linux-kernel - [PATCH v5 3/6] gpiolib: acpi: Export acpi_get

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu,  3 Jun 2021 23:40:04 +0100
From:   Daniel Scally <djrscally@...il.com>
To:     "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Daniel Scally <djrscally@...il.com>,
        Lee Jones <lee.jones@...aro.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Maximilian Luz <luzmaximilian@...il.com>,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-i2c@...r.kernel.org,
        platform-driver-x86@...r.kernel.org, devel@...ica.org
Cc:     Len Brown <lenb@...nel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Wolfram Sang <wsa@...nel.org>,
        Mark Gross <mgross@...ux.intel.com>,
        Robert Moore <robert.moore@...el.com>,
        Erik Kaneda <erik.kaneda@...el.com>,
        laurent.pinchart@...asonboard.com, kieran.bingham@...asonboard.com,
        Andy Shevchenko <andy.shevchenko@...il.com>
Subject: [PATCH v5 3/6] gpiolib: acpi: Export acpi_get_gpiod()

We need to be able to translate GPIO resources in an ACPI device's _CRS
into GPIO descriptor array. Those are represented in _CRS as a pathname
to a GPIO device plus the pin's index number: the acpi_get_gpiod()
function is perfect for that purpose.

As it's currently only used internally within the GPIO layer, provide and
export a wrapper function that additionally holds a reference to the GPIO
device.

Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
Signed-off-by: Daniel Scally <djrscally@...il.com>
---
Changes since v4:
	- None

 drivers/gpio/gpiolib-acpi.c   | 28 ++++++++++++++++++++++++++++
 include/linux/gpio/consumer.h |  2 ++
 2 files changed, 30 insertions(+)

diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index 5b4111e4be3f..684ddb35d83b 100644
--- a/drivers/gpio/gpiolib-acpi.c
+++ b/drivers/gpio/gpiolib-acpi.c
@@ -128,6 +128,34 @@ static struct gpio_desc *acpi_get_gpiod(char *path, int pin)
 	return gpiochip_get_desc(chip, pin);
 }
 
+/**
+ * acpi_get_and_request_gpiod() - Translate ACPI GPIO pin to GPIO descriptor
+ *                               and hold a refcount to the GPIO device.
+ * @path:      ACPI GPIO controller full path name, (e.g. "\\_SB.GPO1")
+ * @pin:       ACPI GPIO pin number (0-based, controller-relative)
+ * @label:     Label to pass to gpiod_request()
+ *
+ * This function is a simple pass-through to acpi_get_gpiod(), except that
+ * as it is intended for use outside of the GPIO layer (in a similar fashion to
+ * gpiod_get_index() for example) it also holds a reference to the GPIO device.
+ */
+struct gpio_desc *acpi_get_and_request_gpiod(char *path, int pin, char *label)
+{
+	struct gpio_desc *gpio;
+	int ret;
+
+	gpio = acpi_get_gpiod(path, pin);
+	if (IS_ERR(gpio))
+		return gpio;
+
+	ret = gpiod_request(gpio, label);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return gpio;
+}
+EXPORT_SYMBOL_GPL(acpi_get_and_request_gpiod);
+
 static irqreturn_t acpi_gpio_irq_handler(int irq, void *data)
 {
 	struct acpi_gpio_event *event = data;
diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
index c73b25bc9213..566feb56601f 100644
--- a/include/linux/gpio/consumer.h
+++ b/include/linux/gpio/consumer.h
@@ -692,6 +692,8 @@ int devm_acpi_dev_add_driver_gpios(struct device *dev,
 				   const struct acpi_gpio_mapping *gpios);
 void devm_acpi_dev_remove_driver_gpios(struct device *dev);
 
+struct gpio_desc *acpi_get_and_request_gpiod(char *path, int pin, char *label);
+
 #else  /* CONFIG_GPIOLIB && CONFIG_ACPI */
 
 struct acpi_device;
-- 
2.25.1