dibs: Create class dibs

Create '/sys/class/dibs' to represent multiple kinds of dibs devices in
sysfs. Show s390/ism devices as well as dibs_loopback devices.

Show attribute fabric_id using dibs_ops.get_fabric_id(). This can help
users understand which dibs devices are connected to the same fabric in
different systems and which dibs devices are loopback devices
(fabric_id 0xffff)

Instead of using the same name as the pci device, give the ism devices
their own readable names based on uid or fid from the HW definition.

smc_loopback was never visible in sysfs. dibs_loopback is now represented
as a virtual device.

For the SMC feature "software defined pnet-id" either the ib device name or
the PCI-ID (actually the parent device name) can be used for SMC-R entries.
Mimic this behaviour for SMC-D, and check the parent device name as well.
So device name or PCI-ID can be used for ism and device name can be used
for dibs-loopback. Note that this:
IB_DEVICE_NAME_MAX - 1 == smc_pnet_policy.[SMC_PNETID_IBNAME].len
is the length of smcd_name. Future SW-pnetid cleanup patches to could use a
meaningful define, but that would touch too much unrelated code here.

Examples:
---------
ism before:
> ls /sys/bus/pci/devices/0000:00:00.0/0000:00:00.0
uevent

ism now:
> ls /sys/bus/pci/devices/0000:00:00.0/dibs/ism30
device -> ../../../0000:00:00.0/
fabric_id
subsystem -> ../../../../../class/dibs/
uevent

dibs loopback:
> ls /sys/devices/virtual/dibs/lo/
fabric_id
subsystem -> ../../../../class/dibs/
uevent

dibs class:
> ls -l /sys/class/dibs/
ism30 -> ../../devices/pci0000:00/0000:00:00.0/dibs/ism30/
lo -> ../../devices/virtual/dibs/lo/

For comparison:
> ls -l /sys/class/net/
enc8410 -> ../../devices/qeth/0.0.8410/net/enc8410/
ens1693 -> ../../devices/pci0001:00/0001:00:00.0/net/ens1693/
lo -> ../../devices/virtual/net/lo/

Signed-off-by: Julian Ruess <julianr@linux.ibm.com>
Co-developed-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Link: https://patch.msgid.link/20250918110500.1731261-10-wintera@linux.ibm.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

2 files changed, 44 insertions, 1 deletions

diff --git a/drivers/dibs/dibs_main.c b/drivers/dibs/dibs_main.c
index 610b6c452211..b3f21805aa59 100644
--- a/drivers/dibs/dibs_main.c
+++ b/drivers/dibs/dibs_main.c
@@ -20,6 +20,8 @@
 MODULE_DESCRIPTION("Direct Internal Buffer Sharing class");
 MODULE_LICENSE("GPL");
 
+static struct class *dibs_class;
+
 /* use an array rather a list for fast mapping: */
 static struct dibs_client *clients[MAX_DIBS_CLIENTS];
 static u8 max_client;
@@ -105,12 +107,35 @@ struct dibs_dev *dibs_dev_alloc(void)
 	if (!dibs)
 		return dibs;
 	dibs->dev.release = dibs_dev_release;
+	dibs->dev.class = dibs_class;
 	device_initialize(&dibs->dev);
 
 	return dibs;
 }
 EXPORT_SYMBOL_GPL(dibs_dev_alloc);
 
+static ssize_t fabric_id_show(struct device *dev, struct device_attribute *attr,
+			      char *buf)
+{
+	struct dibs_dev *dibs;
+	u16 fabric_id;
+
+	dibs = container_of(dev, struct dibs_dev, dev);
+	fabric_id = dibs->ops->get_fabric_id(dibs);
+
+	return sysfs_emit(buf, "0x%04x\n", fabric_id);
+}
+static DEVICE_ATTR_RO(fabric_id);
+
+static struct attribute *dibs_dev_attrs[] = {
+	&dev_attr_fabric_id.attr,
+	NULL,
+};
+
+static const struct attribute_group dibs_dev_attr_group = {
+	.attrs = dibs_dev_attrs,
+};
+
 int dibs_dev_add(struct dibs_dev *dibs)
 {
 	int i, ret;
@@ -119,6 +144,11 @@ int dibs_dev_add(struct dibs_dev *dibs)
 	if (ret)
 		return ret;
 
+	ret = sysfs_create_group(&dibs->dev.kobj, &dibs_dev_attr_group);
+	if (ret) {
+		dev_err(&dibs->dev, "sysfs_create_group failed for dibs_dev\n");
+		goto err_device_del;
+	}
 	mutex_lock(&dibs_dev_list.mutex);
 	mutex_lock(&clients_lock);
 	for (i = 0; i < max_client; ++i) {
@@ -130,6 +160,11 @@ int dibs_dev_add(struct dibs_dev *dibs)
 	mutex_unlock(&dibs_dev_list.mutex);
 
 	return 0;
+
+err_device_del:
+	device_del(&dibs->dev);
+	return ret;
+
 }
 EXPORT_SYMBOL_GPL(dibs_dev_add);
 
@@ -158,6 +193,10 @@ static int __init dibs_init(void)
 	memset(clients, 0, sizeof(clients));
 	max_client = 0;
 
+	dibs_class = class_create("dibs");
+	if (IS_ERR(&dibs_class))
+		return PTR_ERR(&dibs_class);
+
 	rc = dibs_loopback_init();
 	if (rc)
 		pr_err("%s fails with %d\n", __func__, rc);
@@ -168,6 +207,7 @@ static int __init dibs_init(void)
 static void __exit dibs_exit(void)
 {
 	dibs_loopback_exit();
+	class_destroy(dibs_class);
 }
 
 module_init(dibs_init);
diff --git a/drivers/s390/net/ism_drv.c b/drivers/s390/net/ism_drv.c
index 4096ea9faa7e..ab1d61eb3e3b 100644
--- a/drivers/s390/net/ism_drv.c
+++ b/drivers/s390/net/ism_drv.c
@@ -629,6 +629,7 @@ static void ism_dev_exit(struct ism_dev *ism)
 static int ism_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 {
 	struct dibs_dev *dibs;
+	struct zpci_dev *zdev;
 	struct ism_dev *ism;
 	int ret;
 
@@ -672,7 +673,9 @@ static int ism_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		goto err_dibs;
 
 	dibs->dev.parent = &pdev->dev;
-	dev_set_name(&dibs->dev, "%s", dev_name(&pdev->dev));
+
+	zdev = to_zpci(pdev);
+	dev_set_name(&dibs->dev, "ism%x", zdev->uid ? zdev->uid : zdev->fid);
 
 	ret = dibs_dev_add(dibs);
 	if (ret)