linux/drivers/pci/hotplug/acpiphp_ibm.c
Lukas Wunner 125450f814 PCI: hotplug: Embed hotplug_slot
When the PCI hotplug core and its first user, cpqphp, were introduced in
February 2002 with historic commit a8a2069f432c, cpqphp allocated a slot
struct for its internal use plus a hotplug_slot struct to be registered
with the hotplug core and linked the two with pointers:
https://git.kernel.org/tglx/history/c/a8a2069f432c

Nowadays, the predominant pattern in the tree is to embed ("subclass")
such structures in one another and cast to the containing struct with
container_of().  But it wasn't until July 2002 that container_of() was
introduced with historic commit ec4f214232cf:
https://git.kernel.org/tglx/history/c/ec4f214232cf

pnv_php, introduced in 2016, did the right thing and embedded struct
hotplug_slot in its internal struct pnv_php_slot, but all other drivers
cargo-culted cpqphp's design and linked separate structs with pointers.

Embedding structs is preferrable to linking them with pointers because
it requires fewer allocations, thereby reducing overhead and simplifying
error paths.  Casting an embedded struct to the containing struct
becomes a cheap subtraction rather than a dereference.  And having fewer
pointers reduces the risk of them pointing nowhere either accidentally
or due to an attack.

Convert all drivers to embed struct hotplug_slot in their internal slot
struct.  The "private" pointer in struct hotplug_slot thereby becomes
unused, so drop it.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>  # drivers/pci/hotplug/rpa*
Acked-by: Sebastian Ott <sebott@linux.ibm.com>        # drivers/pci/hotplug/s390*
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com> # drivers/platform/x86
Cc: Len Brown <lenb@kernel.org>
Cc: Scott Murray <scott@spiteful.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Oliver OHalloran <oliveroh@au1.ibm.com>
Cc: Gavin Shan <gwshan@linux.vnet.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Corentin Chary <corentin.chary@gmail.com>
Cc: Darren Hart <dvhart@infradead.org>
2018-09-18 17:52:15 -05:00

490 lines
14 KiB
C

// 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);