The addition of DT bindings for enabling and tuning spread spectrum
clocking generation can be applied specifically to the PLLs.
The "" value for the fsl,ssc-method property is specifically intended to
specify a "no SSC" case, as in the example, when you don't want to
configure spread spectrum for one of the PLLs, thus avoiding the use of
a method that would only make sense if SSC were being set.
Signed-off-by: Dario Binacchi <dario.binacchi@xxxxxxxxxxxxxxxxxxxx>
---
Changes in v6:
- Improve the commit message
- change minItems from 7 to 1 for all the ssc properties added
- change maxItems from 10 to 4 for alle the ssc properties added
- update the DTS example
Changes in v4:
- Drop "fsl,ssc-clocks" property. The other added properties now refer
to the clock list.
- Updated minItems and maxItems of
- clocks
- clock-names
- fsl,ssc-modfreq-hz
- fsl,ssc-modrate-percent
- fsl,ssc-modmethod
- Updated the dts examples
Changes in v3:
- Added in v3
- The dt-bindings have been moved from fsl,imx8m-anatop.yaml to
imx8m-clock.yaml. The anatop device (fsl,imx8m-anatop.yaml) is
indeed more or less a syscon, so it represents a memory area
accessible by ccm (imx8m-clock.yaml) to setup the PLLs.
Changes in v2:
- Add "allOf:" and place it after "required:" block, like in the
example schema.
- Move the properties definition to the top-level.
- Drop unit types as requested by the "make dt_binding_check" command.
.../bindings/clock/imx8m-clock.yaml | 38 +++++++++++++++++++
1 file changed, 38 insertions(+)
diff --git a/Documentation/devicetree/bindings/clock/imx8m-clock.yaml b/Documentation/devicetree/bindings/clock/imx8m-clock.yaml
index 05bc01960045..37cc6a6e89d4 100644
--- a/Documentation/devicetree/bindings/clock/imx8m-clock.yaml
+++ b/Documentation/devicetree/bindings/clock/imx8m-clock.yaml
@@ -43,6 +43,37 @@ properties:
ID in its "clocks" phandle cell. See include/dt-bindings/clock/imx8m-clock.h
for the full list of i.MX8M clock IDs.
+ fsl,ssc-modfreq-hz:
+ description:
+ The values of modulation frequency (Hz unit) for each clock
+ supporting spread spectrum (i. e. audio_pll1, audio_pll2,
+ dram_pll and video_pll).
+ minItems: 1
+ maxItems: 4
+
+ fsl,ssc-modrate-percent:
+ description:
+ The percentage values of modulation rate for each clock
+ supporting spread spectrum (i. e. audio_pll1, audio_pll2,
+ dram_pll and video_pll).
+ minItems: 1
+ maxItems: 4
+
+ fsl,ssc-modmethod:
+ $ref: /schemas/types.yaml#/definitions/non-unique-string-array
+ description:
+ The modulation techniques for each clock supporting spread
+ spectrum (i. e. audio_pll1, audio_pll2, dram_pll and
+ video_pll).
+ minItems: 1
+ maxItems: 4
+ items:
+ enum:
+ - ""
+ - down-spread
+ - up-spread
+ - center-spread
+
required:
- compatible
- reg
@@ -76,6 +107,10 @@ allOf:
- const: clk_ext2
- const: clk_ext3
- const: clk_ext4
+ fsl,ssc-modfreq-hz: false
+ fsl,ssc-modrate-percent: false
+ fsl,ssc-modmethod: false
+
else:
properties:
clocks:
@@ -124,6 +159,9 @@ examples:
clock-names = "osc_32k", "osc_24m", "clk_ext1", "clk_ext2",
"clk_ext3", "clk_ext4", "audio_pll1", "audio_pll2",
"dram_pll", "video_pll";
+ fsl,ssc-modfreq-hz = <6818>, <0>, <0>, <2419>;
+ fsl,ssc-modrate-percent = <3>, <0>, <0>, <7>;
+ fsl,ssc-modmethod = "down-spread", "", "", "center-spread";
};
- |
--
2.43.0
