This series intends to address a problem I had when using the Si5351A as
a runtime adjustable audio bit clock. The basic issue is that the driver
in its current form unconditionally resets the PLL whenever adjusting
its rate. But this reset causes an unwanted ~1.4 ms LOW signal glitch in
the clock output.
As a remedy, a new property is added to control the reset behaviour of
the PLLs more precisely. In the process I also converted the bindings to
YAML.
Changes:
v5 -> v6:
- collect Rob's Reviewed-bys
- no further changes, resend only
v4 -> v5:
- address Rob's comments:
- min/maxItems on top-level clocks:
- remove unnecessary else:
- remove spurious |
v3 -> v4:
- remove spurious | per Rob's suggestion
- simplify conditional clocks/clock-names per Rob's suggestion
- remove mention of clkout[0-7] still being admissible in the commit
body of patch 1 - while the Linux driver still tolerates this, the
new dt-bindings do not
v2 -> v3:
- address further comments from Rob:
- drop unnecessary refs and minItems
- simplify if conditions for chip variants
- ignore his comment about dropping '|', as line would be >80 columns
- move additionalProperties: false close to type: object
- define clocks/clock-names at top-level
- drop patch to dove-cubox dts per Krzysztof's comment - will send
separately
- collect Sebastian's Acked-by
v1 -> v2:
- address Rob's comments on the two dt-bindings patches
- new patch to correct the clock node names in the only upstream device
tree using si5351
---
Alvin Šipraga (3):
dt-bindings: clock: si5351: convert to yaml
dt-bindings: clock: si5351: add PLL reset mode property
clk: si5351: allow PLLs to be adjusted without reset
.../devicetree/bindings/clock/silabs,si5351.txt | 126 ----------
.../devicetree/bindings/clock/silabs,si5351.yaml | 265 +++++++++++++++++++++
drivers/clk/clk-si5351.c | 47 +++-
include/linux/platform_data/si5351.h | 2 +
4 files changed, 311 insertions(+), 129 deletions(-)
---
base-commit: f6abdcb2444f6ebe06e19cd9eee767c7c46612ae
change-id: 20231014-alvin-clk-si5351-no-pll-reset-ecfac0a6550c
From: Alvin Šipraga <[email protected]>
The following additional properties are described:
- clock-names
- clock-frequency of the clkout child nodes
In order to suppress warnings from the DT schema validator, the clkout
child nodes are prescribed names clkout@[0-7] rather than clkout[0-7].
The example is refined as follows:
- correct the usage of property pll-master -> silabs,pll-master
- give an example of how the silabs,pll-reset property can be used
I made myself maintainer of the file as I cannot presume that anybody
else wants the responsibility.
Cc: Sebastian Hesselbarth <[email protected]>
Cc: Rabeeh Khoury <[email protected]>
Reviewed-by: Rob Herring <[email protected]>
Signed-off-by: Alvin Šipraga <[email protected]>
---
.../devicetree/bindings/clock/silabs,si5351.txt | 126 -----------
.../devicetree/bindings/clock/silabs,si5351.yaml | 241 +++++++++++++++++++++
2 files changed, 241 insertions(+), 126 deletions(-)
diff --git a/Documentation/devicetree/bindings/clock/silabs,si5351.txt b/Documentation/devicetree/bindings/clock/silabs,si5351.txt
deleted file mode 100644
index bfda6af76bee..000000000000
--- a/Documentation/devicetree/bindings/clock/silabs,si5351.txt
+++ /dev/null
@@ -1,126 +0,0 @@
-Binding for Silicon Labs Si5351a/b/c programmable i2c clock generator.
-
-Reference
-[1] Si5351A/B/C Data Sheet
- https://www.skyworksinc.com/-/media/Skyworks/SL/documents/public/data-sheets/Si5351-B.pdf
-
-The Si5351a/b/c are programmable i2c clock generators with up to 8 output
-clocks. Si5351a also has a reduced pin-count package (MSOP10) where only
-3 output clocks are accessible. The internal structure of the clock
-generators can be found in [1].
