rk_gpio: implement PIC masking methods and mask unhandled IRQs

The Rockchip GPIO controller implements PIC operations for the INTRNG
framework but is missing four masking methods that INTRNG calls during
the filter/ithread handoff: pic_disable_intr, pic_enable_intr,
pic_pre_ithread, pic_post_ithread.

Without them, level-sensitive interrupt sources connected to a
Rockchip GPIO pin re-fire continuously while their ithread runs.  On
a RockPro64 with a FUSB302B Type-C controller (i2c) attached to
gpio1 INT_N, the system enters a ~210 kHz interrupt storm the moment
the fusb302 driver attaches and INT_N goes low.

Two complementary changes:

1. Add the four pic_disable_intr/pic_enable_intr/pic_pre_ithread/
   pic_post_ithread method bodies.  Each toggles the pin's
   RK_GPIO_INTMASK bit so the source is masked during the in-flight
   ithread window and unmasked on return, honouring the generic
   INTRNG mask/unmask sequence.

2. When the GPIO IRQ filter dispatches a pin and finds no consumer
   registered, mask the pin at the controller (INTMASK=1, INTEN=0)
   before continuing.  Level-triggered sources keep asserting until
   acked, so a single stuck pin used to flood the console with
   thousands of "Interrupt pin=N unhandled" lines per second.  The
   mask survives until something re-attaches and re-enables the IRQ
   via the standard pic_enable_intr path.

Affects all level-triggered IRQs on Rockchip GPIO banks; edge-
triggered IRQs were already self-acking and unaffected.

Signed-off-by:	Kyle Crenshaw <B1nc0d3x@gmail.com>
Reviewed by:	mhorne
MFC after:	2 weeks
Pull Request:	https://github.com/freebsd/freebsd-src/pull/2197

0 files changed, 0 insertions, 0 deletions