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Date: Thu, 10 Nov 2022 16:15:16 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: Linus Walleij <linus.walleij@...aro.org>,
Bartosz Golaszewski <brgl@...ev.pl>,
linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
linux-gpio@...r.kernel.org
Subject: Re: [PATCH v3 6/6] gpiolib: add support for software nodes
On Wed, Nov 09, 2022 at 11:30:44AM -0800, Dmitry Torokhov wrote:
> Now that static device properties understand notion of child nodes and
> references, let's teach gpiolib to handle them:
>
> - GPIOs are represented as a references to software nodes representing
> gpiochip
> - references must have 2 arguments - GPIO number within the chip and
> GPIO flags (GPIO_ACTIVE_LOW/GPIO_ACTIVE_HIGH, etc)
> - a new PROPERTY_ENTRY_GPIO() macro is supplied to ensure the above
> - name of the software node representing gpiochip must match label of
> the gpiochip, as we use it to locate gpiochip structure at runtime
>
> The following illustrates use of software nodes to describe a "System"
> button that is currently specified via use of gpio_keys_platform_data
> in arch/mips/alchemy/board-mtx1.c. It follows bindings specified in
> Documentation/devicetree/bindings/input/gpio-keys.yaml.
>
> static const struct software_node mxt1_gpiochip2_node = {
> .name = "alchemy-gpio2",
> };
>
> static const struct property_entry mtx1_gpio_button_props[] = {
> PROPERTY_ENTRY_U32("linux,code", BTN_0),
> PROPERTY_ENTRY_STRING("label", "System button"),
> PROPERTY_ENTRY_GPIO("gpios", &mxt1_gpiochip2_node, 7, GPIO_ACTIVE_LOW),
> { }
> };
>
> Similarly, arch/arm/mach-tegra/board-paz00.c can be converted to:
>
> static const struct software_node tegra_gpiochip_node = {
> .name = "tegra-gpio",
> };
>
> static struct property_entry wifi_rfkill_prop[] __initdata = {
> PROPERTY_ENTRY_STRING("name", "wifi_rfkill"),
> PROPERTY_ENTRY_STRING("type", "wlan"),
> PROPERTY_ENTRY_GPIO("reset-gpios",
> &tegra_gpiochip_node, 25, GPIO_ACTIVE_HIGH);
> PROPERTY_ENTRY_GPIO("shutdown-gpios",
> &tegra_gpiochip_node, 85, GPIO_ACTIVE_HIGH);
> { },
> };
>
> static struct platform_device wifi_rfkill_device = {
> .name = "rfkill_gpio",
> .id = -1,
> };
>
> ...
>
> software_node_register(&tegra_gpiochip_node);
> device_create_managed_software_node(&wifi_rfkill_device.dev,
> wifi_rfkill_prop, NULL);
Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Acked-by: Linus Walleij <linus.walleij@...aro.org>
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
> ---
> drivers/gpio/Makefile | 1 +
> drivers/gpio/gpiolib-swnode.c | 123 ++++++++++++++++++++++++++++++++++++++++++
> drivers/gpio/gpiolib-swnode.h | 14 +++++
> drivers/gpio/gpiolib.c | 7 +++
> include/linux/gpio/property.h | 11 ++++
> 5 files changed, 156 insertions(+)
>
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index 8629e9eaf79e..010587025fc8 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -10,6 +10,7 @@ obj-$(CONFIG_OF_GPIO) += gpiolib-of.o
> obj-$(CONFIG_GPIO_CDEV) += gpiolib-cdev.o
> obj-$(CONFIG_GPIO_SYSFS) += gpiolib-sysfs.o
> obj-$(CONFIG_GPIO_ACPI) += gpiolib-acpi.o
> +obj-$(CONFIG_GPIOLIB) += gpiolib-swnode.o
>
> # Device drivers. Generally keep list sorted alphabetically
> obj-$(CONFIG_GPIO_REGMAP) += gpio-regmap.o
> diff --git a/drivers/gpio/gpiolib-swnode.c b/drivers/gpio/gpiolib-swnode.c
> new file mode 100644
> index 000000000000..dd9ccac214d1
> --- /dev/null
> +++ b/drivers/gpio/gpiolib-swnode.c
> @@ -0,0 +1,123 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Software Node helpers for the GPIO API
> + *
> + * Copyright 2022 Google LLC
> + */
> +#include <linux/err.h>
> +#include <linux/errno.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/gpio/driver.h>
> +#include <linux/kernel.h>
> +#include <linux/printk.h>
> +#include <linux/property.h>
> +#include <linux/string.h>
> +
> +#include "gpiolib.h"
> +#include "gpiolib-swnode.h"
> +
> +static void swnode_format_propname(const char *con_id, char *propname,
> + size_t max_size)
> +{
> + /*
> + * Note we do not need to try both -gpios and -gpio suffixes,
> + * as, unlike OF and ACPI, we can fix software nodes to conform
> + * to the proper binding.
