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 e59884cc12a718f16df09981b9fda2fffd81e9c4..48191e62a3ccd2174e859d9a5e58a2de6bfdc190 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 f92788ccdba270e4a665df40c4e83026a9698792..505308253d23ce49fed4b8f947437170ffa5571c 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 2b43f5f5033d13cca9af2bd4c70c96fe641757c7..bc8e40cf2b65adc4c8ac0e1a56909b4dc2f078dc 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