[PATCH v4 09/14] swiotlb: Refactor swiotlb_tbl_{map,unmap}_single

[Claire Chang <tientzu@xxxxxxxxxxxx>]

Refactor swiotlb_tbl_{map,unmap}_single to make the code reusable for
dev_swiotlb_{alloc,free}.

Signed-off-by: Claire Chang <tientzu@xxxxxxxxxxxx>
---
 kernel/dma/swiotlb.c | 116 ++++++++++++++++++++++++++-----------------
 1 file changed, 71 insertions(+), 45 deletions(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 6fdebde8fb1f..f64cbe6e84cc 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -509,14 +509,12 @@ static void swiotlb_bounce(phys_addr_t orig_addr, 
phys_addr_t tlb_addr,
        }
 }
 
-phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr,
-               size_t mapping_size, size_t alloc_size,
-               enum dma_data_direction dir, unsigned long attrs)
+static int swiotlb_tbl_find_free_region(struct device *hwdev,
+                                       dma_addr_t tbl_dma_addr,
+                                       size_t alloc_size, unsigned long attrs)
 {
        struct swiotlb *swiotlb = get_swiotlb(hwdev);
-       dma_addr_t tbl_dma_addr = phys_to_dma_unencrypted(hwdev, 
swiotlb->start);
        unsigned long flags;
-       phys_addr_t tlb_addr;
        unsigned int nslots, stride, index, wrap;
        int i;
        unsigned long mask;
@@ -531,15 +529,6 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, 
phys_addr_t orig_addr,
 #endif
                panic("Can not allocate SWIOTLB buffer earlier and can't now 
provide you with the DMA bounce buffer");
 
-       if (mem_encrypt_active())
-               pr_warn_once("Memory encryption is active and system is using 
DMA bounce buffers\n");
-
-       if (mapping_size > alloc_size) {
-               dev_warn_once(hwdev, "Invalid sizes (mapping: %zd bytes, alloc: 
%zd bytes)",
-                             mapping_size, alloc_size);
-               return (phys_addr_t)DMA_MAPPING_ERROR;
-       }
-
        mask = dma_get_seg_boundary(hwdev);
 
        tbl_dma_addr &= mask;
@@ -601,7 +590,6 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, 
phys_addr_t orig_addr,
                                swiotlb->list[i] = 0;
                        for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != 
IO_TLB_SEGSIZE - 1) && swiotlb->list[i]; i--)
                                swiotlb->list[i] = ++count;
-                       tlb_addr = swiotlb->start + (index << IO_TLB_SHIFT);
 
                        /*
                         * Update the indices to avoid searching in the next
@@ -624,45 +612,20 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, 
phys_addr_t orig_addr,
        if (!(attrs & DMA_ATTR_NO_WARN) && printk_ratelimit())
                dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes), total 
%lu (slots), used %lu (slots)\n",
                         alloc_size, swiotlb->nslabs, tmp_io_tlb_used);
-       return (phys_addr_t)DMA_MAPPING_ERROR;
+       return -ENOMEM;
+
 found:
        swiotlb->used += nslots;
        spin_unlock_irqrestore(&swiotlb->lock, flags);
 
-       /*
-        * Save away the mapping from the original address to the DMA address.
-        * This is needed when we sync the memory.  Then we sync the buffer if
-        * needed.
-        */
-       for (i = 0; i < nslots; i++)
-               swiotlb->orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT);
-       if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
-           (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
-               swiotlb_bounce(orig_addr, tlb_addr, mapping_size, 
DMA_TO_DEVICE);
-
-       return tlb_addr;
+       return index;
 }
 
-/*
- * tlb_addr is the physical address of the bounce buffer to unmap.
- */
-void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
-                             size_t mapping_size, size_t alloc_size,
-                             enum dma_data_direction dir, unsigned long attrs)
+static void swiotlb_tbl_release_region(struct device *hwdev, int index, size_t 
size)
 {
        struct swiotlb *swiotlb = get_swiotlb(hwdev);
        unsigned long flags;
-       int i, count, nslots = ALIGN(alloc_size, 1 << IO_TLB_SHIFT) >> 
IO_TLB_SHIFT;
-       int index = (tlb_addr - swiotlb->start) >> IO_TLB_SHIFT;
-       phys_addr_t orig_addr = swiotlb->orig_addr[index];
-
-       /*
-        * First, sync the memory before unmapping the entry
-        */
-       if (orig_addr != INVALID_PHYS_ADDR &&
-           !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
-           ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))
-               swiotlb_bounce(orig_addr, tlb_addr, mapping_size, 
DMA_FROM_DEVICE);
+       int i, count, nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
 
        /*
         * Return the buffer to the free list by setting the corresponding
@@ -694,6 +657,69 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, 
phys_addr_t tlb_addr,
        spin_unlock_irqrestore(&swiotlb->lock, flags);
 }
 
+phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr,
+                                  size_t mapping_size, size_t alloc_size,
+                                  enum dma_data_direction dir,
+                                  unsigned long attrs)
+{
+       struct swiotlb *swiotlb = get_swiotlb(hwdev);
+       dma_addr_t tbl_dma_addr = phys_to_dma_unencrypted(hwdev, 
swiotlb->start);
+       phys_addr_t tlb_addr;
+       unsigned int nslots, index;
+       int i;
+
+       if (mem_encrypt_active())
+               pr_warn_once("Memory encryption is active and system is using 
DMA bounce buffers\n");
+
+       if (mapping_size > alloc_size) {
+               dev_warn_once(hwdev, "Invalid sizes (mapping: %zd bytes, alloc: 
%zd bytes)",
+                             mapping_size, alloc_size);
+               return (phys_addr_t)DMA_MAPPING_ERROR;
+       }
+
+       index = swiotlb_tbl_find_free_region(hwdev, tbl_dma_addr, alloc_size, 
attrs);
+       if (index < 0)
+               return (phys_addr_t)DMA_MAPPING_ERROR;
+
+       tlb_addr = swiotlb->start + (index << IO_TLB_SHIFT);
+
+       /*
+        * Save away the mapping from the original address to the DMA address.
+        * This is needed when we sync the memory.  Then we sync the buffer if
+        * needed.
+        */
+       nslots = ALIGN(alloc_size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
+       for (i = 0; i < nslots; i++)
+               swiotlb->orig_addr[index + i] = orig_addr + (i << IO_TLB_SHIFT);
+       if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
+           (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
+               swiotlb_bounce(orig_addr, tlb_addr, mapping_size, 
DMA_TO_DEVICE);
+
+       return tlb_addr;
+}
+
+/*
+ * tlb_addr is the physical address of the bounce buffer to unmap.
+ */
+void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
+                             size_t mapping_size, size_t alloc_size,
+                             enum dma_data_direction dir, unsigned long attrs)
+{
+       struct swiotlb *swiotlb = get_swiotlb(hwdev);
+       int index = (tlb_addr - swiotlb->start) >> IO_TLB_SHIFT;
+       phys_addr_t orig_addr = swiotlb->orig_addr[index];
+
+       /*
+        * First, sync the memory before unmapping the entry
+        */
+       if (orig_addr != INVALID_PHYS_ADDR &&
+           !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
+           ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))
+               swiotlb_bounce(orig_addr, tlb_addr, mapping_size, 
DMA_FROM_DEVICE);
+
+       swiotlb_tbl_release_region(hwdev, index, alloc_size);
+}
+
 void swiotlb_tbl_sync_single(struct device *hwdev, phys_addr_t tlb_addr,
                             size_t size, enum dma_data_direction dir,
                             enum dma_sync_target target)
-- 
2.30.0.478.g8a0d178c01-goog