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Message-ID: <20230127-uml-pci-platform-v1-1-ec6b45d2829f@axis.com>
Date: Fri, 27 Jan 2023 15:30:27 +0100
From: Vincent Whitchurch <vincent.whitchurch@...s.com>
To: Richard Weinberger <richard@....at>,
Anton Ivanov <anton.ivanov@...bridgegreys.com>,
Johannes Berg <johannes@...solutions.net>
CC: <robh@...nel.org>, <devicetree@...ts.infradead.org>,
<linux-um@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
<kernel@...s.com>, Vincent Whitchurch <vincent.whitchurch@...s.com>
Subject: [PATCH] virt-pci: add platform bus support
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@...s.com>
---
My first approach to getting platform drivers working on UML was by
adding a minimal PCI-to-platform bridge driver, which worked without
modifications to virt-pci, but that got shot down:
https://lore.kernel.org/lkml/20230120-simple-mfd-pci-v1-1-c46b3d6601ef@axis.com/
---
arch/um/drivers/virt-pci.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 91 insertions(+)
diff --git a/arch/um/drivers/virt-pci.c b/arch/um/drivers/virt-pci.c
index 3ac220dafec4..0ff69d6ad253 100644
--- a/arch/um/drivers/virt-pci.c
+++ b/arch/um/drivers/virt-pci.c
@@ -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;
@@ -480,6 +484,9 @@ 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) {
@@ -561,6 +568,55 @@ 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;
@@ -574,6 +630,9 @@ 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)
@@ -623,6 +682,12 @@ 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);
@@ -860,6 +925,30 @@ 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;
@@ -868,6 +957,8 @@ 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"))
---
base-commit: 1b929c02afd37871d5afb9d498426f83432e71c2
change-id: 20230127-uml-pci-platform-ef851ba75f80
Best regards,
--
Vincent Whitchurch <vincent.whitchurch@...s.com>
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