From: Michael Walle <michael@walle.cc>
To: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc: "Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
linux-gpio <linux-gpio@vger.kernel.org>,
linux-devicetree <devicetree@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-hwmon@vger.kernel.org, linux-pwm@vger.kernel.org,
LINUXWATCHDOG <linux-watchdog@vger.kernel.org>,
arm-soc <linux-arm-kernel@lists.infradead.org>,
"Linus Walleij" <linus.walleij@linaro.org>,
"Rob Herring" <robh+dt@kernel.org>,
"Jean Delvare" <jdelvare@suse.com>,
"Guenter Roeck" <linux@roeck-us.net>,
"Lee Jones" <lee.jones@linaro.org>,
"Thierry Reding" <thierry.reding@gmail.com>,
"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
"Wim Van Sebroeck" <wim@linux-watchdog.org>,
"Shawn Guo" <shawnguo@kernel.org>, "Li Yang" <leoyang.li@nxp.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Jason Cooper" <jason@lakedaemon.net>,
"Marc Zyngier" <maz@kernel.org>,
"Mark Brown" <broonie@kernel.org>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>
Subject: Re: [PATCH v3 10/16] gpio: add a reusable generic gpio_chip using regmap
Date: Mon, 25 May 2020 12:20:25 +0200 [thread overview]
Message-ID: <951244aab2ff553a463f7431ba09bf27@walle.cc> (raw)
In-Reply-To: <CAMpxmJXctc5cbrjSeJxa7DfmjiVsbyhqAbEKt-gtayKhQj0Cnw@mail.gmail.com>
Am 2020-05-25 11:05, schrieb Bartosz Golaszewski:
> wt., 12 maj 2020 o 16:41 Michael Walle <michael@walle.cc> napisał(a):
>>
>> >> +
>> >> +MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
>> >> +MODULE_DESCRIPTION("GPIO generic regmap driver core");
>> >> +MODULE_LICENSE("GPL");
>> >> diff --git a/include/linux/gpio-regmap.h b/include/linux/gpio-regmap.h
>> >> new file mode 100644
>> >> index 000000000000..a868cbcde6e9
>> >> --- /dev/null
>> >> +++ b/include/linux/gpio-regmap.h
>> >> @@ -0,0 +1,69 @@
>> >> +/* SPDX-License-Identifier: GPL-2.0-only */
>> >> +
>> >> +#ifndef _LINUX_GPIO_REGMAP_H
>> >> +#define _LINUX_GPIO_REGMAP_H
>> >> +
>> >> +struct gpio_regmap;
>> >> +
>> >> +#define GPIO_REGMAP_ADDR_ZERO ((unsigned long)(-1))
>> >> +#define GPIO_REGMAP_ADDR(addr) ((addr) ? : GPIO_REGMAP_ADDR_ZERO)
>> >> +
>> >
>> > What if the addr is actually 0?
>>
>> Then the driver has to set GPIO_REGMAP_ADDR_ZERO or use the
>> convenience
>> macro GPIO_REGMAP_ADDR.
>>
>> So you can have
>>
>> struct gpio_regmap_config config = { 0 };
>> config.reg_dat_base = 0x10;
>> config.reg_dir_out_base = 0x20;
>>
>> or
>>
>> config.reg_dat_base = GPIO_REGMAP_ADDR_ZERO;
>>
>> or if you can't be sure if the RHS value might be zero:
>>
>> config.reg_dat_base = GPIO_REGMAP_ADDR(reg);
>>
>>
>> > Maybe drop GPIO_REGMAP_ADDR and require users to set unused registers
>> > to GPIO_REGMAP_ADDR_ZERO?
>>
>> Thats bad because:
>> * you'd have to set plenty of unused base registers for a simple
>> driver
>> * if there will be additional properties in the future, you have to
>> touch
>> all other drivers, because they are initialized as 0 (ie. valid
>> reg
>> 0).
>>
>> >> +/**
>> >> + * struct gpio_regmap_config - Description of a generic regmap
>> >> gpio_chip.
>> >> + *
>> >> + * @parent: The parent device
>> >> + * @regmap: The regmap used to access the registers
>> >> + * given, the name of the device is used
>> >> + * @label: (Optional) Descriptive name for GPIO
>> >> controller.
>> >> + * If not given, the name of the device is used.
>> >> + * @ngpio: Number of GPIOs
>> >> + * @reg_dat_base: (Optional) (in) register base address
>> >> + * @reg_set_base: (Optional) set register base address
>> >> + * @reg_clr_base: (Optional) clear register base address
>> >> + * @reg_dir_in_base: (Optional) out setting register base address
>> >> + * @reg_dir_out_base: (Optional) in setting register base address
>> >
>> > The two above are inverted I think?
>> good catch.
>>
>> > Also: why the limitation of only supporting one at a time?
>>
>> they should be exclusive, either you have a register where you set the
>> output bits to one, or the input bits. Maybe this need a bit more
>> context
>> above. in gpio-mmio.c you can set both and both are used in
>> set_direction(), but only one is read in get_direction().
>>
>> That being said, I have no strong opinion wether they should be
>> exclusive
>> or not, besides the symmetry of set_/get_direction().
