diff options
authorMichal Sojka <sojkam1@fel.cvut.cz>2017-03-16 14:50:08 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-04-08 18:13:27 +0200
commit171058fb0883247b3a484a542b5dc89753c57cb5 (patch)
parent8b932edfb8788862f10434c1018ad8a6078e0115 (diff)
uio: Allow handling of non page-aligned memory regions
Since commit b65502879556 ("uio: we cannot mmap unaligned page contents") addresses and sizes of UIO memory regions must be page-aligned. If the address in the BAR register is not page-aligned (which is the case of the mf264 card), the mentioned commit forces the UIO driver to round the address down to the page size. Then, there is no easy way for user-space to learn the offset of the actual memory region within the page, because the offset seen in /sys/class/uio/uio?/maps/map?/offset is calculated from the rounded address and thus it is always zero. Fix that problem by including the offset in struct uio_mem. UIO drivers can set this field and userspace can read its value from /sys/class/uio/uio?/maps/map?/offset. The following commits update the uio_mf264 driver to set this new offs field. Drivers for hardware with page-aligned BARs need not to be modified provided that they initialize struct uio_info (which contains uio_mem) with zeros. Signed-off-by: Michal Sojka <sojkam1@fel.cvut.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2 files changed, 9 insertions, 6 deletions
diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 60ce7fd54e89..1c196f87e9d9 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -66,7 +66,7 @@ static ssize_t map_size_show(struct uio_mem *mem, char *buf)
static ssize_t map_offset_show(struct uio_mem *mem, char *buf)
- return sprintf(buf, "0x%llx\n", (unsigned long long)mem->addr & ~PAGE_MASK);
+ return sprintf(buf, "0x%llx\n", (unsigned long long)mem->offs);
struct map_sysfs_entry {
diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h
index 32c0e83d6239..3c85c81b0027 100644
--- a/include/linux/uio_driver.h
+++ b/include/linux/uio_driver.h
@@ -23,11 +23,13 @@ struct uio_map;
* struct uio_mem - description of a UIO memory region
* @name: name of the memory region for identification
- * @addr: address of the device's memory (phys_addr is used since
- * addr can be logical, virtual, or physical & phys_addr_t
- * should always be large enough to handle any of the
- * address types)
- * @size: size of IO
+ * @addr: address of the device's memory rounded to page
+ * size (phys_addr is used since addr can be
+ * logical, virtual, or physical & phys_addr_t
+ * should always be large enough to handle any of
+ * the address types)
+ * @offs: offset of device memory within the page
+ * @size: size of IO (multiple of page size)
* @memtype: type of memory addr points to
* @internal_addr: ioremap-ped version of addr, for driver internal use
* @map: for use by the UIO core only.
@@ -35,6 +37,7 @@ struct uio_map;
struct uio_mem {
const char *name;
phys_addr_t addr;
+ unsigned long offs;
resource_size_t size;
int memtype;
void __iomem *internal_addr;

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