set_attention_status - callback method to set the attention LED
	* @slot: the hotplug_slot to work with
	* @status: what to set the LED to (0 or 1)
	*
	* Description: This method is registered with the acpiphp module as a
	* callback to do the device specific task of setting the LED status.
	*/
	static int ibm_set_attention_status(struct hotplug_slot *slot, u8 status)
	{
	union acpi_object args[2];
	struct acpi_object_list params = { .pointer = args, .count = 2 };
	acpi_status stat;
	unsigned long long rc;
	union apci_descriptor *ibm_slot;
	int id = hpslot_to_sun(slot);

	ibm_slot = ibm_slot_from_id(id);
	if (!ibm_slot) {
	pr_err("APLS null ACPI descriptor for slot %d\n", id);
	return -ENODEV;
	}

	pr_debug("%s: set slot %d (%d) attention status to %d\n", __func__,
	ibm_slot->slot.slot_num, ibm_slot->slot.slot_id,
	(status ? 1 : 0));

	args[0].type = ACPI_TYPE_INTEGER;
	args[0].integer.value = ibm_slot->slot.slot_id;
	args[1].type = ACPI_TYPE_INTEGER;
	args[1].integer.value = (status) ? 1 : 0;

	kfree(ibm_slot);

	stat = acpi_evaluate_integer(ibm_acpi_handle, "APLS", &params, &rc);
	if (ACPI_FAILURE(stat)) {
	pr_err("APLS evaluation failed: 0x%08x\n", stat);
	return -ENODEV;
	} else if (!rc) {
	pr_err("APLS method failed: 0x%08llx\n", rc);
	return -ERANGE;
	}
	return 0;
	}

	/**
	* ibm_get_attention_status - callback method to get attention LED status
	* @slot: the hotplug_slot to work with
	* @status: returns what the LED is set to (0 or 1)
	*
	* Description: This method is registered with the acpiphp module as a
	* callback to do the device specific task of getting the LED status.
	*
	* Because there is no direct method of getting the LED status directly
	* from an ACPI call, we read the aPCI table and parse out our
	* slot descriptor to read the status from that.
	*/
	static int ibm_get_attention_status(struct hotplug_slot slot, u8 status)
	{
	union apci_descriptor *ibm_slot;
	int id = hpslot_to_sun(slot);

	ibm_slot = ibm_slot_from_id(id);
	if (!ibm_slot) {
	pr_err("APLS null ACPI descriptor for slot %d\n", id);
	return -ENODEV;
	}

	if (ibm_slot->slot.attn & 0xa0 \|\| ibm_slot->slot.status[1] & 0x08)
	*status = 1;
	else
	*status = 0;

	pr_debug("%s: get slot %d (%d) attention status is %d\n", __func__,
	ibm_slot->slot.slot_num, ibm_slot->slot.slot_id,
	*status);

	kfree(ibm_slot);
	return 0;
	}

	/**
	* ibm_handle_events - listens for ACPI events for the IBM37D0 device
	* @handle: an ACPI handle to the device that caused the event
	* @event: the event info (device specific)
	* @context: passed context (our notification struct)
	*
	* Description: This method is registered as a callback with the ACPI
	* subsystem it is called when this device has an event to notify the OS of.
	*
	* The events actually come from the device as two events that get
	* synthesized into one event with data by this function. The event
	* ID comes first and then the slot number that caused it. We report
	* this as one event to the OS.
	*
	* From section 5.6.2.2 of the ACPI 2.0 spec, I understand that the OSPM will
	* only re-enable the interrupt that causes this event AFTER this method
	* has returned, thereby enforcing serial access for the notification struct.
	*/
	static void ibm_handle_events(acpi_handle handle, u32 event, void *context)
	{
	u8 detail = event & 0x0f;
	u8 subevent = event & 0xf0;
	struct notification *note = context;

	pr_debug("%s: Received notification %02x\n", __func__, event);

	if (subevent == 0x80) {
	pr_debug("%s: generating bus event\n", __func__);
	acpi_bus_generate_netlink_event(note->device->pnp.device_class,
	dev_name(&note->device->dev),
	note->event, detail);
	} else
	note->event = event;
	}

