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From: Amey Narkhede <ameynarkhede03@gmail.com>
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: alex.williamson@redhat.com,
	Raphael Norwitz <raphael.norwitz@nutanix.com>,
	linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
	kw@linux.com, Shanker Donthineni <sdonthineni@nvidia.com>,
	Sinan Kaya <okaya@kernel.org>,
	Amey Narkhede <ameynarkhede03@gmail.com>
Subject: [PATCH v5 4/7] PCI/sysfs: Allow userspace to query and set device reset mechanism
Date: Sun, 30 May 2021 00:55:24 +0530	[thread overview]
Message-ID: <20210529192527.2708-5-ameynarkhede03@gmail.com> (raw)
In-Reply-To: <20210529192527.2708-1-ameynarkhede03@gmail.com>

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@redhat.com>
Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Co-developed-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Amey Narkhede <ameynarkhede03@gmail.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@gmail.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@redhat.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


  parent reply	other threads:[~2021-05-29 19:25 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-29 19:25 [PATCH v5 0/7] Expose and manage PCI device reset Amey Narkhede
2021-05-29 19:25 ` [PATCH v5 1/7] PCI: Add pcie_reset_flr to follow calling convention of other reset methods Amey Narkhede
2021-05-29 19:25 ` [PATCH v5 2/7] PCI: Add new array for keeping track of ordering of " Amey Narkhede
2021-06-02 21:37   ` Shanker R Donthineni
2021-06-05 20:55   ` Bjorn Helgaas
2021-05-29 19:25 ` [PATCH v5 3/7] PCI: Remove reset_fn field from pci_dev Amey Narkhede
2021-06-02 22:16   ` Shanker R Donthineni
2021-06-05 20:57   ` Bjorn Helgaas
2021-05-29 19:25 ` Amey Narkhede [this message]
2021-06-02 22:17   ` [PATCH v5 4/7] PCI/sysfs: Allow userspace to query and set device reset mechanism Shanker R Donthineni
2021-06-06 12:58   ` Krzysztof Wilczyński
2021-06-06 14:27     ` Shanker R Donthineni
2021-05-29 19:25 ` [PATCH v5 5/7] PCI: Add support for a function level reset based on _RST method Amey Narkhede
2021-06-05 20:53   ` Bjorn Helgaas
2021-06-06  0:04     ` Shanker R Donthineni
2021-06-06  5:00     ` Shanker R Donthineni
2021-06-09 12:51     ` Shanker R Donthineni
2021-05-29 19:25 ` [PATCH v5 6/7] PCI: Enable NO_BUS_RESET quirk for Nvidia GPUs Amey Narkhede
2021-05-29 19:25 ` [PATCH v5 7/7] PCI: Change the type of probe argument in reset functions Amey Narkhede
2021-06-02 22:15   ` Shanker R Donthineni

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