Date:	Tue, 25 Mar 2008 13:50:05 +0900
From:	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
To:	Alex Chiang <achiang@...com>,
	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
	Greg KH <gregkh@...e.de>, Gary Hade <garyhade@...ibm.com>,
	Kristen Carlson Accardi <kristen.c.accardi@...el.com>,
	Matthew Wilcox <matthew@....cx>, warthog19@...lescrag.net,
	rick.jones2@...com, linux-kernel@...r.kernel.org,
	linux-pci@...ey.karlin.mff.cuni.cz, linux-acpi@...r.kernel.org
Subject: Re: [PATCH 4/4] ACPI PCI slot detection driver

Acked-by: Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>

Thanks,
Kenji Kaneshige


Alex Chiang wrote:
> Detect all physical PCI slots as described by ACPI, and create
> entries in /sys/bus/pci/slots/.
> 
> Not all physical slots are hotpluggable, and the acpiphp module
> does not detect them. Now we know the physical PCI geography of
> our system, without caring about hotplug.
> 
> v10 -> v11:
> 	Thanks to Kenji Kanishige for the following updates:
> 	- Fix dmi table for Fujitsu PRIMEQUEST
> 	- Fix _STA evaluation
> 	- Use list_head for pci slot list
> 	- Fix slot removal path
> 
> v9 -> v10:
> 	Allow an hp driver to override the pci_slot kobject name.
> 
> v8 -> v9:
> 	Add DMI quirk for Fujitsu machines; eval _STA before _SUN
> 
> v6 -> v8:
> 	No change
> 
> v5 -> v6:
> 	Add debugging information.
> 
> v4 -> v5:
> 	Convert to a tristate module.
> 
> 	Remove #ifdef CONFIG_ACPI_PCI_SLOT, as struct pci_slot
> 	objects are properly refcounted, and multiple calls to
> 	pci_create/destroy_slot work just fine.
> 
> 	Remove prior -EBUSY changes, as they have been folded
> 	into the Introduce pci_slot patch.
> 
> v3 -> v4:
> 	Always attempt to call pci_create_slot from pcihp_core to
> 	cover cases of
> 		a) user did not say Y to Kconfig option ACPI_PCI_SLOT
> 		b) native PCIe hotplug driver registering on a
> 		non-ACPI system.
> 
> 	Return -EBUSY if an hp driver attempts to register a slot
> 	that is already registered to another driver. Do not
> 	consider that to be an error condition in acpiphp and pciehp.
> 
> v2 -> v3:
> 	Add Kconfig option to driver, allowing users to [de]config
> 	this driver. If configured, take slightly different code
> 	paths in pci_hp_register and pci_hp_deregister.
> 
> v1 -> v2:
> 	Now recursively discovering p2p bridges and slots
> 	underneath them. Hopefully, this will prevent us
> 	from trying to register the same slot multiple times.
> 
> Signed-off-by: Alex Chiang <achiang@...com>
> ---
>  drivers/acpi/Kconfig                   |    9 +
>  drivers/acpi/Makefile                  |    1 +
>  drivers/acpi/pci_slot.c                |  370 ++++++++++++++++++++++++++++++++
>  drivers/pci/hotplug/pci_hotplug_core.c |   16 ++
>  drivers/pci/hotplug/pciehp_core.c      |    2 +-
>  drivers/pci/hotplug/sgi_hotplug.c      |    2 +-
>  6 files changed, 398 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/acpi/pci_slot.c
> 
> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> index b4f5e85..4ccb0e7 100644
> --- a/drivers/acpi/Kconfig
> +++ b/drivers/acpi/Kconfig
> @@ -335,6 +335,15 @@ config ACPI_EC
>  	  the battery and thermal drivers.  If you are compiling for a 
>  	  mobile system, say Y.
>  
> +config ACPI_PCI_SLOT
> +	tristate "PCI slot detection driver"
> +	default n
> +	help
> +	  This driver will attempt to discover all PCI slots in your system,
> +	  and creates entries in /sys/bus/pci/slots/. This feature can
> +	  help you correlate PCI bus addresses with the physical geography
> +	  of your slots. If you are unsure, say N.