-
-==I2C device node==
-
-Required properties:
-- compatible: shall be one of the following:
- "silabs,si5351a" - Si5351a, QFN20 package
- "silabs,si5351a-msop" - Si5351a, MSOP10 package
- "silabs,si5351b" - Si5351b, QFN20 package
- "silabs,si5351c" - Si5351c, QFN20 package
-- reg: i2c device address, shall be 0x60 or 0x61.
-- #clock-cells: from common clock binding; shall be set to 1.
-- clocks: from common clock binding; list of parent clock
- handles, shall be xtal reference clock or xtal and clkin for
- si5351c only. Corresponding clock input names are "xtal" and
- "clkin" respectively.
-- #address-cells: shall be set to 1.
-- #size-cells: shall be set to 0.
-
-Optional properties:
-- silabs,pll-source: pair of (number, source) for each pll. Allows
- to overwrite clock source of pll A (number=0) or B (number=1).
-
-==Child nodes==
-
-Each of the clock outputs can be overwritten individually by
-using a child node to the I2C device node. If a child node for a clock
-output is not set, the eeprom configuration is not overwritten.
-
-Required child node properties:
-- reg: number of clock output.
-
-Optional child node properties:
-- silabs,clock-source: source clock of the output divider stage N, shall be
- 0 = multisynth N
- 1 = multisynth 0 for output clocks 0-3, else multisynth4
- 2 = xtal
- 3 = clkin (si5351c only)
-- silabs,drive-strength: output drive strength in mA, shall be one of {2,4,6,8}.
-- silabs,multisynth-source: source pll A(0) or B(1) of corresponding multisynth
- divider.
-- silabs,pll-master: boolean, multisynth can change pll frequency.
-- silabs,pll-reset: boolean, clock output can reset its pll.
-- silabs,disable-state : clock output disable state, shall be
- 0 = clock output is driven LOW when disabled
- 1 = clock output is driven HIGH when disabled
- 2 = clock output is FLOATING (HIGH-Z) when disabled
- 3 = clock output is NEVER disabled
-
-==Example==
-
-/* 25MHz reference crystal */
-ref25: ref25M {
- compatible = "fixed-clock";
- #clock-cells = <0>;
- clock-frequency = <25000000>;
-};
-
-i2c-master-node {
-
- /* Si5351a msop10 i2c clock generator */
- si5351a: clock-generator@60 {
- compatible = "silabs,si5351a-msop";
- reg = <0x60>;
- #address-cells = <1>;
- #size-cells = <0>;
- #clock-cells = <1>;
-
- /* connect xtal input to 25MHz reference */
- clocks = <&ref25>;
- clock-names = "xtal";
-
- /* connect xtal input as source of pll0 and pll1 */
- silabs,pll-source = <0 0>, <1 0>;
-
- /*
- * overwrite clkout0 configuration with:
- * - 8mA output drive strength
- * - pll0 as clock source of multisynth0
- * - multisynth0 as clock source of output divider
- * - multisynth0 can change pll0
- * - set initial clock frequency of 74.25MHz
- */
- clkout0 {
- reg = <0>;
- silabs,drive-strength = <8>;
- silabs,multisynth-source = <0>;
- silabs,clock-source = <0>;
- silabs,pll-master;
- clock-frequency = <74250000>;
- };
-
- /*
- * overwrite clkout1 configuration with:
- * - 4mA output drive strength
- * - pll1 as clock source of multisynth1
- * - multisynth1 as clock source of output divider
- * - multisynth1 can change pll1
- */
- clkout1 {
- reg = <1>;
- silabs,drive-strength = <4>;
- silabs,multisynth-source = <1>;
- silabs,clock-source = <0>;
- pll-master;
- };
-
- /*
- * overwrite clkout2 configuration with:
- * - xtal as clock source of output divider
- */
- clkout2 {
- reg = <2>;
- silabs,clock-source = <2>;
- };
- };
-};
diff --git a/Documentation/devicetree/bindings/clock/silabs,si5351.yaml b/Documentation/devicetree/bindings/clock/silabs,si5351.yaml
new file mode 100644
index 000000000000..494fa49a0c1b
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/silabs,si5351.yaml
@@ -0,0 +1,241 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/clock/silabs,si5351.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Silicon Labs Si5351A/B/C programmable I2C clock generators
+
+description: |
+ The Silicon Labs Si5351A/B/C are programmable I2C clock generators with up to
+ 8 outputs. Si5351A also has a reduced pin-count package (10-MSOP) where only 3
+ output clocks are accessible. The internal structure of the clock generators
+ can be found in [1].
