dt:/bindings: DRA7 ATL (Audio Tracking Logic) clock bindings

Audio Tracking Logic is designed to be used by HD Radio applications to
synchronize the audio output clocks to the baseband clock. ATL can be also
used to track errors between two reference clocks (BWS, AWS) and generate a modulated
clock output which averages to some desired frequency.
In essence ATL is generating a clock to be used by an audio codec and also
to be used by the SoC as MCLK.

To be able to integrate the ATL provided clocks to the clock tree we need
two types of DT binding:
- DT clock nodes to represent the ATL clocks towards the CCF
- binding for the ATL IP itself which is going to handle the hw
  configuration

The reason for this type of setup is that ATL itself is a separate device
in the SoC, it has it's own address space and clock domain. Other IPs can
use the ATL generated clock as their functional clock (McASPs for example)
and external components like audio codecs can also use the very same clock
as their MCLK.

The ATL IP in DRA7 contains 4 ATL instences.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Tero Kristo <t-kristo@ti.com>

1 files changed, 96 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/clock/ti/dra7-atl.txt b/Documentation/devicetree/bindings/clock/ti/dra7-atl.txt
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+++ b/Documentation/devicetree/bindings/clock/ti/dra7-atl.txt
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+Device Tree Clock bindings for ATL (Audio Tracking Logic) of DRA7 SoC.
+
+The ATL IP is used to generate clock to be used to synchronize baseband and
+audio codec. A single ATL IP provides four ATL clock instances sharing the same
+functional clock but can be configured to provide different clocks.
+ATL can maintain a clock averages to some desired frequency based on the bws/aws
+signals - can compensate the drift between the two ws signal.
+
+In order to provide the support for ATL and it's output clocks (which can be used
+internally within the SoC or external components) two sets of bindings is needed:
+
+Clock tree binding:
+This binding uses the common clock binding[1].
+To be able to integrate the ATL clocks with DT clock tree.
+Provides ccf level representation of the ATL clocks to be used by drivers.
+Since the clock instances are part of a single IP this binding is used as a node
+for the DT clock tree, the IP driver is needed to handle the actual configuration
+of the IP.
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+Required properties:
+- compatible : shall be "ti,dra7-atl-clock"
+- #clock-cells : from common clock binding; shall be set to 0.
+- clocks : link phandles to functional clock of ATL
+
+Binding for the IP driver:
+This binding is used to configure the IP driver which is going to handle the
+configuration of the IP for the ATL clock instances.
+
+Required properties:
+- compatible : shall be "ti,dra7-atl"
+- reg : base address for the ATL IP
+- ti,provided-clocks : List of phandles to the clocks associated with the ATL
+- clocks : link phandles to functional clock of ATL
+- clock-names : Shall be set to "fck"
+- ti,hwmods : Shall be set to "atl"
+
+Optional properties:
+Configuration of ATL instances:
+- atl{0/1/2/3} {
+        - bws : Baseband word select signal selection
+        - aws : Audio word select signal selection
+};
+
+For valid word select signals, see the dt-bindings/clk/ti-dra7-atl.h include
+file.
+
+Examples:
+/* clock bindings for atl provided clocks */
+atl_clkin0_ck: atl_clkin0_ck {
+        #clock-cells = <0>;
+        compatible = "ti,dra7-atl-clock";
+        clocks = <&atl_gfclk_mux>;
+};
+
+atl_clkin1_ck: atl_clkin1_ck {
+        #clock-cells = <0>;
+        compatible = "ti,dra7-atl-clock";
+        clocks = <&atl_gfclk_mux>;
+};
+
+atl_clkin2_ck: atl_clkin2_ck {
+        #clock-cells = <0>;
+        compatible = "ti,dra7-atl-clock";
+        clocks = <&atl_gfclk_mux>;
+};
+
+atl_clkin3_ck: atl_clkin3_ck {
+        #clock-cells = <0>;
+        compatible = "ti,dra7-atl-clock";
+        clocks = <&atl_gfclk_mux>;
+};
+
+/* binding for the IP */
+atl: atl@4843c000 {
+        compatible = "ti,dra7-atl";
+        reg = <0x4843c000 0x3ff>;
+        ti,hwmods = "atl";
+        ti,provided-clocks = <&atl_clkin0_ck>, <&atl_clkin1_ck>,
+                                <&atl_clkin2_ck>, <&atl_clkin3_ck>;
+        clocks = <&atl_gfclk_mux>;
+        clock-names = "fck";
+        status = "disabled";
+};
+
+#include <dt-bindings/clk/ti-dra7-atl.h>
+
+&atl {
+        status = "okay";
+
+        atl2 {
+                bws = <DRA7_ATL_WS_MCASP2_FSX>;
+                aws = <DRA7_ATL_WS_MCASP3_FSX>;
+        };
+};