linux-kernel - Re: [PATCH 6/6] pinctrl: sunxi: Add driver for Allwinner D1/D1s

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Message-ID: <ef4454cb-a387-7dda-67e3-7493a89be8e7@sholland.org>
Date:   Sat, 2 Jul 2022 10:43:05 -0500
From:   Samuel Holland <samuel@...lland.org>
To:     Andre Przywara <andre.przywara@....com>
Cc:     Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Maxime Ripard <mripard@...nel.org>, Ondrej Jirman <x@....cz>,
        Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-gpio@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-sunxi@...ts.linux.dev,
        Heiko Stuebner <heiko@...ech.de>
Subject: Re: [PATCH 6/6] pinctrl: sunxi: Add driver for Allwinner D1/D1s

On 7/2/22 9:47 AM, Andre Przywara wrote:
> On Sat, 25 Jun 2022 21:11:47 -0500
> Samuel Holland <samuel@...lland.org> wrote:
> 
> Hi Samuel,
> 
>> These SoCs contain a pinctrl with a new register layout. Use the variant
>> parameter to set the right register offsets. This pinctrl also increases
>> the number of functions per pin from 8 to 16, taking advantage of all 4
>> bits in the mux config field (so far, only functions 0-8 and 14-15 are
>> used). This increases the maximum possible number of functions.
>>
>> D1s is a low pin count version of the D1 SoC, with some pins omitted.
>> The remaining pins have the same function assignments as D1.
> 
> So do we actually need this extra variant, if there are no conflicts?
> The D1s seems to be a simple subset of the D1. I think we followed the
> same approach for the H616 already, where there are more pins in the
> pinctrl driver than the manual describes, and which are used in other
> package variants, like the T507.
> In case of the H616, those pins are there, you can program them (which
> is not the case for not implemented pins otherwise), they are just not
> connected to the package.
> I would expect a DT to never reference them, and even if, it doesn't do
> any harm other than just not working.

I am following the example of V3/V3s here, so it seems we are inconsistent on
this point. I needed to supply one variant for the register layout anyway, so I
though I might as well be "accurate".

But with Allwinner releasing lots of packages per die, it is probably overkill
to have a separate compatible per packge. As you note, there is no harm in
configuring pins that do not map to any pad.

Some notes for completeness:
 - D1 documents all three JTAG functions (ARM, RISC-V, and DSP), although the
ARM JTAG does not work.
 - D1s/F133 only documents the RISC-V JTAG function.
 - T113 only documents the ARM and DSP JTAG functions.
 - T113 adds a CAN function on mux 8 of PB2-PB5. The CAN controller accidentally
made it in to one version of the D1 datasheet, so it may unofficially exist there.

None of these variations are conflicting.

