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From: Stefan Wahren <stefan.wahren@i2se.com>
To: Linus Walleij <linus.walleij@linaro.org>,
	Bartosz Golaszewski <brgl@bgdev.pl>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Ray Jui <rjui@broadcom.com>,
	Scott Branden <sbranden@broadcom.com>,
	bcm-kernel-feedback-list@broadcom.com,
	Arnd Bergmann <arnd@arndb.de>, Phil Elwell <phil@raspberrypi.com>,
	linux-arm-kernel@lists.infradead.org, linux-gpio@vger.kernel.org,
	Stefan Wahren <stefan.wahren@i2se.com>
Subject: [PATCH RFC 1/2] gpiolib: of: Introduce hook for missing gpio-ranges
Date: Wed,  9 Mar 2022 20:43:45 +0100	[thread overview]
Message-ID: <1646855026-9132-2-git-send-email-stefan.wahren@i2se.com> (raw)
In-Reply-To: <1646855026-9132-1-git-send-email-stefan.wahren@i2se.com>

Since commit 2ab73c6d8323 ("gpio: Support GPIO controllers without pin-ranges")
the device tree nodes of GPIO controller need the gpio-ranges property to
handle gpio-hogs. Unfortunately it's impossible to guarantee that every new
kernel is shipped with an updated device tree binary.

In order to provide backward compatibility with those older DTB, we need a
callback within of_gpiochip_add_pin_range() so the relevant platform driver
can handle this case.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
---
 drivers/gpio/gpiolib-of.c   |  5 +++++
 include/linux/gpio/driver.h | 12 ++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 91dcf2c..45b6edb 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -933,6 +933,11 @@ static int of_gpiochip_add_pin_range(struct gpio_chip *chip)
 	if (!np)
 		return 0;
 
+	if (!of_property_read_bool(np, "gpio-ranges") &&
+	    chip->of_gpio_ranges_fallback) {
+		return chip->of_gpio_ranges_fallback(chip, np);
+	}
+
 	group_names = of_find_property(np, group_names_propname, NULL);
 
 	for (;; index++) {
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index b0728c8..47a5ea0 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -489,6 +489,18 @@ struct gpio_chip {
 	 */
 	int (*of_xlate)(struct gpio_chip *gc,
 			const struct of_phandle_args *gpiospec, u32 *flags);
+
+	/**
+	 * @of_gpio_ranges_fallback
+	 *
+	 * Optional hook for the case that no gpio-ranges property is defined
+	 * within the device tree node "np" (usually DT before introduction
+	 * of gpio-ranges). So this callback is helpful to provide the
+	 * necessary backward compatibility for the pin ranges.
+	 */
+	int (*of_gpio_ranges_fallback)(struct gpio_chip *gc,
+				       struct device_node *np);
+
 #endif /* CONFIG_OF_GPIO */
 };
 
-- 
2.7.4


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  reply	other threads:[~2022-03-09 19:46 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-09 19:43 [PATCH RFC 0/2] " Stefan Wahren
2022-03-09 19:43 ` Stefan Wahren [this message]
2022-03-15 15:17   ` [PATCH RFC 1/2] " Bartosz Golaszewski
2022-03-09 19:43 ` [PATCH RFC 2/2] pinctrl: bcm2835: implement " Stefan Wahren
2022-03-10  3:24 ` [PATCH RFC 0/2] gpiolib: of: Introduce " Florian Fainelli
2022-03-17  1:15 ` Linus Walleij
2022-03-17  2:02   ` Florian Fainelli
2022-03-17 11:48     ` Stefan Wahren
2022-03-17 17:17       ` Florian Fainelli
2022-03-17 19:23         ` Stefan Wahren
2022-03-21 18:21           ` Florian Fainelli
2022-03-24 19:00             ` Linus Walleij
2022-03-24 19:23               ` Florian Fainelli

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