From patchwork Tue Sep 8 07:13:30 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xu Yilun X-Patchwork-Id: 11762677 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id EA5ED746 for ; Tue, 8 Sep 2020 07:19:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DC12021D1A for ; Tue, 8 Sep 2020 07:19:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729269AbgIHHSD (ORCPT ); Tue, 8 Sep 2020 03:18:03 -0400 Received: from mga09.intel.com ([134.134.136.24]:30573 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729246AbgIHHSC (ORCPT ); Tue, 8 Sep 2020 03:18:02 -0400 IronPort-SDR: RV9utV7ksloTlCOhj9ft8L0rDC/J2HXyziceEBZM6Jkxsu3HNdTJRoTXIrOi4SemC2O/cYYhzm xaQgmZxtwasA== X-IronPort-AV: E=McAfee;i="6000,8403,9737"; a="159058737" X-IronPort-AV: E=Sophos;i="5.76,404,1592895600"; d="scan'208";a="159058737" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Sep 2020 00:18:01 -0700 IronPort-SDR: 16kxSz8FcibQjPAMjNL4fMfj/Uu0qMWU1yqlgh+aBu3zVs17c5oJ3mqCj+w2OBdwPmPu9UnxmK aM6CJrdBkFIw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.76,404,1592895600"; d="scan'208";a="448677709" Received: from yilunxu-optiplex-7050.sh.intel.com ([10.239.159.141]) by orsmga004.jf.intel.com with ESMTP; 08 Sep 2020 00:17:59 -0700 From: Xu Yilun To: mdf@kernel.org, alex.williamson@redhat.com, kwankhede@nvidia.com, linux-fpga@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: trix@redhat.com, lgoncalv@redhat.com, yilun.xu@intel.com Subject: [PATCH 1/3] fpga: dfl: add driver_override support Date: Tue, 8 Sep 2020 15:13:30 +0800 Message-Id: <1599549212-24253-2-git-send-email-yilun.xu@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1599549212-24253-1-git-send-email-yilun.xu@intel.com> References: <1599549212-24253-1-git-send-email-yilun.xu@intel.com> Sender: linux-fpga-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fpga@vger.kernel.org Add support for overriding the default matching of a dfl device to a dfl driver. It follows the same way that can be used for PCI and platform devices. This patch adds the 'driver_override' sysfs file. It can be used by VFIO to bind dfl devices for user accessing. Signed-off-by: Xu Yilun --- Documentation/ABI/testing/sysfs-bus-dfl | 20 ++++++++++++ drivers/fpga/dfl.c | 54 ++++++++++++++++++++++++++++++++- include/linux/fpga/dfl-bus.h | 2 ++ 3 files changed, 75 insertions(+), 1 deletion(-) diff --git a/Documentation/ABI/testing/sysfs-bus-dfl b/Documentation/ABI/testing/sysfs-bus-dfl index 23543be..cf1357a 100644 --- a/Documentation/ABI/testing/sysfs-bus-dfl +++ b/Documentation/ABI/testing/sysfs-bus-dfl @@ -13,3 +13,23 @@ Contact: Xu Yilun Description: Read-only. It returns feature identifier local to its DFL FIU type. Format: 0x%x + +What: /sys/bus/dfl/devices/.../driver_override +Date: Sep 2020 +KernelVersion: 5.10 +Contact: Xu Yilun +Description: This file allows the driver for a device to be specified. When + specified, only a driver with a name matching the value written + to driver_override will have an opportunity to bind to the + device. The override is specified by writing a string to the + driver_override file (echo vfio-mdev-dfl > driver_override) and + may be cleared with an empty string (echo > driver_override). + This returns the device to standard matching rules binding. + Writing to driver_override does not automatically unbind the + device from its current driver or make any attempt to + automatically load the specified driver. If no driver with a + matching name is currently loaded in the kernel, the device + will not bind to any driver. This also allows devices to + opt-out of driver binding using a driver_override name such as + "none". Only a single driver may be specified in the override, + there is no support for parsing delimiters. diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c index 02a6780..98f88ee 100644 --- a/drivers/fpga/dfl.c +++ b/drivers/fpga/dfl.c @@ -262,6 +262,10 @@ static int dfl_bus_match(struct device *dev, struct device_driver *drv) struct dfl_driver *ddrv = to_dfl_drv(drv); const struct dfl_device_id *id_entry; + /* When driver_override is set, only bind to the matching driver */ + if (ddev->driver_override) + return !strcmp(ddev->driver_override, drv->name); + id_entry = ddrv->id_table; if (id_entry) { while (id_entry->feature_id) { @@ -304,6 +308,53 @@ static int dfl_bus_uevent(struct device *dev, struct kobj_uevent_env *env) ddev->type, ddev->feature_id); } +static ssize_t driver_override_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct dfl_device *ddev = to_dfl_dev(dev); + ssize_t len; + + device_lock(dev); + len = sprintf(buf, "%s\n", ddev->driver_override); + device_unlock(dev); + return len; +} + +static ssize_t driver_override_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct dfl_device *ddev = to_dfl_dev(dev); + char *driver_override, *old, *cp; + + /* We need to keep extra room for a newline */ + if (count >= (PAGE_SIZE - 1)) + return -EINVAL; + + driver_override = kstrndup(buf, count, GFP_KERNEL); + if (!driver_override) + return -ENOMEM; + + cp = strchr(driver_override, '\n'); + if (cp) + *cp = '\0'; + + device_lock(dev); + old = ddev->driver_override; + if (strlen(driver_override)) { + ddev->driver_override = driver_override; + } else { + kfree(driver_override); + ddev->driver_override = NULL; + } + device_unlock(dev); + + kfree(old); + + return count; +} +static DEVICE_ATTR_RW(driver_override); + static ssize_t type_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -325,6 +376,7 @@ static DEVICE_ATTR_RO(feature_id); static struct attribute *dfl_dev_attrs[] = { &dev_attr_type.attr, &dev_attr_feature_id.attr, + &dev_attr_driver_override.attr, NULL, }; ATTRIBUTE_GROUPS(dfl_dev); @@ -470,7 +522,7 @@ static int dfl_devs_add(struct dfl_feature_platform_data *pdata) int __dfl_driver_register(struct dfl_driver *dfl_drv, struct module *owner) { - if (!dfl_drv || !dfl_drv->probe || !dfl_drv->id_table) + if (!dfl_drv || !dfl_drv->probe) return -EINVAL; dfl_drv->drv.owner = owner; diff --git a/include/linux/fpga/dfl-bus.h b/include/linux/fpga/dfl-bus.h index 2a2b283..09a9ee1 100644 --- a/include/linux/fpga/dfl-bus.h +++ b/include/linux/fpga/dfl-bus.h @@ -43,6 +43,8 @@ struct dfl_device { unsigned int num_irqs; struct dfl_fpga_cdev *cdev; const struct dfl_device_id *id_entry; + + char *driver_override; }; /**