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Subject: Re: [PATCH v4] Add virtio-input driver.
On Tue, Mar 24, 2015 at 01:08:46PM +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@redhat.com>
Looks good overallm though I think I still see a couple of minor issues.
> ---
> MAINTAINERS | 6 +
> drivers/virtio/Kconfig | 10 ++
> drivers/virtio/Makefile | 1 +
> drivers/virtio/virtio_input.c | 363 ++++++++++++++++++++++++++++++++++++++
> include/uapi/linux/Kbuild | 1 +
> include/uapi/linux/virtio_ids.h | 1 +
> include/uapi/linux/virtio_input.h | 76 ++++++++
> 7 files changed, 458 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 358eb01..6f233dd 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -10442,6 +10442,12 @@ 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..fc99a15
> --- /dev/null
> +++ b/drivers/virtio/virtio_input.c
> @@ -0,0 +1,363 @@
> +#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];
> + spinlock_t lock;
> + bool ready;
> +};
> +
> +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 long flags;
> + unsigned int len;
> +
> + spin_lock_irqsave(&vi->lock, flags);
> + if (vi->ready) {
> + 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);
> + }
> + spin_unlock_irqrestore(&vi->lock, flags);
> +}
> +
> +static int virtinput_send_status(struct virtio_input *vi,
> + u16 type, u16 code, s32 value)
> +{
> + struct virtio_input_event *stsbuf;
> + struct scatterlist sg[1];
> + unsigned long flags;
> + 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));
> +
> + spin_lock_irqsave(&vi->lock, flags);
> + if (vi->ready) {
> + rc = virtqueue_add_outbuf(vi->sts, sg, 1, stsbuf, GFP_ATOMIC);
> + virtqueue_kick(vi->sts);
> + } else {
> + rc = -ENODEV;
> + }
> + spin_unlock_irqrestore(&vi->lock, flags);
> +
> + 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 long flags;
> + unsigned int len;
> +
> + spin_lock_irqsave(&vi->lock, flags);
> + while ((stsbuf = virtqueue_get_buf(vi->sts, &len)) != NULL)
> + kfree(stsbuf);
> + spin_unlock_irqrestore(&vi->lock, flags);
> +}
> +
> +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 *virtio_bits;
> +
> + bytes = virtinput_cfg_select(vi, select, subsel);
> + if (!bytes)
> + return;
> + if (bitcount > bytes * 8)
> + bitcount = bytes * 8;
> +
> + /*
> + * Bitmap in virtio config space is a simple stream of bytes,
> + * with the first byte carrying bits 0-7, second bits 8-15 and
> + * so on.
> + */
> + virtio_bits = kzalloc(bytes, GFP_KERNEL);
> + if (!virtio_bits)
> + return;
> + virtio_cread_bytes(vi->vdev, offsetof(struct virtio_input_config,
> + u.bitmap),
> + virtio_bits, bytes);
> + for (bit = 0; bit < bitcount; bit++) {
> + if (virtio_bits[bit / 8] & (1 << (bit % 8)))
> + __set_bit(bit, bits);
> + }
> + kfree(virtio_bits);
> +
> + if (select == VIRTIO_INPUT_CFG_EV_BITS)
> + __set_bit(subsel, vi->idev->evbit);
> +}
> +
> +static void virtinput_cfg_abs(struct virtio_input *vi, int abs)
> +{
> + u32 mi, ma, re, fu, fl;
> +
> + 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.res, &re);
> + virtio_cread(vi->vdev, struct virtio_input_config, u.abs.fuzz, &fu);
> + virtio_cread(vi->vdev, struct virtio_input_config, u.abs.flat, &fl);
> + input_set_abs_params(vi->idev, abs, mi, ma, fu, fl);
> + input_abs_set_res(vi->idev, abs, re);
> +}
> +
> +static int virtinput_init_vqs(struct virtio_input *vi)
> +{
> + struct virtqueue *vqs[2];
> + vq_callback_t *cbs[] = { virtinput_recv_events,
> + virtinput_recv_status };
> + static const char *names[] = { "events", "status" };
> + int err;
> +
> + err = vi->vdev->config->find_vqs(vi->vdev, 2, vqs, cbs, names);
> + if (err)
> + return err;
> + vi->evt = vqs[0];
> + vi->sts = vqs[1];
> +
> + return 0;
> +}
> +
> +static void virtinput_fill_evt(struct virtio_input *vi)
> +{
> + unsigned long flags;
> + int i, size;
> +
> + spin_lock_irqsave(&vi->lock, flags);
> + 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]);
> + virtqueue_kick(vi->evt);
> + spin_unlock_irqrestore(&vi->lock, flags);
> +}
> +
> +static int virtinput_probe(struct virtio_device *vdev)
> +{
