Virtio interface
This attempts to implement a "virtual I/O" layer which should allow
common drivers to be efficiently used across most virtual I/O
mechanisms. It will no-doubt need further enhancement.
The virtio drivers add buffers to virtio queues; as the buffers are consumed
the driver "interrupt" callbacks are invoked.
There is also a generic implementation of config space which drivers can query
to get setup information from the host.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dor Laor <dor.laor@qumranet.com>
Cc: Arnd Bergmann <arnd@arndb.de>
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
new file mode 100644
index 0000000..f640e0b
--- /dev/null
+++ b/drivers/virtio/virtio.c
@@ -0,0 +1,171 @@
+#include <linux/virtio.h>
+#include <linux/spinlock.h>
+#include <linux/virtio_config.h>
+
+static ssize_t device_show(struct device *_d,
+ struct device_attribute *attr, char *buf)
+{
+ struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
+ return sprintf(buf, "%hu", dev->id.device);
+}
+static ssize_t vendor_show(struct device *_d,
+ struct device_attribute *attr, char *buf)
+{
+ struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
+ return sprintf(buf, "%hu", dev->id.vendor);
+}
+static ssize_t status_show(struct device *_d,
+ struct device_attribute *attr, char *buf)
+{
+ struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
+ return sprintf(buf, "0x%08x", dev->config->get_status(dev));
+}
+static struct device_attribute virtio_dev_attrs[] = {
+ __ATTR_RO(device),
+ __ATTR_RO(vendor),
+ __ATTR_RO(status),
+ __ATTR_NULL
+};
+
+static inline int virtio_id_match(const struct virtio_device *dev,
+ const struct virtio_device_id *id)
+{
+ if (id->device != dev->id.device)
+ return 0;
+
+ return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor != dev->id.vendor;
+}
+
+/* This looks through all the IDs a driver claims to support. If any of them
+ * match, we return 1 and the kernel will call virtio_dev_probe(). */
+static int virtio_dev_match(struct device *_dv, struct device_driver *_dr)
+{
+ unsigned int i;
+ struct virtio_device *dev = container_of(_dv,struct virtio_device,dev);
+ const struct virtio_device_id *ids;
+
+ ids = container_of(_dr, struct virtio_driver, driver)->id_table;
+ for (i = 0; ids[i].device; i++)
+ if (virtio_id_match(dev, &ids[i]))
+ return 1;
+ return 0;
+}
+
+static struct bus_type virtio_bus = {
+ .name = "virtio",
+ .match = virtio_dev_match,
+ .dev_attrs = virtio_dev_attrs,
+};
+
+static void add_status(struct virtio_device *dev, unsigned status)
+{
+ dev->config->set_status(dev, dev->config->get_status(dev) | status);
+}
+
+static int virtio_dev_probe(struct device *_d)
+{
+ int err;
+ struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
+ struct virtio_driver *drv = container_of(dev->dev.driver,
+ struct virtio_driver, driver);
+
+ add_status(dev, VIRTIO_CONFIG_S_DRIVER);
+ err = drv->probe(dev);
+ if (err)
+ add_status(dev, VIRTIO_CONFIG_S_FAILED);
+ else
+ add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
+ return err;
+}
+
+int register_virtio_driver(struct virtio_driver *driver)
+{
+ driver->driver.bus = &virtio_bus;
+ driver->driver.probe = virtio_dev_probe;
+ return driver_register(&driver->driver);
+}
+EXPORT_SYMBOL_GPL(register_virtio_driver);
+
+void unregister_virtio_driver(struct virtio_driver *driver)
+{
+ driver_unregister(&driver->driver);
+}
+EXPORT_SYMBOL_GPL(unregister_virtio_driver);
+
+int register_virtio_device(struct virtio_device *dev)
+{
+ int err;
+
+ dev->dev.bus = &virtio_bus;
+ sprintf(dev->dev.bus_id, "%u", dev->index);
+
+ /* Acknowledge that we've seen the device. */
+ add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
+
+ /* device_register() causes the bus infrastructure to look for a
+ * matching driver. */
+ err = device_register(&dev->dev);
+ if (err)
+ add_status(dev, VIRTIO_CONFIG_S_FAILED);
+ return err;
+}
+EXPORT_SYMBOL_GPL(register_virtio_device);
+
+void unregister_virtio_device(struct virtio_device *dev)
+{
+ device_unregister(&dev->dev);
+}
+EXPORT_SYMBOL_GPL(unregister_virtio_device);
+
+int __virtio_config_val(struct virtio_device *vdev,
+ u8 type, void *val, size_t size)
+{
+ void *token;
+ unsigned int len;
+
+ token = vdev->config->find(vdev, type, &len);
+ if (!token)
+ return -ENOENT;
+
+ if (len != size)
+ return -EIO;
+
+ vdev->config->get(vdev, token, val, size);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(__virtio_config_val);
+
+int virtio_use_bit(struct virtio_device *vdev,
+ void *token, unsigned int len, unsigned int bitnum)
+{
+ unsigned long bits[16];
+
+ /* This makes it convenient to pass-through find() results. */
+ if (!token)
+ return 0;
+
+ /* bit not in range of this bitfield? */
+ if (bitnum * 8 >= len / 2)
+ return 0;
+
+ /* Giant feature bitfields are silly. */
+ BUG_ON(len > sizeof(bits));
+ vdev->config->get(vdev, token, bits, len);
+
+ if (!test_bit(bitnum, bits))
+ return 0;
+
+ /* Set acknowledge bit, and write it back. */
+ set_bit(bitnum + len * 8 / 2, bits);
+ vdev->config->set(vdev, token, bits, len);
+ return 1;
+}
+EXPORT_SYMBOL_GPL(virtio_use_bit);
+
+static int virtio_init(void)
+{
+ if (bus_register(&virtio_bus) != 0)
+ panic("virtio bus registration failed");
+ return 0;
+}
+core_initcall(virtio_init);
