// 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__);
        if (acpi_bus_get_device(ibm_acpi_handle, &device)) {
                pr_err("%s: acpi_bus_get_device 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);