Re: [PATCH 1/1] Add virtio-input driver.

On Thu, Mar 19, 2015 at 01:29:49PM +0100, David Herrmann wrote:

Hi

(CC: Dmitry)

On Thu, Mar 19, 2015 at 10:13 AM, Gerd Hoffmann [off-list ref] wrote:

quoted

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 <redacted>
---
 drivers/virtio/Kconfig            |  10 ++
 drivers/virtio/Makefile           |   1 +
 drivers/virtio/virtio_input.c     | 313 ++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/virtio_ids.h   |   1 +
 include/uapi/linux/virtio_input.h |  65 ++++++++
 5 files changed, 390 insertions(+)
 create mode 100644 drivers/virtio/virtio_input.c
 create mode 100644 include/uapi/linux/virtio_input.h

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..2d425cf
--- /dev/null
+++ b/drivers/virtio/virtio_input.c

@@ -0,0 +1,313 @@
+#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];
+};
+
+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);

What is serial? Serial number?

quoted

+
+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;
+
+       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);
+}
+
+static int virtinput_send_status(struct virtio_input *vi,
+                                u16 type, u16 code, s32 value)
+{
+       struct virtio_input_event *stsbuf;
+       struct scatterlist sg[1];
+
+       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));
+       virtqueue_add_outbuf(vi->sts, sg, 1, stsbuf, GFP_ATOMIC);
+       virtqueue_kick(vi->sts);

GFP_ATOMIC, eww. But everyone does that for input_event() callbacks..
we should fix that for user-space input one day.

quoted

+       return 0;
+}
+
+static void virtinput_recv_status(struct virtqueue *vq)
+{
+       struct virtio_input *vi = vq->vdev->priv;
+       struct virtio_input_event *stsbuf;
+       unsigned int len;
+
+       while ((stsbuf = virtqueue_get_buf(vi->sts, &len)) != NULL)
+               kfree(stsbuf);
+       virtqueue_kick(vq);
+}
+
+static int virtinput_status(struct input_dev *idev, unsigned int type,
+                           unsigned int code, int value)
+{
+       struct virtio_input *vi = input_get_drvdata(idev);
+
+       return virtinput_send_status(vi, type, code, value);
+}
+
+static size_t virtinput_cfg_select(struct virtio_input *vi,
+                                  u8 select, u8 subsel)
+{
+       u8 size;
+
+       virtio_cwrite(vi->vdev, struct virtio_input_config, select, &select);
+       virtio_cwrite(vi->vdev, struct virtio_input_config, subsel, &subsel);
+       virtio_cread(vi->vdev, struct virtio_input_config, size, &size);
+       return size;
+}
+
+static void virtinput_cfg_bits(struct virtio_input *vi, int select, int subsel,
+                              unsigned long *bits, unsigned int bitcount)
+{
+       unsigned int bit;
+       size_t bytes;
+       u8 cfg = 0;
+
+       bytes = virtinput_cfg_select(vi, select, subsel);
+       if (!bytes)
+               return;
+       if (bitcount > bytes*8)
+               bitcount = bytes*8;
+       if (select == VIRTIO_INPUT_CFG_EV_BITS)
+               set_bit(subsel, vi->idev->evbit);
+       for (bit = 0; bit < bitcount; bit++) {
+               if ((bit % 8) == 0)
+                       virtio_cread(vi->vdev, struct virtio_input_config,
+                                    u.bitmap[bit/8], &cfg);
+               if (cfg & (1 << (bit % 8)))
+                       set_bit(bit, bits);
+       }
+}
+
+static void virtinput_cfg_abs(struct virtio_input *vi, int abs)
+{
+       u32 size, mi, ma, fu, fl;
+
+       size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_ABS_INFO, abs);
+       virtio_cread(vi->vdev, struct virtio_input_config, u.abs.min, &mi);
+       virtio_cread(vi->vdev, struct virtio_input_config, u.abs.max, &ma);
+       virtio_cread(vi->vdev, struct virtio_input_config, u.abs.fuzz, &fu);
+       virtio_cread(vi->vdev, struct virtio_input_config, u.abs.flat, &fl);

abs.resolution is missing. Please add it, we really also need to add
it to uinput one day.

quoted

+       input_set_abs_params(vi->idev, abs,
+                            le32_to_cpu(mi), le32_to_cpu(ma),
+                            le32_to_cpu(fu), le32_to_cpu(fl));
+}
+
+static int virtinput_init_vqs(struct virtio_input *vi)
+{
+       struct virtqueue *vqs[2];
+       vq_callback_t *cbs[] = { virtinput_recv_events,
+                                virtinput_recv_status };
+       const char *names[] = { "events", "status" };
+       int i, err, size;
+
+       err = vi->vdev->config->find_vqs(vi->vdev, 2, vqs, cbs, names);
+       if (err)
+               return err;
+       vi->evt = vqs[0];
+       vi->sts = vqs[1];
+
+       size = virtqueue_get_vring_size(vi->evt);
+       if (size > ARRAY_SIZE(vi->evts))
+               size = ARRAY_SIZE(vi->evts);
+       for (i = 0; i < size; i++)
+               virtinput_queue_evtbuf(vi, &vi->evts[i]);
+
+       return 0;
+}
+
+static int virtinput_probe(struct virtio_device *vdev)
+{
+       struct virtio_input *vi;
+       size_t size;
+       int abs, err;
+
+       vi = kzalloc(sizeof(*vi), GFP_KERNEL);
+       if (!vi) {
+               err = -ENOMEM;
+               goto out1;
+       }
+       vdev->priv = vi;
+       vi->vdev = vdev;
+
+       err = virtinput_init_vqs(vi);
+       if (err)
+               goto out2;
+
+       vi->idev = input_allocate_device();
+       if (!vi->idev) {
+               err = -ENOMEM;
+               goto out3;
+       }
+       input_set_drvdata(vi->idev, vi);
+
+       size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_ID_NAME, 0);
+       virtio_cread_bytes(vi->vdev, offsetof(struct virtio_input_config, u),
+                          vi->name, min(size, sizeof(vi->name)));
+       size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_ID_SERIAL, 0);
+       virtio_cread_bytes(vi->vdev, offsetof(struct virtio_input_config, u),
+                          vi->serial, min(size, sizeof(vi->serial)));
+       snprintf(vi->phys, sizeof(vi->phys),
+                "virtio%d/input0", vdev->index);
+
+       virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_PROP_BITS, 0,
+                          vi->idev->propbit, INPUT_PROP_CNT);
+       size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_REP);
+       if (size)
+               set_bit(EV_REP, vi->idev->evbit);
+
+       vi->idev->name = vi->name;
+       vi->idev->phys = vi->phys;

Can you set vi->idev->uniq to the virtio-bus path?

No, uniq can't be phys as phys is unique within the system while uniq is
like serial number or UUID and should never repeat.

Thanks.

-- 
Dmitry