[PATCH v3 2/7] of: introduce of_dma_get_range() helper

Santosh Shilimkar
2014-04-24T15:34:57Z

From: Grygorii Strashko <grygorii.strashko@ti.com>

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: Rob Herring <robh+dt@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
---
drivers/of/address.c | 87 ++++++++++++++++++++++++++++++++++++++++++++
include/linux/of_address.h | 8 ++++
2 files changed, 95 insertions(+)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index cb4242a..c54baee 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 5f6ed6b..4d7b325 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
--
1.7.9.5