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Message-Id: <20210409192324.30080-6-ameynarkhede03@gmail.com>
Date: Sat, 10 Apr 2021 00:53:24 +0530
From: Amey Narkhede <ameynarkhede03@...il.com>
To: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: alex.williamson@...hat.com, raphael.norwitz@...anix.com,
linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
Amey Narkhede <ameynarkhede03@...il.com>
Subject: [PATCH v2 5/5] PCI/sysfs: Allow userspace to query and set device reset mechanism
Add reset_method sysfs attribute to enable user to
query and set user preferred device reset methods and
their ordering.
Reviewed-by: Alex Williamson <alex.williamson@...hat.com>
Reviewed-by: Raphael Norwitz <raphael.norwitz@...anix.com>
Co-developed-by: Alex Williamson <alex.williamson@...hat.com>
Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
Signed-off-by: Amey Narkhede <ameynarkhede03@...il.com>
---
Documentation/ABI/testing/sysfs-bus-pci | 16 +++++
drivers/pci/pci-sysfs.c | 91 ++++++++++++++++++++++++-
2 files changed, 104 insertions(+), 3 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index 25c9c3977..36fba7ebf 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -121,6 +121,22 @@ Description:
child buses, and re-discover devices removed earlier
from this part of the device tree.
+What: /sys/bus/pci/devices/.../reset_method
+Date: March 2021
+Contact: Amey Narkhede <ameynarkhede03@...il.com>
+Description:
+ Some devices allow an individual function to be reset
+ without affecting other functions in the same slot.
+ For devices that have this support, a file named reset_method
+ will be present in sysfs. Reading this file will give names
+ of the device supported reset methods and their ordering.
+ Writing the name or comma separated list of names of any of
+ the device supported reset methods to this file will set the
+ reset methods and their ordering to be used when resetting
+ the device. Writing empty string to this file will disable
+ ability to reset the device and writing "default" will return
+ to the original value.
+
What: /sys/bus/pci/devices/.../reset
Date: July 2009
Contact: Michael S. Tsirkin <mst@...hat.com>
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 388895099..cf2f66270 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1304,6 +1304,84 @@ static const struct bin_attribute pcie_config_attr = {
.write = pci_write_config,
};
+static ssize_t reset_method_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct pci_dev *pdev = to_pci_dev(dev);
+ ssize_t len = 0;
+ int i, prio;
+
+ for (prio = PCI_RESET_FN_METHODS; prio; prio--) {
+ for (i = 0; i < PCI_RESET_FN_METHODS; i++) {
+ if (prio == pdev->reset_methods[i]) {
+ len += sysfs_emit_at(buf, len, "%s%s",
+ len ? "," : "",
+ pci_reset_fn_methods[i].name);
+ break;
+ }
+ }
+
+ if (i == PCI_RESET_FN_METHODS)
+ break;
+ }
+
+ return len;
+}
+
+static ssize_t reset_method_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ u8 reset_methods[PCI_RESET_FN_METHODS];
+ struct pci_dev *pdev = to_pci_dev(dev);
+ u8 prio = PCI_RESET_FN_METHODS;
+ char *name;
+ int i;
+
+ /*
+ * Initialize reset_method such that 0xff indicates
+ * supported but not currently enabled reset methods
+ * as we only use priority values which are within
+ * the range of PCI_RESET_FN_METHODS array size
+ */
+ for (i = 0; i < PCI_RESET_FN_METHODS; i++)
+ reset_methods[i] = pdev->reset_methods[i] ? 0xff : 0;
+
+ if (sysfs_streq(buf, "")) {
+ pci_warn(pdev, "All device reset methods disabled by user");
+ goto set_reset_methods;
+ }
+
+ if (sysfs_streq(buf, "default")) {
+ for (i = 0; i < PCI_RESET_FN_METHODS; i++)
+ reset_methods[i] = reset_methods[i] ? prio-- : 0;
+ goto set_reset_methods;
+ }
+
+ while ((name = strsep((char **)&buf, ",")) != NULL) {
+ for (i = 0; i < PCI_RESET_FN_METHODS; i++) {
+ if (reset_methods[i] &&
+ sysfs_streq(name, pci_reset_fn_methods[i].name)) {
+ reset_methods[i] = prio--;
+ break;
+ }
+ }
+ if (i == PCI_RESET_FN_METHODS)
+ return -EINVAL;
+ }
+
+ if (reset_methods[0] &&
+ reset_methods[0] != PCI_RESET_FN_METHODS)
+ pci_warn(pdev, "Device specific reset disabled/de-prioritized by user");
+
+set_reset_methods:
+ memcpy(pdev->reset_methods, reset_methods, sizeof(reset_methods));
+ return count;
+}
+
+static DEVICE_ATTR_RW(reset_method);
+
static ssize_t reset_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
@@ -1337,11 +1415,16 @@ static int pci_create_capabilities_sysfs(struct pci_dev *dev)
if (pci_reset_supported(dev)) {
retval = device_create_file(&dev->dev, &dev_attr_reset);
if (retval)
- goto error;
+ goto err_reset;
+ retval = device_create_file(&dev->dev, &dev_attr_reset_method);
+ if (retval)
+ goto err_method;
}
return 0;
-error:
+err_method:
+ device_remove_file(&dev->dev, &dev_attr_reset);
+err_reset:
pcie_vpd_remove_sysfs_dev_files(dev);
return retval;
}
@@ -1417,8 +1500,10 @@ int __must_check pci_create_sysfs_dev_files(struct pci_dev *pdev)
static void pci_remove_capabilities_sysfs(struct pci_dev *dev)
{
pcie_vpd_remove_sysfs_dev_files(dev);
- if (pci_reset_supported(dev))
+ if (pci_reset_supported(dev)) {
device_remove_file(&dev->dev, &dev_attr_reset);
+ device_remove_file(&dev->dev, &dev_attr_reset_method);
+ }
}
/**
--
2.31.1
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