[PATCH v6 15/20] tegra: fdt: Add function to return peripheral/clock ID

[Simon Glass <sjg@chromium.org>]

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>
---
Changes in v4:
- Add fdtdec function to return peripheral ID

Changes in v6:
- Move peripheral decode function into Tegra's clock.c

 arch/arm/cpu/armv7/tegra2/clock.c        |   19 +++++++++++++++++++
 arch/arm/include/asm/arch-tegra2/clock.h |   13 +++++++++++++
 2 files changed, 32 insertions(+), 0 deletions(-)

diff --git a/arch/arm/cpu/armv7/tegra2/clock.c b/arch/arm/cpu/armv7/tegra2/clock.c
index 11d2346..ffbfc28 100644
--- a/arch/arm/cpu/armv7/tegra2/clock.c
+++ b/arch/arm/cpu/armv7/tegra2/clock.c
@@ -28,6 +28,7 @@
 #include <asm/arch/tegra2.h>
 #include <common.h>
 #include <div64.h>
+#include <fdtdec.h>
 
 /*
  * This is our record of the current clock rate of each clock. We don't
@@ -918,6 +919,24 @@ void clock_ll_start_uart(enum periph_id periph_id)
 	reset_set_enable(periph_id, 0);
 }
 
+
+int clock_decode_periph_id(const void *blob, int node)
+{
+	enum periph_id id;
+	int err, valid;
+	u32 cell[2];
+
+	err = fdtdec_get_int_array(blob, node, "clocks", cell,
+				   ARRAY_SIZE(cell));
+	if (err)
+		return -1;
+	id = cell[1];
+
+	valid = clock_periph_id_isvalid(id);
+	assert(valid);
+	return valid ? id : PERIPH_ID_NONE;
+}
+
 int clock_verify(void)
 {
 	struct clk_pll *pll = get_pll(CLOCK_ID_PERIPH);
diff --git a/arch/arm/include/asm/arch-tegra2/clock.h b/arch/arm/include/asm/arch-tegra2/clock.h
index 080ef18..6b12c76 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
  *
-- 
1.7.7.3