Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753602AbaDECHu (ORCPT ); Fri, 4 Apr 2014 22:07:50 -0400 Received: from mail.active-venture.com ([67.228.131.205]:50638 "EHLO mail.active-venture.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751879AbaDECHk (ORCPT ); Fri, 4 Apr 2014 22:07:40 -0400 X-Originating-IP: 108.223.40.66 Message-ID: <533F6561.2090205@roeck-us.net> Date: Fri, 04 Apr 2014 19:07:29 -0700 From: Guenter Roeck User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Kim Phillips , Alex Williamson CC: Kim Phillips , gregkh@linuxfoundation.org, stuart.yoder@freescale.com, kvm@vger.kernel.org, jan.kiszka@siemens.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, mhocko@suse.cz, bhelgaas@google.com, Varun.Sethi@freescale.com, kvmarm@lists.cs.columbia.edu, rafael.j.wysocki@intel.com, agraf@suse.de, linux-pci@vger.kernel.org, konrad.wilk@oracle.com, d.kasatkin@samsung.com, tj@kernel.org, scottwood@freescale.com, a.motakis@virtualopensystems.com, tech@virtualopensystems.com, Bharat.Bhushan@freescale.com, toshi.kani@hp.com, a.rigo@virtualopensystems.com, iommu@lists.linux-foundation.org, joe@perches.com, christoffer.dall@linaro.org Subject: Re: [RFC PATCH] PCI: Introduce new device binding path using pci_dev.driver_override References: <20140401161851.18815.31108.stgit@bling.home> <20140401185212.7229f2c114c7e95089f00e90@linaro.org> <20140402002324.GA2662@kroah.com> <20140402170638.51745f5c231a7632422e4cc5@linaro.org> <1396479728.476.410.camel@ul30vt.home> <20140404203512.5b5ac8a134a71065518712c3@freescale.com> In-Reply-To: <20140404203512.5b5ac8a134a71065518712c3@freescale.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/04/2014 06:35 PM, Kim Phillips wrote: > Needed by platform device drivers, such as the vfio-platform driver [1], > in order to bypass the existing OF, ACPI, id_table and name string matches, > and successfully be able to be bound to any device, like so: > > echo vfio-platform > /sys/bus/platform/devices/fff51000.ethernet/driver_override > echo fff51000.ethernet > /sys/bus/platform/devices/fff51000.ethernet/driver/unbind > echo fff51000.ethernet > /sys/bus/platform/drivers_probe > > This mimics "PCI: Introduce new device binding path using > pci_dev.driver_override" [2], which is an interface enhancement > for more deterministic PCI device binding, e.g., when in the > presence of hotplug. > > [1] http://lkml.iu.edu/hypermail/linux/kernel/1402.1/00177.html > [2] http://thread.gmane.org/gmane.linux.kernel.iommu/4605 > > Signed-off-by: Kim Phillips > --- > if this looks ok, should it be included in the next version of the > vfio-platform submission series, like last time ([1] above)? > > Documentation/ABI/testing/sysfs-bus-platform | 17 ++++++++++ > drivers/base/platform.c | 46 ++++++++++++++++++++++++++++ > include/linux/platform_device.h | 1 + > 3 files changed, 64 insertions(+) > create mode 100644 Documentation/ABI/testing/sysfs-bus-platform > > diff --git a/Documentation/ABI/testing/sysfs-bus-platform b/Documentation/ABI/testing/sysfs-bus-platform > new file mode 100644 > index 0000000..6b14a6a > --- /dev/null > +++ b/Documentation/ABI/testing/sysfs-bus-platform > @@ -0,0 +1,17 @@ > +What: /sys/bus/platform/devices/.../driver_override > +Date: April 2014 > +Contact: Kim Phillips > +Description: > + This file allows the driver for a device to be specified > + which will override standard OF, ACPI, ID table, and name > + matching. 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 may be cleared by > + writing an empty string (ex. echo > driver_override), returning > + 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 name. If no driver with a matching name > + is currently loaded in the kernel, no match will be found. > + This also allows devices to opt-out of driver binding using > + a driver_override name such as "none". > diff --git a/drivers/base/platform.c b/drivers/base/platform.c > index e714709..ded1db1 100644 > --- a/drivers/base/platform.c > +++ b/drivers/base/platform.c > @@ -22,6 +22,7 @@ > #include > #include > #include > +#include > > #include "base.h" > #include "power/power.h" > @@ -690,8 +691,49 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *a, > } > static DEVICE_ATTR_RO(modalias); > > +static ssize_t driver_override_store(struct device *dev, > + struct device_attribute *attr, > + const char *buf, size_t count) > +{ > + struct platform_device *pdev = to_platform_device(dev); > + char *driver_override, *old = pdev->driver_override; > + > + if (count > PATH_MAX) > + return -EINVAL; > + > + driver_override = kstrndup(buf, count, GFP_KERNEL); > + if (!driver_override) > + return -ENOMEM; > + > + while (strlen(driver_override) && > + driver_override[strlen(driver_override) - 1] == '\n') > + driver_override[strlen(driver_override) - 1] = '\0'; > + Seems to me that something like cp = strchr(driver_override, '\n'); if (cp) *cp = '\0'; would be much simpler. Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/