On Wed, Apr 14, 2021 at 10:44 PM Billy Tsai <billy_tsai@xxxxxxxxxxxxxx> wrote: > > Hi Rob, > > On 2021/4/15, 6:16 AM,Rob Herringwrote: > > On Wed, Apr 14, 2021 at 06:49:38PM +0800, Billy Tsai wrote: > >> This patch adds device bindings for aspeed pwm-tach device which is a > >> multi-function device include pwn and tach function and pwm device which > >> should be the sub-node of pwm-tach device. > >> > >> Signed-off-by: Billy Tsai <billy_tsai@xxxxxxxxxxxxxx> > >> Change-Id: I18d9dea14c3a04e1b7e38ffecd49d45917b9b545 > > > >Drop > > > >> --- > >> .../bindings/mfd/aspeed,ast2600-pwm-tach.yaml | 60 +++++++++++++++++++ > >> .../bindings/pwm/aspeed,ast2600-pwm.yaml | 44 ++++++++++++++ > >> 2 files changed, 104 insertions(+) > >> create mode 100644 Documentation/devicetree/bindings/mfd/aspeed,ast2600-pwm-tach.yaml > >> create mode 100644 Documentation/devicetree/bindings/pwm/aspeed,ast2600-pwm.yaml > >> > >> diff --git a/Documentation/devicetree/bindings/mfd/aspeed,ast2600-pwm-tach.yaml b/Documentation/devicetree/bindings/mfd/aspeed,ast2600-pwm-tach.yaml > >> new file mode 100644 > >> index 000000000000..eaf8bdf8d44e > >> --- /dev/null > >> +++ b/Documentation/devicetree/bindings/mfd/aspeed,ast2600-pwm-tach.yaml > >> @@ -0,0 +1,60 @@ > >> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) > >> +# Copyright (C) 2021 ASPEED, Inc. > >> +%YAML 1.2 > >> +--- > >> +$id: http://devicetree.org/schemas/mfd/aspeed,ast2600-pwm-tach.yaml# > >> +$schema: http://devicetree.org/meta-schemas/core.yaml# > >> + > >> +title: PWM Tach controller Device Tree Bindings > >> + > >> +description: | > >> + The PWM Tach controller is represented as a multi-function device which > >> + includes: > >> + PWM > >> + Tach > > > But is it really? A PWM and tach sounds like a fan controller. Look at > > Our PWM is not only for fans but also used for the motor, led, buzzer, and so on. > So I want to split the function into two devices with a multi-function device. > One for PWM output and one for tach monitor. > > > other existing PWM+tach bindings we have for fans. > > I didn't see the PWM+tach bindings can you give some example for me, thanks. Let me grep 'tach' for you: Documentation/devicetree/bindings/hwmon/aspeed-pwm-tacho.txt Documentation/devicetree/bindings/hwmon/npcm750-pwm-fan.txt Hey, look at that, there's already one for ASpeed. So the question is how is the newer h/w different? > > >> + > >> +maintainers: > >> + - Billy Tsai <billy_tsai@xxxxxxxxxxxxxx> > >> + > >> +properties: > >> + compatible: > >> + items: > >> + - enum: > >> + - aspeed,ast2600-pwm-tach > >> + - const: syscon > >> + - const: simple-mfd > >> + reg: > >> + maxItems: 1 > >> + "#address-cells": > >> + const: 1 > >> + "#size-cells": > >> + const: 1 > >> + > >> +required: > >> + - compatible > >> + - reg > >> + - "#address-cells" > >> + - "#size-cells" > >> + > >> +additionalProperties: > >> + type: object > > > As you know the 2 node names, they should be documented. However, see > > below. > > >> + > >> +examples: > >> + - | > >> + pwm_tach: pwm_tach@1e610000 { > >> + compatible = "aspeed,ast2600-pwm-tach", "syscon", "simple-mfd"; > >> + #address-cells = <1>; > >> + #size-cells = <1>; > >> + reg = <0x1e610000 0x100>; > >> + > >> + pwm: pwm@0 { > >> + compatible = "aspeed,ast2600-pwm"; > >> + #pwm-cells = <3>; > >> + reg = <0x0 0x100>; > >> + }; > >> + > >> + tach: tach@1 { > >> + compatible = "aspeed,ast2600-tach"; > >> + reg = <0x0 0x100>; > > > You have 2 nodes at the same address. Not valid. > > Our pwm and tach is used the same base address and the offset is like below: > > PWM0 used 0x0 0x4, Tach0 used 0x8 0xc > PWM1 used 0x10 0x14, Tach1 used 0x18 0x1c > ... > > I will remove the reg property from pwm and tach node and remove the "#address-cells" and > "#size-cells" from the parent node. That's not really the solution... > > >> + }; > > > There's no real need for 2 child nodes. The parent node can be a PWM > > provider. > > However, In our usage, the parent node is a mfd, not a simple PWM device only. I don't want to > combine the different functions with the one device node. Looks like a single h/w block to me. If you want to divide that up into multiple drivers, then that's an OS problem. A single node can be multiple providers. For example, on the existing aspeed binding, just add '#pwm-cells' to the node if you want to also expose it as a PWM provider. Rob