> +
>  config ACPI_POWER
>  	bool
>  	default y
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index 40b0fca..579c29c 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -48,6 +48,7 @@ obj-$(CONFIG_ACPI_DOCK)		+= dock.o
>  obj-$(CONFIG_ACPI_BAY)		+= bay.o
>  obj-$(CONFIG_ACPI_VIDEO)	+= video.o
>  obj-y				+= pci_root.o pci_link.o pci_irq.o pci_bind.o
> +obj-$(CONFIG_ACPI_PCI_SLOT)	+= pci_slot.o
>  obj-$(CONFIG_ACPI_POWER)	+= power.o
>  obj-$(CONFIG_ACPI_PROCESSOR)	+= processor.o
>  obj-$(CONFIG_ACPI_CONTAINER)	+= container.o
> diff --git a/drivers/acpi/pci_slot.c b/drivers/acpi/pci_slot.c
> new file mode 100644
> index 0000000..2b48ea7
> --- /dev/null
> +++ b/drivers/acpi/pci_slot.c
> @@ -0,0 +1,370 @@
> +/*
> + *  pci_slot.c - ACPI PCI Slot Driver
> + *
> + *  The code here is heavily leveraged from the acpiphp module.
> + *  Thanks to Matthew Wilcox <matthew@....cx> for much guidance.
> + *  Thanks to Kenji Kaneshige <kaneshige.kenji@...fujitsu.com> for code
> + *  review and fixes.
> + *
> + *  Copyright (C) 2007 Alex Chiang <achiang@...com>
> + *  Copyright (C) 2007 Hewlett-Packard Development Company, L.P.
> + *
> + *  This program is free software; you can redistribute it and/or modify it
> + *  under the terms and conditions of the GNU General Public License,
> + *  version 2, as published by the Free Software Foundation.
> + *
> + *  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.,
> + *  51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/types.h>
> +#include <linux/pci.h>
> +#include <linux/acpi.h>
> +#include <acpi/acpi_bus.h>
> +#include <acpi/acpi_drivers.h>
> +
> +static int debug;
> +static int check_sta_before_sun;
> +
> +#define DRIVER_VERSION 	"0.1"
> +#define DRIVER_AUTHOR	"Alex Chiang <achiang@...com>"
> +#define DRIVER_DESC	"ACPI PCI Slot Detection Driver"
> +MODULE_AUTHOR(DRIVER_AUTHOR);
> +MODULE_DESCRIPTION(DRIVER_DESC);
> +MODULE_LICENSE("GPL");
> +MODULE_PARM_DESC(debug, "Debugging mode enabled or not");
> +module_param(debug, bool, 0644);
> +
> +#define _COMPONENT		ACPI_PCI_COMPONENT
> +ACPI_MODULE_NAME("pci_slot");
> +
> +#define MY_NAME "pci_slot"
> +#define err(format, arg...) printk(KERN_ERR "%s: " format , MY_NAME , ## arg)
> +#define info(format, arg...) printk(KERN_INFO "%s: " format , MY_NAME , ## arg)
> +#define dbg(format, arg...)					\
> +	do {							\
> +		if (debug)					\
> +			printk(KERN_DEBUG "%s: " format,	\
> +				MY_NAME , ## arg);		\
> +	} while (0)
> +
> +struct acpi_pci_slot {
> +	acpi_handle root_handle;	/* handle of the root bridge */
> +	struct pci_slot *pci_slot;	/* corresponding pci_slot */
> +	struct list_head list;		/* node in the list of slots */
> +};
> +
> +static int acpi_pci_slot_add(acpi_handle handle);
> +static void acpi_pci_slot_remove(acpi_handle handle);
> +
> +static LIST_HEAD(slot_list);
> +static DEFINE_MUTEX(slot_list_lock);
> +static struct acpi_pci_driver acpi_pci_slot_driver = {
> +	.add = acpi_pci_slot_add,
> +	.remove = acpi_pci_slot_remove,
> +};
> +
> +static int
> +check_slot(acpi_handle handle, int *device, unsigned long *sun)
> +{
> +	int retval = 0;
> +	unsigned long adr, sta;
> +	acpi_status status;
> +	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
> +
> +	acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
> +	dbg("Checking slot on path: %s\n", (char *)buffer.pointer);
> +
> +	if (check_sta_before_sun) {
> +		/* If SxFy doesn't have _STA, we just assume it's there */
> +		status = acpi_evaluate_integer(handle, "_STA", NULL, &sta);
> +		if (ACPI_SUCCESS(status) && !(sta & ACPI_STA_DEVICE_PRESENT)) {
> +			retval = -1;
> +			goto out;
> +		}
> +	}
> +
> +	status = acpi_evaluate_integer(handle, "_ADR", NULL, &adr);
> +	if (ACPI_FAILURE(status)) {
> +		dbg("_ADR returned %d on %s\n", status, (char *)buffer.pointer);
> +		retval = -1;
> +		goto out;
> +	}
> +
> +	*device = (adr >> 16) & 0xffff;
> +
> +	/* No _SUN == not a slot == bail */
