On 5/16/23 11:36 PM, Vignesh Raghavendra wrote:
On 17/05/23 00:16, Andrew Davis wrote:
This node's register space is not accessed by any other node, which
is the traditional use for the "syscon" hint.
Unfortunately that's not the case across SoCs. Eg AM65x See TRM section
Table 5-582. CTRLMMR_EPWM0_CTRL Register Field Descriptions
Not sure what version of the TRM you have, latest (Rev. E) has this
register as Table 5-636.. but I found it and see your point here.
TB_CLKEN is clubbed with SYNCIN_SEL and ePWM tripzone configuration
signals which may require register to be shared with other drivers in future
This looks to only be a problem in AM65x, all later devices we have fixed
the issue and now group the clock enable bits all together.
Do we actually expect this to be an issue and have a user of these
other bits? If so then we modeled this region wrong in AM65x DT, these
registers are not "tbclk gate registers" any more then they are to the
other functions they provide. These registers should be a syscon node
and then each function within should be a child node.
syscon@4140 {
compatible = "ti,am654-epwm-crtl", "syscon";
reg = <0x4140 0x18>;
ehrpwm_tbclk: clock {
compatible = "ti,am654-ehrpwm-tbclk";
#clock-cells = <1>;
};
pwm_mux: mux-controller {
compatible = "mmio-mux";
#mux-control-cells = <1>;
};
};
Something like that. That way we do not give preference to one device
and have to have it give out shared registers.
Either that or split the binding compatible, one for AM65x with syscon
and one for all later device compatibles that do not share the register:
compatible:
oneOf:
- items:
- const: ti,am654-ehrpwm-tbclk
- const: syscon
- items:
- enum:
- ti,am64-epwm-tbclk
- ti,am62-epwm-tbclk
Would rather the first option.
Andrew
It looks to have been
added here to make use of a Linux kernel helper syscon_node_to_regmap().
The Linux driver now uses a more appropriate helper that does not
require the hint, so let's remove it from the binding.
Signed-off-by: Andrew Davis <afd@xxxxxx>
---
.../devicetree/bindings/clock/ti,am654-ehrpwm-tbclk.yaml | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/Documentation/devicetree/bindings/clock/ti,am654-ehrpwm-tbclk.yaml b/Documentation/devicetree/bindings/clock/ti,am654-ehrpwm-tbclk.yaml
index 66765116aff5..64b8bce5962c 100644
--- a/Documentation/devicetree/bindings/clock/ti,am654-ehrpwm-tbclk.yaml
+++ b/Documentation/devicetree/bindings/clock/ti,am654-ehrpwm-tbclk.yaml
@@ -16,7 +16,6 @@ properties:
- ti,am654-ehrpwm-tbclk
- ti,am64-epwm-tbclk
- ti,am62-epwm-tbclk
- - const: syscon
"#clock-cells":
const: 1
@@ -33,8 +32,8 @@ additionalProperties: false
examples:
- |
- ehrpwm_tbclk: syscon@4140 {
- compatible = "ti,am654-ehrpwm-tbclk", "syscon";
+ ehrpwm_tbclk: clock@4140 {
+ compatible = "ti,am654-ehrpwm-tbclk";
reg = <0x4140 0x18>;
#clock-cells = <1>;
};