+
+ [1] Si5351A/B/C Data Sheet
+ https://www.skyworksinc.com/-/media/Skyworks/SL/documents/public/data-sheets/Si5351-B.pdf
+
+maintainers:
+ - Alvin Šipraga <[email protected]>
+
+properties:
+ compatible:
+ enum:
+ - silabs,si5351a # Si5351A, 20-QFN package
+ - silabs,si5351a-msop # Si5351A, 10-MSOP package
+ - silabs,si5351b # Si5351B, 20-QFN package
+ - silabs,si5351c # Si5351C, 20-QFN package
+
+ reg:
+ enum:
+ - 0x60
+ - 0x61
+
+ "#address-cells":
+ const: 1
+
+ "#size-cells":
+ const: 0
+
+ "#clock-cells":
+ const: 1
+
+ clocks:
+ minItems: 1
+ maxItems: 2
+
+ clock-names:
+ minItems: 1
+ items:
+ - const: xtal
+ - const: clkin
+
+ silabs,pll-source:
+ $ref: /schemas/types.yaml#/definitions/uint32-matrix
+ description: |
+ A list of cell pairs containing a PLL index and its source. Allows to
+ overwrite clock source of the internal PLLs.
+ items:
+ items:
+ - description: PLL A (0) or PLL B (1)
+ enum: [ 0, 1 ]
+ - description: PLL source, XTAL (0) or CLKIN (1, Si5351C only).
+ enum: [ 0, 1 ]
+
+patternProperties:
+ "^clkout@[0-7]$":
+ type: object
+
+ additionalProperties: false
+
+ properties:
+ reg:
+ description: Clock output number.
+
+ clock-frequency: true
+
+ silabs,clock-source:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ description: |
+ Source clock of the this output's divider stage.
+
+ 0 - use multisynth N for this output, where N is the output number
+ 1 - use either multisynth 0 (if output number is 0-3) or multisynth 4
+ (otherwise) for this output
+ 2 - use XTAL for this output
+ 3 - use CLKIN for this output (Si5351C only)
+
+ silabs,drive-strength:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ enum: [ 2, 4, 6, 8 ]
+ description: Output drive strength in mA.
+
+ silabs,multisynth-source:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ enum: [ 0, 1 ]
+ description:
+ Source PLL A (0) or B (1) for the corresponding multisynth divider.
+
+ silabs,pll-master:
+ type: boolean
+ description: |
+ The frequency of the source PLL is allowed to be changed by the
+ multisynth when setting the rate of this clock output.
+
+ silabs,pll-reset:
+ type: boolean
+ description: Reset the source PLL when enabling this clock output.
