swiotlb: add the late swiotlb initialization function with iotlb memory

This enables the caller to initialize swiotlb with its own iotlb
memory late in the bootup.

See git commit eb605a5754d050a25a9f00d718fb173f24c486ef
"swiotlb: add swiotlb_tbl_map_single library function" which will
explain the full details of what it can be used for.

CC: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
[v1: Fold in smatch warning]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 24 insertions, 9 deletions

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 45bc1f83a5ad..f114bf6a8e13 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -170,7 +170,7 @@ void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
  * Statically reserve bounce buffer space and initialize bounce buffer data
  * structures for the software IO TLB used to implement the DMA API.
  */
-void __init
+static void __init
 swiotlb_init_with_default_size(size_t default_size, int verbose)
 {
         unsigned long bytes;
@@ -206,8 +206,9 @@ swiotlb_init(int verbose)
 int
 swiotlb_late_init_with_default_size(size_t default_size)
 {
-        unsigned long i, bytes, req_nslabs = io_tlb_nslabs;
+        unsigned long bytes, req_nslabs = io_tlb_nslabs;
         unsigned int order;
+        int rc = 0;
 
         if (!io_tlb_nslabs) {
                 io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
@@ -229,16 +230,32 @@ swiotlb_late_init_with_default_size(size_t default_size)
                 order--;
         }
 
-        if (!io_tlb_start)
-                goto cleanup1;
-
+        if (!io_tlb_start) {
+                io_tlb_nslabs = req_nslabs;
+                return -ENOMEM;
+        }
         if (order != get_order(bytes)) {
                 printk(KERN_WARNING "Warning: only able to allocate %ld MB "
                        "for software IO TLB\n", (PAGE_SIZE << order) >> 20);
                 io_tlb_nslabs = SLABS_PER_PAGE << order;
-                bytes = io_tlb_nslabs << IO_TLB_SHIFT;
         }
+        rc = swiotlb_late_init_with_tbl(io_tlb_start, io_tlb_nslabs);
+        if (rc)
+                free_pages((unsigned long)io_tlb_start, order);
+        return rc;
+}
+
+int
+swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
+{
+        unsigned long i, bytes;
+
+        bytes = nslabs << IO_TLB_SHIFT;
+
+        io_tlb_nslabs = nslabs;
+        io_tlb_start = tlb;
         io_tlb_end = io_tlb_start + bytes;
+
         memset(io_tlb_start, 0, bytes);
 
         /*
@@ -288,10 +305,8 @@ cleanup3:
         io_tlb_list = NULL;
 cleanup2:
         io_tlb_end = NULL;
-        free_pages((unsigned long)io_tlb_start, order);
         io_tlb_start = NULL;
-cleanup1:
-        io_tlb_nslabs = req_nslabs;
+        io_tlb_nslabs = 0;
         return -ENOMEM;
 }