[RFC PATCH v3 2/6] swiotlb: Add restricted DMA pool

[Claire Chang <tientzu@xxxxxxxxxxxx>]

Add the initialization function to create restricted DMA pools from
matching reserved-memory nodes in the device tree.

Signed-off-by: Claire Chang <tientzu@xxxxxxxxxxxx>
---
 include/linux/device.h  |   4 ++
 include/linux/swiotlb.h |   7 +-
 kernel/dma/Kconfig      |   1 +
 kernel/dma/swiotlb.c    | 144 ++++++++++++++++++++++++++++++++++------
 4 files changed, 131 insertions(+), 25 deletions(-)

diff --git a/include/linux/device.h b/include/linux/device.h
index 89bb8b84173e..ca6f71ec8871 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -413,6 +413,7 @@ struct dev_links_info {
  * @dma_pools: Dma pools (if dma'ble device).
  * @dma_mem:   Internal for coherent mem override.
  * @cma_area:  Contiguous memory area for dma allocations
+ * @dma_io_tlb_mem: Internal for swiotlb io_tlb_mem override.
  * @archdata:  For arch-specific additions.
  * @of_node:   Associated device tree node.
  * @fwnode:    Associated device node supplied by platform firmware.
@@ -515,6 +516,9 @@ struct device {
 #ifdef CONFIG_DMA_CMA
        struct cma *cma_area;           /* contiguous memory area for dma
                                           allocations */
+#endif
+#ifdef CONFIG_SWIOTLB
+       struct io_tlb_mem       *dma_io_tlb_mem;
 #endif
        /* arch specific additions */
        struct dev_archdata     archdata;
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index dd8eb57cbb8f..a1bbd7788885 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -76,12 +76,13 @@ extern enum swiotlb_force swiotlb_force;
  *
  * @start:     The start address of the swiotlb memory pool. Used to do a quick
  *             range check to see if the memory was in fact allocated by this
- *             API.
+ *             API. For restricted DMA pool, this is device tree adjustable.
  * @end:       The end address of the swiotlb memory pool. Used to do a quick
  *             range check to see if the memory was in fact allocated by this
- *             API.
+ *             API. For restricted DMA pool, this is device tree adjustable.
  * @nslabs:    The number of IO TLB blocks (in groups of 64) between @start and
- *             @end. This is command line adjustable via setup_io_tlb_npages.
+ *             @end. For default swiotlb, this is command line adjustable via
+ *             setup_io_tlb_npages.
  * @used:      The number of used IO TLB block.
  * @list:      The free list describing the number of free entries available
  *             from each index.
diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig
index 479fc145acfc..131a0a66781b 100644
--- a/kernel/dma/Kconfig
+++ b/kernel/dma/Kconfig
@@ -82,6 +82,7 @@ config ARCH_HAS_FORCE_DMA_UNENCRYPTED
 config SWIOTLB
        bool
        select NEED_DMA_MAP_STATE
+       select OF_EARLY_FLATTREE
 
 #
 # Should be selected if we can mmap non-coherent mappings to userspace.
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index e4368159f88a..7fb2ac087d23 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -36,6 +36,11 @@
 #include <linux/scatterlist.h>
 #include <linux/mem_encrypt.h>
 #include <linux/set_memory.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/of_reserved_mem.h>
+#include <linux/slab.h>
 #ifdef CONFIG_DEBUG_FS
 #include <linux/debugfs.h>
 #endif
@@ -319,20 +324,21 @@ static void swiotlb_cleanup(void)
        max_segment = 0;
 }
 
-int
-swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
+static int swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start,
+                                  size_t size)
 {
-       struct io_tlb_mem *mem = &io_tlb_default_mem;
-       unsigned long i, bytes;
+       unsigned long i;
+       void *vaddr = phys_to_virt(start);
 
-       bytes = nslabs << IO_TLB_SHIFT;
+       size = ALIGN(size, 1 << IO_TLB_SHIFT);
+       mem->nslabs = size >> IO_TLB_SHIFT;
+       mem->nslabs = ALIGN(mem->nslabs, IO_TLB_SEGSIZE);
 
-       mem->nslabs = nslabs;
-       mem->start = virt_to_phys(tlb);
-       mem->end = mem->start + bytes;
+       mem->start = start;
+       mem->end = mem->start + size;
 
-       set_memory_decrypted((unsigned long)tlb, bytes >> PAGE_SHIFT);
-       memset(tlb, 0, bytes);
+       set_memory_decrypted((unsigned long)vaddr, size >> PAGE_SHIFT);
+       memset(vaddr, 0, size);
 
