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Date: Sat, 21 Mar 2015 23:23:08 +0100
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Gerd Hoffmann <kraxel@...hat.com>
Cc: virtio-dev@...ts.oasis-open.org,
virtualization@...ts.linux-foundation.org,
David Herrmann <dh.herrmann@...il.com>,
Dmitry Torokhov <dmitry.torokhov@...il.com>,
Rusty Russell <rusty@...tcorp.com.au>,
open list <linux-kernel@...r.kernel.org>,
"open list:ABI/API" <linux-api@...r.kernel.org>
Subject: Re: [PATCH v2] Add virtio-input driver.
On Fri, Mar 20, 2015 at 01:39:29PM +0100, Gerd Hoffmann wrote:
> 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@...hat.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@...hat.com>
> +S: Maintained
> +F: drivers/virtio/virtio_input.c
> +F: include/uapi/linux/virtio_input.h
> +
> VIA RHINE NETWORK DRIVER
> M: Roger Luethi <rl@...lgate.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);
> +}
> +
You can't take a mutex in an interrupt callback.
since you do everything with GFP_ATOMIC, I would say
just switch lock to a spinlock.
You can virtqueue_kick if contention becomes a problem.
Sent more comments on v1.
--
MST
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