	/**
	* ibm_get_table_from_acpi - reads the APLS buffer from ACPI
	* @bufp: address to pointer to allocate for the table
	*
	* Description: This method reads the APLS buffer in from ACPI and
	* stores the "stripped" table into a single buffer
	* it allocates and passes the address back in bufp.
	*
	* If NULL is passed in as buffer, this method only calculates
	* the size of the table and returns that without filling
	* in the buffer.
	*
	* Returns < 0 on error or the size of the table on success.
	*/
	static int ibm_get_table_from_acpi(char **bufp)
	{
	union acpi_object *package;
	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
	acpi_status status;
	char *lbuf = NULL;
	int i, size = -EIO;

	status = acpi_evaluate_object(ibm_acpi_handle, "APCI", NULL, &buffer);
	if (ACPI_FAILURE(status)) {
	pr_err("%s: APCI evaluation failed\n", __func__);
	return -ENODEV;
	}

	package = (union acpi_object *) buffer.pointer;
	if (!(package) \|\|
	(package->type != ACPI_TYPE_PACKAGE) \|\|
	!(package->package.elements)) {
	pr_err("%s: Invalid APCI object\n", __func__);
	goto read_table_done;
	}

	for (size = 0, i = 0; i < package->package.count; i++) {
	if (package->package.elements[i].type != ACPI_TYPE_BUFFER) {
	pr_err("%s: Invalid APCI element %d\n", __func__, i);
	goto read_table_done;
	}
	size += package->package.elements[i].buffer.length;
	}

	if (bufp == NULL)
	goto read_table_done;

	lbuf = kzalloc(size, GFP_KERNEL);
	pr_debug("%s: element count: %i, ASL table size: %i, &table = 0x%p\n",
	__func__, package->package.count, size, lbuf);

	if (lbuf) {
	*bufp = lbuf;
	} else {
	size = -ENOMEM;
	goto read_table_done;
	}

	size = 0;
	for (i = 0; i < package->package.count; i++) {
	memcpy(&lbuf[size],
	package->package.elements[i].buffer.pointer,
	package->package.elements[i].buffer.length);
	size += package->package.elements[i].buffer.length;
	}

	read_table_done:
	kfree(buffer.pointer);
	return size;
	}

	/**
	* ibm_read_apci_table - callback for the sysfs apci_table file
	* @filp: the open sysfs file
	* @kobj: the kobject this binary attribute is a part of
	* @bin_attr: struct bin_attribute for this file
	* @buffer: the kernel space buffer to fill
	* @pos: the offset into the file
	* @size: the number of bytes requested
	*
	* Description: Gets registered with sysfs as the reader callback
	* to be executed when /sys/bus/pci/slots/apci_table gets read.
	*
	* Since we don't get notified on open and close for this file,
	* things get really tricky here...
	* our solution is to only allow reading the table in all at once.
	*/
	static ssize_t ibm_read_apci_table(struct file filp, struct kobject kobj,
	struct bin_attribute *bin_attr,
	char *buffer, loff_t pos, size_t size)
	{
	int bytes_read = -EINVAL;
	char *table = NULL;

	pr_debug("%s: pos = %d, size = %zd\n", __func__, (int)pos, size);

	if (pos == 0) {
	bytes_read = ibm_get_table_from_acpi(&table);
	if (bytes_read > 0 && bytes_read <= size)
	memcpy(buffer, table, bytes_read);
	kfree(table);
	}
	return bytes_read;
	}

