[PATCH v8 04/15] swiotlb: Add restricted DMA pool initialization

[Claire Chang <tientzu@xxxxxxxxxxxx>]

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

Signed-off-by: Claire Chang <tientzu@xxxxxxxxxxxx>
---
 include/linux/device.h  |  4 +++
 include/linux/swiotlb.h |  3 +-
 kernel/dma/swiotlb.c    | 76 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 82 insertions(+), 1 deletion(-)

diff --git a/include/linux/device.h b/include/linux/device.h
index 959cb9d2c9ab..e78e1ce0b1b1 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -416,6 +416,7 @@ 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.
@@ -521,6 +522,9 @@ struct device {
 #ifdef CONFIG_DMA_CMA
 	struct cma *cma_area;		/* contiguous memory area for dma
 					   allocations */
+#endif
+#ifdef CONFIG_DMA_RESTRICTED_POOL
+	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 216854a5e513..03ad6e3b4056 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -72,7 +72,8 @@ extern enum swiotlb_force swiotlb_force;
  *		range check to see if the memory was in fact allocated by this
  *		API.
  * @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/swiotlb.c b/kernel/dma/swiotlb.c
index b849b01a446f..d99b403144a8 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -39,6 +39,13 @@
 #ifdef CONFIG_DEBUG_FS
 #include <linux/debugfs.h>
 #endif
+#ifdef CONFIG_DMA_RESTRICTED_POOL
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/of_reserved_mem.h>
+#include <linux/slab.h>
+#endif
 
 #include <asm/io.h>
 #include <asm/dma.h>
@@ -690,3 +697,72 @@ static int __init swiotlb_create_default_debugfs(void)
 late_initcall(swiotlb_create_default_debugfs);
 
 #endif
+
+#ifdef CONFIG_DMA_RESTRICTED_POOL
+static int rmem_swiotlb_device_init(struct reserved_mem *rmem,
+				    struct device *dev)
+{
+	struct io_tlb_mem *mem = rmem->priv;
+	unsigned long nslabs = rmem->size >> IO_TLB_SHIFT;
+
+	if (dev->dma_io_tlb_mem)
+		return 0;
+
+	/*
+	 * Since multiple devices can share the same pool, the private data,
+	 * io_tlb_mem struct, will be initialized by the first device attached
+	 * to it.
+	 */
+	if (!mem) {
+		mem = kzalloc(struct_size(mem, slots, nslabs), GFP_KERNEL);
+		if (!mem)
+			return -ENOMEM;
+
+		swiotlb_init_io_tlb_mem(mem, rmem->base, nslabs, false);
+
+		rmem->priv = mem;
+
+		if (IS_ENABLED(CONFIG_DEBUG_FS))
+			swiotlb_create_debugfs(mem, rmem->name);
+	}
+
+	dev->dma_io_tlb_mem = mem;
+
+	return 0;
+}
+
+static void rmem_swiotlb_device_release(struct reserved_mem *rmem,
+					struct device *dev)
+{
+	if (dev)
+		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;
+
+	if (PageHighMem(pfn_to_page(PHYS_PFN(rmem->base)))) {
+		pr_err("Restricted DMA pool must be accessible within the linear mapping.");
+		return -EINVAL;
+	}
+
+	rmem->ops = &rmem_swiotlb_ops;
+	pr_info("Reserved memory: created restricted DMA 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);
+#endif /* CONFIG_DMA_RESTRICTED_POOL */
-- 
2.31.1.818.g46aad6cb9e-goog