of/address: Introduce of_dma_get_max_cpu_address()

Introduce of_dma_get_max_cpu_address(), which provides the highest CPU
physical address addressable by all DMA masters in the system. It's
specially useful for setting memory zones sizes at early boot time.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201119175400.9995-4-nsaenzjulienne@suse.de
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/drivers/of/address.c b/drivers/of/address.c
index eb9ab4f1e80b00c124e916ded75dfa597897ce75..09c0af7fd1c4480d6bd9f17bb4051bd49b514d0e 100644 (file)
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -1024,6 +1024,48 @@ out:
 }
 #endif /* CONFIG_HAS_DMA */
 
+/**
+ * of_dma_get_max_cpu_address - Gets highest CPU address suitable for DMA
+ * @np: The node to start searching from or NULL to start from the root
+ *
+ * Gets the highest CPU physical address that is addressable by all DMA masters
+ * in the sub-tree pointed by np, or the whole tree if NULL is passed. If no
+ * DMA constrained device is found, it returns PHYS_ADDR_MAX.
+ */
+phys_addr_t __init of_dma_get_max_cpu_address(struct device_node *np)
+{
+       phys_addr_t max_cpu_addr = PHYS_ADDR_MAX;
+       struct of_range_parser parser;
+       phys_addr_t subtree_max_addr;
+       struct device_node *child;
+       struct of_range range;
+       const __be32 *ranges;
+       u64 cpu_end = 0;
+       int len;
+
+       if (!np)
+               np = of_root;
+
+       ranges = of_get_property(np, "dma-ranges", &len);
+       if (ranges && len) {
+               of_dma_range_parser_init(&parser, np);
+               for_each_of_range(&parser, &range)
+                       if (range.cpu_addr + range.size > cpu_end)
+                               cpu_end = range.cpu_addr + range.size - 1;
+
+               if (max_cpu_addr > cpu_end)
+                       max_cpu_addr = cpu_end;
+       }
+
+       for_each_available_child_of_node(np, child) {
+               subtree_max_addr = of_dma_get_max_cpu_address(child);
+               if (max_cpu_addr > subtree_max_addr)
+                       max_cpu_addr = subtree_max_addr;
+       }
+
+       return max_cpu_addr;
+}
+
 /**
  * of_dma_is_coherent - Check if device is coherent
  * @np:        device node

diff --git a/include/linux/of.h b/include/linux/of.h
index 5d51891cbf1a68b38dbe65745555759b7dd653e0..9ed5b8532c30318786831c0fb1183f86d40e4073 100644 (file)
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -558,6 +558,8 @@ int of_map_id(struct device_node *np, u32 id,
               const char *map_name, const char *map_mask_name,
               struct device_node **target, u32 *id_out);
 
+phys_addr_t of_dma_get_max_cpu_address(struct device_node *np);
+
 #else /* CONFIG_OF */
 
 static inline void of_core_init(void)
@@ -995,6 +997,11 @@ static inline int of_map_id(struct device_node *np, u32 id,
        return -EINVAL;
 }
 
+static inline phys_addr_t of_dma_get_max_cpu_address(struct device_node *np)
+{
+       return PHYS_ADDR_MAX;
+}
+
 #define of_match_ptr(_ptr)     NULL
 #define of_match_node(_matches, _node) NULL
 #endif /* CONFIG_OF */