> + struct virtio_input *vi;
> + size_t size;
> + int abs, err;
> +
> + if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
> + return -ENODEV;
> +
> + vi = kzalloc(sizeof(*vi), GFP_KERNEL);
> + if (!vi)
> + return -ENOMEM;
> +
> + vdev->priv = vi;
> + vi->vdev = vdev;
> + spin_lock_init(&vi->lock);
> +
> + err = virtinput_init_vqs(vi);
> + if (err)
> + goto err_init_vq;
> +
> + vi->idev = input_allocate_device();
> + if (!vi->idev) {
> + err = -ENOMEM;
> + goto err_input_alloc;
> + }
> + 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.string),
> + 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.string),
> + vi->serial, min(size, sizeof(vi->serial)));
> + snprintf(vi->phys, sizeof(vi->phys),
> + "virtio%d/input0", vdev->index);
> + vi->idev->name = vi->name;
> + vi->idev->phys = vi->phys;
> + vi->idev->uniq = vi->serial;
> +
> + size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_ID_DEVIDS, 0);
> + if (size >= sizeof(struct virtio_input_devids)) {
> + virtio_cread(vi->vdev, struct virtio_input_config,
> + u.ids.bustype, &vi->idev->id.bustype);
> + virtio_cread(vi->vdev, struct virtio_input_config,
> + u.ids.vendor, &vi->idev->id.vendor);
> + virtio_cread(vi->vdev, struct virtio_input_config,
> + u.ids.product, &vi->idev->id.product);
> + virtio_cread(vi->vdev, struct virtio_input_config,
> + u.ids.version, &vi->idev->id.version);
> + } else {
> + vi->idev->id.bustype = BUS_VIRTUAL;
> + }
> +
> + 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->dev.parent = &vdev->dev;
> + vi->idev->event = virtinput_status;
> +
> + /* device -> kernel */
> + virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_KEY,
> + vi->idev->keybit, KEY_CNT);
> + virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_REL,
> + vi->idev->relbit, REL_CNT);
> + virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_ABS,
> + vi->idev->absbit, ABS_CNT);
> + virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_MSC,
> + vi->idev->mscbit, MSC_CNT);
> + virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_SW,
> + vi->idev->swbit, SW_CNT);
> +
> + /* kernel -> device */
> + virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_LED,
> + vi->idev->ledbit, LED_CNT);
> + virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_SND,
> + vi->idev->sndbit, SND_CNT);
> +
> + if (test_bit(EV_ABS, vi->idev->evbit)) {
> + for (abs = 0; abs < ABS_CNT; abs++) {
> + if (!test_bit(abs, vi->idev->absbit))
> + continue;
> + virtinput_cfg_abs(vi, abs);
> + }
> + }
> + err = input_register_device(vi->idev);
> + if (err)
> + goto err_input_register;
vi->ready is false here so you might lose status updates.
Losing updates isn't too terrible, but seems easy to fix:
virtio_device_ready(vdev);
vi->ready = true;
err = input_register_device(vi->idev);
...
err_input_register:
vi->ready = false;
it's up to you whether to do this.
> +
> + virtio_device_ready(vdev);
> + vi->ready = true;
> + virtinput_fill_evt(vi);
> + return 0;
> +
> +err_input_register:
> + input_free_device(vi->idev);
> +err_input_alloc:
> + vdev->config->del_vqs(vdev);
> +err_init_vq:
> + kfree(vi);
> + return err;
> +}
> +
> +static void virtinput_remove(struct virtio_device *vdev)
> +{
> + struct virtio_input *vi = vdev->priv;
> +
> + vi->ready = false;
This one needs to be done under a lock, otherwise
we can't be sure no callbacks are running here.
> + input_unregister_device(vi->idev);
> + vdev->config->del_vqs(vdev);
> + kfree(vi);
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int virtinput_freeze(struct virtio_device *vdev)
> +{
> + struct virtio_input *vi = vdev->priv;
> +
> + vi->ready = false;
Same here I think.
> + vdev->config->del_vqs(vdev);
> + return 0;
> +}
> +
> +static int virtinput_restore(struct virtio_device *vdev)
> +{
> + struct virtio_input *vi = vdev->priv;
> + int err;
> +
> + err = virtinput_init_vqs(vi);
> + if (err)
> + return err;
> +
> + virtio_device_ready(vdev);
> + vi->ready = true;
> + virtinput_fill_evt(vi);
> + return 0;
> +}
> +#endif
> +
> +static unsigned int features[] = {
> +};
an emoty line won't hurt here.
