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Message-Id: <20210529192527.2708-5-ameynarkhede03@gmail.com>
Date: Sun, 30 May 2021 00:55:24 +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>,
Amey Narkhede <ameynarkhede03@...il.com>
Subject: [PATCH v5 4/7] 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 | 105 ++++++++++++++++++++++++
2 files changed, 121 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index ef00fada2..cf6dbbb3c 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 316f70c3e..04b3d6565 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1334,6 +1334,110 @@ static const struct attribute_group pci_dev_rom_attr_group = {
.is_bin_visible = pci_dev_rom_attr_is_visible,
};
+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_METHODS_NUM; prio; prio--) {
+ for (i = 0; i < PCI_RESET_METHODS_NUM; 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_METHODS_NUM)
+ 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_METHODS_NUM];
+ struct pci_dev *pdev = to_pci_dev(dev);
+ u8 prio = PCI_RESET_METHODS_NUM;
+ 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_METHODS_NUM; 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_METHODS_NUM; i++)
+ reset_methods[i] = reset_methods[i] ? prio-- : 0;
+ goto set_reset_methods;
+ }
+
+ while ((name = strsep((char **)&buf, ",")) != NULL) {
+ if (sysfs_streq(name, ""))
+ continue;
+
+ name = strim(name);
+
+ for (i = 0; i < PCI_RESET_METHODS_NUM; i++) {
+ if (reset_methods[i] &&
+ sysfs_streq(name, pci_reset_fn_methods[i].name)) {
+ reset_methods[i] = prio--;
+ break;
+ }
+ }
+ if (i == PCI_RESET_METHODS_NUM)
+ return -EINVAL;
+ }
+
+ if (reset_methods[0] &&
+ reset_methods[0] != PCI_RESET_METHODS_NUM)
+ 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 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;
+}
+
+static 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,
+};
+
static ssize_t reset_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
@@ -1491,6 +1595,7 @@ 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,
--
2.31.1
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