On Wed, 2021-03-24 at 11:04 -0600, Rob Herring wrote:

On Fri, Mar 12, 2021 at 12:17:02PM -0600, Robert Hancock wrote:

quoted

Add new silabs,xaxb-ext-clk and silabs,iovdd-33 properties.

Changed vdd-supply on top-level node to optional since it is not actually
used by the driver.

Removed vdd-supply from output sub-nodes, as it was not supported by the
driver and it is not easily possible to support this in that location with
the kernel regulator infrastructure. Changed to have vddX-supply
attributes for each output on the top-level device node.

Signed-off-by: Robert Hancock <redacted>
---
 .../devicetree/bindings/clock/silabs,si5341.txt  | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/clock/silabs,si5341.txt

b/Documentation/devicetree/bindings/clock/silabs,si5341.txt
index 504cce3abe46..1cf7e002cb16 100644

--- a/Documentation/devicetree/bindings/clock/silabs,si5341.txt
+++ b/Documentation/devicetree/bindings/clock/silabs,si5341.txt

@@ -24,9 +24,8 @@ it.
 
 The device type, speed grade and revision are determined runtime by

probing.
 
-The driver currently only supports XTAL input mode, and does not support
any
-fancy input configurations. They can still be programmed into the chip and
-the driver will leave them "as is".
+The driver currently does not support any fancy input configurations. They
can
+still be programmed into the chip and the driver will leave them "as is".
 
 ==I2C device node==
 

@@ -45,9 +44,9 @@ Required properties:
 	corresponding to inputs. Use a fixed clock for the "xtal" input.
 	At least one must be present.
 - clock-names: One of: "xtal", "in0", "in1", "in2"
-- vdd-supply: Regulator node for VDD
 
 Optional properties:
+- vdd-supply: Regulator node for VDD
 - vdda-supply: Regulator node for VDDA
 - vdds-supply: Regulator node for VDDS
 - silabs,pll-m-num, silabs,pll-m-den: Numerator and denominator for PLL

@@ -60,7 +59,14 @@ Optional properties:
   be initialized, and always performs the soft-reset routine. Since this

will
   temporarily stop all output clocks, don't do this if the chip is
generating
   the CPU clock for example.
+- silabs,xaxb-ext-clk: When present, indicates that the XA/XB pins are
used
+  in EXTCLK (external reference clock) rather than XTAL (crystal) mode.
 - interrupts: Interrupt for INTRb pin.
+- silabs,iovdd-33: When present, indicates that the I2C lines are using
3.3V
+  rather than 1.8V thresholds.

How does communication over I2C to set the register for this work if the 
register setting is wrong? I guess it's just leakage current...

It appears the communication still works, just less optimally? From the
reference manual:

"The IO_VDD_SEL configuration bit optimizes the VIL, VIH, VOL,and VOH
thresholds to match the VDDS voltage. By default the IO_VDD_SEL bit is set to
the VDD option. The serial interface pins are always 3.3 V tolerant even when
the device's VDD pin is supplied from a 1.8 V source. When the I2C or SPI host
is operating at 3.3 V and the Si5340/41 at VDD = 1.8 V, the host must write the
IO_VDD_SEL configuration bit to the VDDA option. This will ensure that both the
host and the serial interface are operating at the optimum voltage thresholds."

quoted

+- vddX-supply (where X is an output index): Regulator node for VDD for the
+  specified output. The driver selects the output VDD_SEL setting based on
this
+  voltage.

This is called vddoX in the datasheet.

Indeed, that would likely make more sense. Will update for v3.

quoted

 - #address-cells: shall be set to 1.
 - #size-cells: shall be set to 0.
 

@@ -77,8 +83,6 @@ Required child node properties:
 - reg: number of clock output.
 
 Optional child node properties:
-- vdd-supply: Regulator node for VDD for this output. The driver selects

default
-	values for common-mode and amplitude based on the voltage.
 - silabs,format: Output format, one of:
 	1 = differential (defaults to LVDS levels)
 	2 = low-power (defaults to HCSL levels)
-- 
2.27.0

-- 
Robert Hancock
Senior Hardware Designer, Calian Advanced Technologies
www.calian.com