linux-kernel - RE: uio: uio_pci_generic: add missing memory mappings

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Date:   Mon, 26 Apr 2021 10:29:48 -0400
From:   firas ashkar <firas.ashkar@...oirfairelinux.com>
To:     mst@...hat.com
Cc:     gregkh@...uxfoundation.org,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: RE: uio: uio_pci_generic: add missing memory mappings

Hi,
pls find attached a trivial but necessary patch, this change is based on [drivers/uio/uio_pdrv_genirq.c], 
it adds missing memory resources/mappings from the underlying pci device, thus the userspace applications
can memory map and directly access them. This patch also includes minor style changes.

The change was tested on following hardware: AltaData ARINC 429 MiniPCIE module on imx8qm-apalis-ixora-v1.2
board.

Signed-off-by: Firas Ashkar <firas.ashkar@...oirfairelinux.com>

-- 
Firas Ashkar
Developpeur Système Embarqué

savoirfairelinux.com  | Montréal, Québec

Tél.: +1 514 276 5468 ext. 118

----------
>From 40fde25c762e4b7db211da56d8f2f8dd72c1e29c Mon Sep 17 00:00:00 2001
From: Firas Ashkar <firas.ashkar@...oirfairelinux.com>
Date: Fri, 23 Apr 2021 10:38:28 -0400
Subject: [PATCH 1/1] uio: uio_pci_generic: add memory mappings

import memory resources from underlaying pci device, thus allowing
userspace applications to memory map those resources.

Signed-off-by: Firas Ashkar <firas.ashkar@...oirfairelinux.com>
---
 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@...hat.com>"
-#define DRIVER_DESC	"Generic UIO driver for PCI 2.3 devices"
+#define DRIVER_VERSION "0.01.0"
+#define DRIVER_AUTHOR "Michael S. Tsirkin <mst@...hat.com>"
+#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