tegra: fdt: Add function to return peripheral/clock ID

A common requirement is to find the clock ID for a peripheral. This is the
second cell of the 'clocks' property (the first being the phandle itself).

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/arch/arm/include/asm/arch-tegra2/clock.h b/arch/arm/include/asm/arch-tegra2/clock.h
index 080ef18e81..6b12c76e8d 100644
--- a/arch/arm/include/asm/arch-tegra2/clock.h
+++ b/arch/arm/include/asm/arch-tegra2/clock.h
@@ -177,6 +177,7 @@ enum periph_id {
 	PERIPH_ID_CRAM2,
 
 	PERIPH_ID_COUNT,
+	PERIPH_ID_NONE = -1,
 };
 
 /* Converts a clock number to a clock register: 0=L, 1=H, 2=U */
@@ -355,6 +356,18 @@ unsigned clock_get_rate(enum clock_id clkid);
  */
 void clock_ll_start_uart(enum periph_id periph_id);
 
+/**
+ * Decode a peripheral ID from a device tree node.
+ *
+ * This works by looking up the peripheral's 'clocks' node and reading out
+ * the second cell, which is the clock number / peripheral ID.
+ *
+ * @param blob		FDT blob to use
+ * @param node		Node to look at
+ * @return peripheral ID, or PERIPH_ID_NONE if none
+ */
+enum periph_id clock_decode_periph_id(const void *blob, int node);
+
 /*
  * Checks that clocks are valid and prints a warning if not
  *