From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Date: Wed, 9 Oct 2019 17:34:44 +0300
Subject: gpiolib: Initialize the hardware with a callback

Git-commit: 9411e3aaa6342eb730daa55cf3377463a37d2aa7
Patch-mainline: v5.4-rc4
References: jsc#SLE-15847

After changing the drivers to use GPIO core to add an IRQ chip
it appears that some of them requires a hardware initialization
before adding the IRQ chip.

Add an optional callback ->init_hw() to allow that drivers
to initialize hardware if needed.

This change is a part of the fix NULL pointer dereference
brought to the several drivers recently.

Cc: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
---
 drivers/gpio/gpiolib.c      |   22 +++++++++++++++++++++-
 include/linux/gpio/driver.h |    8 ++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -86,6 +86,7 @@ static int gpiochip_add_irqchip(struct g
 				struct lock_class_key *lock_key,
 				struct lock_class_key *request_key);
 static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip);
+static int gpiochip_irqchip_init_hw(struct gpio_chip *gpiochip);
 static int gpiochip_irqchip_init_valid_mask(struct gpio_chip *gpiochip);
 static void gpiochip_irqchip_free_valid_mask(struct gpio_chip *gpiochip);
 
@@ -1409,6 +1410,10 @@ int gpiochip_add_data_with_key(struct gp
 	if (ret)
 		goto err_remove_acpi_chip;
 
+	ret = gpiochip_irqchip_init_hw(chip);
+	if (ret)
+		goto err_remove_acpi_chip;
+
 	ret = gpiochip_add_irqchip(chip, lock_key, request_key);
 	if (ret)
 		goto err_remove_irqchip_mask;
@@ -1621,6 +1626,16 @@ static struct gpio_chip *find_chip_by_na
  * The following is irqchip helper code for gpiochips.
  */
 
+static int gpiochip_irqchip_init_hw(struct gpio_chip *gc)
+{
+	struct gpio_irq_chip *girq = &gc->irq;
+
+	if (!girq->init_hw)
+		return 0;
+
+	return girq->init_hw(gc);
+}
+
 static int gpiochip_irqchip_init_valid_mask(struct gpio_chip *gc)
 {
 	struct gpio_irq_chip *girq = &gc->irq;
@@ -2445,8 +2460,13 @@ static inline int gpiochip_add_irqchip(s
 {
 	return 0;
 }
-
 static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip) {}
+
+static inline int gpiochip_irqchip_init_hw(struct gpio_chip *gpiochip)
+{
+	return 0;
+}
+
 static inline int gpiochip_irqchip_init_valid_mask(struct gpio_chip *gpiochip)
 {
 	return 0;
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -199,6 +199,14 @@ struct gpio_irq_chip {
 	unsigned int *map;
 
 	/**
+	 * @init_hw: optional routine to initialize hardware before
+	 * an IRQ chip will be added. This is quite useful when
+	 * a particular driver wants to clear IRQ related registers
+	 * in order to avoid undesired events.
+	 */
+	int (*init_hw)(struct gpio_chip *chip);
+
+	/**
 	 * @threaded:
 	 *
 	 * True if set the interrupt handling uses nested threads.