On 10/15/20 11:02 PM, Xu Yilun wrote: > 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. > > Signed-off-by: Xu Yilun <[email protected]> > --- > Documentation/ABI/testing/sysfs-bus-dfl | 28 ++++++++++++++--- > drivers/fpga/dfl.c | 54 > ++++++++++++++++++++++++++++++++- > include/linux/dfl.h | 2 ++ > 3 files changed, 79 insertions(+), 5 deletions(-) > > diff --git a/Documentation/ABI/testing/sysfs-bus-dfl > b/Documentation/ABI/testing/sysfs-bus-dfl > index 23543be..db7e8d3 100644 > --- a/Documentation/ABI/testing/sysfs-bus-dfl > +++ b/Documentation/ABI/testing/sysfs-bus-dfl > @@ -1,15 +1,35 @@ > What: /sys/bus/dfl/devices/dfl_dev.X/type > -Date: Aug 2020 > -KernelVersion: 5.10 > +Date: Oct 2020 > +KernelVersion: 5.11 > Contact: Xu Yilun <[email protected]> > Description: Read-only. It returns type of DFL FIU of the device. Now DFL > supports 2 FIU types, 0 for FME, 1 for PORT. > Format: 0x%x > > What: /sys/bus/dfl/devices/dfl_dev.X/feature_id > -Date: Aug 2020 > -KernelVersion: 5.10 > +Date: Oct 2020 > +KernelVersion: 5.11 > Contact: Xu Yilun <[email protected]> > Description: Read-only. It returns feature identifier local to its DFL FIU > type. > Format: 0x%x
These updates, do not match the comment. Consider splitting this out. > + > +What: /sys/bus/dfl/devices/.../driver_override > +Date: Oct 2020 > +KernelVersion: 5.11 > +Contact: Xu Yilun <[email protected]> I am looking at description and trying to make it consistent with sysfs-bus-pci > +Description: This file allows the driver for a device to be specified. 'to be specified which will override the standard dfl bus feature id to driver mapping.' > 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 dfl-uio-pdev > 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 511b20f..bc35750 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) { > @@ -303,6 +307,53 @@ static int dfl_bus_uevent(struct device *dev, struct > kobj_uevent_env *env) > ddev->type, ddev->feature_id); > } > I am looking at other implementations of driver_override* and looking for consistency. > +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); len = snprintf(buf, PAGE_SIZE ... > + 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) > { > @@ -324,6 +375,7 @@ 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); > @@ -469,7 +521,7 @@ 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) id_table is still needed for the normal case. Instead of removing this check, could you add something like || (!dfl_drv->is_override && !dfl_drv->id_table) Tom > return -EINVAL; > > dfl_drv->drv.owner = owner; > diff --git a/include/linux/dfl.h b/include/linux/dfl.h > index 7affba2f..e1b2471 100644 > --- a/include/linux/dfl.h > +++ b/include/linux/dfl.h > @@ -32,6 +32,7 @@ enum dfl_id_type { > * @num_irqs: number of IRQs supported by this dfl device. > * @cdev: pointer to DFL FPGA container device this dfl device belongs to. > * @id_entry: matched id entry in dfl driver's id table. > + * @driver_override: driver name to force a match > */ > struct dfl_device { > struct device dev; > @@ -43,6 +44,7 @@ struct dfl_device { > unsigned int num_irqs; > struct dfl_fpga_cdev *cdev; > const struct dfl_device_id *id_entry; > + char *driver_override; > }; > > /**
