linux-kernel - Re: [PATCH v5 2/2] gpio: add a reusable generic gpio

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Date:   Thu, 28 May 2020 13:04:16 +0200
From:   Michael Walle <michael@...le.cc>
To:     linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Mark Brown <broonie@...nel.org>,
        Pierre-Louis Bossart <pierre-louis.bossart@...el.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH v5 2/2] gpio: add a reusable generic gpio_chip using
 regmap

Am 2020-05-28 05:58, schrieb Michael Walle:
> There are quite a lot simple GPIO controller which are using regmap to
> access the hardware. This driver tries to be a base to unify existing
> code into one place. This won't cover everything but it should be a 
> good
> starting point.
> 
> It does not implement its own irq_chip because there is already a
> generic one for regmap based devices. Instead, the irq_chip will be
> instantiated in the parent driver and its irq domain will be associate
> to this driver.
> 
> For now it consists of the usual registers, like set (and an optional
> clear) data register, an input register and direction registers.
> Out-of-the-box, it supports consecutive register mappings and mappings
> where the registers have gaps between them with a linear mapping 
> between
> GPIO offset and bit position. For weirder mappings the user can 
> register
> its own .xlate().
> 
> Signed-off-by: Michael Walle <michael@...le.cc>
> ---
>  drivers/gpio/Kconfig        |   4 +
>  drivers/gpio/Makefile       |   1 +
>  drivers/gpio/gpio-regmap.c  | 352 ++++++++++++++++++++++++++++++++++++
>  include/linux/gpio-regmap.h |  70 +++++++
>  4 files changed, 427 insertions(+)
>  create mode 100644 drivers/gpio/gpio-regmap.c
>  create mode 100644 include/linux/gpio-regmap.h
> 
[..]

> --- /dev/null
> +++ b/include/linux/gpio-regmap.h
> @@ -0,0 +1,70 @@
> +/* 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)
> +
> +/**
> + * 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
> + * @names:		(Optional) Array of names for 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) in setting register base address
> + * @reg_dir_out_base:	(Optional) out setting register base address
> + * @reg_stride:		(Optional) May be set if the registers (of the
> + *			same type, dat, set, etc) are not consecutive.
> + * @ngpio_per_reg:	Number of GPIOs per register
> + * @irq_domain:		(Optional) IRQ domain if the controller is
> + *			interrupt-capable
> + * @reg_mask_xlate:     (Optional) Translates base address and GPIO
> + *			offset to a register/bitmask pair. If not
> + *			given the default gpio_regmap_simple_xlate()
> + *			is used.
> + *
> + * The reg_mask_xlate translates a given base address and GPIO offset 
> to
> + * register and mask pair. The base address is one of the given 
> reg_*_base.
> + *
> + * All base addresses may have the special value GPIO_REGMAP_ADDR_ZERO
> + * which forces the address to the value 0.
> + */
> +struct gpio_regmap_config {
> +	struct device *parent;
> +	struct regmap *regmap;
> +
> +	const char *label;
> +	int ngpio;

damn.. I shouldn't send patches early in the morning. I've forgot to 
actually
enable my GPIO driver before compiling. And of course.. it doesn't 
compile.

const char *const *names;

is missing here. So I have to send a v6 anyway. Let's wait what Linus 
and Bert
says about the location of the gpio-regmap.h header.

Sorry for the noise.

-michael

> +
> +	unsigned int reg_dat_base;
> +	unsigned int reg_set_base;
> +	unsigned int reg_clr_base;
> +	unsigned int reg_dir_in_base;
> +	unsigned int reg_dir_out_base;
> +	int reg_stride;
> +	int ngpio_per_reg;
> +	struct irq_domain *irq_domain;
> +
> +	int (*reg_mask_xlate)(struct gpio_regmap *gpio, unsigned int base,
> +			      unsigned int offset, unsigned int *reg,
> +			      unsigned int *mask);
> +};
> +
> +struct gpio_regmap *gpio_regmap_register(const struct
> gpio_regmap_config *config);
> +void gpio_regmap_unregister(struct gpio_regmap *gpio);
> +struct gpio_regmap *devm_gpio_regmap_register(struct device *dev,
> +					      const struct gpio_regmap_config *config);
> +void gpio_regmap_set_drvdata(struct gpio_regmap *gpio, void *data);
> +void *gpio_regmap_get_drvdata(struct gpio_regmap *gpio);
> +
> +#endif /* _LINUX_GPIO_REGMAP_H */