From: Vineeth Vijayan vneethv@linux.ibm.com
stable inclusion from linux-4.19.207 commit cf5b3bd01970a902f25f66704713ae2893898119
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[ Upstream commit d3683c055212bf910d4e318f7944910ce10dbee6 ]
Introduce dev_busid, which exports the device-id associated with the io-subchannel (and message-subchannel). The dev_busid indicates that of the device which may be physically installed on the corrosponding subchannel. The dev_busid value "none" indicates that the subchannel is not valid, there is no I/O device currently associated with the subchannel.
The dev_busid information would be helpful to write device-specific udev-rules associated with the subchannel. The dev_busid interface would be available even when the sch is not bound to any driver or if there is no operational device connected on it. Hence this attribute can be used to write udev-rules which are specific to the device associated with the subchannel.
Signed-off-by: Vineeth Vijayan vneethv@linux.ibm.com Reviewed-by: Peter Oberparleiter oberpar@linux.ibm.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- drivers/s390/cio/css.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c index 825a8f2703b4f..6efe50d70c4bf 100644 --- a/drivers/s390/cio/css.c +++ b/drivers/s390/cio/css.c @@ -364,9 +364,26 @@ static ssize_t pimpampom_show(struct device *dev, } static DEVICE_ATTR_RO(pimpampom);
+static ssize_t dev_busid_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct subchannel *sch = to_subchannel(dev); + struct pmcw *pmcw = &sch->schib.pmcw; + + if ((pmcw->st == SUBCHANNEL_TYPE_IO || + pmcw->st == SUBCHANNEL_TYPE_MSG) && pmcw->dnv) + return sysfs_emit(buf, "0.%x.%04x\n", sch->schid.ssid, + pmcw->dev); + else + return sysfs_emit(buf, "none\n"); +} +static DEVICE_ATTR_RO(dev_busid); + static struct attribute *io_subchannel_type_attrs[] = { &dev_attr_chpids.attr, &dev_attr_pimpampom.attr, + &dev_attr_dev_busid.attr, NULL, }; ATTRIBUTE_GROUPS(io_subchannel_type);