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SubjectRE: [PATCH 02/02] virtio: Add virtio platform driver
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What purpose this virtio platform driver serves? Are you trying to make driver layers here and each virtio device driver can hook up into this platform driver. Is that correct ?

Thanks
-Bharat


> -----Original Message-----
> From: virtualization-bounces@lists.linux-foundation.org
> [mailto:virtualization-bounces@lists.linux-foundation.org] On Behalf Of
> Magnus Damm
> Sent: Tuesday, June 21, 2011 3:56 PM
> To: linux-kernel@vger.kernel.org
> Cc: vapier@gentoo.org; mst@redhat.com; linux-sh@vger.kernel.org; Magnus
> Damm; virtualization@lists.linux-foundation.org
> Subject: [PATCH 02/02] virtio: Add virtio platform driver
>
> From: Magnus Damm <damm@opensource.se>
>
> This patch adds a virtio platform driver. The code is based on the lguest
> implementation available in drivers/lguest/lguest_device.c
>
> The iomem resource is used to point out the lguest device descriptor, and
> the platform data contains two separate callbacks for notification.
>
> Signed-off-by: Magnus Damm <damm@opensource.se>
> ---
>
> drivers/virtio/Kconfig | 11 +
> drivers/virtio/Makefile | 1
> drivers/virtio/virtio_platform.c | 282
> ++++++++++++++++++++++++++++++++++++++
> include/linux/virtio_platform.h | 12 +
> 4 files changed, 306 insertions(+)
>
> --- 0002/drivers/virtio/Kconfig
> +++ work/drivers/virtio/Kconfig 2011-03-03 15:56:53.000000000 +0900
> @@ -35,3 +35,14 @@ config VIRTIO_BALLOON
>
> config VIRTIO_LGUEST
> tristate
> +
> +config VIRTIO_PLATFORM
> + tristate "Platform driver for virtio devices (EXPERIMENTAL)"
> + select VIRTIO
> + select VIRTIO_RING
> + select VIRTIO_LGUEST
> + ---help---
> + This drivers provides support for virtio based paravirtual device
> + drivers over a platform bus.
> +
> + If unsure, say N.
> --- 0002/drivers/virtio/Makefile
> +++ work/drivers/virtio/Makefile 2011-03-03 15:56:53.000000000 +0900
> @@ -3,3 +3,4 @@ obj-$(CONFIG_VIRTIO_RING) += virtio_ring
> obj-$(CONFIG_VIRTIO_PCI) += virtio_pci.o
> obj-$(CONFIG_VIRTIO_BALLOON) += virtio_balloon.o
> obj-$(CONFIG_VIRTIO_LGUEST) += virtio_lguest.o
> +obj-$(CONFIG_VIRTIO_PLATFORM) += virtio_platform.o
> --- /dev/null
> +++ work/drivers/virtio/virtio_platform.c 2011-03-03 16:07:31.000000000
> +0900
> @@ -0,0 +1,282 @@
> +#include <linux/init.h>
> +#include <linux/virtio.h>
> +#include <linux/virtio_config.h>
> +#include <linux/virtio_ring.h>
> +#include <linux/lguest_device.h>
> +#include <linux/lguest_launcher.h>
> +#include <linux/virtio_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/interrupt.h>
> +#include <linux/err.h>
> +#include <linux/slab.h>
> +#include <linux/io.h>
> +
> +static void __iomem *virtio_map(unsigned long phys_addr, unsigned long
> +pages) {
> + return ioremap_nocache(phys_addr, PAGE_SIZE*pages); }
> +
> +static void virtio_unmap(void __iomem *addr) {
> + iounmap(addr);
> +}
> +
> +static void set_status(struct virtio_device *vdev, u8 status) {
> + struct platform_device *pdev = to_platform_device(vdev-
> >dev.parent);
> + struct virtio_platform_data *pdata = pdev->dev.platform_data;
> +
> + to_lgdev(vdev)->desc->status = status;
> + pdata->notify_virtio(pdev);
> +}
> +
> +static void lg_set_status(struct virtio_device *vdev, u8 status) {
> + BUG_ON(!status);
> + set_status(vdev, status);
> +}
> +
> +static void lg_reset(struct virtio_device *vdev) {
> + set_status(vdev, 0);
> +}
> +
> +/*
> + * Virtqueues
> + *
> + * The other piece of infrastructure virtio needs is a "virtqueue": a
> +way of
> + * the Guest device registering buffers for the other side to read from
> +or
> + * write into (ie. send and receive buffers). Each device can have
> +multiple
> + * virtqueues: for example the console driver uses one queue for
> +sending and
> + * another for receiving.
