staging: unisys: add visorbus driver

This base driver provides bus functionality to visorhid, visorhba,
and visornic which will be later added to our driver base. Visorbus
supports sPar bus model and manages bus specific functionality. It
maintains the sysfs subtree /sys/devices/visorbus*/.It is
responsible for device creation and destruction of the devices on
its bus.

Signed-off-by: Erik Arfvidson <erik.arfvidson@unisys.com>
Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 192 insertions, 0 deletions

diff --git a/drivers/staging/unisys/visorbus/devmajorminor_attr.c b/drivers/staging/unisys/visorbus/devmajorminor_attr.c
new file mode 100644
index 0000000..ceb4bb7
--- /dev/null
+++ b/drivers/staging/unisys/visorbus/devmajorminor_attr.c
@@ -0,0 +1,192 @@
+/* devmajorminor_attr.c
+ *
+ * Copyright (C) 2010 - 2013 UNISYS CORPORATION
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ */
+
+/* Implement publishing of device node attributes under:
+ *
+ *     /sys/bus/visorbus<x>/dev<y>/devmajorminor
+ *
+ */
+
+#include "devmajorminor_attr.h"
+#define CURRENT_FILE_PC VISOR_BUS_PC_devmajorminor_attr_c
+
+#define to_devmajorminor_attr(_attr) \
+	container_of(_attr, struct devmajorminor_attribute, attr)
+#define to_visor_device_from_kobjdevmajorminor(obj) \
+	container_of(obj, struct visor_device, kobjdevmajorminor)
+
+struct devmajorminor_attribute {
+	struct attribute attr;
+	int slot;
+	 ssize_t (*show)(struct visor_device *, int slot, char *buf);
+	 ssize_t (*store)(struct visor_device *, int slot, const char *buf,
+			  size_t count);
+};
+
+static ssize_t DEVMAJORMINOR_ATTR(struct visor_device *dev, int slot, char *buf)
+{
+	int maxdevnodes = ARRAY_SIZE(dev->devnodes) / sizeof(dev->devnodes[0]);
+
+	if (slot < 0 || slot >= maxdevnodes)
+		return 0;
+	return snprintf(buf, PAGE_SIZE, "%d:%d\n",
+			dev->devnodes[slot].major, dev->devnodes[slot].minor);
+}
+
+static ssize_t
+devmajorminor_attr_show(struct kobject *kobj, struct attribute *attr, char *buf)
+{
+	struct devmajorminor_attribute *devmajorminor_attr =
+	    to_devmajorminor_attr(attr);
+	struct visor_device *dev = to_visor_device_from_kobjdevmajorminor(kobj);
+	ssize_t ret = 0;
+
+	if (devmajorminor_attr->show)
+		ret = devmajorminor_attr->show(dev,
+					       devmajorminor_attr->slot, buf);
+	return ret;
+}
+
+static ssize_t
+devmajorminor_attr_store(struct kobject *kobj,
+			 struct attribute *attr, const char *buf, size_t count)
+{
+	struct devmajorminor_attribute *devmajorminor_attr =
+	    to_devmajorminor_attr(attr);
+	struct visor_device *dev = to_visor_device_from_kobjdevmajorminor(kobj);
+	ssize_t ret = 0;
+
+	if (devmajorminor_attr->store)
+		ret = devmajorminor_attr->store(dev,
+						devmajorminor_attr->slot,
+						buf, count);
+	return ret;
+}
+
+int
+devmajorminor_create_file(struct visor_device *dev, const char *name,
+			  int major, int minor)
+{
+	int maxdevnodes = ARRAY_SIZE(dev->devnodes) / sizeof(dev->devnodes[0]);
+	struct devmajorminor_attribute *myattr = NULL;
+	int x = -1, rc = 0, slot = -1;
+
+	register_devmajorminor_attributes(dev);
+	for (slot = 0; slot < maxdevnodes; slot++)
+		if (!dev->devnodes[slot].attr)
+			break;
+	if (slot == maxdevnodes) {
+		rc = -ENOMEM;
+		goto away;
+	}
+	myattr = kmalloc(sizeof(*myattr), GFP_KERNEL);
+	if (!myattr) {
+		rc = -ENOMEM;
+		goto away;
+	}
+	memset(myattr, 0, sizeof(struct devmajorminor_attribute));
+	myattr->show = DEVMAJORMINOR_ATTR;
+	myattr->store = NULL;
+	myattr->slot = slot;
+	myattr->attr.name = name;
+	myattr->attr.mode = S_IRUGO;
+	dev->devnodes[slot].attr = myattr;
+	dev->devnodes[slot].major = major;
+	dev->devnodes[slot].minor = minor;
+	x = sysfs_create_file(&dev->kobjdevmajorminor, &myattr->attr);
+	if (x < 0) {
+		rc = x;
+		goto away;
+	}
+	kobject_uevent(&dev->device.kobj, KOBJ_ONLINE);
+away:
+	if (rc < 0) {
+		kfree(myattr);
+		myattr = NULL;
+		dev->devnodes[slot].attr = NULL;
+	}
+	return rc;
+}
+
+void
+devmajorminor_remove_file(struct visor_device *dev, int slot)
+{
+	int maxdevnodes = ARRAY_SIZE(dev->devnodes) / sizeof(dev->devnodes[0]);
+	struct devmajorminor_attribute *myattr = NULL;
+
+	if (slot < 0 || slot >= maxdevnodes)
+		return;
+	myattr = (struct devmajorminor_attribute *)(dev->devnodes[slot].attr);
+	if (myattr)
+		return;
+	sysfs_remove_file(&dev->kobjdevmajorminor, &myattr->attr);
+	kobject_uevent(&dev->device.kobj, KOBJ_OFFLINE);
+	dev->devnodes[slot].attr = NULL;
+	kfree(myattr);
+}
+
+void
+devmajorminor_remove_all_files(struct visor_device *dev)
+{
+	int i = 0;
+	int maxdevnodes = ARRAY_SIZE(dev->devnodes) / sizeof(dev->devnodes[0]);
+
+	for (i = 0; i < maxdevnodes; i++)
+		devmajorminor_remove_file(dev, i);
+}
+
+static const struct sysfs_ops devmajorminor_sysfs_ops = {
+	.show = devmajorminor_attr_show,
+	.store = devmajorminor_attr_store,
+};
+
+static struct kobj_type devmajorminor_kobj_type = {
+	.sysfs_ops = &devmajorminor_sysfs_ops
+};
+
+int
+register_devmajorminor_attributes(struct visor_device *dev)
+{
+	int rc = 0, x = 0;
+
+	if (dev->kobjdevmajorminor.parent)
+		goto away;	/* already registered */
+	x = kobject_init_and_add(&dev->kobjdevmajorminor,
+				 &devmajorminor_kobj_type, &dev->device.kobj,
+				 "devmajorminor");
+	if (x < 0) {
+		rc = x;
+		goto away;
+	}
+
+	kobject_uevent(&dev->kobjdevmajorminor, KOBJ_ADD);
+
+away:
+	return rc;
+}
+
+void
+unregister_devmajorminor_attributes(struct visor_device *dev)
+{
+	if (!dev->kobjdevmajorminor.parent)
+		return;		/* already unregistered */
+	devmajorminor_remove_all_files(dev);
+
+	kobject_del(&dev->kobjdevmajorminor);
+	kobject_put(&dev->kobjdevmajorminor);
+	dev->kobjdevmajorminor.parent = NULL;
+}