Messages in this thread | | | Subject | Re: [PATCH v6 03/15] pinctrl: bcm: add bcm63xx base code | From | Álvaro Fernández Rojas <> | Date | Thu, 11 Mar 2021 18:00:40 +0100 |
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Hi Rob and Linus,
El 11/03/2021 a las 17:13, Linus Walleij escribió: > On Thu, Mar 11, 2021 at 3:58 PM Rob Herring <robh+dt@kernel.org> wrote: >> On Wed, Mar 10, 2021 at 6:09 PM Linus Walleij <linus.walleij@linaro.org> wrote: >>> On Wed, Mar 10, 2021 at 6:51 PM Rob Herring <robh+dt@kernel.org> wrote: >>> >>>>> +static const struct of_device_id bcm63xx_gpio_of_match[] = { >>>>> + { .compatible = "brcm,bcm6318-gpio", }, >>>>> + { .compatible = "brcm,bcm6328-gpio", }, >>>>> + { .compatible = "brcm,bcm6358-gpio", }, >>>>> + { .compatible = "brcm,bcm6362-gpio", }, >>>>> + { .compatible = "brcm,bcm6368-gpio", }, >>>>> + { .compatible = "brcm,bcm63268-gpio", }, >>>> >>>> All these would be moved to gpio-mmio.c (or maybe that can have a >>>> fallback compatible?). >>> >>> This is gpio-regmap.c and it can only be used as a library >>> by a certain driver. gpio-mmio.c can be used stand-alone >>> for certain really simple hardware (though most use that >>> as a library as well). >> >> I don't really care which one is used, but the problem is that this >> choice is leaking into the binding design. > > Aha I guess I misunderstood your comment. > >> The primary problem here is >> once someone uses regmap, then they think they must have a syscon and >> can abandon using 'reg' and normal address properties as Linux happens >> to not use them (currently). I think we really need some better regmap >> vs. mmio handling to eliminate this duplication of foo-mmio and >> foo-regmap drivers and difference in binding design. Not sure exactly >> what that looks like, but basically some sort of 'reg' property to >> regmap creation. > > I see the problem. Yeah we should try to be more strict around > these things. To me there are syscons and "other regmaps", > where syscon is a real hurdle of registers while "other regmaps" > are just regmaps by convenience. > > Documentation/devicetree/bindings/mfd/syscon.yaml > describes what a syscon really is so if everyone could > just read the documentation that would be great ... > >> Given we already have a Broadcom GPIO binding for what looks to be >> similar to this one, I'm left wondering what's the real difference >> here? > > Which one is similar? I can take a look.
@Linus I think @Rob is referring to brcm,bcm6345-gpio: https://github.com/torvalds/linux/blob/a74e6a014c9d4d4161061f770c9b4f98372ac778/drivers/gpio/gpio-mmio.c#L686
However, the real difference between BCM6345 (and BCM6338) is that these SoCs have no pin controller at all, only a GPIO controller:
BCM6345: typedef struct GpioControl { uint16 unused0; byte unused1; byte TBusSel; uint16 unused2; uint16 GPIODir; byte unused3; byte Leds; uint16 GPIOio; uint32 UartCtl; } GpioControl;
BCM6338: typedef struct GpioControl { uint32 unused0; uint32 GPIODir; /* bits 7:0 */ uint32 unused1; uint32 GPIOio; /* bits 7:0 */ uint32 LEDCtrl; uint32 SpiSlaveCfg; uint32 vRegConfig; } GpioControl;
BCM6348 and newer also have pinctrl. That's the main difference between that driver @Rob's referring to and the ones in this patch series.
> > We currently have four Broadcom GPIO bindings, > which are stand alone GPIO blocks and eight Broadcom > pin controllers that all do GPIO as well. > > This family of pin controllers are (as per subject) is > the bcm63xx series which is a MIPS-based family of SoCs > found in routers, top bindings in > Documentation/devicetree/bindings/mips/brcm/soc.txt > These all have a GPIO block as part of the pin controller > and the GPIO block is a distinct sub-function of the > pin controller, and it has up to 32 GPIOs per block, > hence it has its own subnode inside the pin controller. > > This driver follows the pattern of the Ingenic > pin controller, another MIPS SoC: > Documentation/devicetree/bindings/pinctrl/ingenic,pinctrl.yaml > > Another SoC with several GPIO blocks inside the pin > controller is SparX5 and that also follows this pattern: > Documentation/devicetree/bindings/pinctrl/microchip,sparx5-sgpio.yaml > (This has an example with more than one GPIO block > inside the pin controller.) > > Yours, > Linus Walleij >
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