dm: clk: Add support for decoding clocks from the device tree

Add a method which can locate a clock for a device, given its index. This
uses the normal device tree bindings to return the clock device and the
first argument which is normally used as a peripheral ID in U-Boot.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>

diff --git a/drivers/clk/clk-uclass.c b/drivers/clk/clk-uclass.c
index 19f6f07c6f43ead3c12813afe6bb6d3a15b7073b..8a4c5680df6619d9101579fc52a635c2693b3cd4 100644 (file)
--- a/drivers/clk/clk-uclass.c
+++ b/drivers/clk/clk-uclass.c
@@ -12,6 +12,8 @@
 #include <dm/lists.h>
 #include <dm/root.h>
 
+DECLARE_GLOBAL_DATA_PTR;
+
 ulong clk_get_rate(struct udevice *dev)
 {
        struct clk_ops *ops = clk_get_ops(dev);
@@ -62,6 +64,32 @@ ulong clk_set_periph_rate(struct udevice *dev, int periph, ulong rate)
        return ops->set_periph_rate(dev, periph, rate);
 }
 
+#if CONFIG_IS_ENABLED(OF_CONTROL)
+int clk_get_by_index(struct udevice *dev, int index, struct udevice **clk_devp)
+{
+       struct fdtdec_phandle_args args;
+       int ret;
+
+       assert(*clk_devp);
+       ret = fdtdec_parse_phandle_with_args(gd->fdt_blob, dev->of_offset,
+                                            "clocks", "#clock-cells", 0, index,
+                                            &args);
+       if (ret) {
+               debug("%s: fdtdec_parse_phandle_with_args failed: err=%d\n",
+                     __func__, ret);
+               return ret;
+       }
+
+       ret = uclass_get_device_by_of_offset(UCLASS_CLK, args.node, clk_devp);
+       if (ret) {
+               debug("%s: uclass_get_device_by_of_offset failed: err=%d\n",
+                     __func__, ret);
+               return ret;
+       }
+       return args.args_count > 0 ? args.args[0] : 0;
+}
+#endif
+
 UCLASS_DRIVER(clk) = {
        .id             = UCLASS_CLK,
        .name           = "clk",

diff --git a/include/clk.h b/include/clk.h
index 941808a50e253a83dda83d8fecaaa01c5292d50b..ca20c3dd27c1c5de8a66c3049c6d042e2b05d433 100644 (file)
--- a/include/clk.h
+++ b/include/clk.h
@@ -8,6 +8,7 @@
 #ifndef _CLK_H_
 #define _CLK_H_
 
+#include <errno.h>
 #include <linux/types.h>
 
 struct udevice;
@@ -105,4 +106,27 @@ ulong clk_get_periph_rate(struct udevice *dev, int periph);
  */
 ulong clk_set_periph_rate(struct udevice *dev, int periph, ulong rate);
 
+#if CONFIG_IS_ENABLED(OF_CONTROL)
+/**
+ * clk_get_by_index() - look up a clock referenced by a device
+ *
+ * Parse a device's 'clocks' list, returning information on the indexed clock,
+ * ensuring that it is activated.
+ *
+ * @dev:       Device containing the clock reference
+ * @index:     Clock index to return (0 = first)
+ * @clk_devp:  Returns clock device
+ * @return:    Peripheral ID for the device to control. This is the first
+ *             argument after the clock node phandle. If there is no arguemnt,
+ *             returns 0. Return -ve error code on any error
+ */
+int clk_get_by_index(struct udevice *dev, int index, struct udevice **clk_devp);
+#else
+static inline int clk_get_by_index(struct udevice *dev, int index,
+                                  struct udevice **clk_devp)
+{
+       return -ENOSYS;
+}
+#endif
+
 #endif /* _CLK_H_ */