> +	status = acpi_evaluate_integer(handle, "_SUN", NULL, sun);
> +	if (ACPI_FAILURE(status)) {
> +		dbg("_SUN returned %d on %s\n", status, (char *)buffer.pointer);
> +		retval = -1;
> +		goto out;
> +	}
> +
> +out:
> +	kfree(buffer.pointer);
> +	return retval;
> +}
> +
> +struct callback_args {
> +	acpi_walk_callback	user_function;	/* only for walk_p2p_bridge */
> +	struct pci_bus		*pci_bus;
> +	acpi_handle		root_handle;
> +};
> +
> +/*
> + * register_slot
> + *
> + * Called once for each SxFy object in the namespace. Don't worry about
> + * calling pci_create_slot multiple times for the same pci_bus:device,
> + * since each subsequent call simply bumps the refcount on the pci_slot.
> + *
> + * The number of calls to pci_destroy_slot from unregister_slot is
> + * symmetrical.
> + */
> +static acpi_status
> +register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
> +{
> +	int device;
> +	unsigned long sun;
> +	char name[KOBJ_NAME_LEN];
> +	struct acpi_pci_slot *slot;
> +	struct pci_slot *pci_slot;
> +	struct callback_args *parent_context = context;
> +	struct pci_bus *pci_bus = parent_context->pci_bus;
> +
> +	if (check_slot(handle, &device, &sun))
> +		return AE_OK;
> +
> +	slot = kmalloc(sizeof(*slot), GFP_KERNEL);
> +	if (!slot) {
> +		err("%s: cannot allocate memory\n", __func__);
> +		return AE_OK;
> +	}
> +
> +	snprintf(name, sizeof(name), "%u", (u32)sun);
> +	pci_slot = pci_create_slot(pci_bus, device, name);
> +	if (IS_ERR(pci_slot)) {
> +		err("pci_create_slot returned %ld\n", PTR_ERR(pci_slot));
> +		kfree(slot);
> +	}
> +
> +	slot->root_handle = parent_context->root_handle;
> +	slot->pci_slot = pci_slot;
> +	INIT_LIST_HEAD(&slot->list);
> +	mutex_lock(&slot_list_lock);
> +	list_add(&slot->list, &slot_list);
> +	mutex_unlock(&slot_list_lock);
> +
> +	dbg("pci_slot: %#lx, pci_bus: %x, device: %d, name: %s\n",
> +		(uint64_t)pci_slot, pci_bus->number, device, name);
> +
> +	return AE_OK;
> +}
> +
> +/*
> + * walk_p2p_bridge - discover and walk p2p bridges
> + * @handle: points to an acpi_pci_root
> + * @context: p2p_bridge_context pointer
> + *
> + * Note that when we call ourselves recursively, we pass a different
> + * value of pci_bus in the child_context.
> + */
> +static acpi_status
> +walk_p2p_bridge(acpi_handle handle, u32 lvl, void *context, void **rv)
> +{
> +	int device, function;
> +	unsigned long adr;
> +	acpi_status status;
> +	acpi_handle dummy_handle;
> +	acpi_walk_callback user_function;
> +
> +	struct pci_dev *dev;
> +	struct pci_bus *pci_bus;
> +	struct callback_args child_context;
> +	struct callback_args *parent_context = context;
> +
> +	pci_bus = parent_context->pci_bus;
> +	user_function = parent_context->user_function;
> +
> +	status = acpi_get_handle(handle, "_ADR", &dummy_handle);
> +	if (ACPI_FAILURE(status))
> +		return AE_OK;
> +
> +	status = acpi_evaluate_integer(handle, "_ADR", NULL, &adr);
> +	if (ACPI_FAILURE(status))
> +		return AE_OK;
> +
> +	device = (adr >> 16) & 0xffff;
> +	function = adr & 0xffff;
> +
> +	dev = pci_get_slot(pci_bus, PCI_DEVFN(device, function));
> +	if (!dev || !dev->subordinate)
> +		goto out;
> +
> +	child_context.pci_bus = dev->subordinate;
> +	child_context.user_function = user_function;
> +	child_context.root_handle = parent_context->root_handle;
> +
> +	dbg("p2p bridge walk, pci_bus = %x\n", dev->subordinate->number);
> +	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
> +				     user_function, &child_context, NULL);
> +	if (ACPI_FAILURE(status))
> +		goto out;
> +
> +	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
> +				     walk_p2p_bridge, &child_context, NULL);
> +out:
> +	pci_dev_put(dev);
> +	return AE_OK;
> +}
> +
> +#define ACPI_STA_FUNCTIONING            (0x00000008)
> +
> +/*
> + * walk_root_bridge - generic root bridge walker
> + * @handle: points to an acpi_pci_root
> + * @user_function: user callback for slot objects
> + *
> + * Call user_function for all objects underneath this root bridge.
