[PATCH v5 2/9] swiotlb: make io_tlb_default_mem local to swiotlb.c

[Petr Tesarik <petrtesarik@xxxxxxxxxxxxxxx>]

From: Petr Tesarik <petr.tesarik.ext@xxxxxxxxxx>

SWIOTLB implementation details should not be exposed to the rest of the
kernel. This will allow to make changes to the implementation without
modifying non-swiotlb code.

To avoid breaking existing users, provide helper functions for the few
required fields.

As a bonus, using a helper function to initialize struct device allows to
get rid of an #ifdef in driver core.

Signed-off-by: Petr Tesarik <petr.tesarik.ext@xxxxxxxxxx>
---
 arch/mips/pci/pci-octeon.c |  2 +-
 drivers/base/core.c        |  4 +---
 drivers/xen/swiotlb-xen.c  |  2 +-
 include/linux/swiotlb.h    | 19 ++++++++++++++++++-
 kernel/dma/swiotlb.c       | 31 ++++++++++++++++++++++++++++++-
 5 files changed, 51 insertions(+), 7 deletions(-)

diff --git a/arch/mips/pci/pci-octeon.c b/arch/mips/pci/pci-octeon.c
index e457a18cbdc5..d19d9d456309 100644
--- a/arch/mips/pci/pci-octeon.c
+++ b/arch/mips/pci/pci-octeon.c
@@ -664,7 +664,7 @@ static int __init octeon_pci_setup(void)
 
                /* BAR1 movable regions contiguous to cover the swiotlb */
                octeon_bar1_pci_phys =
-                       io_tlb_default_mem.start & ~((1ull << 22) - 1);
+                       default_swiotlb_base() & ~((1ull << 22) - 1);
 
                for (index = 0; index < 32; index++) {
                        union cvmx_pci_bar1_indexx bar1_index;
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 3dff5037943e..46d1d78c5beb 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -3108,9 +3108,7 @@ void device_initialize(struct device *dev)
     defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)
        dev->dma_coherent = dma_default_coherent;
 #endif
-#ifdef CONFIG_SWIOTLB
-       dev->dma_io_tlb_mem = &io_tlb_default_mem;
-#endif
+       swiotlb_dev_init(dev);
 }
 EXPORT_SYMBOL_GPL(device_initialize);
 
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 67aa74d20162..946bd56f0ac5 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -381,7 +381,7 @@ xen_swiotlb_sync_sg_for_device(struct device *dev, struct 
scatterlist *sgl,
 static int
 xen_swiotlb_dma_supported(struct device *hwdev, u64 mask)
 {
-       return xen_phys_to_dma(hwdev, io_tlb_default_mem.end - 1) <= mask;
+       return xen_phys_to_dma(hwdev, default_swiotlb_limit()) <= mask;
 }
 
 const struct dma_map_ops xen_swiotlb_dma_ops = {
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 4e52cd5e0bdc..3b372364a144 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -110,7 +110,6 @@ struct io_tlb_mem {
        atomic_long_t used_hiwater;
 #endif
 };
-extern struct io_tlb_mem io_tlb_default_mem;
 
 static inline bool is_swiotlb_buffer(struct device *dev, phys_addr_t paddr)
 {
@@ -128,13 +127,21 @@ static inline bool is_swiotlb_force_bounce(struct device 
*dev)
 
 void swiotlb_init(bool addressing_limited, unsigned int flags);
 void __init swiotlb_exit(void);
+void swiotlb_dev_init(struct device *dev);
 size_t swiotlb_max_mapping_size(struct device *dev);
 bool is_swiotlb_active(struct device *dev);
 void __init swiotlb_adjust_size(unsigned long size);
+phys_addr_t default_swiotlb_base(void);
+phys_addr_t default_swiotlb_limit(void);
 #else
 static inline void swiotlb_init(bool addressing_limited, unsigned int flags)
 {
 }
+
+static inline void swiotlb_dev_init(struct device *dev)
+{
+}
+
 static inline bool is_swiotlb_buffer(struct device *dev, phys_addr_t paddr)
 {
        return false;
@@ -159,6 +166,16 @@ static inline bool is_swiotlb_active(struct device *dev)
 static inline void swiotlb_adjust_size(unsigned long size)
 {
 }
+
+static inline phys_addr_t default_swiotlb_base(void)
+{
+       return 0;
+}
+
+static inline phys_addr_t default_swiotlb_limit(void)
+{
+       return 0;
+}
 #endif /* CONFIG_SWIOTLB */
 
 extern void swiotlb_print_info(void);
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 66fc8ec9ae45..6734ef7b9d8d 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -71,7 +71,7 @@ struct io_tlb_slot {
 static bool swiotlb_force_bounce;
 static bool swiotlb_force_disable;
 
-struct io_tlb_mem io_tlb_default_mem;
+static struct io_tlb_mem io_tlb_default_mem;
 
 static unsigned long default_nslabs = IO_TLB_DEFAULT_SIZE >> IO_TLB_SHIFT;
 static unsigned long default_nareas;
@@ -489,6 +489,15 @@ void __init swiotlb_exit(void)
        memset(mem, 0, sizeof(*mem));
 }
 
+/**
+ * swiotlb_dev_init() - initialize swiotlb fields in &struct device
+ * @dev:       Device to be initialized.
+ */
+void swiotlb_dev_init(struct device *dev)
+{
+       dev->dma_io_tlb_mem = &io_tlb_default_mem;
+}
+
 /*
  * Return the offset into a iotlb slot required to keep the device happy.
  */
@@ -961,6 +970,26 @@ bool is_swiotlb_active(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(is_swiotlb_active);
 
+/**
+ * default_swiotlb_base() - get the base address of the default SWIOTLB
+ *
+ * Get the lowest physical address used by the default software IO TLB pool.
+ */
+phys_addr_t default_swiotlb_base(void)
+{
+       return io_tlb_default_mem.start;
+}
+
+/**
+ * default_swiotlb_limit() - get the address limit of the default SWIOTLB
+ *
+ * Get the highest physical address used by the default software IO TLB pool.
+ */
+phys_addr_t default_swiotlb_limit(void)
+{
+       return io_tlb_default_mem.end - 1;
+}
+
 #ifdef CONFIG_DEBUG_FS
 
 static int io_tlb_used_get(void *data, u64 *val)
-- 
2.25.1