> For the table below: I checked every pin against the D1 manual (yes,
> that took an hour), and found only one small issue and some nits in
> PortE, see inline.
> 
>> Signed-off-by: Samuel Holland <samuel@...lland.org>
>> ---
>>
>>  drivers/pinctrl/sunxi/Kconfig             |   5 +
>>  drivers/pinctrl/sunxi/Makefile            |   1 +
>>  drivers/pinctrl/sunxi/pinctrl-sun20i-d1.c | 860 ++++++++++++++++++++++
>>  drivers/pinctrl/sunxi/pinctrl-sunxi.c     |  16 +-
>>  drivers/pinctrl/sunxi/pinctrl-sunxi.h     |   7 +
>>  5 files changed, 884 insertions(+), 5 deletions(-)
>>  create mode 100644 drivers/pinctrl/sunxi/pinctrl-sun20i-d1.c
>>
>> diff --git a/drivers/pinctrl/sunxi/Kconfig b/drivers/pinctrl/sunxi/Kconfig
>> index 33751a6a0757..a6ac1c1f2585 100644
>> --- a/drivers/pinctrl/sunxi/Kconfig
>> +++ b/drivers/pinctrl/sunxi/Kconfig
>> @@ -84,6 +84,11 @@ config PINCTRL_SUN9I_A80_R
>>  	depends on RESET_CONTROLLER
>>  	select PINCTRL_SUNXI
>>  
>> +config PINCTRL_SUN20I_D1
>> +	bool "Support for the Allwinner D1 PIO"
>> +	default RISCV && ARCH_SUNXI
>> +	select PINCTRL_SUNXI
>> +
>>  config PINCTRL_SUN50I_A64
>>  	bool "Support for the Allwinner A64 PIO"
>>  	default ARM64 && ARCH_SUNXI
>> diff --git a/drivers/pinctrl/sunxi/Makefile b/drivers/pinctrl/sunxi/Makefile
>> index d3440c42b9d6..2ff5a55927ad 100644
>> --- a/drivers/pinctrl/sunxi/Makefile
>> +++ b/drivers/pinctrl/sunxi/Makefile
>> @@ -20,6 +20,7 @@ obj-$(CONFIG_PINCTRL_SUN8I_A83T_R)	+= pinctrl-sun8i-a83t-r.o
>>  obj-$(CONFIG_PINCTRL_SUN8I_H3)		+= pinctrl-sun8i-h3.o
>>  obj-$(CONFIG_PINCTRL_SUN8I_H3_R)	+= pinctrl-sun8i-h3-r.o
>>  obj-$(CONFIG_PINCTRL_SUN8I_V3S)		+= pinctrl-sun8i-v3s.o
>> +obj-$(CONFIG_PINCTRL_SUN20I_D1)		+= pinctrl-sun20i-d1.o
>>  obj-$(CONFIG_PINCTRL_SUN50I_H5)		+= pinctrl-sun50i-h5.o
>>  obj-$(CONFIG_PINCTRL_SUN50I_H6)		+= pinctrl-sun50i-h6.o
>>  obj-$(CONFIG_PINCTRL_SUN50I_H6_R)	+= pinctrl-sun50i-h6-r.o
>> diff --git a/drivers/pinctrl/sunxi/pinctrl-sun20i-d1.c b/drivers/pinctrl/sunxi/pinctrl-sun20i-d1.c
>> new file mode 100644
>> index 000000000000..7247c1f1d92c
>> --- /dev/null
>> +++ b/drivers/pinctrl/sunxi/pinctrl-sun20i-d1.c
>> @@ -0,0 +1,860 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Allwinner D1 SoC pinctrl driver.
>> + *
>> + * Copyright (c) 2020 wuyan@...winnertech.com
>> + * Copyright (c) 2021-2022 Samuel Holland <samuel@...lland.org>
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/pinctrl/pinctrl.h>
>> +
>> +#include "pinctrl-sunxi.h"
>> +
>> +static const struct sunxi_desc_pin d1_pins[] = {
>> +	/* PB */
>> +	SUNXI_PIN_VARIANT(SUNXI_PINCTRL_PIN(B, 0),
>> +		PINCTRL_SUN20I_D1,
>> +		SUNXI_FUNCTION(0x0, "gpio_in"),
>> +		SUNXI_FUNCTION(0x1, "gpio_out"),
>> +		SUNXI_FUNCTION(0x2, "pwm"),
> 
> The manual mentions the PWM channel number in the pin name, and it
> seems like in other pinctrl drivers we use the number either in the
> function name, or at least in the comment.
> Shall we do one of them here as well?

I originally had the numbers in the function name, but then I realized that no
pin has multiple PWM muxes, so I removed them. As you mention, other drivers
have them, so I will add them back.

> And the mux numbers for pwm are all over the place, so lets hope we
> never need pwm in U-Boot ;-)

PWM is used for the CPU voltage regulator on at least one board (Nezha), but I
think we can get away without U-Boot support for that. And including the PWM
number in the function name will improve things somewhat.

I will fix the typos you noted below.

Regards,
Samuel