ARM: tegra: add APIs the clock uclass driver will need

A future patch will implement a clock uclass driver for Tegra. That driver
will call into Tegra's existing clock code to simplify the transition;
this avoids tieing the clock uclass patches into significant refactoring
of the existing custom clock API implementation.

Some of the Tegra clock APIs that manipulate peripheral clocks require
both the peripheral clock ID and parent clock ID to be passed in together.
However, the clock uclass API does not require any such "parent"
parameter, so the clock driver must determine this information itself.
This patch implements new Tegra- specific clock API
clock_get_periph_parent() for this purpose.

The new API is implemented in the core Tegra clock code rather than SoC-
specific clock code. The implementation uses various SoC-/clock-specific
data. That data is only available in SoC-specific clock code.
Consequently, two new internal APIs are added that enable the core clock
code to retrieve this information from the SoC-specific clock code. Due to
the structure of the Tegra clock code, this leads to some unfortunate code
duplication. However, this situation predates this patch.

Ideally, future work will de-duplicate the Tegra clock code, and migrate
it into drivers/clk/tegra. However, such refactoring is kept separate from
this series.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/arch/arm/mach-tegra/clock.c b/arch/arm/mach-tegra/clock.c
index 597f6286d6c..cf8bc38925d 100644
--- a/arch/arm/mach-tegra/clock.c
+++ b/arch/arm/mach-tegra/clock.c
@@ -206,6 +206,29 @@ int clock_ll_set_source_bits(enum periph_id periph_id, int mux_bits,
 	return 0;
 }
 
+static int clock_ll_get_source_bits(enum periph_id periph_id, int mux_bits)
+{
+	u32 *reg = get_periph_source_reg(periph_id);
+	u32 val = readl(reg);
+
+	switch (mux_bits) {
+	case MASK_BITS_31_30:
+		val >>= OUT_CLK_SOURCE_31_30_SHIFT;
+		val &= OUT_CLK_SOURCE_31_30_MASK;
+		return val;
+	case MASK_BITS_31_29:
+		val >>= OUT_CLK_SOURCE_31_29_SHIFT;
+		val &= OUT_CLK_SOURCE_31_29_MASK;
+		return val;
+	case MASK_BITS_31_28:
+		val >>= OUT_CLK_SOURCE_31_28_SHIFT;
+		val &= OUT_CLK_SOURCE_31_28_MASK;
+		return val;
+	default:
+		return -1;
+	}
+}
+
 void clock_ll_set_source(enum periph_id periph_id, unsigned source)
 {
 	clock_ll_set_source_bits(periph_id, MASK_BITS_31_30, source);
@@ -363,6 +386,20 @@ static int adjust_periph_pll(enum periph_id periph_id, int source,
 	return 0;
 }
 
+enum clock_id clock_get_periph_parent(enum periph_id periph_id)
+{
+	int err, mux_bits, divider_bits, type;
+	int source;
+
+	err = get_periph_clock_info(periph_id, &mux_bits, &divider_bits, &type);
+	if (err)
+		return CLOCK_ID_NONE;
+
+	source = clock_ll_get_source_bits(periph_id, mux_bits);
+
+	return get_periph_clock_id(periph_id, source);
+}
+
 unsigned clock_adjust_periph_pll_div(enum periph_id periph_id,
 		enum clock_id parent, unsigned rate, int *extra_div)
 {