> + *
> + * Fortunately for us, a very fast shared-memory-plus-descriptors
> +virtqueue
> + * already exists in virtio_ring.c. We just need to connect it up.
> + *
> + * We start with the information we need to keep about each virtqueue.
> + */
> +
> +/*D:140 This is the information we remember about each virtqueue. */
> +struct lguest_vq_info {
> + /* A copy of the information contained in the device config. */
> + struct lguest_vqconfig config;
> +
> + /* The address where we mapped the virtio ring, so we can unmap it.
> */
> + void __iomem *pages;
> +};
> +
> +/*
> + * When the virtio_ring code wants to prod the Host, it calls us here
> +and we
> + * call the board specific callback. We hand a pointer to the
> +configuration
> + * so the board code knows which virtqueue we're talking about.
> + */
> +static void lg_notify(struct virtqueue *vq) {
> + struct platform_device *pdev = to_platform_device(vq->vdev-
> >dev.parent);
> + struct virtio_platform_data *pdata = pdev->dev.platform_data;
> + struct lguest_vq_info *lvq = vq->priv;
> +
> + pdata->notify_virtqueue(pdev, &lvq->config); }
> +
> +/*
> + * This routine finds the Nth virtqueue described in the configuration
> +of
> + * this device and sets it up.
> + *
> + * This is kind of an ugly duckling. It'd be nicer to have a standard
> + * representation of a virtqueue in the configuration space, but it
> +seems that
> + * everyone wants to do it differently. The KVM coders want the Guest
> +to
> + * allocate its own pages and tell the Host where they are, but for
> +lguest it's
> + * simpler for the Host to simply tell us where the pages are.
> + */
> +static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
> + unsigned index,
> + void (*callback)(struct virtqueue *vq),
> + const char *name)
> +{
> + struct lguest_device *ldev = to_lgdev(vdev);
> + struct lguest_vq_info *lvq;
> + struct virtqueue *vq;
> + int err;
> +
> + /* We must have this many virtqueues. */
> + if (index >= ldev->desc->num_vq)
> + return ERR_PTR(-ENOENT);
> +
> + lvq = kmalloc(sizeof(*lvq), GFP_KERNEL);
> + if (!lvq)
> + return ERR_PTR(-ENOMEM);
> +
> + /*
> + * Make a copy of the "struct lguest_vqconfig" entry, which sits
> after
> + * the descriptor. We need a copy because the config space might
> not
> + * be aligned correctly.
> + */
> + memcpy(&lvq->config, lg_vq(ldev->desc)+index, sizeof(lvq->config));
> +
> + dev_info(&vdev->dev, "Mapping virtqueue %i addr %lx\n", index,
> + (unsigned long)lvq->config.pfn << PAGE_SHIFT);
> + /* Figure out how many pages the ring will take, and map that
> memory */
> + lvq->pages = virtio_map((unsigned long)lvq->config.pfn <<
> PAGE_SHIFT,
> + DIV_ROUND_UP(vring_size(lvq->config.num,
> + LGUEST_VRING_ALIGN),
> + PAGE_SIZE));
> + if (!lvq->pages) {
> + err = -ENOMEM;
> + goto free_lvq;
> + }
> +
> + /*
> + * OK, tell virtio_ring.c to set up a virtqueue now we know its
> size
> + * and we've got a pointer to its pages.
> + */
> + vq = vring_new_virtqueue(lvq->config.num, LGUEST_VRING_ALIGN,
> + vdev, lvq->pages, lg_notify, callback, name);
> + if (!vq) {
> + err = -ENOMEM;
> + goto unmap;
> + }
> +
> + /*
> + * Tell the interrupt for this virtqueue to go to the virtio_ring
> + * interrupt handler.
> + *
> + * FIXME: We used to have a flag for the Host to tell us we could
> use
> + * the interrupt as a source of randomness: it'd be nice to have
> that
> + * back.
> + */
> + err = request_irq(lvq->config.irq, vring_interrupt, IRQF_SHARED,
> + dev_name(&vdev->dev), vq);
> + if (err)
> + goto destroy_vring;
> +
> + /*
> + * Last of all we hook up our 'struct lguest_vq_info" to the
> + * virtqueue's priv pointer.
