gpio: Don't fiddle with irqchips marked as immutable

In order to move away from gpiolib messing with the internals of
unsuspecting irqchips, add a flag by which irqchips advertise
that they are not to be messed with, and do solemnly swear that
they correctly call into the gpiolib helpers when required.

Also nudge the users into converting their drivers to the
new model.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220419141846.598305-2-maz@kernel.org

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index e59884c..48191e6 100644 (file)
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1475,6 +1475,11 @@ static void gpiochip_set_irq_hooks(struct gpio_chip *gc)
 {
        struct irq_chip *irqchip = gc->irq.chip;
 
+       if (irqchip->flags & IRQCHIP_IMMUTABLE)
+               return;
+
+       chip_warn(gc, "not an immutable chip, please consider fixing it!\n");
+
        if (!irqchip->irq_request_resources &&
            !irqchip->irq_release_resources) {
                irqchip->irq_request_resources = gpiochip_irq_reqres;
@@ -1633,7 +1638,7 @@ static void gpiochip_irqchip_remove(struct gpio_chip *gc)
                irq_domain_remove(gc->irq.domain);
        }
 
-       if (irqchip) {
+       if (irqchip && !(irqchip->flags & IRQCHIP_IMMUTABLE)) {
                if (irqchip->irq_request_resources == gpiochip_irq_reqres) {
                        irqchip->irq_request_resources = NULL;
                        irqchip->irq_release_resources = NULL;

diff --git a/include/linux/irq.h b/include/linux/irq.h
index f92788c..5053082 100644 (file)
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -569,6 +569,7 @@ struct irq_chip {
  * IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND:  Invokes __enable_irq()/__disable_irq() for wake irqs
  *                                    in the suspend path if they are in disabled state
  * IRQCHIP_AFFINITY_PRE_STARTUP:      Default affinity update before startup
+ * IRQCHIP_IMMUTABLE:                Don't ever change anything in this chip
  */
 enum {
        IRQCHIP_SET_TYPE_MASKED                 = (1 <<  0),
@@ -582,6 +583,7 @@ enum {
        IRQCHIP_SUPPORTS_NMI                    = (1 <<  8),
        IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND        = (1 <<  9),
        IRQCHIP_AFFINITY_PRE_STARTUP            = (1 << 10),
+       IRQCHIP_IMMUTABLE                       = (1 << 11),
 };
 
 #include <linux/irqdesc.h>

diff --git a/kernel/irq/debugfs.c b/kernel/irq/debugfs.c
index 2b43f5f..bc8e40c 100644 (file)
--- a/kernel/irq/debugfs.c
+++ b/kernel/irq/debugfs.c
@@ -58,6 +58,7 @@ static const struct irq_bit_descr irqchip_flags[] = {
        BIT_MASK_DESCR(IRQCHIP_SUPPORTS_LEVEL_MSI),
        BIT_MASK_DESCR(IRQCHIP_SUPPORTS_NMI),
        BIT_MASK_DESCR(IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND),
+       BIT_MASK_DESCR(IRQCHIP_IMMUTABLE),
 };
 
 static void