	/**
	* ibm_find_acpi_device - callback to find our ACPI device
	* @handle: the ACPI handle of the device we are inspecting
	* @lvl: depth into the namespace tree
	* @context: a pointer to our handle to fill when we find the device
	* @rv: a return value to fill if desired
	*
	* Description: Used as a callback when calling acpi_walk_namespace
	* to find our device. When this method returns non-zero
	* acpi_walk_namespace quits its search and returns our value.
	*/
	static acpi_status __init ibm_find_acpi_device(acpi_handle handle,
	u32 lvl, void context, void *rv)
	{
	acpi_handle phandle = (acpi_handle )context;
	unsigned long long current_status = 0;
	acpi_status status;
	struct acpi_device_info *info;
	int retval = 0;

	status = acpi_get_object_info(handle, &info);
	if (ACPI_FAILURE(status)) {
	pr_err("%s: Failed to get device information status=0x%x\n",
	__func__, status);
	return retval;
	}

	acpi_bus_get_status_handle(handle, &current_status);

	if (current_status && (info->valid & ACPI_VALID_HID) &&
	(!strcmp(info->hardware_id.string, IBM_HARDWARE_ID1) \|\|
	!strcmp(info->hardware_id.string, IBM_HARDWARE_ID2))) {
	pr_debug("found hardware: %s, handle: %p\n",
	info->hardware_id.string, handle);
	*phandle = handle;
	/* returning non-zero causes the search to stop
	* and returns this value to the caller of
	* acpi_walk_namespace, but it also causes some warnings
	* in the acpi debug code to print...
	*/
	retval = FOUND_APCI;
	}
	kfree(info);
	return retval;
	}

	static int __init ibm_acpiphp_init(void)
	{
	int retval = 0;
	acpi_status status;
	struct acpi_device *device;
	struct kobject *sysdir = &pci_slots_kset->kobj;

	pr_debug("%s\n", __func__);

	if (acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
	ACPI_UINT32_MAX, ibm_find_acpi_device, NULL,
	&ibm_acpi_handle, NULL) != FOUND_APCI) {
	pr_err("%s: acpi_walk_namespace failed\n", __func__);
	retval = -ENODEV;
	goto init_return;
	}
	pr_debug("%s: found IBM aPCI device\n", __func__);
	device = acpi_fetch_acpi_dev(ibm_acpi_handle);
	if (!device) {
	pr_err("%s: acpi_fetch_acpi_dev failed\n", __func__);
	retval = -ENODEV;
	goto init_return;
	}
	if (acpiphp_register_attention(&ibm_attention_info)) {
	retval = -ENODEV;
	goto init_return;
	}

	ibm_note.device = device;
	status = acpi_install_notify_handler(ibm_acpi_handle,
	ACPI_DEVICE_NOTIFY, ibm_handle_events,
	&ibm_note);
	if (ACPI_FAILURE(status)) {
	pr_err("%s: Failed to register notification handler\n",
	__func__);
	retval = -EBUSY;
	goto init_cleanup;
	}

	ibm_apci_table_attr.size = ibm_get_table_from_acpi(NULL);
	retval = sysfs_create_bin_file(sysdir, &ibm_apci_table_attr);

	return retval;

	init_cleanup:
	acpiphp_unregister_attention(&ibm_attention_info);
	init_return:
	return retval;
	}

	static void __exit ibm_acpiphp_exit(void)
	{
	acpi_status status;
	struct kobject *sysdir = &pci_slots_kset->kobj;

	pr_debug("%s\n", __func__);

	if (acpiphp_unregister_attention(&ibm_attention_info))
	pr_err("%s: attention info deregistration failed", __func__);

	status = acpi_remove_notify_handler(
	ibm_acpi_handle,
	ACPI_DEVICE_NOTIFY,
	ibm_handle_events);
	if (ACPI_FAILURE(status))
	pr_err("%s: Notification handler removal failed\n", __func__);
	/* remove the /sys entries */
	sysfs_remove_bin_file(sysdir, &ibm_apci_table_attr);
	}

	module_init(ibm_acpiphp_init);
	module_exit(ibm_acpiphp_exit);