On Tue, 2014-05-20 at 19:25 -0500, Kim Phillips wrote: > From: Kim Phillips <kim.phillips@xxxxxxxxxxxxx> > > Needed by platform device drivers, such as the vfio-platform driver > later in series, 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" [1], which is an interface enhancement > for more deterministic PCI device binding, e.g., when in the > presence of hotplug. > > [1] https://lists.cs.columbia.edu/pipermail/kvmarm/2014-May/009527.html > > Suggested-by: Alex Williamson <alex.williamson@xxxxxxxxxx> > Signed-off-by: Kim Phillips <kim.phillips@xxxxxxxxxxxxx> Looks largely identical to the PCI version of the same that has been accepted for v3.16 and ack'd by GregKH. Reviewed-by: Alex Williamson <alex.williamson@xxxxxxxxxx> > --- > changes in v2 patch of v5 of this patchseries: > - rebased onto today's Linus' ToT > - added kfree to match PCI counterpart fix, as Alex Williamson > just posted a v3 of the patch (thanks Christoffer for the > notification) > - in the commit text, replaced vfio platform driver reference with > 'later in series', and updated the PCI version mailing list reference > to the v3 version. > > Is it safe to assume this patch will continue to as part of the VFIO > platform driver patchseries, and be submitted by Antonis? If so, can > we start collecting some {Reviewed,Acked}-bys? Thanks, Kim. > > Documentation/ABI/testing/sysfs-bus-platform | 20 ++++++++++++ > drivers/base/platform.c | 47 ++++++++++++++++++++++++++++ > include/linux/platform_device.h | 1 + > 3 files changed, 68 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..5172a61 > --- /dev/null > +++ b/Documentation/ABI/testing/sysfs-bus-platform > @@ -0,0 +1,20 @@ > +What: /sys/bus/platform/devices/.../driver_override > +Date: April 2014 > +Contact: Kim Phillips <kim.phillips@xxxxxxxxxxxxx> > +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 is specified by writing a string > + to the driver_override file (echo vfio-platform > \ > + 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/base/platform.c b/drivers/base/platform.c > index 5b47210..4f47563 100644 > --- a/drivers/base/platform.c > +++ b/drivers/base/platform.c > @@ -23,6 +23,7 @@ > #include <linux/pm_runtime.h> > #include <linux/idr.h> > #include <linux/acpi.h> > +#include <linux/limits.h> > > #include "base.h" > #include "power/power.h" > @@ -188,6 +189,7 @@ static void platform_device_release(struct device *dev) > kfree(pa->pdev.dev.platform_data); > kfree(pa->pdev.mfd_cell); > kfree(pa->pdev.resource); > + kfree(pa->pdev.driver_override); > kfree(pa); > } > > @@ -695,8 +697,49 @@ 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, *cp; > + > + if (count > PATH_MAX) > + return -EINVAL; > + > + driver_override = kstrndup(buf, count, GFP_KERNEL); > + if (!driver_override) > + return -ENOMEM; > + > + cp = strchr(driver_override, '\n'); > + if (cp) > + *cp = '\0'; > + > + if (strlen(driver_override)) { > + pdev->driver_override = driver_override; > + } else { > + kfree(driver_override); > + pdev->driver_override = NULL; > + } > + > + kfree(old); > + > + return count; > +} > + > +static ssize_t driver_override_show(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct platform_device *pdev = to_platform_device(dev); > + > + return sprintf(buf, "%s\n", pdev->driver_override); > +} > +static DEVICE_ATTR_RW(driver_override); > + > + > static struct attribute *platform_dev_attrs[] = { > &dev_attr_modalias.attr, > + &dev_attr_driver_override.attr, > NULL, > }; > ATTRIBUTE_GROUPS(platform_dev); > @@ -752,6 +795,10 @@ static int platform_match(struct device *dev, struct device_driver *drv) > struct platform_device *pdev = to_platform_device(dev); > struct platform_driver *pdrv = to_platform_driver(drv); > > + /* When driver_override is set, only bind to the matching driver */ > + if (pdev->driver_override) > + return !strcmp(pdev->driver_override, drv->name); > + > /* Attempt an OF style match first */ > if (of_driver_match_device(dev, drv)) > return 1; > diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h > index 16f6654..153d303 100644 > --- a/include/linux/platform_device.h > +++ b/include/linux/platform_device.h > @@ -28,6 +28,7 @@ struct platform_device { > struct resource *resource; > > const struct platform_device_id *id_entry; > + char *driver_override; /* Driver name to force a match */ > > /* MFD cell pointer */ > struct mfd_cell *mfd_cell; -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
