swiotlb: Convert swiotlb_force from int to enum

Convert the flag swiotlb_force from an int to an enum, to prepare for
the advent of more possible values.

Suggested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

8 files changed, 27 insertions, 18 deletions

diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 3f74d0d98de6..02265a589ef5 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -524,7 +524,8 @@ EXPORT_SYMBOL(dummy_dma_ops);
 
 static int __init arm64_dma_init(void)
 {
-        if (swiotlb_force || max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT))
+        if (swiotlb_force == SWIOTLB_FORCE ||
+            max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT))
                 swiotlb = 1;
 
         return atomic_pool_init();
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 212c4d1e2f26..716d1226ba69 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -401,7 +401,8 @@ static void __init free_unused_memmap(void)
  */
 void __init mem_init(void)
 {
-        if (swiotlb_force || max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT))
+        if (swiotlb_force == SWIOTLB_FORCE ||
+            max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT))
                 swiotlb_init(1);
 
         set_max_mapnr(pfn_to_page(max_pfn) - mem_map);
diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
index 36049af2715e..410efb2c7b80 100644
--- a/arch/x86/kernel/pci-swiotlb.c
+++ b/arch/x86/kernel/pci-swiotlb.c
@@ -68,7 +68,7 @@ static struct dma_map_ops swiotlb_dma_ops = {
  */
 int __init pci_swiotlb_detect_override(void)
 {
-        if (swiotlb_force)
+        if (swiotlb_force == SWIOTLB_FORCE)
                 swiotlb = 1;
 
         return swiotlb;
diff --git a/arch/x86/xen/pci-swiotlb-xen.c b/arch/x86/xen/pci-swiotlb-xen.c
index a9fafb5c8738..a0b36a9d5df1 100644
--- a/arch/x86/xen/pci-swiotlb-xen.c
+++ b/arch/x86/xen/pci-swiotlb-xen.c
@@ -48,7 +48,7 @@ int __init pci_xen_swiotlb_detect(void)
          * activate this IOMMU. If running as PV privileged, activate it
          * irregardless.
          */
-        if ((xen_initial_domain() || swiotlb || swiotlb_force))
+        if (xen_initial_domain() || swiotlb || swiotlb_force == SWIOTLB_FORCE)
                 xen_swiotlb = 1;
 
         /* If we are running under Xen, we MUST disable the native SWIOTLB.
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 478fb91e3df2..aba12009422e 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -392,7 +392,7 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
         if (dma_capable(dev, dev_addr, size) &&
             !range_straddles_page_boundary(phys, size) &&
                 !xen_arch_need_swiotlb(dev, phys, dev_addr) &&
-                !swiotlb_force) {
+                (swiotlb_force != SWIOTLB_FORCE)) {
                 /* we are not interested in the dma_addr returned by
                  * xen_dma_map_page, only in the potential cache flushes executed
                  * by the function. */
@@ -552,7 +552,7 @@ xen_swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
                 phys_addr_t paddr = sg_phys(sg);
                 dma_addr_t dev_addr = xen_phys_to_bus(paddr);
 
-                if (swiotlb_force ||
+                if (swiotlb_force == SWIOTLB_FORCE ||
                     xen_arch_need_swiotlb(hwdev, paddr, dev_addr) ||
                     !dma_capable(hwdev, dev_addr, sg->length) ||
                     range_straddles_page_boundary(paddr, sg->length)) {
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 183f37c8a5e1..71d104e4c849 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -9,7 +9,12 @@ struct device;
 struct page;
 struct scatterlist;
 
-extern int swiotlb_force;
+enum swiotlb_force {
+        SWIOTLB_NORMAL,         /* Default - depending on HW DMA mask etc. */
+        SWIOTLB_FORCE,          /* swiotlb=force */
+};
+
+extern enum swiotlb_force swiotlb_force;
 
 /*
  * Maximum allowable number of contiguous slabs to map,
diff --git a/include/trace/events/swiotlb.h b/include/trace/events/swiotlb.h
index 7ea4c5e7c448..5e2e30a7efce 100644
--- a/include/trace/events/swiotlb.h
+++ b/include/trace/events/swiotlb.h
@@ -11,16 +11,16 @@ TRACE_EVENT(swiotlb_bounced,
         TP_PROTO(struct device *dev,
                  dma_addr_t dev_addr,
                  size_t size,
-                 int swiotlb_force),
+                 enum swiotlb_force swiotlb_force),
 
         TP_ARGS(dev, dev_addr, size, swiotlb_force),
 
         TP_STRUCT__entry(
-                __string(       dev_name,       dev_name(dev)   )
-                __field(        u64,    dma_mask                )
-                __field(        dma_addr_t,     dev_addr        )
-                __field(        size_t, size                    )
-                __field(        int,    swiotlb_force           )
+                __string(       dev_name,       dev_name(dev)           )
+                __field(        u64,    dma_mask                        )
+                __field(        dma_addr_t,     dev_addr                )
+                __field(        size_t, size                            )
+                __field(        enum swiotlb_force,     swiotlb_force   )
         ),
 
         TP_fast_assign(
@@ -37,7 +37,9 @@ TRACE_EVENT(swiotlb_bounced,
                 __entry->dma_mask,
                 (unsigned long long)__entry->dev_addr,
                 __entry->size,
-                __entry->swiotlb_force ? "swiotlb_force" : "" )
+                __print_symbolic(__entry->swiotlb_force,
+                        { SWIOTLB_NORMAL,       "NORMAL" },
+                        { SWIOTLB_FORCE,        "FORCE" }))
 );
 
 #endif /*  _TRACE_SWIOTLB_H */
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index cb1b54ee8527..a32dce6d5101 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -53,7 +53,7 @@
  */
 #define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
 
-int swiotlb_force;
+enum swiotlb_force swiotlb_force;
 
 /*
  * Used to do a quick range check in swiotlb_tbl_unmap_single and
@@ -107,7 +107,7 @@ setup_io_tlb_npages(char *str)
         if (*str == ',')
                 ++str;
         if (!strcmp(str, "force"))
-                swiotlb_force = 1;
+                swiotlb_force = SWIOTLB_FORCE;
 
         return 0;
 }
@@ -763,7 +763,7 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
          * we can safely return the device addr and not worry about bounce
          * buffering it.
          */
-        if (dma_capable(dev, dev_addr, size) && !swiotlb_force)
+        if (dma_capable(dev, dev_addr, size) && swiotlb_force != SWIOTLB_FORCE)
                 return dev_addr;
 
         trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force);
@@ -904,7 +904,7 @@ swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems,
                 phys_addr_t paddr = sg_phys(sg);
                 dma_addr_t dev_addr = phys_to_dma(hwdev, paddr);
 
-                if (swiotlb_force ||
+                if (swiotlb_force == SWIOTLB_FORCE ||
                     !dma_capable(hwdev, dev_addr, sg->length)) {
                         phys_addr_t map = map_single(hwdev, sg_phys(sg),
                                                      sg->length, dir, attrs);