linux-kernel - [PATCH v2 3/3] uio_mf624: Align memory regions to page size and set correct offsets

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Date:   Thu, 16 Mar 2017 14:50:10 +0100
From:   Michal Sojka <sojkam1@....cvut.cz>
To:     Greg KH <gregkh@...uxfoundation.org>,
        Michal Sojka <sojkam1@....cvut.cz>
Cc:     linux-kernel@...r.kernel.org, lisovy@...il.com
Subject: [PATCH v2 3/3] uio_mf624: Align memory regions to page size and set correct offsets

mf624 card has its registers not aligned to pages. Since commit
b65502879556 ("uio: we cannot mmap unaligned page contents") mmap()ing
mf624 registers fails, because now the uio drivers must set
uio_mem->addr to be page-aligned.

We align the address here and set the newly introduced offs field to
the offset of the mf264 registers within the page so that userspace
can find the address of the mmap()ed register by reading
/sys/class/uio/uio?/maps/map?/offset.

Tested with real mf624 card.

Signed-off-by: Michal Sojka <sojkam1@....cvut.cz>
---
 drivers/uio/uio_mf624.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/uio/uio_mf624.c b/drivers/uio/uio_mf624.c
index 8f30fa1af2ab..35187c052e8c 100644
--- a/drivers/uio/uio_mf624.c
+++ b/drivers/uio/uio_mf624.c
@@ -129,11 +129,15 @@ static int mf624_irqcontrol(struct uio_info *info, s32 irq_on)
 
 static int mf624_setup_mem(struct pci_dev *dev, int bar, struct uio_mem *mem, const char *name)
 {
+	resource_size_t start = pci_resource_start(dev, bar);
+	resource_size_t len = pci_resource_len(dev, bar);
+
 	mem->name = name;
-	mem->addr = pci_resource_start(dev, bar);
+	mem->addr = start & PAGE_MASK;
+	mem->offs = start & ~PAGE_MASK;
 	if (!mem->addr)
 		return -ENODEV;
-	mem->size = pci_resource_len(dev, bar);
+	mem->size = ((start & ~PAGE_MASK) + len + PAGE_SIZE - 1) & PAGE_MASK;
 	mem->memtype = UIO_MEM_PHYS;
 	mem->internal_addr = pci_ioremap_bar(dev, bar);
 	if (!mem->internal_addr)
-- 
2.11.0