> + * Walk p2p bridges underneath us and call user_function on those too.
> + */
> +static int
> +walk_root_bridge(acpi_handle handle, acpi_walk_callback user_function)
> +{
> +	int seg, bus;
> +	unsigned long tmp;
> +	acpi_status status;
> +	acpi_handle dummy_handle;
> +	struct pci_bus *pci_bus;
> +	struct callback_args context;
> +
> +	/* If the bridge doesn't have _STA, we assume it is always there */
> +	status = acpi_get_handle(handle, "_STA", &dummy_handle);
> +	if (ACPI_SUCCESS(status)) {
> +		status = acpi_evaluate_integer(handle, "_STA", NULL, &tmp);
> +		if (ACPI_FAILURE(status)) {
> +			info("%s: _STA evaluation failure\n", __func__);
> +			return 0;
> +		}
> +		if ((tmp & ACPI_STA_FUNCTIONING) == 0)
> +			/* don't register this object */
> +			return 0;
> +	}
> +
> +	status = acpi_evaluate_integer(handle, "_SEG", NULL, &tmp);
> +	seg = ACPI_SUCCESS(status) ? tmp : 0;
> +
> +	status = acpi_evaluate_integer(handle, "_BBN", NULL, &tmp);
> +	bus = ACPI_SUCCESS(status) ? tmp : 0;
> +
> +	pci_bus = pci_find_bus(seg, bus);
> +	if (!pci_bus)
> +		return 0;
> +
> +	context.pci_bus = pci_bus;
> +	context.user_function = user_function;
> +	context.root_handle = handle;
> +
> +	dbg("root bridge walk, pci_bus = %x\n", pci_bus->number);
> +	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
> +				     user_function, &context, NULL);
> +	if (ACPI_FAILURE(status))
> +		return status;
> +
> +	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
> +				     walk_p2p_bridge, &context, NULL);
> +	if (ACPI_FAILURE(status))
> +		err("%s: walk_p2p_bridge failure - %d\n", __func__, status);
> +
> +	return status;
> +}
> +
> +/*
> + * acpi_pci_slot_add
> + * @handle: points to an acpi_pci_root
> + */
> +static int
> +acpi_pci_slot_add(acpi_handle handle)
> +{
> +	acpi_status status;
> +
> +	status = walk_root_bridge(handle, register_slot);
> +	if (ACPI_FAILURE(status))
> +		err("%s: register_slot failure - %d\n", __func__, status);
> +
> +	return status;
> +}
> +
> +/*
> + * acpi_pci_slot_remove
> + * @handle: points to an acpi_pci_root
> + */
> +static void
> +acpi_pci_slot_remove(acpi_handle handle)
> +{
> +	struct acpi_pci_slot *slot, *tmp;
> +
> +	mutex_lock(&slot_list_lock);
> +	list_for_each_entry_safe(slot, tmp, &slot_list, list) {
> +		if (slot->root_handle == handle) {
> +			list_del(&slot->list);
> +			pci_destroy_slot(slot->pci_slot);
> +			kfree(slot);
> +		}
> +	}
> +	mutex_unlock(&slot_list_lock);
> +}
> +
> +#ifdef CONFIG_DMI
> +static int do_sta_before_sun(const struct dmi_system_id *d)
> +{
> +	info("%s detected: will evaluate _STA before calling _SUN\n", d->ident);
> +	check_sta_before_sun = 1;
> +	return 0;
> +}
> +
> +static struct dmi_system_id acpi_pci_slot_dmi_table[] __initdata = {
> +	/*
> +	 * Fujitsu Primequest machines will return 1023 to indicate an
> +	 * error if the _SUN method is evaluated on SxFy objects that
> +	 * are not present (as indicated by _STA), so for those machines,
> +	 * we want to check _STA before evaluating _SUN.
