[PATCH 09/17] pci: Add pci_mmap_resource_range() and use it for ARM64
From: David Woodhouse
Date: Wed Mar 22 2017 - 09:26:31 EST
From: David Woodhouse <dwmw@xxxxxxxxxxxx>
Starting to leave behind the legacy of the pci_mmap_page_range()
interface which takes "user-visible" BAR addresses. This takes just the
resource and offset.
For now, both APIs coexist and depending on the platform, one is
implemented as a wrapper around the other.
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
---
Documentation/filesystems/sysfs-pci.txt | 5 +-
arch/arm64/include/asm/pci.h | 3 ++
drivers/pci/Makefile | 2 +-
drivers/pci/mmap.c | 90 +++++++++++++++++++++++++++++++++
drivers/pci/pci-sysfs.c | 11 +---
include/linux/pci.h | 19 +++++--
6 files changed, 115 insertions(+), 15 deletions(-)
create mode 100644 drivers/pci/mmap.c
diff --git a/Documentation/filesystems/sysfs-pci.txt b/Documentation/filesystems/sysfs-pci.txt
index 25b7f1c..3e1016e 100644
--- a/Documentation/filesystems/sysfs-pci.txt
+++ b/Documentation/filesystems/sysfs-pci.txt
@@ -113,7 +113,10 @@ Supporting PCI access on new platforms
--------------------------------------
In order to support PCI resource mapping as described above, Linux platform
-code must define HAVE_PCI_MMAP and provide a pci_mmap_page_range function.
+code must define HAVE_PCI_MMAP and either provide a pci_mmap_page_range()
+function or (preferably) also define ARCH_GENERIC_PCI_MMAP_RESOURCE to use
+the generic implementation.
+
Platforms are free to only support subsets of the mmap functionality, but
useful return codes should be provided.
diff --git a/arch/arm64/include/asm/pci.h b/arch/arm64/include/asm/pci.h
index b9a7ba9..021da94 100644
--- a/arch/arm64/include/asm/pci.h
+++ b/arch/arm64/include/asm/pci.h
@@ -22,6 +22,9 @@
*/
#define PCI_DMA_BUS_IS_PHYS (0)
+#define HAVE_PCI_MMAP 1
+#define ARCH_GENERIC_PCI_MMAP_RESOURCE 1
+
extern int isa_dma_bridge_buggy;
#ifdef CONFIG_PCI
diff --git a/drivers/pci/Makefile b/drivers/pci/Makefile
index 8db5079..3d40e41 100644
--- a/drivers/pci/Makefile
+++ b/drivers/pci/Makefile
@@ -4,7 +4,7 @@
obj-y += access.o bus.o probe.o host-bridge.o remove.o pci.o \
pci-driver.o search.o pci-sysfs.o rom.o setup-res.o \
- irq.o vpd.o setup-bus.o vc.o
+ irq.o vpd.o setup-bus.o vc.o mmap.o
obj-$(CONFIG_PROC_FS) += proc.o
obj-$(CONFIG_SYSFS) += slot.o
diff --git a/drivers/pci/mmap.c b/drivers/pci/mmap.c
new file mode 100644
index 0000000..bf28dae
--- /dev/null
+++ b/drivers/pci/mmap.c
@@ -0,0 +1,90 @@
+/*
+ * mmap.c â generic PCI resource mmap helper
+ *
+ * Copyright  2017 Amazon.com, Inc. or its affiliates.
