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Wysocki" , Amey Narkhede Subject: [PATCH v9 4/8] PCI/sysfs: Allow userspace to query and set device reset mechanism Date: Mon, 5 Jul 2021 19:51:34 +0530 Message-Id: <20210705142138.2651-5-ameynarkhede03@gmail.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210705142138.2651-1-ameynarkhede03@gmail.com> References: <20210705142138.2651-1-ameynarkhede03@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org 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 Signed-off-by: Alex Williamson Signed-off-by: Amey Narkhede --- Documentation/ABI/testing/sysfs-bus-pci | 19 +++++ drivers/pci/pci-sysfs.c | 103 ++++++++++++++++++++++++ 2 files changed, 122 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci index ef00fada2..43f4e33c7 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 +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 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 diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index 316f70c3e..8a740e211 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -1334,6 +1334,108 @@ 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, idx; + + for (i = 0; i < PCI_NUM_RESET_METHODS; i++) { + idx = pdev->reset_methods[i]; + if (!idx) + break; + + len += sysfs_emit_at(buf, len, "%s%s", len ? "," : "", + pci_reset_fn_methods[idx].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 n = 0; + char *name, *options = NULL; + u8 reset_methods[PCI_NUM_RESET_METHODS] = { 0 }; + + if (count >= (PAGE_SIZE - 1)) + return -EINVAL; + + if (sysfs_streq(buf, "")) { + pci_warn(pdev, "All device reset methods disabled by user"); + goto set_reset_methods; + } + + 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) { + int i; + + if (sysfs_streq(name, "")) + continue; + + name = strim(name); + + for (i = 1; i < PCI_NUM_RESET_METHODS; i++) { + if (sysfs_streq(name, pci_reset_fn_methods[i].name) && + !pci_reset_fn_methods[i].reset_fn(pdev, 1)) { + reset_methods[n++] = i; + break; + } + } + + if (i == PCI_NUM_RESET_METHODS) { + kfree(options); + return -EINVAL; + } + } + + if (!pci_reset_fn_methods[1].reset_fn(pdev, 1) && reset_methods[0] != 1) + pci_warn(pdev, "Device specific reset disabled/de-prioritized by user"); + +set_reset_methods: + memcpy(pdev->reset_methods, reset_methods, sizeof(reset_methods)); + kfree(options); + 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 +1593,7 @@ 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, -- 2.32.0