        /*
         * Allocate and initialize the free list array.  This array is used
@@ -356,13 +362,6 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
                mem->orig_addr[i] = INVALID_PHYS_ADDR;
        }
        mem->index = 0;
-       no_iotlb_memory = false;
-
-       swiotlb_print_info();
-
-       late_alloc = 1;
-
-       swiotlb_set_max_segment(mem->nslabs << IO_TLB_SHIFT);
 
        return 0;
 
@@ -375,6 +374,27 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
        return -ENOMEM;
 }
 
+int swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
+{
+       struct io_tlb_mem *mem = &io_tlb_default_mem;
+       unsigned long bytes = nslabs << IO_TLB_SHIFT;
+       int ret;
+
+       ret = swiotlb_init_io_tlb_mem(mem, virt_to_phys(tlb), bytes);
+       if (ret)
+               return ret;
+
+       no_iotlb_memory = false;
+
+       swiotlb_print_info();
+
+       late_alloc = 1;
+
+       swiotlb_set_max_segment(bytes);
+
+       return 0;
+}
+
 void __init swiotlb_exit(void)
 {
        struct io_tlb_mem *mem = &io_tlb_default_mem;
@@ -703,16 +723,96 @@ bool is_swiotlb_active(void)
 
 #ifdef CONFIG_DEBUG_FS
 
-static int __init swiotlb_create_debugfs(void)
+static void swiotlb_create_debugfs(struct io_tlb_mem *mem, const char *name,
+                                  struct dentry *node)
 {
-       struct io_tlb_mem *mem = &io_tlb_default_mem;
-
-       mem->debugfs = debugfs_create_dir("swiotlb", NULL);
+       mem->debugfs = debugfs_create_dir(name, node);
        debugfs_create_ulong("io_tlb_nslabs", 0400, mem->debugfs, &mem->nslabs);
        debugfs_create_ulong("io_tlb_used", 0400, mem->debugfs, &mem->used);
+}
+
+static int __init swiotlb_create_default_debugfs(void)
+{
+       swiotlb_create_debugfs(&io_tlb_default_mem, "swiotlb", NULL);
+
        return 0;
 }
 
-late_initcall(swiotlb_create_debugfs);
+late_initcall(swiotlb_create_default_debugfs);
 
 #endif
+
+static int rmem_swiotlb_device_init(struct reserved_mem *rmem,
+                                   struct device *dev)
+{
+       struct io_tlb_mem *mem = rmem->priv;
+       int ret;
+
+       if (dev->dma_io_tlb_mem)
+               return -EBUSY;
+
+       if (!mem) {
+               mem = kzalloc(sizeof(*mem), GFP_KERNEL);
+               if (!mem)
+                       return -ENOMEM;
+
+               if (!memremap(rmem->base, rmem->size, MEMREMAP_WB)) {
+                       ret = -EINVAL;
+                       goto cleanup;
+               }
+
+               ret = swiotlb_init_io_tlb_mem(mem, rmem->base, rmem->size);
+               if (ret)
+                       goto cleanup;
+
+               rmem->priv = mem;
+       }
+
+#ifdef CONFIG_DEBUG_FS
+       swiotlb_create_debugfs(mem, dev_name(dev), io_tlb_default_mem.debugfs);
+#endif
+
+       dev->dma_io_tlb_mem = mem;
+
+       return 0;
+
+cleanup:
+       kfree(mem);
+
+       return ret;
+}
+
+static void rmem_swiotlb_device_release(struct reserved_mem *rmem,
+                                       struct device *dev)
+{
+       if (!dev)
+               return;
+
+#ifdef CONFIG_DEBUG_FS
+       debugfs_remove_recursive(dev->dma_io_tlb_mem->debugfs);
+#endif
+       dev->dma_io_tlb_mem = NULL;
+}
+
+static const struct reserved_mem_ops rmem_swiotlb_ops = {
+       .device_init    = rmem_swiotlb_device_init,
+       .device_release = rmem_swiotlb_device_release,
+};
+
+static int __init rmem_swiotlb_setup(struct reserved_mem *rmem)
+{
+       unsigned long node = rmem->fdt_node;
+
+       if (of_get_flat_dt_prop(node, "reusable", NULL) ||
+           of_get_flat_dt_prop(node, "linux,cma-default", NULL) ||
+           of_get_flat_dt_prop(node, "linux,dma-default", NULL) ||
+           of_get_flat_dt_prop(node, "no-map", NULL))
+               return -EINVAL;
+
+       rmem->ops = &rmem_swiotlb_ops;
+       pr_info("Reserved memory: created device swiotlb memory pool at %pa, 
size %ld MiB\n",
+               &rmem->base, (unsigned long)rmem->size / SZ_1M);
+       return 0;
+}
+
+RESERVEDMEM_OF_DECLARE(dma, "restricted-dma-pool", rmem_swiotlb_setup);
-- 
2.29.2.729.g45daf8777d-goog