linux-kernel - [RFT PATCH 11/21] platform: x86: android-tablets: don't access GPIOLIB private members

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Message-Id: <20230905185309.131295-12-brgl@bgdev.pl>
Date:   Tue,  5 Sep 2023 20:52:59 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Aaro Koskinen <aaro.koskinen@....fi>,
        Janusz Krzysztofik <jmkrzyszt@...il.com>,
        Tony Lindgren <tony@...mide.com>,
        Russell King <linux@...linux.org.uk>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Dipen Patel <dipenp@...dia.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Mark Gross <markgross@...nel.org>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
        linux-acpi@...r.kernel.org, timestamp@...ts.linux.dev,
        linux-tegra@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [RFT PATCH 11/21] platform: x86: android-tablets: don't access GPIOLIB private members

From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

We're slowly removing cases of abuse of the GPIOLIB public API. One of
the biggest issues is looking up and accessing struct gpio_chip whose
life-time is tied to the provider and which can disappear from under any
user at any given moment. We have provided new interfaces that use the
opaque struct gpio_device which is reference counted and will soon be
thorougly protected with appropriate locking.

Stop using old interfaces in this driver and switch to safer
alternatives.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
 .../platform/x86/x86-android-tablets/core.c   | 38 ++++++++++---------
 1 file changed, 20 insertions(+), 18 deletions(-)

diff --git a/drivers/platform/x86/x86-android-tablets/core.c b/drivers/platform/x86/x86-android-tablets/core.c
index 2fd6060a31bb..687f84cd193c 100644
--- a/drivers/platform/x86/x86-android-tablets/core.c
+++ b/drivers/platform/x86/x86-android-tablets/core.c
@@ -12,6 +12,7 @@
 
 #include <linux/acpi.h>
 #include <linux/dmi.h>
+#include <linux/gpio/consumer.h>
 #include <linux/gpio/driver.h>
 #include <linux/gpio/machine.h>
 #include <linux/irq.h>
@@ -21,27 +22,28 @@
 #include <linux/string.h>
 
 #include "x86-android-tablets.h"
-/* For gpiochip_get_desc() which is EXPORT_SYMBOL_GPL() */
-#include "../../../gpio/gpiolib.h"
-#include "../../../gpio/gpiolib-acpi.h"
-
-static int gpiochip_find_match_label(struct gpio_chip *gc, void *data)
-{
-	return gc->label && !strcmp(gc->label, data);
-}
 
 int x86_android_tablet_get_gpiod(const char *label, int pin, struct gpio_desc **desc)
 {
+	struct gpio_device *gdev;
 	struct gpio_desc *gpiod;
-	struct gpio_chip *chip;
 
-	chip = gpiochip_find((void *)label, gpiochip_find_match_label);
-	if (!chip) {
-		pr_err("error cannot find GPIO chip %s\n", label);
+	/*
+	 * FIXME: handle GPIOs correctly! This driver should really use struct
+	 * device and GPIO lookup tables.
+	 *
+	 * WONTDO: We do leak this reference, but the whole approach to getting
+	 * GPIOs in this driver is such an abuse of the GPIOLIB API that it
+	 * doesn't make it much worse and it's the only way to keep the
+	 * interrupt requested later functional...
+	 */
+	gdev = gpio_device_find_by_label(label);
+	if (!gdev) {
+		pr_err("error cannot find GPIO device %s\n", label);
 		return -ENODEV;
 	}
 
-	gpiod = gpiochip_get_desc(chip, pin);
+	gpiod = gpio_device_get_desc(gdev, pin);
 	if (IS_ERR(gpiod)) {
 		pr_err("error %ld getting GPIO %s %d\n", PTR_ERR(gpiod), label, pin);
 		return PTR_ERR(gpiod);
@@ -257,9 +259,9 @@ static void x86_android_tablet_cleanup(void)
 
 static __init int x86_android_tablet_init(void)
 {
+	struct gpio_device *gdev __free(gpio_device_put) = NULL;
 	const struct x86_dev_info *dev_info;
 	const struct dmi_system_id *id;
-	struct gpio_chip *chip;
 	int i, ret = 0;
 
 	id = dmi_first_match(x86_android_tablet_ids);
@@ -273,13 +275,13 @@ static __init int x86_android_tablet_init(void)
 	 * _AEI (ACPI Event Interrupt) handlers, disable these.
 	 */
 	if (dev_info->invalid_aei_gpiochip) {
-		chip = gpiochip_find(dev_info->invalid_aei_gpiochip,
-				     gpiochip_find_match_label);
-		if (!chip) {
+		gdev = gpio_device_find_by_label(
+				dev_info->invalid_aei_gpiochip);
+		if (!gdev) {
 			pr_err("error cannot find GPIO chip %s\n", dev_info->invalid_aei_gpiochip);
 			return -ENODEV;
 		}
-		acpi_gpiochip_free_interrupts(chip);
+		acpi_gpio_device_free_interrupts(gdev);
 	}
 
 	/*
-- 
2.39.2