>>
>> -michael
>>
>
> Sorry for the late response, your comments make sense to me. Are you
> going to submit a v4 before the v5.8 merge window?
I'm currently stuck with how to handle the MFD part. Ie. Rob doesn't
seem to like the logicial device numbering - or at least there wasn't
an answer to that one anymore, see patch 5/16.
If you like I could submit this patch on its own. But then there
wouldn't be a user for it.
-michael
next prev parent reply other threads:[~2020-05-25 10:20 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-23 17:45 [PATCH v3 00/16] Add support for Kontron sl28cpld Michael Walle
2020-04-23 17:45 ` [PATCH v3 01/16] include/linux/ioport.h: add helper to define REG resource constructs Michael Walle
2020-04-23 17:45 ` [PATCH v3 02/16] mfd: mfd-core: Don't overwrite the dma_mask of the child device Michael Walle
2020-04-28 12:45 ` Andy Shevchenko
2020-04-28 13:06 ` Robin Murphy
2020-04-28 14:29 ` Andy Shevchenko
2020-04-28 14:49 ` Robin Murphy
2020-04-28 15:25 ` Mark Brown
2020-05-14 20:45 ` Michael Walle
2020-04-23 17:45 ` [PATCH v3 03/16] mfd: mfd-core: match device tree node against reg property Michael Walle
2020-04-29 22:18 ` Michael Walle
2020-05-15 10:28 ` Lee Jones
2020-05-25 17:36 ` Michael Walle
2020-05-26 7:24 ` Lee Jones
2020-05-26 15:54 ` Michael Walle
2020-05-26 16:03 ` Andy Shevchenko
2020-05-27 6:53 ` Lee Jones
2020-06-08 14:24 ` Lee Jones
2020-06-08 15:21 ` Michael Walle
2020-06-08 18:45 ` Lee Jones
2020-04-23 17:45 ` [PATCH v3 04/16] dt-bindings: mfd: Add bindings for sl28cpld Michael Walle
2020-04-28 12:48 ` Andy Shevchenko
2020-04-28 14:39 ` Michael Walle
2020-04-28 14:49 ` Andy Shevchenko
2020-04-23 17:45 ` [PATCH v3 05/16] mfd: Add support for Kontron sl28cpld management controller Michael Walle
2020-04-28 12:50 ` Andy Shevchenko
2020-04-28 14:43 ` Michael Walle
2020-04-28 14:49 ` Andy Shevchenko
2020-04-29 6:27 ` Lee Jones
2020-05-11 21:13 ` Rob Herring
2020-05-11 21:44 ` Michael Walle
2020-05-11 22:29 ` Michael Walle
2020-05-12 21:59 ` Rob Herring
2020-05-13 22:15 ` Michael Walle
2020-04-23 17:45 ` [PATCH v3 06/16] irqchip: add sl28cpld interrupt controller support Michael Walle
2020-04-27 11:40 ` Thomas Gleixner
2020-04-27 17:40 ` Michael Walle
2020-04-27 17:44 ` Mark Brown
2020-04-27 18:01 ` Michael Walle
2020-04-27 18:05 ` Mark Brown
2020-04-27 19:00 ` Thomas Gleixner
2020-04-23 17:45 ` [PATCH v3 07/16] watchdog: add support for sl28cpld watchdog Michael Walle
2020-04-25 17:02 ` Guenter Roeck
2020-04-23 17:45 ` [PATCH v3 08/16] pwm: add support for sl28cpld PWM controller Michael Walle
2020-05-11 20:45 ` Rob Herring
2020-04-23 17:45 ` [PATCH v3 09/16] gpiolib: Introduce gpiochip_irqchip_add_domain() Michael Walle
2020-04-27 11:42 ` Thomas Gleixner
2020-04-27 17:49 ` Michael Walle
2020-04-23 17:45 ` [PATCH v3 10/16] gpio: add a reusable generic gpio_chip using regmap Michael Walle
2020-05-12 12:48 ` Bartosz Golaszewski
2020-05-12 14:41 ` Michael Walle
2020-05-25 9:05 ` Bartosz Golaszewski
2020-05-25 10:20 ` Michael Walle [this message]
2020-05-25 12:59 ` Linus Walleij
2020-05-25 13:25 ` Andy Shevchenko
2020-04-23 17:45 ` [PATCH v3 11/16] gpio: add support for the sl28cpld GPIO controller Michael Walle
2020-04-27 11:45 ` Thomas Gleixner
2020-04-27 17:58 ` Michael Walle
2020-04-23 17:45 ` [PATCH v3 12/16] hwmon: add support for the sl28cpld hardware monitoring controller Michael Walle
2020-04-23 17:45 ` [PATCH v3 13/16] arm64: dts: freescale: sl28: enable sl28cpld Michael Walle
2020-04-23 17:45 ` [PATCH v3 14/16] arm64: dts: freescale: sl28: map GPIOs to input events Michael Walle
2020-04-23 17:45 ` [PATCH v3 15/16] arm64: dts: freescale: sl28: enable LED support Michael Walle
2020-04-23 17:45 ` [PATCH v3 16/16] arm64: dts: freescale: sl28: enable fan support Michael Walle
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