of: introduce of_dma_get_range() helper

The of_dma_get_range() allows to find "dma-range" property for
the specified device and parse it.
 dma-ranges format:
   DMA addr (dma_addr)          : naddr cells
   CPU addr (phys_addr_t)       : pna cells
   size                         : nsize cells

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Olof Johansson <olof@lixom.net>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>

2 files changed, 95 insertions, 0 deletions

diff --git a/drivers/of/address.c b/drivers/of/address.c
index cb4242a69cd5..c54baee87d93 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -721,3 +721,90 @@ void __iomem *of_iomap(struct device_node *np, int index)
         return ioremap(res.start, resource_size(&res));
 }
 EXPORT_SYMBOL(of_iomap);
+
+/**
+ * of_dma_get_range - Get DMA range info
+ * @np:         device node to get DMA range info
+ * @dma_addr:   pointer to store initial DMA address of DMA range
+ * @paddr:      pointer to store initial CPU address of DMA range
+ * @size:       pointer to store size of DMA range
+ *
+ * Look in bottom up direction for the first "dma-ranges" property
+ * and parse it.
+ *  dma-ranges format:
+ *      DMA addr (dma_addr)     : naddr cells
+ *      CPU addr (phys_addr_t)  : pna cells
+ *      size                    : nsize cells
+ *
+ * It returns -ENODEV if "dma-ranges" property was not found
+ * for this device in DT.
+ */
+int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *size)
+{
+        struct device_node *node = of_node_get(np);
+        const __be32 *ranges = NULL;
+        int len, naddr, nsize, pna;
+        int ret = 0;
+        u64 dmaaddr;
+
+        if (!node)
+                return -EINVAL;
+
+        while (1) {
+                naddr = of_n_addr_cells(node);
+                nsize = of_n_size_cells(node);
+                node = of_get_next_parent(node);
+                if (!node)
+                        break;
+
+                ranges = of_get_property(node, "dma-ranges", &len);
+
+                /* Ignore empty ranges, they imply no translation required */
+                if (ranges && len > 0)
+                        break;
+
+                /*
+                 * At least empty ranges has to be defined for parent node if
+                 * DMA is supported
+                 */
+                if (!ranges)
+                        break;
+        }
+
+        if (!ranges) {
+                pr_debug("%s: no dma-ranges found for node(%s)\n",
+                         __func__, np->full_name);
+                ret = -ENODEV;
+                goto out;
+        }
+
+        len /= sizeof(u32);
+
+        pna = of_n_addr_cells(node);
+
+        /* dma-ranges format:
+         * DMA addr     : naddr cells
+         * CPU addr     : pna cells
+         * size         : nsize cells
+         */
+        dmaaddr = of_read_number(ranges, naddr);
+        *paddr = of_translate_dma_address(np, ranges);
+        if (*paddr == OF_BAD_ADDR) {
+                pr_err("%s: translation of DMA address(%pad) to CPU address failed node(%s)\n",
+                       __func__, dma_addr, np->full_name);
+                ret = -EINVAL;
+                goto out;
+        }
+        *dma_addr = dmaaddr;
+
+        *size = of_read_number(ranges + naddr + pna, nsize);
+
+        pr_debug("dma_addr(%llx) cpu_addr(%llx) size(%llx)\n",
+                 *dma_addr, *paddr, *size);
+
+out:
+        of_node_put(node);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(of_dma_get_range);
diff --git a/include/linux/of_address.h b/include/linux/of_address.h
index 5f6ed6b182b8..4d7b325af2ca 100644
--- a/include/linux/of_address.h
+++ b/include/linux/of_address.h
@@ -63,6 +63,8 @@ extern int of_pci_range_parser_init(struct of_pci_range_parser *parser,
 extern struct of_pci_range *of_pci_range_parser_one(
                                         struct of_pci_range_parser *parser,
                                         struct of_pci_range *range);
+extern int of_dma_get_range(struct device_node *np, u64 *dma_addr,
+                                u64 *paddr, u64 *size);
 #else /* CONFIG_OF_ADDRESS */
 static inline struct device_node *of_find_matching_node_by_address(
                                         struct device_node *from,
@@ -90,6 +92,12 @@ static inline struct of_pci_range *of_pci_range_parser_one(
 {
         return NULL;
 }
+
+static inline int of_dma_get_range(struct device_node *np, u64 *dma_addr,
+                                u64 *paddr, u64 *size)
+{
+        return -ENODEV;
+}
 #endif /* CONFIG_OF_ADDRESS */
 
 #ifdef CONFIG_OF