> +static struct virtio_device_id id_table[] = {
> + { VIRTIO_ID_INPUT, VIRTIO_DEV_ANY_ID },
> + { 0 },
> +};
> +
> +static struct virtio_driver virtio_input_driver = {
> + .driver.name = KBUILD_MODNAME,
> + .driver.owner = THIS_MODULE,
> + .feature_table = features,
> + .feature_table_size = ARRAY_SIZE(features),
> + .id_table = id_table,
> + .probe = virtinput_probe,
> + .remove = virtinput_remove,
> +#ifdef CONFIG_PM_SLEEP
> + .freeze = virtinput_freeze,
> + .restore = virtinput_restore,
> +#endif
> +};
> +
> +module_virtio_driver(virtio_input_driver);
> +MODULE_DEVICE_TABLE(virtio, id_table);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Virtio input device driver");
> +MODULE_AUTHOR("Gerd Hoffmann <kraxel@redhat.com>");
> diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
> index 68ceb97..04b829e 100644
> --- a/include/uapi/linux/Kbuild
> +++ b/include/uapi/linux/Kbuild
> @@ -430,6 +430,7 @@ header-y += virtio_blk.h
> header-y += virtio_config.h
> header-y += virtio_console.h
> header-y += virtio_ids.h
> +header-y += virtio_input.h
> header-y += virtio_net.h
> header-y += virtio_pci.h
> header-y += virtio_ring.h
> diff --git a/include/uapi/linux/virtio_ids.h b/include/uapi/linux/virtio_ids.h
> index 284fc3a..5f60aa4 100644
> --- a/include/uapi/linux/virtio_ids.h
> +++ b/include/uapi/linux/virtio_ids.h
> @@ -39,5 +39,6 @@
> #define VIRTIO_ID_9P 9 /* 9p virtio console */
> #define VIRTIO_ID_RPROC_SERIAL 11 /* virtio remoteproc serial link */
> #define VIRTIO_ID_CAIF 12 /* Virtio caif */
> +#define VIRTIO_ID_INPUT 18 /* virtio input */
>
> #endif /* _LINUX_VIRTIO_IDS_H */
> diff --git a/include/uapi/linux/virtio_input.h b/include/uapi/linux/virtio_input.h
> new file mode 100644
> index 0000000..dc61b28
> --- /dev/null
> +++ b/include/uapi/linux/virtio_input.h
> @@ -0,0 +1,76 @@
> +#ifndef _LINUX_VIRTIO_INPUT_H
> +#define _LINUX_VIRTIO_INPUT_H
> +/* This header is BSD licensed so anyone can use the definitions to implement
> + * compatible drivers/servers.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions
> + * are met:
> + * 1. Redistributions of source code must retain the above copyright
> + * notice, this list of conditions and the following disclaimer.
> + * 2. Redistributions in binary form must reproduce the above copyright
> + * notice, this list of conditions and the following disclaimer in the
> + * documentation and/or other materials provided with the distribution.
> + * 3. Neither the name of IBM nor the names of its contributors
> + * may be used to endorse or promote products derived from this software
> + * without specific prior written permission.
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> + * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
> + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
> + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL IBM OR
> + * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
> + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
> + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
> + * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
> + * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
> + * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
> + * SUCH DAMAGE. */
You must include linux/types.h for __le types I think.
> +#include <linux/virtio_ids.h>
This one is there in all other headers, so ok,
though I don't know why.
> +#include <linux/virtio_config.h>
I'm sure you don't need this one.
> +
> +enum virtio_input_config_select {
> + VIRTIO_INPUT_CFG_UNSET = 0x00,
> + VIRTIO_INPUT_CFG_ID_NAME = 0x01,
> + VIRTIO_INPUT_CFG_ID_SERIAL = 0x02,
> + VIRTIO_INPUT_CFG_ID_DEVIDS = 0x03,
> + VIRTIO_INPUT_CFG_PROP_BITS = 0x10,
> + VIRTIO_INPUT_CFG_EV_BITS = 0x11,
> + VIRTIO_INPUT_CFG_ABS_INFO = 0x12,
> +};
> +
> +struct virtio_input_absinfo {
> + __u32 min;
> + __u32 max;
> + __u32 fuzz;
> + __u32 flat;
> + __u32 res;
> +};
> +
> +struct virtio_input_devids {
> + __u16 bustype;
> + __u16 vendor;
> + __u16 product;
> + __u16 version;
> +};
> +
> +struct virtio_input_config {
> + __u8 select;
> + __u8 subsel;
> + __u8 size;
> + __u8 reserved;
Thinking more about it, might it be better to make
this reserved[5] so the union is 8 byte aligned?
Will be helpful if you later want a 64 bit field in the union.
> + union {
> + char string[128];
> + __u8 bitmap[128];
> + struct virtio_input_absinfo abs;
> + struct virtio_input_devids ids;
> + } u;
> +};
> +
> +struct virtio_input_event {
> + __le16 type;
> + __le16 code;
> + __le32 value;
> +};
> +
> +#endif /* _LINUX_VIRTIO_INPUT_H */
> --
> 1.8.3.1
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