+
+ silabs,disable-state:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ enum: [ 0, 1, 2, 3 ]
+ description: |
+ Clock output disable state. The state can be one of:
+
+ 0 - clock output is driven LOW when disabled
+ 1 - clock output is driven HIGH when disabled
+ 2 - clock output is FLOATING (HIGH-Z) when disabled
+ 3 - clock output is never disabled
+
+ allOf:
+ - if:
+ properties:
+ compatible:
+ contains:
+ const: silabs,si5351a-msop
+ then:
+ properties:
+ reg:
+ maximum: 2
+ else:
+ properties:
+ reg:
+ maximum: 7
+
+ - if:
+ properties:
+ compatible:
+ contains:
+ const: silabs,si5351c
+ then:
+ properties:
+ silabs,clock-source:
+ enum: [ 0, 1, 2, 3 ]
+ else:
+ properties:
+ silabs,clock-source:
+ enum: [ 0, 1, 2 ]
+
+ required:
+ - reg
+
+allOf:
+ - if:
+ properties:
+ compatible:
+ contains:
+ enum:
+ - silabs,si5351a
+ - silabs,si5351a-msop
+ - silabs,si5351b
+ then:
+ properties:
+ clocks:
+ maxItems: 1
+ clock-names:
+ maxItems: 1
+
+required:
+ - reg
+ - "#address-cells"
+ - "#size-cells"
+ - "#clock-cells"
+ - clocks
+ - clock-names
+
+unevaluatedProperties: false
+
+examples:
+ - |
+ i2c {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ clock-generator@60 {
+ compatible = "silabs,si5351a-msop";
+ reg = <0x60>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+ #clock-cells = <1>;
+
+ /* Connect XTAL input to 25MHz reference */
+ clocks = <&ref25>;
+ clock-names = "xtal";
+
+ /* Use XTAL input as source of PLL0 and PLL1 */
+ silabs,pll-source = <0 0>, <1 0>;
+
+ /*
+ * Overwrite CLK0 configuration with:
+ * - 8 mA output drive strength
+ * - PLL0 as clock source of multisynth 0
+ * - Multisynth 0 as clock source of output divider
+ * - Multisynth 0 can change PLL0
+ * - Set initial clock frequency of 74.25MHz
+ */
+ clkout@0 {
+ reg = <0>;
+ silabs,drive-strength = <8>;
+ silabs,multisynth-source = <0>;
+ silabs,clock-source = <0>;
+ silabs,pll-master;
+ clock-frequency = <74250000>;
+ };
+
+ /*
+ * Overwrite CLK1 configuration with:
+ * - 4 mA output drive strength
+ * - PLL1 as clock source of multisynth 1
+ * - Multisynth 1 as clock source of output divider
+ * - Multisynth 1 can change PLL1
+ * - Reset PLL1 when enabling this clock output
+ */
+ clkout@1 {
+ reg = <1>;
+ silabs,drive-strength = <4>;
+ silabs,multisynth-source = <1>;
+ silabs,clock-source = <0>;
+ silabs,pll-master;
+ silabs,pll-reset;
+ };
+
+ /*
+ * Overwrite CLK2 configuration with:
+ * - XTAL as clock source of output divider
+ */
+ clkout@2 {
+ reg = <2>;
+ silabs,clock-source = <2>;
+ };
+ };
+ };
--
2.42.1
Quoting Alvin Šipraga (2023-11-24 05:17:42)
> From: Alvin Šipraga <[email protected]>
>
> The following additional properties are described:
>
> - clock-names
> - clock-frequency of the clkout child nodes
>
> In order to suppress warnings from the DT schema validator, the clkout
> child nodes are prescribed names clkout@[0-7] rather than clkout[0-7].
>
> The example is refined as follows:
>
> - correct the usage of property pll-master -> silabs,pll-master
> - give an example of how the silabs,pll-reset property can be used
>
> I made myself maintainer of the file as I cannot presume that anybody
> else wants the responsibility.
>
> Cc: Sebastian Hesselbarth <[email protected]>
> Cc: Rabeeh Khoury <[email protected]>
> Reviewed-by: Rob Herring <[email protected]>
> Signed-off-by: Alvin Šipraga <[email protected]>
> ---
Applied to clk-next