[PATCH 1/1] uio: uio_pci_generic: add memory mappings

From: Firas Ashkar
Date: Fri Apr 23 2021 - 10:38:28 EST


import memory resources from underlaying pci device, thus allowing
userspace applications to memory map those resources.
---
drivers/uio/uio_pci_generic.c | 52 +++++++++++++++++++++++++++++------
1 file changed, 43 insertions(+), 9 deletions(-)

diff --git a/drivers/uio/uio_pci_generic.c
b/drivers/uio/uio_pci_generic.c
index c7d681fef198..809eca95b5bb 100644
--- a/drivers/uio/uio_pci_generic.c
+++ b/drivers/uio/uio_pci_generic.c
@@ -24,9 +24,9 @@
#include <linux/slab.h>
#include <linux/uio_driver.h>

-#define DRIVER_VERSION "0.01.0"
-#define DRIVER_AUTHOR "Michael S. Tsirkin <mst@xxxxxxxxxx>"
-#define DRIVER_DESC "Generic UIO driver for PCI 2.3 devices"
+#define DRIVER_VERSION "0.01.0"
+#define DRIVER_AUTHOR "Michael S. Tsirkin <mst@xxxxxxxxxx>"
+#define DRIVER_DESC "Generic UIO driver for PCI 2.3 devices"

struct uio_pci_generic_dev {
struct uio_info info;
@@ -56,7 +56,8 @@ static int release(struct uio_info *info, struct
inode *inode)
}

/* Interrupt handler. Read/modify/write the command register to
disable
- * the interrupt. */
+ * the interrupt.
+ */
static irqreturn_t irqhandler(int irq, struct uio_info *info)
{
struct uio_pci_generic_dev *gdev =
to_uio_pci_generic_dev(info);
@@ -68,11 +69,12 @@ static irqreturn_t irqhandler(int irq, struct
uio_info *info)
return IRQ_HANDLED;
}

-static int probe(struct pci_dev *pdev,
- const struct pci_device_id *id)
+static int probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
struct uio_pci_generic_dev *gdev;
+ struct uio_mem *uiomem;
int err;
+ int i;

err = pcim_enable_device(pdev);
if (err) {
@@ -84,7 +86,8 @@ static int probe(struct pci_dev *pdev,
if (pdev->irq && !pci_intx_mask_supported(pdev))
return -ENOMEM;

- gdev = devm_kzalloc(&pdev->dev, sizeof(struct
uio_pci_generic_dev), GFP_KERNEL);
+ gdev = devm_kzalloc(&pdev->dev, sizeof(struct
uio_pci_generic_dev),
+ GFP_KERNEL);
if (!gdev)
return -ENOMEM;

@@ -97,8 +100,39 @@ static int probe(struct pci_dev *pdev,
gdev->info.irq_flags = IRQF_SHARED;
gdev->info.handler = irqhandler;
} else {
- dev_warn(&pdev->dev, "No IRQ assigned to device: "
- "no support for interrupts?\n");
+ dev_warn(
+ &pdev->dev,
+ "No IRQ assigned to device: no support for
interrupts?\n");
+ }
+
+ uiomem = &gdev->info.mem[0];
+ for (i = 0; i < MAX_UIO_MAPS; ++i) {
+ struct resource *r = &pdev->resource[i];
+
+ if (r->flags != (IORESOURCE_SIZEALIGN |
IORESOURCE_MEM))
+ continue;
+
+ if (uiomem >= &gdev->info.mem[MAX_UIO_MAPS]) {
+ dev_warn(
+ &pdev->dev,
+ "device has more than " __stringify(
+ MAX_UIO_MAPS) " I/O memory
resources.\n");
+ break;
+ }
+
+ uiomem->memtype = UIO_MEM_PHYS;
+ uiomem->addr = r->start & PAGE_MASK;
+ uiomem->offs = r->start & ~PAGE_MASK;
+ uiomem->size =
+ (uiomem->offs + resource_size(r) + PAGE_SIZE -
1) &
+ PAGE_MASK;
+ uiomem->name = r->name;
+ ++uiomem;
+ }
+
+ while (uiomem < &gdev->info.mem[MAX_UIO_MAPS]) {
+ uiomem->size = 0;
+ ++uiomem;
}

return devm_uio_register_device(&pdev->dev, &gdev->info);
--
2.25.1