irq: Request and release resources for chained IRQs

This addresses a bug in the irqchip core that was triggered
by new code assuming a strict semantic order of the irqchip
calls:

 .irq_request_resources()
 .irq_enable()
 .irq_disable()
 .irq_release_resources()

Mostly this is working fine when handled inside manage.c,
the calls are strictly happening in the above assumed order.

However on a Qualcomm platform I get the following in dmesg:

WARNING: CPU: 0 PID: 1 at ../drivers/gpio/gpiolib.c:3513
	 gpiochip_irq_enable+0x18/0x44
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0
     Not tainted 4.20.0-rc4-00002-g1b8a75b25c6e-dirty #9
Hardware name: Generic DT based system
[<c03124ac>] (unwind_backtrace) from [<c030d994>] (show_stack+0x10/0x14)
[<c030d994>] (show_stack) from [<c0b48aec>] (dump_stack+0x78/0x8c)
[<c0b48aec>] (dump_stack) from [<c03213e4>] (__warn+0xe0/0xf8)
[<c03213e4>] (__warn) from [<c0321514>] (warn_slowpath_null+0x40/0x48)
[<c0321514>] (warn_slowpath_null) from [<c06ad5d0>]
	     (gpiochip_irq_enable+0x18/0x44)
[<c06ad5d0>] (gpiochip_irq_enable) from [<c0371198>] (irq_enable+0x44/0x64)
[<c0371198>] (irq_enable) from [<c0371258>] (__irq_startup+0xa0/0xa8)
[<c0371258>] (__irq_startup) from [<c03712ac>] (irq_startup+0x4c/0x130)
[<c03712ac>] (irq_startup) from [<c03716d0>]
	     (irq_set_chained_handler_and_data+0x4c/0x78)
[<c03716d0>] (irq_set_chained_handler_and_data) from [<c081c17c>]
	     (pm8xxx_probe+0x160/0x22c)
[<c081c17c>] (pm8xxx_probe) from [<c07f439c>] (platform_drv_probe+0x48/0x98)

What happens is that when the pm8xxx driver tries to register
a chained IRQ irq_set_chained_handler_and_data() will eventually
set the type and call irq_startup() and thus the .irq_enable()
callback on the irqchip.

This irqchip is in drivers/pinctrl/qcom/pinctrl-msm.c and known
as TLMM.

However, the irqchip core helpers in GPIO assumes that
the .irq_request_resources() callback is always called before
.irq_enable(), and the latter is where module refcount and
also gpiochip_lock_as_irq() is normally called.

When .irq_enable() is called without .irq_request_resources()
having been called first, it seems like we are enabling
an IRQ on a GPIO line that has not first been locked to be
used as IRQ and we get the above warning. This happens since
as of
commit 461c1a7d4733d ("gpiolib: override irq_enable/disable")
this is strictly assumed for all GPIO-based IRQs.

As it seems reasonable to assume that .irq_request_resources()
is always strictly called before .irq_enable(), we add the
irq_[request|release]_resources() functions to the internal
API and call them also when adding a chained irqchip to
an IRQ.

I am a bit uncertain about the call site for
irq_released_resources() inside chip.c, but it appears this
path is for uninstalling a chained handler.

Cc: stable@vger.kernel.org
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
Fixes: 461c1a7d4733d ("gpiolib: override irq_enable/disable")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
3 files changed