> + */
> + if (con_id)
> + snprintf(propname, max_size, "%s-gpios", con_id);
> + else
> + strscpy(propname, "gpios", max_size);
> +}
> +
> +static int swnode_gpiochip_match_name(struct gpio_chip *chip, void *data)
> +{
> + return !strcmp(chip->label, data);
> +}
> +
> +static struct gpio_chip *swnode_get_chip(struct fwnode_handle *fwnode)
> +{
> + const struct software_node *chip_node;
> + struct gpio_chip *chip;
> +
> + chip_node = to_software_node(fwnode);
> + if (!chip_node || !chip_node->name)
> + return ERR_PTR(-EINVAL);
> +
> + chip = gpiochip_find((void *)chip_node->name, swnode_gpiochip_match_name);
> + return chip ?: ERR_PTR(-EPROBE_DEFER);
> +}
> +
> +struct gpio_desc *swnode_find_gpio(struct fwnode_handle *fwnode,
> + const char *con_id, unsigned int idx,
> + unsigned long *flags)
> +{
> + const struct software_node *swnode;
> + struct fwnode_reference_args args;
> + struct gpio_chip *chip;
> + struct gpio_desc *desc;
> + char propname[32]; /* 32 is max size of property name */
> + int error;
> +
> + swnode = to_software_node(fwnode);
> + if (!swnode)
> + return ERR_PTR(-EINVAL);
> +
> + swnode_format_propname(con_id, propname, sizeof(propname));
> +
> + /*
> + * We expect all swnode-described GPIOs have GPIO number and
> + * polarity arguments, hence nargs is set to 2.
> + */
> + error = fwnode_property_get_reference_args(fwnode, propname, NULL, 2, idx, &args);
> + if (error) {
> + pr_debug("%s: can't parse '%s' property of node '%pfwP[%d]'\n",
> + __func__, propname, fwnode, idx);
> + return ERR_PTR(error);
> + }
> +
> + chip = swnode_get_chip(args.fwnode);
> + fwnode_handle_put(args.fwnode);
> + if (IS_ERR(chip))
> + return ERR_CAST(chip);
> +
> + desc = gpiochip_get_desc(chip, args.args[0]);
> + *flags = args.args[1]; /* We expect native GPIO flags */
> +
> + pr_debug("%s: parsed '%s' property of node '%pfwP[%d]' - status (%d)\n",
> + __func__, propname, fwnode, idx, PTR_ERR_OR_ZERO(desc));
> +
> + return desc;
> +}
> +
> +/**
> + * swnode_gpio_count - count the GPIOs associated with a device / function
> + * @fwnode: firmware node of the GPIO consumer, can be %NULL for
> + * system-global GPIOs
> + * @con_id: function within the GPIO consumer
> + *
> + * Return:
> + * The number of GPIOs associated with a device / function or %-ENOENT,
> + * if no GPIO has been assigned to the requested function.
