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Message-Id: <20210817180500.1253-6-ameynarkhede03@gmail.com>
Date: Tue, 17 Aug 2021 23:34:56 +0530
From: Amey Narkhede <ameynarkhede03@...il.com>
To: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: alex.williamson@...hat.com,
Raphael Norwitz <raphael.norwitz@...anix.com>,
linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
kw@...ux.com, Shanker Donthineni <sdonthineni@...dia.com>,
Sinan Kaya <okaya@...nel.org>, Len Brown <lenb@...nel.org>,
"Rafael J . Wysocki" <rjw@...ysocki.net>,
Amey Narkhede <ameynarkhede03@...il.com>
Subject: [PATCH v16 5/9] PCI: 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.
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>
Reviewed-by: Raphael Norwitz <raphael.norwitz@...anix.com>
---
Documentation/ABI/testing/sysfs-bus-pci | 19 ++++
drivers/pci/pci-sysfs.c | 1 +
drivers/pci/pci.c | 117 ++++++++++++++++++++++++
drivers/pci/pci.h | 2 +
4 files changed, 139 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index ef00fada2..ef66b62bf 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -121,6 +121,25 @@ 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. Initially reading
+ this file will give names of the device supported reset
+ methods and their ordering. After write, this file will
+ give names and ordering of currently enabled reset methods.
+ Writing the name or space 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 316f70c3e..54ee7193b 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1491,6 +1491,7 @@ const struct attribute_group *pci_dev_groups[] = {
&pci_dev_config_attr_group,
&pci_dev_rom_attr_group,
&pci_dev_reset_attr_group,
+ &pci_dev_reset_method_attr_group,
&pci_dev_vpd_attr_group,
#ifdef CONFIG_DMI
&pci_dev_smbios_attr_group,
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 8a516e9ca..53d737708 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5132,6 +5132,123 @@ static const struct pci_reset_fn_method pci_reset_fn_methods[] = {
{ pci_reset_bus_function, .name = "bus" },
};
+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, m;
+
+ for (i = 0; i < PCI_NUM_RESET_METHODS; i++) {
+ m = pdev->reset_methods[i];
+ if (!m)
+ break;
+
+ len += sysfs_emit_at(buf, len, "%s%s", len ? " " : "",
+ pci_reset_fn_methods[m].name);
+ }
+
+ if (len)
+ len += sysfs_emit_at(buf, len, "\n");
+
+ return len;
+}
+
+static ssize_t reset_method_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct pci_dev *pdev = to_pci_dev(dev);
+ int i, m = 0, n = 0;
+ char *name, *options;
+
+ if (count >= (PAGE_SIZE - 1))
+ return -EINVAL;
+
+ if (sysfs_streq(buf, "")) {
+ goto exit;
+ }
+
+ if (sysfs_streq(buf, "default")) {
+ pci_init_reset_methods(pdev);
+ return count;
+ }
+
+ options = kstrndup(buf, count, GFP_KERNEL);
+ if (!options)
+ return -ENOMEM;
+
+ while ((name = strsep(&options, " ")) != NULL) {
+ if (sysfs_streq(name, ""))
+ continue;
+
+ name = strim(name);
+
+ for (m = 1; m < PCI_NUM_RESET_METHODS; m++) {
+ if (sysfs_streq(name, pci_reset_fn_methods[m].name))
+ break;
+ }
+
+ if (m == PCI_NUM_RESET_METHODS) {
+ pci_warn(pdev, "Skip invalid reset method '%s'", name);
+ continue;
+ }
+
+ for (i = 0; i < n; i++) {
+ if (pdev->reset_methods[i] == m)
+ break;
+ }
+
+ if (i < n)
+ continue;
+
+ if (pci_reset_fn_methods[m].reset_fn(pdev, 1)) {
+ pci_warn(pdev, "Unsupported reset method '%s'", name);
+ continue;
+ }
+
+ pdev->reset_methods[n++] = m;
+ BUG_ON(n == PCI_NUM_RESET_METHODS);
+ }
+
+ kfree(options);
+
+exit:
+ /* All the reset methods are invalid */
+ if (n == 0 && m == PCI_NUM_RESET_METHODS)
+ return -EINVAL;
+ pdev->reset_methods[n] = 0;
+ if (pdev->reset_methods[0] == 0) {
+ pci_warn(pdev, "All device reset methods disabled by user");
+ } else if ((pdev->reset_methods[0] != 1) &&
+ !pci_reset_fn_methods[1].reset_fn(pdev, 1)) {
+ pci_warn(pdev, "Device specific reset disabled/de-prioritized by user");
+ }
+ return count;
+}
+static DEVICE_ATTR_RW(reset_method);
+
+static struct attribute *pci_dev_reset_method_attrs[] = {
+ &dev_attr_reset_method.attr,
+ NULL,
+};
+
+static umode_t pci_dev_reset_method_attr_is_visible(struct kobject *kobj,
+ struct attribute *a, int n)
+{
+ struct pci_dev *pdev = to_pci_dev(kobj_to_dev(kobj));
+
+ if (!pci_reset_supported(pdev))
+ return 0;
+
+ return a->mode;
+}
+
+const struct attribute_group pci_dev_reset_method_attr_group = {
+ .attrs = pci_dev_reset_method_attrs,
+ .is_visible = pci_dev_reset_method_attr_is_visible,
+};
+
/**
* __pci_reset_function_locked - reset a PCI device function while holding
* the @dev mutex lock.
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 743895374..31458d48e 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -714,4 +714,6 @@ static inline int pci_acpi_program_hp_params(struct pci_dev *dev)
extern const struct attribute_group aspm_ctrl_attr_group;
#endif
+extern const struct attribute_group pci_dev_reset_method_attr_group;
+
#endif /* DRIVERS_PCI_H */
--
2.32.0
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