| Message ID | 20140404203512.5b5ac8a134a71065518712c3@freescale.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
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 <kim.phillips@freescale.com> > --- > 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 <kim.phillips@freescale.com> > +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 <linux/pm_runtime.h> > #include <linux/idr.h> > #include <linux/acpi.h> > +#include <linux/limits.h> > > #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-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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 <kim.phillips@freescale.com> +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 <linux/pm_runtime.h> #include <linux/idr.h> #include <linux/acpi.h> +#include <linux/limits.h> #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'; + + 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); @@ -747,6 +789,10 @@ 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;
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 <kim.phillips@freescale.com> --- 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