Re: [PATCH v2] Add virtio-input driver.

virtio-input is basically evdev-events-over-virtio, so this driver isn't
much more than reading configuration from config space and forwarding
incoming events to the linux input layer.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 MAINTAINERS                       |   6 +
 drivers/virtio/Kconfig            |  10 ++
 drivers/virtio/Makefile           |   1 +
 drivers/virtio/virtio_input.c     | 335 ++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/Kbuild         |   1 +
 include/uapi/linux/virtio_ids.h   |   1 +
 include/uapi/linux/virtio_input.h |  75 +++++++++
 7 files changed, 429 insertions(+)
 create mode 100644 drivers/virtio/virtio_input.c
 create mode 100644 include/uapi/linux/virtio_input.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 0e1abe8..585e6cd 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS

@@ -10435,6 +10435,12 @@ S:	Maintained
 F:	drivers/vhost/
 F:	include/uapi/linux/vhost.h
 
+VIRTIO INPUT DRIVER
+M:	Gerd Hoffmann <kraxel@redhat.com>
+S:	Maintained
+F:	drivers/virtio/virtio_input.c
+F:	include/uapi/linux/virtio_input.h
+
 VIA RHINE NETWORK DRIVER
 M:	Roger Luethi <rl@hellgate.ch>
 S:	Maintained

diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index b546da5..cab9f3f 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig

@@ -48,6 +48,16 @@ config VIRTIO_BALLOON
 
 	 If unsure, say M.
 
+config VIRTIO_INPUT
+	tristate "Virtio input driver"
+	depends on VIRTIO
+	depends on INPUT
+	---help---
+	 This driver supports virtio input devices such as
+	 keyboards, mice and tablets.
+
+	 If unsure, say M.
+
  config VIRTIO_MMIO
 	tristate "Platform bus driver for memory mapped virtio devices"
 	depends on HAS_IOMEM

diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
index d85565b..41e30e3 100644
--- a/drivers/virtio/Makefile
+++ b/drivers/virtio/Makefile

@@ -4,3 +4,4 @@ obj-$(CONFIG_VIRTIO_PCI) += virtio_pci.o
 virtio_pci-y := virtio_pci_modern.o virtio_pci_common.o
 virtio_pci-$(CONFIG_VIRTIO_PCI_LEGACY) += virtio_pci_legacy.o
 obj-$(CONFIG_VIRTIO_BALLOON) += virtio_balloon.o
+obj-$(CONFIG_VIRTIO_INPUT) += virtio_input.o

diff --git a/drivers/virtio/virtio_input.c b/drivers/virtio/virtio_input.c
new file mode 100644
index 0000000..dd3215e
--- /dev/null
+++ b/drivers/virtio/virtio_input.c

@@ -0,0 +1,335 @@
+#include <linux/module.h>
+#include <linux/virtio.h>
+#include <linux/input.h>
+
+#include <uapi/linux/virtio_ids.h>
+#include <uapi/linux/virtio_input.h>
+
+struct virtio_input {
+	struct virtio_device       *vdev;
+	struct input_dev           *idev;
+	char                       name[64];
+	char                       serial[64];
+	char                       phys[64];
+	struct virtqueue           *evt, *sts;
+	struct virtio_input_event  evts[64];
+	struct mutex               lock;
+};
+
+static ssize_t serial_show(struct device *dev,
+			   struct device_attribute *attr, char *buf)
+{
+	struct input_dev *idev = to_input_dev(dev);
+	struct virtio_input *vi = input_get_drvdata(idev);
+
+	return sprintf(buf, "%s\n", vi->serial);
+}
+static DEVICE_ATTR_RO(serial);
+
+static struct attribute *dev_attrs[] = {
+	&dev_attr_serial.attr,
+	NULL
+};
+
+static umode_t dev_attrs_are_visible(struct kobject *kobj,
+				     struct attribute *a, int n)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct input_dev *idev = to_input_dev(dev);
+	struct virtio_input *vi = input_get_drvdata(idev);
+
+	if (a == &dev_attr_serial.attr && !strlen(vi->serial))
+		return 0;
+
+	return a->mode;
+}
+
+static struct attribute_group dev_attr_grp = {
+	.attrs =	dev_attrs,
+	.is_visible =	dev_attrs_are_visible,
+};
+
+static const struct attribute_group *dev_attr_groups[] = {
+	&dev_attr_grp,
+	NULL
+};
+
+static void virtinput_queue_evtbuf(struct virtio_input *vi,
+				   struct virtio_input_event *evtbuf)
+{
+	struct scatterlist sg[1];
+
+	sg_init_one(sg, evtbuf, sizeof(*evtbuf));
+	virtqueue_add_inbuf(vi->evt, sg, 1, evtbuf, GFP_ATOMIC);
+}
+
+static void virtinput_recv_events(struct virtqueue *vq)
+{
+	struct virtio_input *vi = vq->vdev->priv;
+	struct virtio_input_event *event;
+	unsigned int len;
+
+	mutex_lock(&vi->lock);
+	while ((event = virtqueue_get_buf(vi->evt, &len)) != NULL) {
+		input_event(vi->idev,
+			    le16_to_cpu(event->type),
+			    le16_to_cpu(event->code),
+			    le32_to_cpu(event->value));
+		virtinput_queue_evtbuf(vi, event);
+	}
+	virtqueue_kick(vq);
+	mutex_unlock(&vi->lock);
+}
+
+static int virtinput_send_status(struct virtio_input *vi,
+				 u16 type, u16 code, s32 value)
+{
+	struct virtio_input_event *stsbuf;
+	struct scatterlist sg[1];
+	int rc;
+
+	stsbuf = kzalloc(sizeof(*stsbuf), GFP_ATOMIC);
+	if (!stsbuf)
+		return -ENOMEM;
+
+	stsbuf->type  = cpu_to_le16(type);
+	stsbuf->code  = cpu_to_le16(code);
+	stsbuf->value = cpu_to_le32(value);
+	sg_init_one(sg, stsbuf, sizeof(*stsbuf));
+
+	mutex_lock(&vi->lock);
+	rc = virtqueue_add_outbuf(vi->sts, sg, 1, stsbuf, GFP_ATOMIC);
+	virtqueue_kick(vi->sts);
+	mutex_unlock(&vi->lock);
+
+	if (rc != 0)
+		kfree(stsbuf);
+	return rc;
+}
+
+static void virtinput_recv_status(struct virtqueue *vq)
+{
+	struct virtio_input *vi = vq->vdev->priv;
+	struct virtio_input_event *stsbuf;
+	unsigned int len;
+
+	mutex_lock(&vi->lock);
+	while ((stsbuf = virtqueue_get_buf(vi->sts, &len)) != NULL)
+		kfree(stsbuf);
+	mutex_unlock(&vi->lock);
+}
+