[U-Boot] [PATCH v2] reset: Add generic GPIO reset driver

[Neil Armstrong]

Hi,

On 27/04/2018 14:53, Mario Six wrote:
> Some reset lines are implemented by toggling the line via a GPIO.
> 
> Add a driver to properly drive such reset lines.

You are defining a "gpio-reset" binding which has always been rejected
under Linux, so I'm not sure it's a good idea to add it in U-Boot only...

Neil
> 
> Signed-off-by: Mario Six <mario.six at gdsys.cc>
> ---
> 
> v1 -> v2:
> No changes
> 
> ---
>  drivers/reset/Kconfig      |   7 ++++
>  drivers/reset/Makefile     |   1 +
>  drivers/reset/gpio-reset.c | 100 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 108 insertions(+)
>  create mode 100644 drivers/reset/gpio-reset.c
> 
> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
> index 33c39b7fb6..b6e1da009c 100644
> --- a/drivers/reset/Kconfig
> +++ b/drivers/reset/Kconfig
> @@ -98,4 +98,11 @@ config RESET_SOCFPGA
>  	help
>  	  Support for reset controller on SoCFPGA platform.
> 
> +config GPIO_RESET
> +	bool "Reset driver for GPIO-based reset lines"
> +	depends on DM_RESET
> +	help
> +	  Support a generic reset controller that encapsulates a number of
> +	  GPIOs of which each controls a single reset line.
> +
>  endmenu
> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
> index ad08be4c8c..4a9d4006a3 100644
> --- a/drivers/reset/Makefile
> +++ b/drivers/reset/Makefile
> @@ -15,3 +15,4 @@ obj-$(CONFIG_AST2500_RESET) += ast2500-reset.o
>  obj-$(CONFIG_RESET_ROCKCHIP) += reset-rockchip.o
>  obj-$(CONFIG_RESET_MESON) += reset-meson.o
>  obj-$(CONFIG_RESET_SOCFPGA) += reset-socfpga.o
> +obj-$(CONFIG_GPIO_RESET) += gpio-reset.o
> diff --git a/drivers/reset/gpio-reset.c b/drivers/reset/gpio-reset.c
> new file mode 100644
> index 0000000000..52dd47df60
> --- /dev/null
> +++ b/drivers/reset/gpio-reset.c
> @@ -0,0 +1,100 @@
> +/*
> + * (C) Copyright 2017
> + * Mario Six, Guntermann & Drunck GmbH, mario.six at gdsys.cc
> + *
> + * SPDX-License-Identifier:	GPL-2.0+
> + */
> +
> +#include <common.h>
> +#include <dm.h>
> +#include <reset-uclass.h>
> +#include <asm/gpio.h>
> +
> +struct gpio_reset_priv {
> +	struct gpio_desc gpios[16];
> +	uint gpio_num;
> +};
> +
> +static int gpio_reset_request(struct reset_ctl *reset_ctl)
> +{
> +	struct gpio_reset_priv *priv = dev_get_priv(reset_ctl->dev);
> +
> +	debug("%s(reset_ctl=%p) (dev=%p, id=%lu)\n", __func__, reset_ctl,
> +	      reset_ctl->dev, reset_ctl->id);
> +
> +	/* Reset ID = number of GPIO in list */
> +	if (reset_ctl->id >= priv->gpio_num)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static int gpio_reset_free(struct reset_ctl *reset_ctl)
> +{
> +	debug("%s(reset_ctl=%p) (dev=%p, id=%lu)\n", __func__, reset_ctl,
> +	      reset_ctl->dev, reset_ctl->id);
> +
> +	return 0;
> +}
> +
> +static int gpio_reset_assert(struct reset_ctl *reset_ctl)
> +{
> +	struct gpio_reset_priv *priv = dev_get_priv(reset_ctl->dev);
> +
> +	debug("%s(reset_ctl=%p) (dev=%p, id=%lu)\n", __func__, reset_ctl,
> +	      reset_ctl->dev, reset_ctl->id);
> +
> +	dm_gpio_set_value(&priv->gpios[reset_ctl->id], 1);
> +
> +	return 0;
> +}
> +
> +static int gpio_reset_deassert(struct reset_ctl *reset_ctl)
> +{
> +	struct gpio_reset_priv *priv = dev_get_priv(reset_ctl->dev);
> +
> +	debug("%s(reset_ctl=%p) (dev=%p, id=%lu)\n", __func__, reset_ctl,
> +	      reset_ctl->dev, reset_ctl->id);
> +
> +	dm_gpio_set_value(&priv->gpios[reset_ctl->id], 0);
> +
> +	return 0;
> +}
> +
> +struct reset_ops gpio_reset_ops = {
> +	.request = gpio_reset_request,
> +	.free = gpio_reset_free,
> +	.rst_assert = gpio_reset_assert,
> +	.rst_deassert = gpio_reset_deassert,
> +};
> +
> +static int gpio_reset_probe(struct udevice *dev)
> +{
> +	struct gpio_reset_priv *priv = dev_get_priv(dev);
> +	int ret;
> +
> +	debug("%s(dev=%p)\n", __func__, dev);
> +
> +	ret = gpio_request_list_by_name(dev, "gpios", priv->gpios,
> +					ARRAY_SIZE(priv->gpios), GPIOD_IS_OUT);
> +	if (ret <= 0)
> +		return ret;
> +
> +	priv->gpio_num = ret;
> +
> +	return 0;
> +}
> +
> +static const struct udevice_id gpio_reset[] = {
> +	{ .compatible = "gpio-reset", },
> +	{ /* sentinel */ }
> +};
> +
> +U_BOOT_DRIVER(gpio_reset) = {
> +	.name = "gpio_reset",
> +	.id = UCLASS_RESET,
> +	.of_match = gpio_reset,
> +	.probe = gpio_reset_probe,
> +	.ops = &gpio_reset_ops,
> +	.priv_auto_alloc_size = sizeof(struct gpio_reset_priv),
> +};
> --
> 2.16.1
>