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Wysocki" , Amey Narkhede Subject: [PATCH v16 5/9] PCI: Allow userspace to query and set device reset mechanism Date: Tue, 17 Aug 2021 23:39:33 +0530 Message-Id: <20210817180937.3123-6-ameynarkhede03@gmail.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210817180937.3123-1-ameynarkhede03@gmail.com> References: <20210817180937.3123-1-ameynarkhede03@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 Reviewed-by: Raphael Norwitz --- 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 +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 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