[PATCH v4 04/16] ARM: tegra: clock: add clock_decode_pair helper

[Svyatoslav Ryhel]

Get periph clock id and its parent from device tree.
This works by looking up the peripheral's 'clocks' node and
reading out the second and fourth cells, which are the
peripheral and PLL clock numbers.

Tested-by: Andreas Westman Dorcsak <hedmoo at yahoo.com> # ASUS TF T30
Tested-by: Robert Eckelmann <longnoserob at gmail.com> # ASUS TF101 T20
Tested-by: Svyatoslav Ryhel <clamor95 at gmail.com> # HTC One X
Signed-off-by: Svyatoslav Ryhel <clamor95 at gmail.com>
---
 arch/arm/include/asm/arch-tegra/clock.h | 13 +++++++++++++
 arch/arm/mach-tegra/clock.c             | 23 +++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/arch/arm/include/asm/arch-tegra/clock.h b/arch/arm/include/asm/arch-tegra/clock.h
index 2270501406..61ef81e7fe 100644
--- a/arch/arm/include/asm/arch-tegra/clock.h
+++ b/arch/arm/include/asm/arch-tegra/clock.h
@@ -270,6 +270,19 @@ void clock_ll_start_uart(enum periph_id periph_id);
  */
 int clock_decode_periph_id(struct udevice *dev);
 
+/**
+ * Get periph clock id and its parent from device tree.
+ *
+ * This works by looking up the peripheral's 'clocks' node and reading out
+ * the second and fourth cells, which are the peripheral and PLL clock numbers.
+ *
+ * @param dev          udevice associated with FDT node
+ * @param clk_id       pointer to int array of 2 values
+ *                     first is periph clock, second is
+ *                     its PLL parent according to FDT.
+ */
+int clock_decode_pair(struct udevice *dev, int *clk_id);
+
 /**
  * Checks if the oscillator bypass is enabled (XOBP bit)
  *
diff --git a/arch/arm/mach-tegra/clock.c b/arch/arm/mach-tegra/clock.c
index 11bffc1701..966009f375 100644
--- a/arch/arm/mach-tegra/clock.c
+++ b/arch/arm/mach-tegra/clock.c
@@ -678,6 +678,29 @@ int clock_decode_periph_id(struct udevice *dev)
 	assert(clock_periph_id_isvalid(id));
 	return id;
 }
+
+/*
+ * Get periph clock id and its parent from device tree.
+ *
+ * @param dev		udevice associated with FDT node
+ * @param clk_id	pointer to u32 array of 2 values
+ *			first is periph clock, second is
+ *			its PLL parent according to FDT.
+ */
+int clock_decode_pair(struct udevice *dev, int *clk_id)
+{
+	u32 cell[4];
+	int err;
+
+	err = dev_read_u32_array(dev, "clocks", cell, ARRAY_SIZE(cell));
+	if (err)
+		return -EINVAL;
+
+	clk_id[0] = clk_id_to_periph_id(cell[1]);
+	clk_id[1] = clk_id_to_pll_id(cell[3]);
+
+	return 0;
+}
 #endif /* CONFIG_IS_ENABLED(OF_CONTROL) */
 
 int clock_verify(void)
-- 
2.37.2