> + */
> +int swnode_gpio_count(const struct fwnode_handle *fwnode, const char *con_id)
> +{
> + struct fwnode_reference_args args;
> + char propname[32];
> + int count;
> +
> + swnode_format_propname(con_id, propname, sizeof(propname));
> +
> + /*
> + * This is not very efficient, but GPIO lists usually have only
> + * 1 or 2 entries.
> + */
> + count = 0;
> + while (fwnode_property_get_reference_args(fwnode, propname, NULL, 0,
> + count, &args) == 0) {
> + fwnode_handle_put(args.fwnode);
> + count++;
> + }
> +
> + return count ?: -ENOENT;
> +}
> diff --git a/drivers/gpio/gpiolib-swnode.h b/drivers/gpio/gpiolib-swnode.h
> new file mode 100644
> index 000000000000..af849e56f6bc
> --- /dev/null
> +++ b/drivers/gpio/gpiolib-swnode.h
> @@ -0,0 +1,14 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef GPIOLIB_SWNODE_H
> +#define GPIOLIB_SWNODE_H
> +
> +struct fwnode_handle;
> +struct gpio_desc;
> +
> +struct gpio_desc *swnode_find_gpio(struct fwnode_handle *fwnode,
> + const char *con_id, unsigned int idx,
> + unsigned long *flags);
> +int swnode_gpio_count(const struct fwnode_handle *fwnode, const char *con_id);
> +
> +#endif /* GPIOLIB_SWNODE_H */
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index b1a57fdd96b6..2f4150bf411a 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -26,6 +26,7 @@
> #include "gpiolib.h"
> #include "gpiolib-of.h"
> #include "gpiolib-acpi.h"
> +#include "gpiolib-swnode.h"
> #include "gpiolib-cdev.h"
> #include "gpiolib-sysfs.h"
>
> @@ -3818,6 +3819,10 @@ static struct gpio_desc *gpiod_find_by_fwnode(struct fwnode_handle *fwnode,
> dev_dbg(consumer, "using ACPI '%pfw' for '%s' GPIO lookup\n",
> fwnode, con_id);
> desc = acpi_find_gpio(fwnode, con_id, idx, flags, lookupflags);
> + } else if (is_software_node(fwnode)) {
> + dev_dbg(consumer, "using swnode '%pfw' for '%s' GPIO lookup\n",
> + fwnode, con_id);
> + desc = swnode_find_gpio(fwnode, con_id, idx, lookupflags);
> }
>
> return desc;
> @@ -3935,6 +3940,8 @@ int gpiod_count(struct device *dev, const char *con_id)
> count = of_gpio_get_count(dev, con_id);
> else if (is_acpi_node(fwnode))
> count = acpi_gpio_count(dev, con_id);
> + else if (is_software_node(fwnode))
> + count = swnode_gpio_count(fwnode, con_id);
>
> if (count < 0)
> count = platform_gpio_count(dev, con_id);
> diff --git a/include/linux/gpio/property.h b/include/linux/gpio/property.h
> new file mode 100644
> index 000000000000..6c75c8bd44a0
> --- /dev/null
> +++ b/include/linux/gpio/property.h
> @@ -0,0 +1,11 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +#ifndef __LINUX_GPIO_PROPERTY_H
> +#define __LINUX_GPIO_PROPERTY_H
> +
> +#include <dt-bindings/gpio/gpio.h> /* for GPIO_* flags */
> +#include <linux/property.h>
> +
> +#define PROPERTY_ENTRY_GPIO(_name_, _chip_node_, _idx_, _flags_) \
> + PROPERTY_ENTRY_REF(_name_, _chip_node_, _idx_, _flags_)
> +
> +#endif /* __LINUX_GPIO_PROPERTY_H */
>
> --
> b4 0.11.0-dev-28747
--
With Best Regards,
Andy Shevchenko
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