> + */
> + vq->priv = lvq;
> + return vq;
> +
> +destroy_vring:
> + vring_del_virtqueue(vq);
> +unmap:
> + virtio_unmap(lvq->pages);
> +free_lvq:
> + kfree(lvq);
> + return ERR_PTR(err);
> +}
> +/*:*/
> +
> +/* Cleaning up a virtqueue is easy */
> +static void lg_del_vq(struct virtqueue *vq) {
> + struct lguest_vq_info *lvq = vq->priv;
> +
> + /* Release the interrupt */
> + free_irq(lvq->config.irq, vq);
> + /* Tell virtio_ring.c to free the virtqueue. */
> + vring_del_virtqueue(vq);
> + /* Unmap the pages containing the ring. */
> + virtio_unmap(lvq->pages);
> + /* Free our own queue information. */
> + kfree(lvq);
> +}
> +
> +static void lg_del_vqs(struct virtio_device *vdev) {
> + struct virtqueue *vq, *n;
> +
> + list_for_each_entry_safe(vq, n, &vdev->vqs, list)
> + lg_del_vq(vq);
> +}
> +
> +static int lg_find_vqs(struct virtio_device *vdev, unsigned nvqs,
> + struct virtqueue *vqs[],
> + vq_callback_t *callbacks[],
> + const char *names[])
> +{
> + struct lguest_device *ldev = to_lgdev(vdev);
> + int i;
> +
> + /* We must have this many virtqueues. */
> + if (nvqs > ldev->desc->num_vq)
> + return -ENOENT;
> +
> + for (i = 0; i < nvqs; ++i) {
> + vqs[i] = lg_find_vq(vdev, i, callbacks[i], names[i]);
> + if (IS_ERR(vqs[i]))
> + goto error;
> + }
> + return 0;
> +
> +error:
> + lg_del_vqs(vdev);
> + return PTR_ERR(vqs[i]);
> +}
> +
> +/* The ops structure which hooks everything together. */ static struct
> +virtio_config_ops lguest_config_ops = {
> + .get_features = lg_get_features,
> + .finalize_features = lg_finalize_features,
> + .get = lg_get,
> + .set = lg_set,
> + .get_status = lg_get_status,
> + .set_status = lg_set_status,
> + .reset = lg_reset,
> + .find_vqs = lg_find_vqs,
> + .del_vqs = lg_del_vqs,
> +};
> +
> +static int virtio_platform_probe(struct platform_device *pdev) {
> + struct virtio_platform_data *pdata = pdev->dev.platform_data;
> + struct resource *res;
> + void *devices;
> +
> + if (!pdata) {
> + dev_err(&pdev->dev, "no platform data defined\n");
> + return -EINVAL;
> + }
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (res == NULL) {
> + dev_err(&pdev->dev, "cannot find IO resource\n");
> + return -ENOENT;
> + }
> +
> + /* Devices are pointed out using struct resource */
> + devices = virtio_map(res->start, resource_size(res) >> PAGE_SHIFT);
> + lg_scan_devices(devices, &pdev->dev, &lguest_config_ops);
> + return 0;
> +}
> +
> +static int virtio_platform_remove(struct platform_device *pdev) {
> + return -ENOTSUPP;
> +}
> +
> +static struct platform_driver virtio_platform_driver = {
> + .driver = {
> + .name = "virtio-platform",
> + .owner = THIS_MODULE,
> + },
> + .probe = virtio_platform_probe,
> + .remove = virtio_platform_remove,
> +};
> +
> +static int __init virtio_platform_init(void) {
> + return platform_driver_register(&virtio_platform_driver);
> +}
> +
> +static void __exit virtio_platform_exit(void) {
> + platform_driver_unregister(&virtio_platform_driver);
> +}
> +
> +module_init(virtio_platform_init);
> +module_exit(virtio_platform_exit);
> +
> +MODULE_DESCRIPTION("VirtIO Platform Driver"); MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:virtio-platform");
> --- /dev/null
> +++ work/include/linux/virtio_platform.h 2011-03-03 15:56:54.000000000
> +0900
> @@ -0,0 +1,12 @@
> +#ifndef _LINUX_VIRTIO_PLATFORM_H
> +#define _LINUX_VIRTIO_PLATFORM_H
> +#include <linux/platform_device.h>
> +#include <linux/lguest_launcher.h>
> +
> +struct virtio_platform_data {
> + void (*notify_virtio)(struct platform_device *pdev);
> + void (*notify_virtqueue)(struct platform_device *pdev,
> + struct lguest_vqconfig *config);
> +};
> +
> +#endif /* _LINUX_VIRTIO_PLATFORM_H */
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