Re: [PATCH 4/4] ACPI PCI slot detection driver

Alex Chiang
2008-03-05T20:20:53Z

Hi Kenji-san,

* Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>:
> Hi Alex-san,
>
> Sorry for the delay in responding.
>
>> It wasn't the IBM machine that was breaking; it was Fujitsu. They
>> were returning an error code (the numerical value 1023) when I
>> called the _SUN method on a slot object that existed in the ACPI
>> namespace but was not present (as reported by the _STA method).
>> By the time I got that error report, I'd already dropped the
>> duplicate name detection code, and was letting the kobject
>> infrastructure warn about duplicate names because for my test
>> cases, refcounting was a better solution.
>> [Kenji-san from Fujitsu seemed to be ok with the progress I'd
>> made at the time, he can speak up if he's changed his mind ;)]
>
> Unfortunatelly, I have not tried the new version of slot detection
> driver because of the lack of test environment. Maybe we need more
> several days to wait for test environment.
> BTW, does the new one fixes the issue I reported before? I could not
> find it in the changelog. IIRC, this issue was difficult to solve
> because the root cause of this issue is from the difference of
> interpretation of ACPI spec between HP and Fujitsu (I still don't
> think it's a good idea to evaluate _SUN for the device object whose
> _STA is 0).

It looks like we disagree on how to interpret the spec (IBM
machines interpret the spec the same way HP machines do).

So given that it's two versus one, I modified my
drivers/acpi/pci_slot module to consider Fujitsu machines to be a
quirk. :)

Can you please test patches 1 and 2 that I sent out as v8 of my
series, but replace patch 3 with this patch?

Please note -- you will probably need to modify this block:

{
.callback = do_sta_before_sun,
.ident = "Fujitsu Limited Primequest",
.matches = {
DMI_MATCH(DMI_BIOS_VENDOR, "Fujitsu"),
DMI_MATCH(DMI_BIOS_VERSION, "2.35"),
},
},

To get the correct values for DMI_BIOS_VENDOR and
DMI_BIOS_VERSION, because I was just guessing.

Thanks!

/ac

From: Alex Chiang <achiang@hp.com>
Subject: [PATCH 3/3] ACPI PCI slot detection driver

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.

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@hp.com>
---
drivers/acpi/Kconfig | 9 +
drivers/acpi/Makefile | 1 +
drivers/acpi/pci_slot.c | 361 ++++++++++++++++++++++++++++++++
drivers/pci/hotplug/pci_hotplug_core.c | 11 +-
drivers/pci/hotplug/pciehp_core.c | 2 +-
drivers/pci/hotplug/sgi_hotplug.c | 2 +-
6 files changed, 383 insertions(+), 3 deletions(-)
create mode 100644 drivers/acpi/pci_slot.c

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index f688c21..24013a7 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -347,6 +347,15 @@ 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..869e99f
--- /dev/null
+++ b/drivers/acpi/pci_slot.c
@@ -0,0 +1,361 @@
+/*
+ * pci_slot.c - ACPI PCI Slot Driver
+ *
+ * The code here is heavily leveraged from the acpiphp module.
+ * Thanks to Matthew Wilcox <matthew@wil.cx> for much guidance.
+ *
+ * Copyright (C) 2007 Alex Chiang <achiang@hp.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@hp.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)
+
+static int acpi_pci_slot_add(acpi_handle handle);
+static void acpi_pci_slot_remove(acpi_handle handle);
+
+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 */
+ acpi_evaluate_integer(handle, "_STA", NULL, &sta);
+
+ if (!(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;
+}
+
+/*
+ * unregister_slot
+ *
+ * Called once for each SxFy object in the namespace. Each call to
+ * pci_destroy_slot decrements the refcount on the pci_slot, and
+ * eventually calls kobject_unregister at the appropriate time.
+ */
+static acpi_status
+unregister_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
+{
+ int device;
+ unsigned long sun;
+ struct pci_slot *slot;
+ struct pci_bus *pci_bus = context;
+
+ if (check_slot(handle, &device, &sun))
+ return AE_OK;
+
+ for (slot = pci_bus->slot; slot; slot = slot->next) {
+ if (slot->number == device)
+ pci_destroy_slot(slot);
+ }
+
+ return AE_OK;
+}
+
+/*
+ * 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 pci_slot *pci_slot;
+ struct pci_bus *pci_bus = context;
+
+ if (check_slot(handle, &device, &sun))
+ 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));
+
+ dbg("pci_slot: %#lx, pci_bus: %x, device: %d, name: %s\n",
+ (uint64_t)pci_slot, pci_bus->number, device, name);
+
+ return AE_OK;
+}
+
+struct p2p_bridge_context
+{
+ acpi_walk_callback user_function;
+ struct pci_bus *pci_bus;
+};
+
+/*
+ * 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 p2p_bridge_context child_context;
+ struct p2p_bridge_context *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;
+
+ dbg("p2p bridge walk, pci_bus = %x\n", dev->subordinate->number);
+ status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
+ user_function, dev->subordinate, NULL);
+ if (ACPI_FAILURE(status))
+ goto out;
+
+ child_context.pci_bus = dev->subordinate;
+ child_context.user_function = user_function;
+ 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 p2p_bridge_context 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", __FUNCTION__);
+ 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;
+
+ dbg("root bridge walk, pci_bus = %x\n", pci_bus->number);
+ status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
+ user_function, pci_bus, NULL);
+ if (ACPI_FAILURE(status))
+ return status;
+
+ context.pci_bus = pci_bus;
+ context.user_function = user_function;
+ 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", __FUNCTION__, 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", __FUNCTION__, status);
+
+ return status;
+}
+
+/*
+ * acpi_pci_slot_remove
+ * @handle: points to an acpi_pci_root
+ */
+static void
+acpi_pci_slot_remove(acpi_handle handle)
+{
+ acpi_status status;
+
+ status = walk_root_bridge(handle, unregister_slot);
+ if (ACPI_FAILURE(status))
+ err("%s: unregister_slot failure - %d\n", __FUNCTION__, status);
+}
+
+#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 Limited Primequest",
+ .matches = {
+ DMI_MATCH(DMI_BIOS_VENDOR, ""),
+ DMI_MATCH(DMI_BIOS_VERSION, ""),
+ },
+ },
+ {}
+};
+#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 21bbb5e..b857dd0 100644
--- a/drivers/pci/hotplug/pci_hotplug_core.c
+++ b/drivers/pci/hotplug/pci_hotplug_core.c
@@ -567,6 +567,11 @@ 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);
@@ -613,8 +618,12 @@ int pci_hp_deregister(struct hotplug_slot *hotplug)

slot = hotplug->pci_slot;
fs_remove_slot(slot);
- pci_destroy_slot(slot);
dbg("Removed slot %s from the list\n", hotplug->name);
+
+ hotplug_release(slot);
+ slot->release = NULL;
+ pci_destroy_slot(slot);
+
return 0;
}

diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
index ab45b69..9096908 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)
--
1.5.3.1.g1e61