// 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,
				   const 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_new = 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,
				   const 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);