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, 40 insertions, 0 deletions

diff --git a/arch/arm/include/asm/arch-tegra/clock.h b/arch/arm/include/asm/arch-tegra/clock.h
index e0737f574ad..388afcb7231 100644
--- a/arch/arm/include/asm/arch-tegra/clock.h
+++ b/arch/arm/include/asm/arch-tegra/clock.h
@@ -187,6 +187,16 @@ void clock_ll_set_source_divisor(enum periph_id periph_id, unsigned source,
 		unsigned divisor);
 
 /**
+ * Returns the current parent clock ID of a given peripheral. This can be
+ * useful in order to call clock_*_periph_*() from generic code that has no
+ * specific knowledge of system-level clock tree structure.
+ *
+ * @param periph_id	peripheral to query
+ * @return clock ID of the peripheral's current parent clock
+ */
+enum clock_id clock_get_periph_parent(enum periph_id periph_id);
+
+/**
  * Start a peripheral PLL clock at the given rate. This also resets the
  * peripheral.
  *
@@ -284,6 +294,36 @@ u32 *get_periph_source_reg(enum periph_id periph_id);
 /* Returns a pointer to the given 'simple' PLL */
 struct clk_pll_simple *clock_get_simple_pll(enum clock_id clkid);
 
+/*
+ * Given a peripheral ID, determine where the mux bits are in the peripheral
+ * clock's register, the number of divider bits the clock has, and the SoC-
+ * specific clock type.
+ *
+ * This is an internal API between the core Tegra clock code and the SoC-
+ * specific clock code.
+ *
+ * @param periph_id     peripheral to query
+ * @param mux_bits      Set to number of bits in mux register
+ * @param divider_bits  Set to the relevant MASK_BITS_* value
+ * @param type          Set to the SoC-specific clock type
+ * @return 0 on success, -1 on error
+ */
+int get_periph_clock_info(enum periph_id periph_id, int *mux_bits,
+			  int *divider_bits, int *type);
+
+/*
+ * Given a peripheral ID and clock source mux value, determine the clock_id
+ * of that peripheral's parent.
+ *
+ * This is an internal API between the core Tegra clock code and the SoC-
+ * specific clock code.
+ *
+ * @param periph_id     peripheral to query
+ * @param source        raw clock source mux value
+ * @return the CLOCK_ID_* value @source represents
+ */
+enum clock_id get_periph_clock_id(enum periph_id periph_id, int source);
+
 /**
  * Given a peripheral ID and the required source clock, this returns which
  * value should be programmed into the source mux for that peripheral.