From: Keith Busch <kbusch@xxxxxxxxxx>
Resetting a bus from an end device only works if it's the only function
on or below that bus.
Provide an attribute on the pci_dev bridge device that can perform the
secondary bus reset. This makes it possible for a user to safely reset
multiple devices in a single command using the secondary bus reset
action.
Signed-off-by: Keith Busch <kbusch@xxxxxxxxxx>
---
v1->v2:
Moved the attribute from the pci_bus to the bridge's pci_dev
And renamed it to "reset_subordinate" to distinguish from other
existing device "reset" attributes.
Added documentation.
Follow up patch to warn if the action was potentially harmful.
Documentation/ABI/testing/sysfs-bus-pci | 11 +++++++++++
drivers/pci/pci-sysfs.c | 23 +++++++++++++++++++++++
drivers/pci/pci.c | 2 +-
drivers/pci/pci.h | 1 +
4 files changed, 36 insertions(+), 1 deletion(-)
diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index 7f63c7e977735..5da6a14dc326b 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -163,6 +163,17 @@ Description:
will be present in sysfs. Writing 1 to this file
will perform reset.
+What: /sys/bus/pci/devices/.../reset_subordinate
+Date: October 2024
+Contact: linux-pci@xxxxxxxxxxxxxxx
+Description:
+ This is visible only for bridge devices. If you want to reset
+ all devices attached through the subordinate bus of a specific
+ bridge device, writing 1 to this will try to do it. This will
+ affect all devices attached to the system through this bridge
+ similiar to writing 1 to their individual "reset" file, so use
+ with caution.
+
What: /sys/bus/pci/devices/.../vpd
Date: February 2008
Contact: Ben Hutchings <bwh@xxxxxxxxxx>
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 5d0f4db1cab78..480a99e50612b 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -521,6 +521,28 @@ static ssize_t bus_rescan_store(struct device *dev,
static struct device_attribute dev_attr_bus_rescan = __ATTR(rescan, 0200, NULL,
bus_rescan_store);
+static ssize_t reset_subordinate_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct pci_dev *pdev = to_pci_dev(dev);
+ struct pci_bus *bus = pdev->subordinate;
+ unsigned long val;
+
+ if (kstrtoul(buf, 0, &val) < 0)
+ return -EINVAL;
+
+ if (val) {
+ int ret = __pci_reset_bus(bus);
+
+ if (ret)
+ return ret;
+ }
+
+ return count;
+}
+static DEVICE_ATTR_WO(reset_subordinate);
+
#if defined(CONFIG_PM) && defined(CONFIG_ACPI)
static ssize_t d3cold_allowed_store(struct device *dev,
struct device_attribute *attr,
@@ -625,6 +647,7 @@ static struct attribute *pci_dev_attrs[] = {
static struct attribute *pci_bridge_attrs[] = {
&dev_attr_subordinate_bus_number.attr,
&dev_attr_secondary_bus_number.attr,
+ &dev_attr_reset_subordinate.attr,
NULL,
};
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 7d85c04fbba2a..338dfcd983f1e 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5880,7 +5880,7 @@ EXPORT_SYMBOL_GPL(pci_probe_reset_bus);
*
* Same as above except return -EAGAIN if the bus cannot be locked
*/
-static int __pci_reset_bus(struct pci_bus *bus)
+int __pci_reset_bus(struct pci_bus *bus)
{
int rc;
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 14d00ce45bfa9..1cdc2c9547a7e 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -104,6 +104,7 @@ bool pci_reset_supported(struct pci_dev *dev);
void pci_init_reset_methods(struct pci_dev *dev);
int pci_bridge_secondary_bus_reset(struct pci_dev *dev);
int pci_bus_error_reset(struct pci_dev *dev);
+int __pci_reset_bus(struct pci_bus *bus);
struct pci_cap_saved_data {
u16 cap_nr;
--
2.43.5
