| Message ID | 20230130165435.2347569-1-konrad.dybcio@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | [RFC,1/2] dt-bindings: pincfg-node: Introduce an overridable way to set bias on pins | expand |
On Tue, Jan 31, 2023 at 02:21:38PM +0100, Linus Walleij wrote: > On Tue, Jan 31, 2023 at 12:50 AM Konrad Dybcio <konrad.dybcio@linaro.org> wrote: > > > > +#define DRIVE_STRENGTH 9 > > > +#define DRIVE_STRENGTH_UA 10 > > > > > > drive-strength = <8>; // 8mA drive strength > > > > > > bias-type = <DRIVE_STRENGTH>; > > > > > > OK where do I put my 8 mA now? > > > > > If you look at the 2/2 patch, this property only reads BIAS_ > > values, which can't coexist anyway. > > Well the DT bindings have to be consistent and clear on their > own, no matter how Linux implements it. > > But I'm sure you can make YAML verification such that it is > impossible to use both schemes at the same time, and it's not > like I don't understand what you're getting at. We already don't enforce mutually exclusive combinations. Perhaps someone wants to fix that first? > What I need as input is mainly the DT bindings people opinion > on introducing another orthogonal way of doing something > that is already possible to do another way, just more convenient. > Because that is essentially what is happening here. It's really a 3rd way we're adding because the existing properties have 2 forms which IMO is worse than 2 disjoint ways of doing it. And since this new way can't represent some cases, I don't think it is an improvement. Rob
diff --git a/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml b/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml index be81ed22a036..d4ea563d283e 100644 --- a/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml +++ b/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml @@ -51,6 +51,10 @@ properties: description: use pin-default pull state. Takes as optional argument on hardware supporting it the pull strength in Ohm. + bias-type: + $ref: /schemas/types.yaml#/definitions/uint32 + description: Use the specified bias type. + drive-push-pull: oneOf: - type: boolean diff --git a/include/dt-bindings/pinctrl/pinconf-generic.h b/include/dt-bindings/pinctrl/pinconf-generic.h new file mode 100644 index 000000000000..7d9c7d8f9105 --- /dev/null +++ b/include/dt-bindings/pinctrl/pinconf-generic.h @@ -0,0 +1,40 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2011 ST-Ericsson SA + * Written on behalf of Linaro for ST-Ericsson + * + * Author: Linus Walleij <linus.walleij@linaro.org> + */ + +#ifndef _DT_BINDINGS_PINCTRL_PINCONF_GENERIC_H +#define _DT_BINDINGS_PINCTRL_PINCONF_GENERIC_H + +#define BIAS_BUS_HOLD 0 +#define BIAS_DISABLE 1 +#define BIAS_HIGH_IMPEDANCE 2 +#define BIAS_PULL_DOWN 3 +#define BIAS_PULL_PIN_DEFAULT 4 +#define BIAS_PULL_UP 5 +#define DRIVE_OPEN_DRAIN 6 +#define DRIVE_OPEN_SOURCE 7 +#define DRIVE_PUSH_PULL 8 +#define DRIVE_STRENGTH 9 +#define DRIVE_STRENGTH_UA 10 +#define INPUT_DEBOUNCE 11 +#define INPUT_ENABLE 12 +#define INPUT_SCHMITT 13 +#define INPUT_SCHMITT_ENABLE 14 +#define MODE_LOW_POWER 15 +#define MODE_PWM 16 +#define OUTPUT 17 +#define OUTPUT_ENABLE 18 +#define OUTPUT_IMPEDANCE_OHMS 19 +#define PERSIST_STATE 20 +#define POWER_SOURCE 21 +#define SKEW_DELAY 22 +#define SLEEP_HARDWARE_STATE 23 +#define SLEW_RATE 24 +#define PIN_CONFIG_END 0x7F +#define PIN_CONFIG_MAX 0xFF + +#endif
We came to a point where we sometimes we support a few dozen boards with a given SoC. Sometimes, we have to take into consideration configurations which deviate rather significatly from the reference or most common designs. In the context of pinctrl, this often comes down to wildly different pin configurations. While pins, function and drive-strength are easily overridable, the (mostly) boolean properties associated with setting bias, aren't. This wouldn't be much of a problem if they didn't differ between boards so often, preventing us from having a "nice" baseline setup without inevitably having to go with an ugly /delete-property/. Introduce bias-type, a bias-type- specific property and clone the pinconf-generic type enum into dt-bindings to allow for setting the bias in an easily overridable manner such as: // SoC DT i2c0_pin: i2c0-pin-state { pins = "gpio10"; function = "gpio"; bias-type = <BIAS_PULL_UP>; }; // Deviant board DT &i2c0_pin { bias-type = <BIAS_HIGH_IMPEDANCE>; }; Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org> --- .../bindings/pinctrl/pincfg-node.yaml | 4 ++ include/dt-bindings/pinctrl/pinconf-generic.h | 40 +++++++++++++++++++ 2 files changed, 44 insertions(+) create mode 100644 include/dt-bindings/pinctrl/pinconf-generic.h