+ *
+ * Author: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+
+ */
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/pci.h>
+
+#ifdef HAVE_PCI_MMAP
+
+#ifdef ARCH_GENERIC_PCI_MMAP_RESOURCE
+/* Modern setup: generic pci_mmap_resource_range(), and implement the legacy
+ * pci_mmap_page_range() as a wrapper round it. */
+
+#ifdef HAVE_PCI_MMAP_IO
+/* We don't support this (yet), so prevent archietectures from trying it. */
+#error Generic pci_mmap_io not supported
+#endif
+
+static const struct vm_operations_struct pci_phys_vm_ops = {
+#ifdef CONFIG_HAVE_IOREMAP_PROT
+ .access = generic_access_phys,
+#endif
+};
+
+int pci_mmap_resource_range(struct pci_dev *pdev, int bar,
+ struct vm_area_struct *vma,
+ enum pci_mmap_state mmap_state, int write_combine)
+{
+ unsigned long size;
+
+ if (mmap_state == pci_mmap_io)
+ return -EINVAL;
+
+ size = ((pci_resource_len(pdev, bar) - 1) >> PAGE_SHIFT) + 1;
+ if (vma->vm_pgoff + vma_pages(vma) > size)
+ return -EINVAL;
+
+ if (write_combine)
+ vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
+ else
+ vma->vm_page_prot = pgprot_device(vma->vm_page_prot);
+
+ vma->vm_pgoff += (pci_resource_start(pdev, bar) >> PAGE_SHIFT);
+ vma->vm_ops = &pci_phys_vm_ops;
+
+ return io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
+ vma->vm_end - vma->vm_start, vma->vm_page_prot);
+}
+
+int pci_mmap_page_range(struct pci_dev *pdev, int bar,
+ struct vm_area_struct *vma,
+ enum pci_mmap_state mmap_state, int write_combine)
+{
+ /* Adjust vm_pgoff to be the offset within the resource */
+ resource_size_t start, end;
+
+ pci_resource_to_user(pdev, bar, &pdev->resource[bar], &start, &end);
+ vma->vm_pgoff -= start >> PAGE_SHIFT;
+ return pci_mmap_resource_range(pdev, bar, vma, mmap_state, write_combine);
+}
+
+#else
+/* Legacy setup: Impement pci_mmap_resource_range() as a wrapper around
+ the architecture's pci_mmap_page_range(), converting to "user visible"
+ addresses as necessary. */
+int pci_mmap_resource_range(struct pci_dev *pdev, int bar,
+ struct vm_area_struct *vma,
+ enum pci_mmap_state mmap_state, int write_combine)
+{
+ resource_size_t start, end;
+ /* pci_mmap_page_range() expects the same kind of entry as coming
+ * from /proc/bus/pci/ which is a "user visible" value. If this is
+ * different from the resource itself, arch will do necessary fixup.
+ */
+ pci_resource_to_user(pdev, bar, &pdev->resource[bar], &start, &end);
+ vma->vm_pgoff += start >> PAGE_SHIFT;
+ return pci_mmap_page_range(pdev, bar, vma, mmap_state, write_combine);
+}
+#endif
+#endif /* HAVE_PCI_MMAP */
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 063310a..9663d38 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1019,7 +1019,6 @@ static int pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr,
struct pci_dev *pdev = to_pci_dev(kobj_to_dev(kobj));
int bar = (unsigned long)attr->private;
enum pci_mmap_state mmap_type;
- resource_size_t start, end;
struct resource *res = &pdev->resource[bar];
if (res->flags & IORESOURCE_MEM && iomem_is_exclusive(res->start))
@@ -1033,15 +1032,9 @@ static int pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr,
(u64)pci_resource_len(pdev, bar));
return -EINVAL;
}
-
- /* pci_mmap_page_range() expects the same kind of entry as coming
- * from /proc/bus/pci/ which is a "user visible" value. If this is
- * different from the resource itself, arch will do necessary fixup.
- */
- pci_resource_to_user(pdev, bar, res, &start, &end);
- vma->vm_pgoff += start >> PAGE_SHIFT;
mmap_type = res->flags & IORESOURCE_MEM ? pci_mmap_mem : pci_mmap_io;
- return pci_mmap_page_range(pdev, bar, vma, mmap_type, write_combine);
+
+ return pci_mmap_resource_range(pdev, bar, vma, mmap_type, write_combine);
}
static int pci_mmap_resource_uc(struct file *filp, struct kobject *kobj,
diff --git a/include/linux/pci.h b/include/linux/pci.h
index ebc86c1..4dfec16 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1626,10 +1626,21 @@ static inline int pci_get_new_domain_nr(void) { return -ENOSYS; }
#include <asm/pci.h>
-/* Map a range of PCI memory or I/O space for a device into user space.
- * Architectures provide this function if they set HAVE_PCI_MMAP, and
- * it accepts the 'write_combine' argument when arch_can_pci_mmap_wc()
- * evaluates to nonzero. */
+/* These two functions provide almost identical functionality. Depennding
+ * on the architecture, one will be implemented as a wrapper aroudn the
+ * other (in drivers/pci/mmap.c).
+ *
+ * pci_mmap_resource_range() maps a specific BAR, and vm->vm_pgoff
+ * is expected to be an offset within that region.
+ *
+ * pci_mmap_page_range() is the legacy architecture-specific interface,
+ * which accepts a "user visible" resource address converted by
+ * pci_resource_to_user(), as used in the legacy mmap() interface in
+ * /proc/bus/pci/.
+ */
+int pci_mmap_resource_range(struct pci_dev *dev, int bar,
+ struct vm_area_struct *vma,
+ enum pci_mmap_state mmap_state, int write_combine);
int pci_mmap_page_range(struct pci_dev *pdev, int bar,
struct vm_area_struct *vma,
enum pci_mmap_state mmap_state, int write_combine);
--
2.9.3