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virt-pci: add platform bus support

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This driver registers PCI busses, but the underlying virtio protocol
could just as easily be used to provide a platform bus instead.  If the
virtio device node in the devicetree indicates that it's compatible with
simple-bus, register platform devices instead of handling it as a PCI
bus.

Only one platform bus is allowed and the logic MMIO region for the
platform bus is placed at an arbitrarily-chosen address away from the
PCI region.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Vincent Whitchurch 2023-01-27 15:30:27 +01:00 committed by Richard Weinberger
parent 935f8f7a01
commit 522c532c4f
1 changed files with 91 additions and 0 deletions
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91
arch/um/drivers/virt-pci.c
View File

@ -8,6 +8,7 @@
#include <linux/virtio.h>
#include <linux/virtio_config.h>
#include <linux/logic_iomem.h>
#include <linux/of_platform.h>
#include <linux/irqdomain.h>
#include <linux/virtio_pcidev.h>
#include <linux/virtio-uml.h>
@ -39,6 +40,8 @@ struct um_pci_device {
unsigned long status;
int irq;
bool platform;
};
struct um_pci_device_reg {
@ -48,6 +51,7 @@ struct um_pci_device_reg {
static struct pci_host_bridge *bridge;
static DEFINE_MUTEX(um_pci_mtx);
static struct um_pci_device *um_pci_platform_device;
static struct um_pci_device_reg um_pci_devices[MAX_DEVICES];
static struct fwnode_handle *um_pci_fwnode;
static struct irq_domain *um_pci_inner_domain;
@ -481,6 +485,9 @@ static void um_pci_handle_irq_message(struct virtqueue *vq,
struct virtio_device *vdev = vq->vdev;
struct um_pci_device *dev = vdev->priv;
if (!dev->irq)
return;
/* we should properly chain interrupts, but on ARCH=um we don't care */
switch (msg->op) {
@ -581,6 +588,55 @@ static int um_pci_init_vqs(struct um_pci_device *dev)
return 0;
}
static void __um_pci_virtio_platform_remove(struct virtio_device *vdev,
struct um_pci_device *dev)
{
virtio_reset_device(vdev);
vdev->config->del_vqs(vdev);
mutex_lock(&um_pci_mtx);
um_pci_platform_device = NULL;
mutex_unlock(&um_pci_mtx);
kfree(dev);
}
static int um_pci_virtio_platform_probe(struct virtio_device *vdev,
struct um_pci_device *dev)
{
int ret;
dev->platform = true;
mutex_lock(&um_pci_mtx);
if (um_pci_platform_device) {
mutex_unlock(&um_pci_mtx);
ret = -EBUSY;
goto out_free;
}
ret = um_pci_init_vqs(dev);
if (ret) {
mutex_unlock(&um_pci_mtx);
goto out_free;
}
um_pci_platform_device = dev;
mutex_unlock(&um_pci_mtx);
ret = of_platform_default_populate(vdev->dev.of_node, NULL, &vdev->dev);
if (ret)
__um_pci_virtio_platform_remove(vdev, dev);
return ret;
out_free:
kfree(dev);
return ret;
}
static int um_pci_virtio_probe(struct virtio_device *vdev)
{
struct um_pci_device *dev;
@ -594,6 +650,9 @@ static int um_pci_virtio_probe(struct virtio_device *vdev)
dev->vdev = vdev;
vdev->priv = dev;
if (of_device_is_compatible(vdev->dev.of_node, "simple-bus"))
return um_pci_virtio_platform_probe(vdev, dev);
mutex_lock(&um_pci_mtx);
for (i = 0; i < MAX_DEVICES; i++) {
if (um_pci_devices[i].dev)
@ -643,6 +702,12 @@ static void um_pci_virtio_remove(struct virtio_device *vdev)
struct um_pci_device *dev = vdev->priv;
int i;
if (dev->platform) {
of_platform_depopulate(&vdev->dev);
__um_pci_virtio_platform_remove(vdev, dev);
return;
}
/* Stop all virtqueues */
virtio_reset_device(vdev);
vdev->config->del_vqs(vdev);
@ -880,6 +945,30 @@ void *pci_root_bus_fwnode(struct pci_bus *bus)
return um_pci_fwnode;
}
static long um_pci_map_platform(unsigned long offset, size_t size,
const struct logic_iomem_ops **ops,
void **priv)
{
if (!um_pci_platform_device)
return -ENOENT;
*ops = &um_pci_device_bar_ops;
*priv = &um_pci_platform_device->resptr[0];
return 0;
}
static const struct logic_iomem_region_ops um_pci_platform_ops = {
.map = um_pci_map_platform,
};
static struct resource virt_platform_resource = {
.name = "platform",
.start = 0x10000000,
.end = 0x1fffffff,
.flags = IORESOURCE_MEM,
};
static int __init um_pci_init(void)
{
int err, i;
@ -888,6 +977,8 @@ static int __init um_pci_init(void)
&um_pci_cfgspace_ops));
WARN_ON(logic_iomem_add_region(&virt_iomem_resource,
&um_pci_iomem_ops));
WARN_ON(logic_iomem_add_region(&virt_platform_resource,
&um_pci_platform_ops));
if (WARN(CONFIG_UML_PCI_OVER_VIRTIO_DEVICE_ID < 0,
"No virtio device ID configured for PCI - no PCI support\n"))