> +	 */
> +	{
> +	 .callback = do_sta_before_sun,
> +	 .ident = "Fujitsu PRIMEQUEST",
> +	 .matches = {
> +		DMI_MATCH(DMI_BIOS_VENDOR, "FUJITSU LIMITED"),
> +		DMI_MATCH(DMI_BIOS_VERSION, "PRIMEQUEST"),
> +		},
> +	},
> +	{}
> +};
> +#endif /* CONFIG_DMI */
> +
> +static int __init
> +acpi_pci_slot_init(void)
> +{
> +	dmi_check_system(acpi_pci_slot_dmi_table);
> +	acpi_pci_register_driver(&acpi_pci_slot_driver);
> +	return 0;
> +}
> +
> +static void __exit
> +acpi_pci_slot_exit(void)
> +{
> +	acpi_pci_unregister_driver(&acpi_pci_slot_driver);
> +}
> +
> +module_init(acpi_pci_slot_init);
> +module_exit(acpi_pci_slot_exit);
> diff --git a/drivers/pci/hotplug/pci_hotplug_core.c b/drivers/pci/hotplug/pci_hotplug_core.c
> index 5208786..8181bf6 100644
> --- a/drivers/pci/hotplug/pci_hotplug_core.c
> +++ b/drivers/pci/hotplug/pci_hotplug_core.c
> @@ -566,6 +566,11 @@ int pci_hp_register(struct hotplug_slot *slot, struct pci_bus *bus, int slot_nr)
>  		return -EINVAL;
>  	}
>  
> +	/*
> +	 * No problems if we call this interface from both ACPI_PCI_SLOT
> +	 * driver and call it here again. If we've already created the
> +	 * pci_slot, the interface will simply bump the refcount.
> +	 */
>  	pci_slot = pci_create_slot(bus, slot_nr, slot->name);
>  	if (IS_ERR(pci_slot))
>  		return PTR_ERR(pci_slot);
> @@ -579,6 +584,17 @@ int pci_hp_register(struct hotplug_slot *slot, struct pci_bus *bus, int slot_nr)
>  	slot->pci_slot = pci_slot;
>  	pci_slot->hotplug = slot;
>  
> +	/*
> +	 * Allow pcihp drivers to override the ACPI_PCI_SLOT name.
> +	 */
> +	if (strcmp(kobject_name(&pci_slot->kobj), slot->name)) {
> +		result = kobject_rename(&pci_slot->kobj, slot->name);
> +		if (result) {
> +			pci_destroy_slot(pci_slot);
> +			return result;
> +		}
> +	}
> +
>  	spin_lock(&pci_hotplug_slot_list_lock);
>  	list_add(&slot->slot_list, &pci_hotplug_slot_list);
>  	spin_unlock(&pci_hotplug_slot_list_lock);
> diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
> index e6d3d4d..7561d17 100644
> --- a/drivers/pci/hotplug/pciehp_core.c
> +++ b/drivers/pci/hotplug/pciehp_core.c
> @@ -249,7 +249,7 @@ static int init_slots(struct controller *ctrl)
>  		if (retval == -EBUSY)
>  			goto error_info;
>  		if (retval) {
> -			err ("pci_hp_register failed with error %d\n", retval);
> +			err("pci_hp_register failed with error %d\n", retval);
>  			goto error_info;
>  		}
>  		/* create additional sysfs entries */
> diff --git a/drivers/pci/hotplug/sgi_hotplug.c b/drivers/pci/hotplug/sgi_hotplug.c
> index 8908834..5fd6887 100644
> --- a/drivers/pci/hotplug/sgi_hotplug.c
> +++ b/drivers/pci/hotplug/sgi_hotplug.c
> @@ -668,7 +668,7 @@ static int sn_hotplug_slot_register(struct pci_bus *pci_bus)
>  
>  register_err:
>  	dev_dbg(&pci_bus->self->dev, "bus failed to register with err = %d\n",
> -	        rc);
> +		rc);
>  
>  alloc_err:
>  	if (rc == -ENOMEM)


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