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Subject[PATCH 1/5] gpio: Don't fiddle with irqchips marked as immutable
Date
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 wueh required.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
drivers/gpio/gpiolib.c | 7 ++++++-
include/linux/irq.h | 2 ++
kernel/irq/debugfs.c | 1 +
3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 3859911b61e9..515838708b00 100644
--- 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) {
+ chip_info(gc, "Immutable chip, not updating\n");
+ return;
+ }
+
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 f92788ccdba2..505308253d23 100644
--- 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 2b43f5f5033d..bc8e40cf2b65 100644
--- 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
--
2.30.2
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