From: Grygorii Strashko <grygorii.strashko@xxxxxx>
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: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Olof Johansson <olof@xxxxxxxxx>
Cc: Grant Likely <grant.likely@xxxxxxxxxx>
Cc: Rob Herring <robh+dt@xxxxxxxxxx>
Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
---
drivers/dma/of-dma.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/of_dma.h | 8 +++++
2 files changed, 94 insertions(+)
diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c
index e8fe9dc..9b51768 100644
--- a/drivers/dma/of-dma.c
+++ b/drivers/dma/of-dma.c
@@ -17,6 +17,7 @@
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/of_dma.h>
+#include <linux/of_address.h>
static LIST_HEAD(of_dma_list);
static DEFINE_MUTEX(of_dma_lock);
@@ -218,3 +219,88 @@ struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
&dma_spec->args[0]);
}
EXPORT_SYMBOL_GPL(of_dma_simple_xlate);
+
+/**
+ * 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-range" 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.
+ */
+extern int of_dma_get_range(struct device_node *np, dma_addr_t *dma_addr,
+ phys_addr_t *paddr, phys_addr_t *size)
+{
+ struct device_node *node = np;
+ const u32 *ranges = NULL;
+ int len, naddr, nsize, pna;
+ int ret = 0;
+
+ 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
+ */
+ *dma_addr = of_read_number(ranges, naddr);
+ *paddr = of_translate_dma_address(np, ranges);
+ if (*paddr == OF_BAD_ADDR) {
+ pr_err("%s: translation of DMA address(%#08x) to CPU address failed node(%s)\n",
+ __func__, *dma_addr, np->full_name);
+ ret = -EINVAL;
+ }
+
+ *size = of_read_number(ranges + naddr + pna, nsize);
+
+ pr_debug("dma_addr(%08x) cpu_addr(%pa) size(%pa)\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_dma.h b/include/linux/of_dma.h
index ae36298..f04171a 100644
--- a/include/linux/of_dma.h
+++ b/include/linux/of_dma.h
@@ -41,6 +41,9 @@ extern struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
const char *name);
extern struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
struct of_dma *ofdma);
+
+extern int of_dma_get_range(struct device_node *np, dma_addr_t *dma_addr,
+ phys_addr_t *paddr, phys_addr_t *size);
#else
static inline int of_dma_controller_register(struct device_node *np,
struct dma_chan *(*of_dma_xlate)
@@ -66,6 +69,11 @@ static inline struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_s
return NULL;
}
+static inline int of_dma_get_range(struct device_node *np, dma_addr_t *dma_addr,
+ phys_addr_t *paddr, phys_addr_t *size);
+{
+ return -ENODEV;
+}
#endif
#endif /* __LINUX_OF_DMA_H */
--
1.7.9.5
--
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