[PATCH v3 RESEND] virtio-input: add multi-touch support

[Vasyl Vavrychuk]

From: Mathias Crombez <mathias.crom...@faurecia.com>

Without multi-touch slots allocated, ABS_MT_SLOT events will be lost by
input_handle_abs_event.

Implementation is based on uinput_create_device.

Signed-off-by: Mathias Crombez <mathias.crom...@faurecia.com>
Co-developed-by: Vasyl Vavrychuk <vasyl.vavryc...@opensynergy.com>
Signed-off-by: Vasyl Vavrychuk <vasyl.vavryc...@opensynergy.com>
---
v2: fix patch corrupted by corporate email server
v3: use number of slots from the host

 drivers/virtio/virtio_input.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_input.c b/drivers/virtio/virtio_input.c
index f1f6208edcf5..f643536807dd 100644
--- a/drivers/virtio/virtio_input.c
+++ b/drivers/virtio/virtio_input.c
@@ -7,6 +7,7 @@
 
 #include <uapi/linux/virtio_ids.h>
 #include <uapi/linux/virtio_input.h>
+#include <linux/input/mt.h>
 
 struct virtio_input {
        struct virtio_device       *vdev;
@@ -204,7 +205,7 @@ static int virtinput_probe(struct virtio_device *vdev)
        struct virtio_input *vi;
        unsigned long flags;
        size_t size;
-       int abs, err;
+       int abs, err, nslots;
 
        if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
                return -ENODEV;
@@ -289,6 +290,13 @@ static int virtinput_probe(struct virtio_device *vdev)
                                continue;
                        virtinput_cfg_abs(vi, abs);
                }
+
+               if (test_bit(ABS_MT_SLOT, vi->idev->absbit)) {
+                       nslots = input_abs_get_max(vi->idev, ABS_MT_SLOT) + 1;
+                       err = input_mt_init_slots(vi->idev, nslots, 0);
+                       if (err)
+                               goto err_mt_init_slots;
+               }
        }
 
        virtio_device_ready(vdev);
@@ -304,6 +312,7 @@ static int virtinput_probe(struct virtio_device *vdev)
        spin_lock_irqsave(&vi->lock, flags);
        vi->ready = false;
        spin_unlock_irqrestore(&vi->lock, flags);
+err_mt_init_slots:
        input_free_device(vi->idev);
 err_input_alloc:
        vdev->config->del_vqs(vdev);
-- 
2.23.0